PROPOSED AIRBORNE TOXIC CONTROL MEASURE TO REDUCE 

FORMALDEHYDE EMISSIONS FROM COMPOSITE WOOD PRODUCTS

 

 

Stationary Source Division 

Air Quality Measures Branch 

Release Date: March 9, 2007 

To Be Considered by the Board: April 26, 2007 
State of California 

AIR RESOURCES BOARD 

STAFF REPORT: INITIAL STATEMENT OF REASONS 

FOR PROPOSED RULEMAKING 

Public Hearing to Consider 

ADOPTION OF THE PROPOSED AIRBORNE TOXIC CONTROL MEASURE 

TO REDUCE FORMALDEHYDE EMISSIONS FROM COMPOSITE WOOD 

PRODUCTS 

To be considered by the Air Resources Board on April 26, 2007, at: 

California Environmental Protection Agency 

Headquarters Building 

1001 “I” Street 

Sacramento, California 

Stationary Source Division: 

Robert Fletcher, P.E., Chief, Stationary Source Division 

Robert D. Barham, Ph.D., Assistant Division Chief, Stationary Source Division 

Janette Brooks, Chief, Air Quality Measures Branch 

Jim Aguila, Manager, Substance Evaluation Section 

This report has been prepared by the staff of the Air Resources Board. Publication does not signify that 

the contents reflect the views and policies of the Air Resources Board, nor does mention of trade 

names or commercial products constitute endorsement or recommendation for use. 
Acknowledgements

Contributing Authors

Brent Takemoto, Ph.D. (Lead) 

James Stebbins 

Lynn Baker 

Angela Csondes 

Susie Chung 

Melanie Marty, Ph.D. 

Andy Salmon, Ph.D. 

Robert Blaisdell, Ph.D. 

Reza Mahdavi, Ph.D. 

Peggy Jenkins 

Linying Li 

Webster Tasat 

Andy Delao 

Elizabeth Miller 

Darrell Hawkins 

Michael Poore 

Russell Grace 

Jose Saldana 

Legal Counsel

Robert Jenne, Esq., Office of Legal Affairs 

______________________________________________________________ 

We also wish to acknowledge the assistance and cooperation we received 

from many individuals and organizations. In particular, we would like to 

thank: 

Composite Panel Association, Hardwood Plywood and Veneer Association, 

American Home Furnishers Association, Kitchen Cabinet Manufacturers 

Association, Woodwork Institute, Formaldehyde-Free Coalition, California Wood 

Industries Coalition, Columbia Forest Products, Sierra Pine, Professional Service 

Industries, Inc., General Veneer, G.L. Veneer, Georgia Pacific, Hexion, 
i 

TABLE OF CONTENTS

 

 

Executive Summary ES-1 

I. Introduction ................................................................................................1

A. Regulatory Authority...................................................................................2

B. Formaldehyde in California ........................................................................3

C. Need for Reducing Formaldehyde Emissions from Composite Wood 

Products.....................................................................................................5

D. Regulations Applicable to Formaldehyde...................................................6

E. Indoor Air Quality .......................................................................................7

F. References.................................................................................................7

II. Public Outreach..........................................................................................9

A. Outreach Efforts.........................................................................................9

B. Public Involvement .....................................................................................9

C. Survey of Products Manufactured in 2002 ...............................................11

D. References...............................................................................................12

III. Need for Regulation of Formaldehyde (HCHO) .......................................13

A. Health Effects of Formaldehyde...............................................................13

B. Physical and Chemical Properties............................................................13

C. Sources and Emissions of Formaldehyde................................................14

D. Emissions from Composite Wood Products .............................................19

E. Natural Occurrences ................................................................................20

F. Measured Formaldehyde Concentrations ................................................21

G. Modeled Formaldehyde Concentrations .................................................32

H. Atmospheric Persistence..........................................................................33

I. Risk Characterization ...............................................................................33

J. References...............................................................................................34

IV. Manufacturing of Composite Wood Products...........................................42

A. Background..............................................................................................42

B. Composite Wood Product Manufacturing Plants......................................42
ii 

C. Resins Currently Used in Composite Wood Products ..............................45

D. References...............................................................................................59

V. Assessment of Best Available Control Technology (BACT) .....................63

A. Introduction ..............................................................................................63

B. Product Descriptions and Survey Results ................................................70

C. Present-day Resin Technologies .............................................................75

D. Candidate Low-formaldehyde Resin Systems..........................................83

E. Technical Basis for the Proposed Emission Standards..........................101

F. References.............................................................................................108

VI. Proposed Airborne Toxic Control Measure (ATCM)...............................116

A. Summary of the Proposed Airborne Toxic Control Measure.....................116

B. Alternatives to the Proposed Airborne Toxic Control Measure...............128

C. Conclusion .............................................................................................129

VII. Health Impacts of the Proposed Airborne Toxic Control Measure..........130

A. Overview of the Health Risk Assessment ..............................................130

B. Total Daily Formaldehyde Exposure as the Basis for Risk Assessment 132

C. Factors that Affect the Outcome of a Health Risk Assessment..............155

D. Summary of Potential Health Impacts ....................................................155

E. Multi-pathway Health Risk Assessment .................................................157

F. Statewide Emission and Risk Reduction Benefits..................................157

G. Potential Adverse Health Effects from Replacement Compounds .........159

H. Workplace Exposure ..............................................................................160

I. References.............................................................................................161

VIII. Economic Impacts of the Proposed Airborne Toxic Control Measure ....178

A. Background............................................................................................178

B. Cost of Compliance................................................................................189

C. Cost to the Composite Wood Manufacturing Industry ............................205

D. Distributor and Importer Costs ...............................................................209

E. Fabricator Costs.....................................................................................211

F. Retailer Costs.........................................................................................213

G. Consumer Costs ....................................................................................213
iii 

H. Impacts to Small Business .....................................................................216

I. References.............................................................................................216

IX. Environmental Impacts of the Proposed Airborne Toxic Control Measure

...............................................................................................................221

A. Legal Requirements ...............................................................................221

B. Analysis of Reasonably Foreseeable Environmental Impacts................221

C. Reasonably Foreseeable Feasible Mitigation Measures........................224

D. Reasonably Foreseeable Alternative Means of Compliance..................224

E. Community Health and Environmental Justice.......................................224

F. References.............................................................................................224
iv 

List of Tables

Table ES-1. Proposed Phase 1 and Phase 2 Emission Standards ..................3

Table ES-2. Estimated Reductions in Cancer Risk After Phase 1 and 

Phase 2.........................................................................................6

Table ES-3. Total Estimated Cost to the Industry in 2002 ................................9

Table II-1. Selected ATCM-related Outreach Efforts .....................................9

Table III-1. Physical and Chemical Properties of Formaldehyde ..................14

Table III-2. Product Distribution for Formaldehyde in the U.S. (2003)...........15

Table III-3. Formaldehyde – 2005 Statewide Emission Inventory .................16

Table III-4. Emission Rates of Selected Indoor Sources of Formaldehyde 

(μg/m2/hr)....................................................................................18

Table III-5. Statewide Annual Average Formaldehyde Concentrations 

(μg/m3): 1996-2005.....................................................................22

Table III-6. Summary of Ambient Formaldehyde Concentrations (μg/m3): 1 

January 2005 through 30 April 2006...........................................25

Table III-7. Formaldehyde Emissions in the Top Ten California Counties ....26

Table III-8. Measured Indoor Formaldehyde Concentrations (μg/m3) ...........27

Table IV-1. Advantages and Disadvantages of Urea-formaldehyde 

Resins.........................................................................................47

Table IV-2. Characteristics of Urea-formaldehyde (UF) Resins ....................49

Table IV-3. Characteristics of Phenol-formaldehyde (PF) Resins .................51

Table IV-4. Summary of Melamine-based Resin Properties and Uses..........53

Table IV-5. Advantages and Disadvantages of Polydiphenylmethane 

Diisocyanate (pMDI) Resins .......................................................54

Table IV-6. Characteristics of MDI Resins....................................................55

Table IV-7. Characteristics of Polyvinyl Acetate (PVA) Resins .....................57

Table V-1. List of Researchers, Manufacturers, and Academia 

Contacted ...................................................................................65

Table V-2. Japanese Building Standard Law Classifications for 

Building Material Formaldehyde (HCHO) Emissions ................68

Table V-3. Formaldehyde (HCHO) Emission Standards for Composite 

Wood Products in the U.S., Europe, and Japan .........................70

Table V-4. Measured or Estimated ASTM E1333 Average Data for 

Hardwood Plywood-Veneer Core from Selected U.S. 

Manufacturers.............................................................................72
v 

Table V-5. Measured or Estimated ASTM E1333 Data for Hardwood 

Plywood-Composite Core from Selected U.S. Manufacturers ....73

Table V-6. Effect of Melamine Acetate (Mac) on Plywood Tensile 

Strength ......................................................................................76

Table V-7. Comparison of Strength and HCHO Emission Properties of 

Particleboard Made with Two Melamine-formaldehyde (MF) 

Resins.........................................................................................78

Table V-8. Selected Measures of Tensile Strength (N/mm2

) in 

Plywood Made with Urea-formaldehyde (UF) and 

UF-Methylene Diisocyanate (UF-MDI) Hybrid Resins.................80

Table V-9. Effect of MDI and/or Urea Additions on Selected Resin 

and Panel Properties in Particleboard Made with Phenol-ureaformaldehyde (PUF) Resins........................................................81

Table V-10. Dry and Wet Internal Bond (IB) Strength and Density in 

Particleboard Made Phenol-melamine-urea-formaldehyde 

(PMUF)-MDI Resins ...................................................................82

Table V-11. Soy-based Adhesives: Problems and Solutions .........................86

Table V-12. Physical Properties of Phenol-formaldehyde (PF) and 

Soy-PF Resins............................................................................87

Table V-13. Effect of Tris(hydroxymethyl)nitromethane (TN) Addition 

on the Breaking Loads and Formaldehyde Contents of 

Plywood Made with Quebracho Tannin Resin ............................91

Table V-14. Gel Times (minutes) for Particleboard Made with Phenolformaldehyde (PF) Resins Co-reacted with Urea .......................93

Table V-15. Effect of Urea Addition on Dry and Wet Internal Bond 

Strengths in Softwood Particleboard Bonded Phenolformaldehyde (PF) Resin............................................................94

Table V-16. Effect of Press Time on Dry and Wet Internal Bond Strength 

in Hardwood Particleboard Bonded with a Phenol-ureaformaldehyde (PUF) Resin with Triacetin ...................................95

Table V-17. Minimum American National Standards Institute (ANSI) 

Strength Requirements for Medium (M) Industrial and 

Shelving Grade Particleboard.....................................................97

Table V-18. Strength Responses in Particleboard Made with Phenolformaldehyde (PF) and Cashew Shell Nut Liquid (CNSL) 

Resins.........................................................................................98

Table V-19. Density, Swell, Strength, and Formaldehyde Content in 

Medium Density Fiberboard Made with Ureaformaldehyde (UF) and Quebracho Tannin-based Resins .........99

Table V-20. Dry and Wet Internal Bond Strengths of Medium Density 

Fiberboard Made with Phenol-formaldehyde (PF) and 

Phenol-urea-formaldehyde-tannin (PUFT) Resins....................100
vi 

Table V-21. Proposed Phase 1 (P1) and 2 (P2) Formaldehyde (HCHO) 

Emission Standards for Hardwood Plywood.............................101

Table V-22. Available Low-formaldehyde Hardwood Plywood (HWPW) or 

HWPW-Resins..........................................................................103

Table V-23. Proposed Phase 1 (P1) and 2 (P2) Emission Standards for 

Particleboard.............................................................................104

Table V-24. Available Low-formaldehyde Particleboard (PB) and 

PB-Resin Systems....................................................................104

Table V-25. Proposed Phase 1 (P1) and Phase 2 (P2) Standards for 

Medium Density Fiberboard......................................................105

Table V-26. Available Low-formaldehyde Medium Density Fiberboard 

(MDF) or MDF-resins................................................................106

Table VI-1. Proposed Phase 1 and Phase 2 Standards for Hardwood 

Plywood (HWPW), Particleboard (PB), and Medium Density 

Fiberboard (MDF) .....................................................................117

Table VI-2. Schedule of Composite Wood Product Sell-through for 

Manufacturers...........................................................................119

Table VI-3. Schedule of Composite Wood Product Sell-through for 

Distributors................................................................................121

Table VI-4. Schedule of Composite Wood Product Sell-through for 

Importers...................................................................................123

Table VI-5. Schedule of Composite Wood Product Sell-through for 

Fabricators................................................................................124

Table VI-6. Schedule of Composite Wood Panel Sell-through for 

Retailers....................................................................................126

Table VI-7. Development Plan for Fully Covered Finished Products...........127

Table VII-1. Average and Elevated Formaldehyde Concentrations (μg/m3).133

Table VII-2. Health Effects Values for Formaldehyde ..................................133

Table VII-3. Age-group Specific and Average Child and Adult Activity 

Patterns ....................................................................................156

Table VII-4. Estimates of Total Formaldehyde (HCHO) Exposure and 

Daily Time-weighted Average (TWA) Formaldehyde 

Concentration ...........................................................................157

Table VII-5. Estimated Cancer Risk in Children and Adults After 

Implementation of the Phase 1 and Phase 2 Emission 

Standards .................................................................................158

Table VIII-1. Particleboard Manufacturers in the Composite Panel 

Association ...............................................................................179
vii 

Table VIII-2. Medium Density Fiberboard Manufacturers in the Composite 

Panel Association .....................................................................181

Table. VIII-3. Hardwood Plywood Facilities in North America ........................182

Table VIII-4. Cost per Plant by Type of Affected Product..............................186

Table VIII-5. Change in Return on Owner’s Equity (ROEs) for Typical 

Manufacturers in the Composite Wood Products Industry........187

Table VIII-6. Establishments, Employees, and Payroll by Industry ...............188

Table VIII-7. Unit Cost of Industrial Particleboard: 1995-2005 ......................190

Table VIII-8. Unit Cost of Medium Density Fiberboard: 1995-2005 ...............192

Table VIII-9. Unit Cost of Hardwood Plywood ...............................................193

Table VIII-10. Breakdown of Costs in Particleboard Manufacturing ................197

Table VIII-11. Estimated Cost of UF Resin in Particleboard of Varying 

Thickness..................................................................................198

Table VIII-12. Estimated Price Increase in Particleboard Made to Comply 

with the Phase 2 Standard with an Alternate Resin..................199

Table VIII-13. Estimated Cost of Urea-formaldehyde (UF) Resin in 

Medium Density Fiberboard (MDF) of Varying Thickness ........202

Table VIII-14. Estimated Price Increase in Medium Density Fiberboard 

Made to Comply with the Phase 2 Standard with an Alternate 

Resin ........................................................................................202

Table VIII-15. Estimated Cost of the Urea-formaldehyde (UF) Resin in 

Hardwood Plywood of Varying Board Thickness ......................204

Table VIII-16. Estimated Price Increases in Hardwood Plywood Made 

with Alternate Resins ...............................................................204

Table VIII-17. Estimated Cost of Particleboard, Medium Density Fiberboard, 

and Hardwood Plywood Panels Following the Effective 

Date of the Phase 2 Standard...................................................214
viii 

List of Figures

Figure III-1. Annual Statewide Summary for Ambient Formaldehyde ............23

Figure III-2. Mean Ambient Formaldehyde Concentrations by Air Basin........24

Figure IV-1. Types of Hardwood Plywood ......................................................42

Figure IV-2. Plywood Manufacturing Process.................................................43

Figure IV-3: Schematic of a Particleboard Manufacturing Line.......................44

Figure IV-4. Reaction between a Nucleophile (Nu) and Formaldehyde..........46

Figure IV-5. Addition of Urea and Formaldehyde to Form 

Hydroxymethylureas ...................................................................48

Figure IV-6. Condensation Reaction and Polymerization of UF Resins..........48

Figure IV-7. Addition Reaction for Phenol and Formaldehyde........................50

Figure IV-8. Phenol-formaldehyde (PF) Resin: Condensation Reaction ........50

Figure IV-9. Phenol-Formaldehyde Cross-linked Polymer..............................51

Figure IV-10. Addition Reaction for Formaldehyde and Melamine ...................52

Figure IV-11. Condensation Reaction of Hydroxymethylated Melamines.........52

Figure IV-12. Isocyanate and Water React to Produce a Urethane..................54

Figure IV-13. Reaction of an Amine and Isocyanate to Form a 

Substituted Urea.........................................................................54

Figure IV-14. Urethane Bridge and Substituted Ureas React with 

Isocyanates.................................................................................55

Figure IV-15. Polymerization of PVA ................................................................57

Figure IV-16. Average Yield of Extractives from Different Woods and Barks ...58

Figure IV-17. The A-Ring Unit of a Tannin Compound.....................................59

Figure V-1. Polyurethane Cross-linking in a PF-MDI Hybrid Resin ...............81

Figure V-2. Cationic Polyamidoamine-epichlorohydrin (PAE) .......................84

Figure V-3. Effect of Reaction Time on the Dry and Water-Soaking-and 

Drying (WSAD) Shear Strength of Plywood Made with a 

Soy Protein Isolate-Kymene® Resin1..........................................85

Figure V-4. Dry Internal Bond Strengths for Oriented Strand Board 

made with PF and Soy-PF Resins ..............................................87

Figure V-5. Wet Internal Bond Strengths for Oriented Strand Board 

Made with Phenol-formaldehyde (PF) and Soy-PF Resins.........88

Figure V-6. Chemical Structure of Hexamine ................................................90

Figure V-7. Chemical Structure of a Monoflavonoid Unit...............................90

Figure V-8. Mole Ratios of Free Formaldehyde:Phenol in Phenol-ureaformaldehyde (PUF) and PUF-Tannin Resins ............................92

Figure V-9. Chemical Structure of Triacetin...................................................94
ix 

Figure V-10. Chemical Composition of Cashew Nut Shell Liquid ....................98

Figure VIII-1. Value ($) of U.S. Imports of Particleboard from China: 

1997 to 2006.............................................................................191

Figure VIII-2. Value ($) of U.S. Imports of Medium Density Fiberboard 

from China: 1997 to 2006 .........................................................193

Figure VIII-3. Value ($) of U.S. Imports of Hardwood Plywood from China: 

1997 to 2006.............................................................................194
x 

List of Appendices

Appendix A Proposed Regulation Order 

Appendix B Planning & Technical Support Division. 2007. Estimation of 

2002 Formaldehyde Emission Inventory from Composite

Wood Products. Draft Report 

Appendix C-1 Summary of Refined Air Dispersion Modeling Using ISC3 of 

Formaldehyde from Composite Wood Product Exposure 

Scenarios 

Appendix C-2 Composite Wood Product ATCM – Modeling Scenario No. 1: 

HCHO Emissions from Composite Wood Products Stored at 

a Warehouse Store 

Appendix C-3 California Air Resources Board Memorandum: Vernon 

Hughes to James Aguila, 12 June 2006, RE: Air Quality 

Modeling of Emissions from Composite Wood Products 

Appendix D Basis for Formaldehyde Emission Factors

Appendix E Estimation of the Amount of Composite Wood Products in a 

Home 

Appendix F Basis for Estimating Reductions in Daily Time-Weighted 

Average Formaldehyde Concentration 

Appendix G Calculations of Per Panel and Industry-wide Costs 

Appendix H Comparison of CARB Emission Standards to Other 

International Standards 
ES-1 

Executive Summary 

The California Air Resources Board (CARB) staff is proposing to establish an 

Airborne Toxic Control Measure (ATCM) to reduce formaldehyde emissions from 

composite wood products. “Composite wood products” is a general term for 

wood-based panels made from wood plies, particles, or fibers that are bound 

together with a resin or adhesive. They include hardwood plywood, particleboard 

and medium density fiberboard. These products emit formaldehyde because the 

resins typically used to bond the wood materials contain formaldehyde. 

Emissions from these products result from the release of unreacted 

formaldehyde from the resins and from chemical degradation over time. 

Composite wood products are sold in large volumes to California, and are among 

the highest formaldehyde emitting products used in everyday applications. In 

this regard, formaldehyde is emitted into the air from composite wood products at 

the panel manufacturing plant, fabrication facilities, new home construction, 

remodeling construction, truck, rail, and ship transportation, lumberyards, and 

through windows, doors, and ventilation systems in homes and other buildings. 

The proposed ATCM was developed in consideration of the results of a survey of 

panels produced in 2002, which indicated that actual formaldehyde emissions 

from U.S. composite wood products were much higher than those allowed in 

Europe, Japan, and Australia. 

A. Background 

In 1992, the Board identified formaldehyde as a toxic air contaminant (TAC) 

based primarily on the determination that it was a human carcinogen with no 

known safe level of exposure (CARB, 1992). Because formaldehyde is a TAC, 

CARB is required to prepare a report on the need and appropriate degree of 

regulation to reduce formaldehyde emissions (Health & Safety Code §39665). 

Regulations that bring about reductions in TAC emissions are known as ATCMs. 

State law requires that ATCMs be based on the use of the best available control 

technology (BACT) or a more effective control method, in consideration of cost 

and human health risk (Health & Safety Code §39666), if the TAC has no safe 

level of exposure. Exposure to formaldehyde has both non-cancer and cancer 

health effects. The non-cancer health effects of formaldehyde are eye, nose, 

and/or throat irritation. The International Agency for Research on Cancer 

conducted an evaluation of formaldehyde and concluded that there is sufficient 

evidence that formaldehyde causes nasopharyngeal cancer in humans (i.e., in 

the region of the throat behind the nose). 

Current emissions of formaldehyde from composite wood products are estimated 

to be about 900 tons per year. For the most part, formaldehyde emissions from 

these products are not regulated in the U.S.; although many manufacturers met 

an essentially voluntary standard established by the U.S. Department of Housing 
ES-2 

and Urban Development (HUD) that applies to plywood and particleboard used in 

manufactured homes. Current annual average concentrations of formaldehyde 

in ambient air range from 3 to 4 micrograms per cubic meter (μg/m3

) across 

California, with indoor and in-vehicle concentrations typically many times higher. 

The risk from exposure to annual average concentrations of formaldehyde in 

ambient air is about 20 to 24 potential excess cancer cases per million. The risk 

from current total daily formaldehyde exposure is estimated to range from 86 to 

231 excess cancer cases per million over a lifetime, and from 23 to 63 excess 

cancer cases per million due to exposures during childhood. The proposed 

ATCM would reduce emissions to ambient air and very significantly reduce total 

daily exposures to formaldehyde. Exposures to formaldehyde, which occur 

throughout the day in both the outdoor and indoor environment, pose a serious 

health risk to the people of California. 

B. Staff Proposal 

Because there is no safe threshold exposure level for formaldehyde, we are 

proposing a control measure to limit formaldehyde emissions from three 

composite wood products – hardwood plywood (HWPW), particleboard (PB), and 

medium density fiberboard (MDF) to the maximum amount feasible. Based on 

our survey results, these three products are still primarly being made with ureaformaldehyde resins that have the highest formaldehyde emission rates. 

Formaldehyde emission rates from other composite wood products (e.g., 

oriented strandboard, hardboard, peg board, etc.) used for exterior applications 

are about 90% lower and contribute far less to formaldehyde concentrations in 

California. 

Hardwood plywood is made by gluing together hardwood plies, and used to 

make paneling, flooring, cabinets and furniture. Particleboard is made of wood 

fragments or particles glued together, and used to make countertops, cabinets, 

and floor underlayments. Medium density fiberboard is made of wood fibers 

glued together, and used to make furniture, cabinets, moldings, and door skins. 

The proposed ATCM would reduce emissions of formaldehyde from HWPW, PB, 

and MDF panels, and finished goods, such as furniture and cabinets fabricated 

with those materials. The ATCM would apply to panel manufacturers, 

distributors, importers, fabricators, and retailers. We are excluding from the 

regulation architectural plywood, military specified plywood, plywood used inside 

of motor vehicles, and windows that contain small amounts of HWPW, PB, or 

MDF (i.e., less than 5% by volume of wood products). 

The proposed ATCM would establish new formaldehyde emission standards in 

two phases for HWPW, PB, and MDF, and would also apply to finished goods or 

products utilizing those materials. The intent of the Phase 1 emission standards 

is to set an industry cap and to stop the low-cost, high-emitting products from 
ES-3 

overseas that can no longer be sent to other markets from coming into California. 

The Phase 2 emission standards reflect the use of BACT (Table ES-1). 

Beginning January 1, 2009, the proposed Phase 1 emission standards would 

become effective, starting with HWPW made with a veneer core (HWPW-VC), 

PB, MDF, and thin MDF (tMDF), followed by the standard for HWPW made with 

a composite core (HWPW-CC), six months later (Table ES-1). A separate 

standard is proposed for tMDF that considers the technological limitations 

specific to MDF made to be 8 millimeters or less. Beginning January 1, 2011, a 

comparable suite of increasingly more stringent Phase 2 formaldehyde emissions 

standards is proposed. All of the standards are maximum allowable or “cap” 

standards, and would apply to products made in the U.S. or imported from other 

countries. By “cap” standards, we mean standards that cannot be exceeded. 

Panel producers will need to operate routinely below the “cap” to ensure that they 

standards will always be met. 

 

To ensure compliance with the proposed ATCM, panel manufacturers, foreign 

and domestic, would need to be “third party certified.” This requirement calls for 

independent formaldehyde emission testing of panels and manufacturing 

processes for all manufacturers that sell panels used in the California market. 

Third party certifiers would be required to be approved by the Executive Officer. 

As an incentive, manufacturers that use “no added formaldehyde” resins would 

not be required to conduct third party certification. 

Table ES-1. Proposed Phase 1 and Phase 2 Emission Standards1

 --------------- Standard Concentrations (ppm) --------------- 

Phase 1 Formaldehyde Emission Standards 

Eff. Date HWPW-VC HWPW-CC PB MDF tMDF 

Jan 2009 0.08 ----- 0.18 0.21 0.21 

July 2009 ----- 0.08 ----- ----- ----- 

Phase 2 Formaldehyde Emission Standards 

Eff. Date HWPW-VC HWPW-CC PB MDF tMDF 

Jan 2011 0.05 ----- 0.09 0.11 ----- 

Jan 2012 ----- ----- ----- ----- 0.13 

July 2012 ----- 0.05 ----- ----- ----- 

(1) “ppm” = parts per million; “Eff. Date” = effective date; “HWPW-VC” = hardwood plywood – 

veneer core; “HWPW-CC” = hardwood plywood – composite core;”tMDF” = thin medium density 

fiberboard (8-mm or thinner). “Standard Concentrations” are allowable limits based on 

measurements made using the American Standards & Testing Method E1333-96. 
ES-4 

To provide assurances of compliant products to downstream customers, 

manufacturers would be required to provide chain-of-custody records to their 

customers. An example of such a document would be an invoice that states that 

the composite wood products comply with applicable Phase 1 or Phase 2 

emission standards. These would include the necessary information to track a 

composite wood product to its original manufacturer. Chain-of-custody 

documents must accompany all HWPW, PB, and MDF panels and finished 

goods made with those materials if sold to California. 

Beginning in 2009, all PB, HWPW, and MDF offered for sale in California would 

be required to have a label on each panel or a designation on a bill-of-lading that 

specifies that the product complies with California formaldehyde emission limits. 

Composite wood product manufacturers would be required to verify product 

compliance with prescribed emission testing protocols (i.e., American Standards 

and Testing Method E1333-96). 

Beginning in 2012, businesses that sell in California and utilize PB, HWPW, or 

MDF as a raw material to fabricate other products, would be required to use only 

products that comply with the California formaldehyde emission limit. Fabricators 

are also required to label each finished good or product and provide chain-ofcustody documentation. Moreover, retailers of PB, HWPW, and MDF or products 

containing those materials, could only sell HWPW, PB, or MDF meeting the 

California formaldehyde emission limits or fabricated finished goods or products 

containing composite wood products compliant with the California formaldehyde 

emission limits, imported or domestic. 

C. Options for Meeting the Proposed Emission Standards 

In 2001, staff initiated efforts to determine how formaldehyde emissions from 

HWPW, PB, and MDF could be reduced. The ATCM defines BACT as the 

emission limits in Table ES-1. In our analysis of potential BACT options, we 

initially found that there are “niche” products presently being sold with very low 

formaldehyde emissions. In addition, there are products being made with 

proprietary “no added formaldehyde” resins, such as resins made from soy flour. 

In addition, we learned that manufacturers have an array of options for lowering 

formaldehyde emissions from the urea-formaldehyde resins that they presently 

use, or they could opt to use an alternative resin system. In addition to the 

manufacture of low-formaldehyde content materials, laboratory studies have 

shown that additives can be used to further lower formaldehyde emissions (e.g., 

melamine, hexamine) in panels made with urea-formaldehyde resins beyond 

those levels achieved with today’s use of additives. Alternatively, considerable 

work has been done to demonstrate the utility of tannin-based resins. 
ES-5 

We believe that manufacturers will generally have more than one option for 

meeting the proposed formaldehyde emission standards. To produce products 

that meet the Phase 1 standards, we believe that manufacturers that choose to 

use urea-formaldehyde resins could comply by optimizing their current 

production processes and using resins with lower amounts of formaldehyde. 

Alternatively, manufacturers could opt to follow an alternative compliance option 

and use a “no added formaldehyde” resin, which could also allow for producing 

panels that immediately comply with the proposed Phase 2 standards in Table 

ES-1. 

To meet the Phase 2 standards, we believe that manufacturers that choose to 

continue using urea-formaldehyde resins will need to make further changes. 

They would likely need to use additives such as melamine, in concentrations 

ranging from 8 to 15% by weight, to achieve the emission limits in Table ES-1. In 

terms of alternative resin systems, HWPW manufacturers could use polyvinyl 

acetate resins, which are already being used to make panels for Green Building 

Programs across the U.S. For PB, we believe that a promising alternative resin 

system is phenol-formaldehyde resin, which is the resin currently being used to 

produce exterior-grade products in the U.S. 

D. Emission Reductions and Health Benefits 

Within the category of area-wide sources, formaldehyde emissions from HWPW, 

PB, and MDF in California are estimated to be about 900 tons per year. The 

proposed Phase 1 emission standards for HWPW, PB, and MDF are about 66%, 

49%, and 41% tighter, respectively, than the voluntary HUD-based standard met 

by many manufacturers. Based on the average emissions of existing products, 

the ATCM would reduce emissions of formaldehyde by about 20% in Phase 1. 

The proposed Phase 2 emission standards for HWPW, PB, and MDF are about 

79%, 75%, and 69% tighter, respectively, than the voluntary HUD-based 

standard met by many manufacturers. Based on the average emissions of 

existing products, the ATCM would reduce emissions of formaldehyde by about 

57% in Phase 2. This is an estimated annual emissions reduction of about 180 

tons per year from Phase 1 and 500 tons per year from Phase 2. 

Because these emissions would also substantially reduce indoor formaldehyde 

exposures, the largest benefit would be realized by buyers of new homes. 

Substantial benefits would also be realized by those in existing homes due to 

reduced emissions from new remodeling projects and newly purchased furniture. 

These reductions benefit ambient air quality as nearly all formaldehyde directly 

emitted indoors moves to the outdoors. Most of the formaldehyde moves 

outdoors within hours, primarily through indoor-outdoor air exchange from natural 

ventilation and building leakage. A very small amount of formaldehyde (< 1% up 

to 7%) is estimated to be removed through chemical reactions with other 

compounds in indoor air or on surfaces. 
ES-6 

To estimate the reduction in cancer risk resulting from the implementation of the 

proposed Phase 1 and Phase 2 standards, we calculated the potential cancer 

risk from total formaldehyde exposures to current-average and current-elevated 

formaldehyde concentrations. In the two scenarios, average or elevated outdoor, 

indoor, and in-vehicle formaldehyde concentrations were obtained from the 

literature to estimate daily time-weighted average and elevated exposures, 

respectively. Based on projected decreases in daily average or elevated 

formaldehyde exposure, formaldehyde-related cancer risk in adults would be 

reduced by 35 to 97 excess cancers per million, over a 70-year lifetime exposure 

(Table ES-2). In children, it would result in a reduction of 9 to 26 excess cancers 

per million, based on a 9-year childhood exposure. Risk reductions would be far 

greater for those living in new or nearly new homes, where formaldehyde levels 

can be significantly higher. 

Table ES-2. Estimated Reductions in Cancer Risk After Phase 1 and Phase 21

A. Childhood Exposure: 9-year Exposure to Formaldehyde 

Exposure Scenario TWA 

Formaldehyde 

Cancer Risk 

Per Million 

Cancer Cases 

Reduced 

Current-average 16 μg/m3 23 ----- 

• Post Phase 1 13 μg/m3

 20 3 

• Post Phase 2 9 μg/m3

 14 9 

 

Current-elevated 42 μg/m3 63 ----- 

• Post Phase 1 36 μg/m3

 54 9 

• Post Phase 2 25 μg/m3

 37 26 

B. Lifetime Exposure: 70-year Exposure to Formaldehyde 

Exposure Scenario TWA 

Formaldehyde 

Cancer Risk 

Per Million 

Cancer Cases 

Reduced 

Current-average 16 μg/m3 86 ----- 

• Post Phase 1 14 μg/m3

 74 12 

• Post Phase 2 9 μg/m3

 51 35 

 

Current-elevated 42 μg/m3 231 ----- 

• Post Phase 1 36 μg/m3

 196 35 

• Post Phase 2 25 μg/m3

 134 97 

(1) “TWA formaldehyde” = Daily time-weighted average formaldehyde concentration. “Cancer 

Risk” = number of estimated chances per million of developing cancer in a 9- or 70-years. 
ES-7 

E. Estimated Costs 

HWPW, PB, and MDF panels that comply with the proposed Phase 1 and Phase 

2 standards can be produced using a range of available options used today to 

minimize formaldehyde emissions. For Phase 1, estimated production cost 

increases for HWPW, PB, and MDF panels, were between 1% and 7%. For 

Phase 2, the increases were estimated to range between 8% and 30%. Based 

on these incremental per panel cost increases, the total cost to the industry was 

calculated. In Phase 1, this would average $19 million per year. After full 

implementation of Phase 2, costs were estimated at $127 million per year. 

1. Hardwood Plywood Industry

Presently, about 40% of HWPW produced for California complies with the 

proposed Phase 1 and Phase 2 standards. For the remaining 60%, we believe 

manufacturers could apply a range of low-cost modifications that have been 

proven to lower formaldehyde emissions. As only a modest amount of reduction 

is needed, we believe that the production cost of a Phase 1 compliant HWPW 

panel would be increased by about 1%, due almost entirely to the increase in 

cost for improving the urea-formaldehyde resin (i.e., would raise the production 

cost of a $20 HWPW panel up to $20.25). 

For the proposed Phase 2 standard, manufacturers would likely choose to add 

additional scavengers, namely melamine or hexamine, to reduce formaldehyde 

emissions from panels made with urea-formaldehyde resins. Alternatively, 

selected manufacturers may choose to use polyvinyl acetate resins, which may 

require some minor upgrading of equipment. Through either option, it is 

estimated that the cost to produce a Phase 2 compliant HWPW panel would be 

increased by about 8% to 19% (i.e., would raise the production cost of a $20 

HWPW panel to a range of $21.50 to $23.75). 

2. Particleboard Industry 

Based on the CARB survey of products manufactured in 2002, about 55% of PB 

produced in the U.S. already complies with the proposed Phase 1 standard, and 

only a small amount of specialty products (< 1%) complies with the proposed 

Phase 2 standard. For about 45% of U.S. production, we believe that to produce 

a panel with a urea-formaldehyde resin that complies with the Phase 1 standard, 

manufacturers would apply many of the same measures as noted previously for 

HWPW. By the same reasoning, it is estimated that the production cost of a 

Phase 1 compliant PB panel would be increased by about 4% to 7%, due almost 

entirely to the increase in resin cost (i.e., would raise the production cost of a 

$10.50 PB panel to a range of $11 to $11.80). 
ES-8 

For the proposed Phase 2 standards, manufacturers would likely use a 

melamine-urea-formaldehyde (MUF) resin in combination with the use of lower 

mole ratio urea formaldehyde resins (i.e. F:U<1). We believe that to meet the 

Phase 2 standard, the MUF resin would need to contain about 8% melamine by 

weight. In addition to increased resin costs, it was further assumed that 

processing times would be lengthened by about 10%. Thus, the cost to produce 

a Phase 2 compliant PB panel would be increased by about 17% to 30% (i.e., 

would raise the production cost of $10.50 PB panel to a range of $12.30 to 

$13.80). 

3. Medium Density Fiberboard Industry

Based on the CARB survey of panel products manufactured in 2002, about 25% 

of MDF produced in the U.S. already complies with the proposed Phase 1 

standard, and only a small amount of specialty products (< 1%) complies with the 

proposed Phase 2 standard. For about 75% of U.S. production, manufacturers 

will likely apply similar modifications to their urea-formaldehyde resins, as noted 

for PB and HWPW. Thus, the cost of a Phase 1 compliant MDF panel would be 

increased by about 4% to 6%, due to the increase in resin cost (i.e., would raise 

the price of a $14.00 MDF panel to a range of $14.50 to $15.00). 

For the proposed Phase 2 standards, manufacturers would likely choose to use a 

melamine urea-formaldehyde resin with 12% melamine in combination with the 

use of lower mole ratio urea formaldehyde resins (i.e. F:U <1). In addition to 

increased resin costs, we assumed that processing times would be lengthened 

by about 30%. Thus, we believe that the cost to produce a Phase 2 compliant 

MDF panel would be increased by about 30% (i.e., would raise the price of a 

$14.00 MDF panel to $18.20). A few manufacturers produce MDF with pMDI, 

however pMDI is much more costly than urea formaldehyde resins (see Table 

VIII-14). The cost of an MDF panel made from (polymeric Methylene Diphenyl 

Diisocyanate) pMDI would be increased by about 135%, due to the increase in 

resin cost (i.e., would raise the price of a $14.00 MDF panel to $33). So, staff 

believes that manufacturers would opt to use the less expensive melamine 

fortified, low mole ratio urea-formaldehyde resin to meet the Phase 2 emission 

standard. 

4. Total Combined Cost to the Industry

The above estimated “per panel” production cost increases were used to 

calculate the total cost to the HWPW, PB, and MDF industries and are shown in 

Table ES-3. Using production data for 2002, the total estimated cost in California 

are estimated to be about 19 million dollars annually to meet the Phase 1 

standards and about 127 million dollars annually to meet the Phase 2 standards. 
ES-9 

Table ES-3. Total Estimated Cost to the Industry in 2002 

Product Production 

(Million Panels) 

Phase 1 Annual 

Costs (Millions) 

Phase 2 Annual 

Costs (Millions) 

HWPW 9.3 6 17 

PB 19.5 4 61 

MDF 8.7 9 49 

Total Estimated Cost ----- 19 127 

5. Consumer Costs

Most of the composite wood in a new home is used in cabinets, shelving, 

countertops, and moldings. The increased cost of composite wood products 

would have a limited effect on new home construction costs. Staff estimates that 

for a 2000 square foot home, the increased cost of construction is about $390.00 

for a medium priced house of $574,000.00, the estimated price increase is 

0.07 %. 

Based on the estimated cost of meeting the phase 2 emission standards, the 

increase in the price of a panel would range from about $3.00 to $6.00, among 

various product types. 

F. Comments on the Staff Proposal 

Some manufacturers have expressed concerns about the stringency of the 

proposed Phase 2 standards and the amount of time they are provided to 

implement changes in their plants. We believe that the proposed standards are 

achievable with the application of one or several additives and through 

improvements in the manufacturing process. With respect to the amount of time 

needed to produce compliant products, we understand that most manufacturers 

that intend to sell to California have already begun research to develop new resin 

system(s). As the effective date of the ATCM is about two years into the future 

for Phase 1 and four years before Phase 2, we believe there is sufficient time for 

manufacturers to conduct mill trials and make the necessary production changes 

for their new or modified resin systems. 

Another manufacturer has commented that the Phase 1 standards for HWPW 

should be lower and required sooner, and the Phase 2 standards should also be 

effective sooner than staff is proposing. We are not proposing earlier compliance 

dates because we believe that most HWPW manufacturers will need the 

provided time to research alternatives, and as appropriate, redesign their 

manufacturing operations. We are not proposing lower standards for Phase 1 

because our intent is to set an industry cap to stop the low-cost, high-emitting 

products from coming into California. 
ES-10 

G. Other Formaldehyde Emission Standards 

Presently, the U.S. trails the efforts undertaken in Japan, Europe, and Australia 

to reduce formaldehyde emissions from composite wood products. In Europe, 

concerns over the health effects of formaldehyde emissions from composite 

wood products led to a guideline to limit formaldehyde emissions from 

particleboards, fiberboards, and plywood to 0.1 ppm, which is known as the E1 

classification (Deutsches Institut fur Bautechnik, 1994). Australia has also 

adopted the E1 classification. In Japan, the Japanese Building Standard Law 

(Takabatake, 2003) created a “sick house” regulation which regulates the amount 

of formaldehyde that can be emitted from building materials. 

Staff believes that the proposed Phase 2 standards will limit formaldehyde as 

effectively or more effectively than those being applied elsewhere in Europe or 

Japan. In comparison to the proposed Phase 1 and Phase 2 standards, the E1 

standard is an “average” standard that allows panels to be produced with 

formaldehyde contents higher than the value of the standard. The proposed 

ATCM is a “cap” standard which does not allow for any products with emission 

levels above the cap to be sold to California. To ensure that the panels never 

exceed the standards, manufacturers will need to routinely operate below the 

“cap.” Moreover, in terms of formaldehyde contents, Europe and Japan allow 

multiple grades of panels to be sold for consumer use. Therefore, not all panels 

in Europe and Japan meet a single standard. In Europe, a major portion is made 

to comply with less stringent standards than those proposed by staff, but in 

Japan, the F and F standards bracket the stringency of the 

proposed standards. In the proposed ATCM, all HWPW, PB, and MDF would be 

required to meet a single product-specific standard. The proposed ATCM would 

be the most stringent production standard in the world. 

Unlike Europe and Japan, the U.S. has no comprehensive formaldehyde 

emission regulations for composite wood products. (The only standards are set 

by HUD, but apply only to manufactured homes.) Consequently, the U.S. is a 

growing market for low-cost, high-emitting products from overseas that can no 

longer be sent to other markets. While U.S. manufacturers have made progress 

toward lower formaldehyde emitting products since the 1980’s, voluntary 

reduction efforts in the U.S. continue to lag far behind improvements being made 

in Europe and Japan. The proposed ATCM would apply to HWPW, PB, and 

MDF used in all other applications, there are no comparable federal regulations 

at this time. Note, however, that the HUD standard preempts other standards 

where it applies. Therefore, the proposed ATCM would not apply to 

manufactured homes. 
ES-11 

H. Environmental Impacts 

The primary benefit of the proposed ATCM is a reduction in formaldehyde 

emissions, total public exposure, and excess cancer risk in California. In setting 

new formaldehyde emission standards for HWPW, PB, and MDF, reductions in 

statewide formaldehyde emissions of over 500 tons per year would be expected 

to occur at all points along the product distribution chain. In addition, we will 

request that the U.S. Environmental Protection Agency provide State 

Implementation Plan credits to California for the formaldehyde emission 

reductions from the ATCM. Formaldehyde is a volatile organic compound and a 

precursor to the formation of ozone. We anticipate no significant adverse 

environmental impacts from the implementation of this ATCM. 

I. Environmental Justice 

The proposed ATCM would not cause significant adverse impacts in any 

community. Implementation of the proposed ATCM is aligned with the principle 

of pollution prevention, and would reduce exposures to formaldehyde in all 

communities, including low-income areas and ethnically diverse communities. 

J. References 

California Air Resources Board (CARB). 1992. Final Report on the Identification 

of Formaldehyde as a Toxic Air Contaminant. Part A, Exposure Assessment. 

Technical Support Document, Stationary Source Division, Sacramento, CA. 89 

pp. 

Deutsches Institut fur Bautechnik (DIBt). Guideline on the classification and 

control of wood-panels with regard to formaldehyde emission. Guideline 100, 

DIBt, Berlin, Germany. (English Translation; Original Not Seen) 

Takabatake K. 2003. Japanese Sick House Regulations. Accessed: 6 July 

2006. From: http://strategis.ic.gc.ca/epic/site/imr-ri.nsf/en/gr116049e.html 
Chapter I Page 1 

I. Introduction 

The California Air Resources Board staff is proposing an Airborne Toxic Control 

Measure to reduce formaldehyde (HCHO) emissions from composite wood 

products. “Composite wood products” is a general term for wood-based panels 

made from wood plies, particles, or fibers that are bound together with a resin or 

adhesive. They include hardwood plywood (HWPW), particleboard (PB) and 

medium density fiberboard (MDF), which emit HCHO because the resins typically 

used to bond the wood materials contain HCHO. Emissions from these products 

result from the release of unreacted HCHO from the resins and from chemical 

degradation over time. This chapter discusses our regulatory authority and the 

need for reducing HCHO emissions from composite wood products. 

In the early 1980’s, the California Legislature approved Assembly Bill (AB) 1807 

[Tanner, 1983] – also known as “The Toxic Air Contaminant Identification and 

Control Act.” Pursuant to AB 1807, the California Air Resources Board (CARB) 

established a comprehensive program to identify and control toxic air 

contaminants (TAC) to reduce public exposures to air toxics. Subsequently, the 

Legislature approved AB 2588 [Connelly, 1987], commonly known as the “Air 

Toxics “Hot Spots” Information and Assessment Act.” This legislation called for 

the development of a statewide inventory of air toxic emissions, requirements for 

notifying people exposed to significant air toxic-related health risks, and facility 

plans for reducing air toxic-related health risks. 

In California’s TAC Identification and Control Program, CARB is required to 

consider specific criteria in its efforts to prioritize compounds for identification as 

TACs and for reducing statewide emissions (cf. Health and Safety Code (H&SC) 

§39660(f)). Moreover, data gathered under the AB 2588 “Hot Spots” program 

must also be evaluated. In 1992, CARB listed HCHO as a TAC without an 

identifiable threshold exposure level below which no significant adverse health 

effects are anticipated. 

Because HCHO is a TAC, CARB is required to prepare a report on the need and 

appropriate degree of regulation to reduce HCHO emissions (H&SC §39665). 

Regulations that bring about reductions in TAC emissions are called airborne 

toxic control measures (ATCMs). State law requires that ATCMs be based on 

the use of the best available control technology (BACT) or a more effective 

control method, in consideration of cost and human health risk (H&SC §39666) 

for substances having no identified safe threshold.

This Initial Statement of Reasons (ISOR) for the proposed ATCM to control 

emissions of HCHO from composite wood products provides information on: 

• The purpose of the regulation and CARB’s regulatory authority; 

• The process and data used to develop the regulation; 

• Physical and chemical characteristics of HCHO; 
Chapter I Page 2 

• Sources of HCHO; 

• Annual average ambient HCHO concentrations, exposure, atmospheric 

persistence, and health effects; 

• The major types of composite wood products used in California; 

• How composite wood products are manufactured; and 

• The proposed ATCM and its health, economic, and environmental 

impacts. 

The proposed ATCM is designed to reduce the emissions of HCHO from HWPW, 

PB, and MDF, and finished goods that are fabricated with those materials. As 

HCHO is a carcinogen with no safe threshold exposure level, and because 

annual average ambient HCHO levels in California presently exceed the Office of 

Environmental Health Hazard Assessment’s (OEHHA) chronic reference 

exposure level for HCHO, the proposed ATCM would reduce HCHO emissions to 

ambient air where there are existent risks to public health. Secondarily, the 

proposed ATCM would also lower human exposures to HCHO in homes, 

schools, and workplaces, where indoor HCHO levels are also known to reach 

concentrations that pose serious health risks to sensitive individuals (e.g., 

children, the elderly, and people with pre-existing respiratory challenges). 

A. Regulatory Authority 

The Board’s regulatory authority to control air pollution is set forth in Divisions 

25.5 and 26 of the Health & Safety Code (H&SC). Health & Safety Code §39903 

identifies CARB as: 

“... the state agency charged with coordinating efforts to attain and 

maintain ambient air quality standards, to conduct research into the 

causes of and solutions to air pollution, and to systematically attack 

the serious problem caused by motor vehicles, which is the major 

source of air pollution in many areas of the state.” 

Provisions in Division 26 of the H&SC authorize CARB to control the emissions 

of criteria pollutants (and their precursor) from specific source categories. For 

example, H&SC §41712 directs CARB to adopt regulations to reduce VOC 

emissions from consumer products. There are air pollutants, such as HCHO, 

that are precursors to criteria pollutants and are also TACs. TACs are defined in 

H&SC §39655 as: 

“... an air pollutant which may cause or contribute to an increase in 

mortality or in serious illness, or which may pose a present or potential 

hazard to human health.” 

The Board’s authority to regulate TAC emissions is separately codified in 

H&SC §39650 et seq. (The “Tanner Act”), and in the case of compounds such as 

HCHO, the justification for pursuing emission reductions may derive from more 

than one provisions of the H&SC. 
Chapter I Page 3 

For the proposed ATCM, the authority of CARB to regulate HCHO emissions 

from composite wood products principally derives from the Tanner Act (H&SC 

§39650 et seq.). The Tanner Act established a two-step process to (1) identify 

and (2) control TACs in California. In the first step, a substance is formally 

identified as a TAC based on reviews by CARB and OEHHA. In the second step, 

CARB adopts appropriate regulations, such as ATCMs, to control TAC emissions 

and to reduce human exposure. In 1992, CARB identified HCHO as a TAC with 

no identified “safe” threshold exposure level (title 17, California Code of 

Regulations §93000.) In situations where no safe threshold level has been 

identified for a TAC, the Tanner Act requires CARB to reduce emissions of the 

TAC to the lowest level achievable through application of BACT or a more 

effective control method (H&SC §39666(c)). 

 

In addition to the authority granted to CARB under the Tanner Act, H&SC §41712 

provides CARB with supplementary, independent, authority to regulate HCHO 

emissions from consumer products (i.e., PB and MDF panels) as defined in 

Health & Safety Code §41712(a)(1) as: 

“... a chemically formulated product used by household and 

institutional consumers ...” 

By this definition, PB and MDF panels, but not HWPW panels or finished goods 

made with those materials, are consumer products because they are “chemically 

formulated” products that are produced by processing wood waste (e.g., sawdust 

and other waste wood) to form particles or fibers, which are then combined with 

resins and other chemicals to produce a panel product that is used by household 

and institutional consumers. While wood waste is one of the raw materials in the 

panel product, the wood is highly processed and the panel product is created by 

applying heat and pressure to induce chemical reactions between the proteins in 

wood and the resins and other chemicals added to the mixture (see subsection 

IV.C.) As PB and MDF are consumer products, H&SC §41712(b) requires CARB 

to adopt regulations to achieve the maximum feasible reductions in volatile 

organic compounds (VOCs) emitted by consumer products. Because HCHO is 

both a TAC and a VOC, under H&SC §41712, CARB has the authority to adopt 

HCHO emission standards for PB and MDF as a VOC control measure for 

consumer products. 

B. Formaldehyde in California

Formaldehyde is directly emitted from a variety of mobile, stationary, area-wide, 

and natural sources in California (see subsection III.B.). Composite wood 

products (i.e., HWPW, PB, and MDF) are responsible for about 5% of these 

emissions, and the emissions from these products occur both outdoors and 

indoors. Formaldehyde is emitted to ambient, outdoor air from newly made and 

standing stocks of composite wood products stored at manufacturing facilities, 

construction sites, and lumberyards, and during transport of composite wood 

products by rail, truck, or ship. Indoor emissions come from composite wood 
Chapter I Page 4 

products used as structural components or amenities inside buildings. Over 

time, studies demonstrate that HCHO emissions produced indoors from an array 

of sources, including composite wood products (Battelle, 1996), make their way 

outdoors through normal air exchange mechanisms (subsection III.F.), and 

contribute to concentrations measured in ambient air. 

 

Ambient HCHO concentrations (i.e., outside) result from both direct HCHO 

emissions and from secondary HCHO formation in the atmosphere (see 

subsection III.C.). While the major mobile and stationary sources of direct HCHO 

emissions have previously been regulated by CARB or the U.S. Environmental 

Protection Agency (USEPA), composite wood products are an important source 

of HCHO emissions contributing to human exposure in California that have not 

yet been controlled. Presently, the statewide annual average HCHO 

concentration in ambient air exceeds the chronic reference exposure level for 

HCHO that presents a known risk to public health (OEHHA, 2005). Thus, 

reducing ambient HCHO concentrations is of principal concern from a public 

health perspective, requiring both reductions in directly emitted HCHO and in 

VOC emissions that contribute to secondary HCHO formation. Since the 1970’s, 

CARB has adopted a suite of increasingly stringent VOC control measures for 

mobile sources as a means to substantially reduce VOC emissions, including 

HCHO, to achieve state and federal ambient air quality standards for ozone. 

Reducing VOC emissions has historically been a primary focus of state air quality 

regulators and reductions have been achieved from nearly every significant 

source of VOC emissions (CARB, 2007). In spite of these efforts, there is a 

continuing need for additional VOC control measures to garner the remaining 

VOC reductions needed to achieve state and federal ozone standards. 

“Hot spots” are areas where concentrations of a TAC in ambient air, such as 

HCHO, are greater than regional or statewide average TAC concentrations. The 

elimination of “hot spots” has been the primary rationale for many of the ATCMs 

adopted by CARB in the past (e.g., CARB, 2006). In this regard, results from 

computer modeling analyses indicate that composite wood products may 

contribute to HCHO “hot spots” close to a range of sources where these products 

are present (subsection III.G.). The modeling results indicate that maximum 

HCHO concentrations in these “hot spots” represent a health risk to proximate 

receptors. This risk would be reduced by controlling HCHO emissions from 

composite wood products. 

 

In addition to the health risk posed by HCHO in the ambient air, an additional 

health risk exists from indoor concentrations of HCHO. As indoor levels in many 

situations exceed outdoor levels, potential health risks to building occupants are 

likely to be greater. Although composite wood products contribute only a small 

percentage to the HCHO levels that occur in the ambient air, these products are 

responsible for a large portion of HCHO exposure that occurs indoors. These 

combined outdoor and indoor exposures lead to substantial total exposures to 

HCHO for adults and children. 
Chapter I Page 5 

C. Need for Reducing Formaldehyde Emissions from Composite Wood 

Products

Formaldehyde is an air pollutant that is both a TAC and a precursor to the 

formation of ozone. In choosing to control HCHO emissions from composite 

wood products, staff considered four factors. As mentioned previously, one 

factor is that composite wood products are an important uncontrolled source of 

HCHO emissions. While there are a number of other sources of HCHO, there is 

no identified safe threshold exposure level and this ATCM contributes to reducing 

ambient HCHO to the lowest level achievable. Also, with respect to ambient air, 

the second factor considered by staff is that emissions from composite wood 

products contribute to ambient HCHO “hot spots,” such as in proximity to a 

lumberyard. 

The third factor considered by staff is that controlling HCHO emissions from 

composite wood products will provide the greatest benefit in terms of reducing 

the total air pollution related health risk from HCHO. Recognizing that the 

Tanner Act requires CARB staff to consider all relevant factors, including the 

potential exposure to a TAC in indoor environments, in deciding what sources of 

HCHO to prioritize for regulation (H&SC §39660.5 and 39665), reducing HCHO 

emissions from composite wood products will dramatically reduce indoor health 

risks, and thus significantly reduce total exposure and risks from HCHO 

emissions in California. Thus, it is appropriate for the CARB staff to give priority 

to developing an ATCM for this source of HCHO. 

The fourth factor considered by staff is that significant VOC reductions that would 

be achieved in setting stringent HCHO emission standards for composite wood 

products. The reductions from this source category are part of the CARB’s 

overall effort to establish VOC standards for numerous categories of consumer 

products. Because California needs VOC emission reductions to achieve state 

and federal ambient air quality standards, it has been necessary to develop 

standards for products from which very low levels of emissions reductions could 

be achieved (e.g., limits on contact adhesives effected 11 tons per year of VOC 

emission reductions) (CARB, 2004). As HCHO is also a VOC, the proposed 

ATCM would reduce HCHO emissions from HWPW, PB, and MDF by 

approximately 500 tons per year after adoption of the Phase 2 standards in 2012. 

Moreover, HCHO is a highly reactive VOC, which means that any reduction in 

HCHO emissions will have an impact in reducing ozone formation. Because of 

its high reactivity, the benefits of reducing HCHO emissions will be much greater 

than for other VOCs that are less reactive. 
Chapter I Page 6 

D. Regulations Applicable to Formaldehyde 

1. Airborne Toxic Control Measures

No specific ATCM to control HCHO emissions has been adopted by CARB, since 

HCHO was identified as a TAC in 1992. However, HCHO emissions from mobile 

sources have been reduced as a result of regulations that lower exhaust 

emissions of non-methane hydrocarbons from vehicles in light-duty, mediumduty, and heavy-duty weight classifications. In addition, exhaust emission 

standards limiting formaldehyde emissions have been established. 

2. Comparable Federal Regulations 

The USEPA identified HCHO as a hazardous air pollutant (HAP) in the federal 

Clean Air Act Amendments of 1990. In 1992, CARB formally identified HCHO as 

a TAC (CARB, 1992). 

In 1985, the U.S. Department of Housing and Urban Development (HUD) 

established HCHO emission limits for PB and HWPW used to construct mobile 

homes (Newton et al., 1986). As the standards apply only to PB and HWPW, 

and specifically when used in the manufacture of mobile homes, they in effect 

apply to a niche product, and not to composite wood products for use in other 

applications. These standards were instrumental in actuating substantial HCHO 

emission reductions in PB and HWPW which are bonded with urea-formaldehyde 

resins. However, exposures to HCHO in indoor settings, including but not limited 

to mobile homes, can still be found at levels that posed significant health risks 

(CARB, 2005), even after the HUD requirement for the use of lower-emitting 

composite wood products. 

To control air toxic emissions in the USEPA’s National Emission Standards for 

Hazardous Air Pollutants Program, toxic emission limits were established for 

plywood and other composite wood product manufacturing facilities (USEPA, 

2002). This rule applies to emissions generated at manufacturing facilities, but 

does not apply to emissions from the products themselves. 

While federal statutes have been enacted to control HCHO emissions from 

HWPW and PB for use in mobile homes and from composite wood product 

manufacturing facilities, there is no comparable, existing federal regulation to the 

proposed ATCM. 

3. Safe Drinking Water and Toxic Enforcement Act of 1986

Formaldehyde was listed as a carcinogen on January 1, 1988, under the Safe 

Drinking Water and Toxic Enforcement Act of 1986 (i.e., Proposition 65), which 

requires the State to publish a list of chemicals known to cause cancer, birth 
Chapter I Page 7 

defects, or other reproductive effects (OEHHA, 2005). The list is updated at least 

once a year, and currently includes over 750 chemicals. 

E. Indoor Air Quality 

With respect to air pollution, a principal responsibility of state and federal 

environmental protection agencies is to protect public health by ensuring the air 

is clean. Since the 1970’s, substantial reductions in ambient air pollutant levels 

have been realized through efforts aimed at lowering emissions from motor 

vehicles, stationary sources, and many other sources. While these efforts have 

been beneficial to public health in California and the rest of the nation, studies 

have found that people spend 90% or more of their time indoors (University of 

California, Berkeley, 1991), where less is known about the sources of indoor air 

pollution or the potential health risks that could be occurring. 

In the early 1990’s, CARB released an indoor air quality guideline titled 

“Formaldehyde in the Home,” which identified the major sources of HCHO in 

homes and what people could do to reduce indoor HCHO exposures (CARB, 

1991). Composite wood products such as PB, HWPW, and MDF were listed as 

major sources of HCHO emissions in California homes, where average HCHO 

concentrations were reported to be 70 to 80 and 50 parts per billion (ppb) in 

mobile and conventional homes, respectively. Subsequent research confirmed 

the importance of composite wood products as a source of HCHO in indoor 

environments (Battelle, 1996), which in combination with HCHO emissions from 

other consumer goods and products, allowed for intermittent exposures well 

above levels determined to cause chronic health effects (OEHHA, 2005). These 

same concerns were reiterated in a recent report to the California Legislature 

titled “Indoor Air Pollution in California,” submitted in response to the 

requirements of AB 1173 [Keeley, 2002] (CARB, 2005). 

F. References 

Battelle. 1996. Determination of Formaldehyde and Toluene Diisocyanate 

Emissions from Indoor Residential Sources. Final Report, CARB Contract No. 

93-315, Sacramento, CA. 119 pp. 

California Air Resources Board (CARB). 1991. Formaldehyde in the Home. 

Indoor Air Quality Guideline, Research Division, Sacramento, CA. 5 pp. 

CARB. 1992. Final Report on the Identification of Formaldehyde as a Toxic Air 

Contaminant. Part A, Exposure Assessment. Technical Support Document, 

Stationary Source Division, Sacramento, CA. 89 pp.

CARB. 1993. The Identification of Federal Hazardous Air Pollutants as Toxic Air 

Contaminants. Staff Report, Stationary Source Division, Sacramento, CA. 8 pp. 
Chapter I Page 8 

CARB. 2004. Initial Statement of Reasons for the Proposed Amendments to the 

California Aerosol Coating Products, Antiperspirants and Deodorants, and 

Consumer Products Regulations, Test Method 310, and Airborne Toxic Control 

Measure for Para-dichlorobenzene Solid Air Freshener and Toilet/Urinal Care 

Products. Stationary Source Division, Sacramento, CA. 

CARB. 2005. Indoor Air Pollution in California. Report to the Legislature, 

Pursuant to Health & Safety Code §39930. Research Division, Sacramento, CA. 

248 pp. 

CARB. 2006. Proposed Amendments to the Hexavalent Chromium Airborne 

Toxic Control Measure for Chrome Plating and Chromic Acid Anodizing 

Operations. Stationary Source Division, Sacramento, CA. 125 pp. 

CARB. 2007. Air Resources Board’s Proposed State Strategy for California’s 

2007 State Implementation Plan. Draft Report, Planning & Technical Support 

Division, Sacramento, CA. From: http://www.arb.ca.gov/planning/sip/sip.htm 

Accessed: 14 February 2007. 

Newton LR, WH Anderson, HS Lagroon, and KA Stephens. 1986. Large-scale 

test chamber methodology for urea-formaldehyde bonded wood products. In: B 

Meyer, BA Kottes Andrews, and RM Reinhardt (eds). Formaldehyde Release 

from Wood Products. ACS Symposium Series No. 316: 154-187. 

OEHHA. 2005. Proposition 65 in Plain Language. Accessed: 8 February 2007. 

From: http://www.oehha.ca.gov/prop65/background/p65plain.html 

U.S. Environmental Protection Agency (USEPA). 2002. Regulatory Impact 

Analysis of the Proposed Plywood and Composite Wood Products NESHAP. 

Final Report, Office of Air Quality Planning and Standards, Research Triangle 

Park, NC. 

University of California, Berkeley. 1991. Activity Patterns of California 

Residents. Final Report, CARB Contract No. A6-177-33, Research Division, 

Sacramento, CA. 63 pp. 
Chapter II Page 9 

II. Public Outreach 

This chapter summarizes the numerous public meetings held with stakeholders 

since fall 2001 when plans were announced to develop an ATCM to reduce 

HCHO emissions from composite wood products. 

A. Outreach Efforts 

Table II-1 lists selected key public meetings, conference calls, or presentations to 

discuss various aspects of the proposed ATCM to reduce HCHO emissions from 

composite wood products. The meeting notices and related information are 

posted at: http://arb.ca.gov/toxics/compwood/workshops.htm. 

Table II-1. Selected ATCM-related Outreach Efforts

Date Purpose of Meeting/Activity 

Sep 2001 • Initial public meeting on proposed ATCM concept 

Oct 2001 • Focused meeting with non-manufacturer groups 

Nov 2001 • Public meeting on format and content of the product survey 

Jan 2002 • Focused meeting to refine the product survey 

Apr 2003 • Distribute survey to U.S. manufacturers 

Apr 2004 • Stakeholder meeting to discuss survey results 

Aug 2004 • Public meeting on survey results and need for ATCM

Oct 2004 • Public meeting on ATCM data needs and enforcement 

May 2006 • Public meeting to release first draft regulation 

Jun 2006 • Public meeting on enforcement and revised draft regulation 

Aug 2006 • Site-visit to a particleboard manufacturing plant 

• Site-visit to the Port of Oakland 

Sep 2006 • Presentation at National Green Building Conference

Oct 2006 • Site-visit to architectural plywood facilities 

• Conference call – Finished Product Testing 

• Public meeting to release second revision of draft regulation

Nov 2006 • Meeting with wood importing association 

Dec 2006 • Site-visits to a testing lab and plywood manufacturing plant 

B. Public Involvement 

Manufacturers, industry associations, government agencies, researchers, and 

environmental organizations were contacted and asked to provide input 

throughout the ATCM development process. In addition to hosting public 

meetings, information (e.g., meeting notices, slide presentations) was posted on 

ARB’s website at: http://www.arb.ca.gov/toxics/compwood/compwood.htm. A 

composite wood list-serve was developed to keep approximately 540 

stakeholders notified of progress being made with respect to ATCM 
Chapter II Page 10 

development. In addition, as specified in Health & Safety Code §39665(c), 

relevant comments on the ATCM have been included in the administrative 

record. Comments are listed as a reference to the chapter, and are available 

from CARB staff upon request (Various, 2005-2007). 

1. Industry

Manufacturers and industry associations have been active participants 

throughout the ATCM development process. Their involvement has included: 

• Contacting staff by telephone and email; 

• Providing facility tours; 

• Responding to the 2003 Composite Wood Survey; and 

• Participating in conference calls and public meetings. 

In 2006, a major effort was initiated to open a dialogue with industry associations 

and individual manufacturers, fabricators, and retailers. In addition to the three 

public workshops (Table II-1), the outreach effort included over 30 face-to-face 

meetings, over 20 conference calls, approximately 10 facility site-visits, and two 

presentations at national conventions/conferences. Among the industry 

associations that were contacted and/or provided input during the ATCM 

development process are: 

• American Home Furnishings Alliance 

• American Homeowners Association 

• APA – The Engineered Wood Association 

• Australian Wood Panels Association, Inc. 

• Business & Industrial Furniture Manufacturers Association 

• California Building Industry Association 

• California Manufactured Housing Institute 

• California Wood Industries Coalition 

• Composite Panel Association 

• Consulate General – People’s Republic of China 

• Door & Access System Manufacturers Association 

• Forintek Canada Corporation 

• Formaldehyde Council, Inc. 

• Formaldehyde-free Coalition 

• Hardwood Plywood & Veneer Association 

• Healthy Building Network 

• International Wood Products Association 

• Kitchen Cabinet Manufacturers Association 

• National Retail Federation 

• National Wood Flooring Association 

• Window & Door Manufacturers Association 

• Woodwork Institute 
Chapter II Page 11 

In addition, meetings and conference calls with a number of individual companies 

were held throughout 2006. Through these contacts, it was learned that the 

proposed California regulations were being discussed at international wood 

products meetings in Asia and Europe. While the proposed ATCM has the 

potential to impact many economic sectors, a concerted effort was made to 

contact and solicit input from as many affected industries as possible. 

2. Government Agencies

In addition to consulting with CARB staff in the Enforcement, Monitoring and 

Laboratory, Planning and Technical Support, and Research Divisions, input and 

cooperation was received from other State agencies and local air districts. 

Concerning issues related to health risk assessment, numerous meetings and 

conference calls were held with the OEHHA to seek their input on the 

methodology used to assess health risks for the proposed ATCM. Similarly, 

regular updates were provided to the California Air Pollution Control Officers 

Association’s (CAPCOA) Toxic Air Risk Managers Advisory Committee on 

progress made on ATCM development. A separate presentation was also made 

to CAPCOA’s Enforcement Managers. 

Owing to the nature of the HCHO emission test procedures used in the 

composite wood products industry, contacts were made with the California 

Department of Health Services, which is in the process of developing a test 

facility in their San Francisco Bay Area Laboratory that would be comparable to 

test facilities operated by the Composite Panel Association and the Hardwood 

Plywood & Veneer Association, the principal industry associations in the U.S. An 

agreement is being developed to utilize the test facility that will be operated by 

the Department of Health Services. 

C. Survey of Products Manufactured in 2002 

A survey was conducted in 2003 to gather data on composite wood products 

manufactured in 2002. In 2003, a survey package was sent to over 200 U.S. 

manufacturers (http://www.arb.ca.gov/toxics/compwood/survey2002.htm). 

Manufacturers were asked to provide information about the range of products 

they produced, types of resins they used, amount of product sales in California, 

chemical composition of the resins used, and equipment used in manufacturing 

(CARB, 2003). Fifty-seven responses were received, and those data were 

analyzed and presented at a public meeting in August 2004. Results of the 

survey are discussed in detail in Chapter V. 
Chapter II Page 12 

D. References 

California Air Resources Board. 2003. Composite Wood Survey Package. 

From: http://www.arb.ca.gov/toxics/compwood/survey.htm Accessed: 8 February 

2007. 

Various. 2005-2007. Collection of Relevant Comments Concerning the 

Proposed ATCM to Control Formaldehyde Emissions from Composite Wood 

Products. Compiled by Stationary Source Division, Sacramento, CA. 
Chapter III Page 13 

III. Need for Regulation of Formaldehyde 

Under Health and Safety Code Section 39665, ARB is required to prepare a 

report on the need and appropriate degree of regulation for compounds identified 

as toxic air contaminants. This chapter meets the requirements of State Law and 

provides an overview of the physical and chemical properties of formaldehyde, 

sources, emissions, measured concentrations in various environments, and 

atmospheric persistence. 

A. Health Effects of Formaldehyde 

Exposure to HCHO has both non-cancer and cancer health effects. The noncancer health effects of HCHO are eye, nose, and/or throat irritation (OEHHA, 

2005b). In 2004, the International Agency for Research on Cancer conducted an 

evaluation of formaldehyde and concluded that there is sufficient evidence that 

HCHO causes nasopharyngeal cancer in humans (i.e., in the region of the throat 

behind the nose) (National Cancer Institute, Not Dated). The risk from exposure 

to annual average HCHO concentrations in ambient air alone is about 20 to 24 

excess cancer cases per million based on a 70 year lifetime exposure. The 

number of excess cancer cases per million rises considerably when HCHO 

exposure from current total daily HCHO exposure is considered. A detailed, 

comprehensive review of the non-cancer and cancer health effects of HCHO is 

contained in Chapter VII. 

B. Physical and Chemical Properties 

Formaldehyde (HCHO) is a colorless, volatile, flammable gas at room 

temperature and pressure. It has a pungent, highly irritating, suffocating odor 

and may cause a burning sensation to the eyes, nose, and lungs at high 

concentrations. Pure HCHO is not available commercially and is generally 

produced, sold and transported as water solutions (formalin) with concentrations 

ranging from 25 to 56 weight percent (%) (Gerberich and Seaman, 1994). It is 

very soluble in water, alcohols and other polar solvents (Lide, 1999). Table III-1 

summarizes some of the physical and chemical properties of HCHO. 

Formaldehyde is also known as methanal, methylene oxide, oxymethylene, 

methylaldehyde, and oxomethane (USDHHS, 1999). The commercial forms of 

formaldehyde include paraformaldehyde, formalin solutions, polymers, resins, 

and other derivatives. 

Formaldehyde is a member of the family of aldehydes, its simple structure is 

composed of two hydrogens directly attached to a carbonyl group (Wade, 1999). 

Formaldehyde exhibits most of the general chemical properties of aldehydes, 

except it is more reactive than longer chain aldehydes. Formaldehyde is a very 

strong electrophile. It can participate in electrophilic aromatic substitution 

reactions with aromatic compounds and can undergo electrophilic addition 

reaction with alkenes. Compared to other carbonyl compounds, HCHO has good 
Chapter III Page 14 

thermal stability and is able to undergo a broad range of chemical reactions, 

many of which are useful in commercial processes (CARB, 1992). 

Formaldehyde gas can undergo slow polymerization to trimer, trioxane, and 

paraformaldehyde at temperatures below 80 oC (Canadian Centre for 

Occupational Health & Safety, 2005; Reuss et al., 1988). In aqueous solutions, 

HCHO reacts with water to form methylene glycol (CARB, 1992). Traces of polar 

impurities, such as water, methanol, alkalies, and acids considerably speed up 

the polymerization process (Reuss et al., 1988; Walker, 1964). 

When pure liquid HCHO is warmed to room temperature in a sealed container it 

undergoes rapid polymerization with evolution of heat (Gerberich and Seaman, 

1994). In order to prevent polymerization of HCHO, methanol is generally added 

as a stabilizing agent (Merck, 1989). The uncatalyzed decomposition of HCHO 

is slow (below 300 oC), which yields carbon monoxide and hydrogen gas 

(Gerberich and Seaman, 1994). When catalyzed by metals such as platinum, 

copper, chromia, and alumina, HCHO decomposition can produce methanol, 

methyl formate, formic acid, carbon dioxide, and methane. Formic acid is formed 

when HCHO is oxidized via atmospheric oxygen. When stored, HCHO solutions 

should be kept tightly sealed in order to prevent formic acid formation. 

Table III-1. Physical and Chemical Properties of Formaldehyde1

Chemical Formula: HCHO 

CAS Registry Number: 50-00-0 

Molecular Weight: 30.03 

Boiling Point: -19.5 oC 

Melting Point: -118 oC 

Vapor Pressure: 3284 mm Hg at 20 oC 

Vapor Density: 1.03 (aq); 1.08 (gas) 

Density/Specific Gravity: 1.067 (air = 1) 

Log Octanol/Water Partition 

Coefficient: 

0.35 

Conversion Factor: 1 ppm = 1.23 mg/m3 

Solubility in Water: Very soluble (40g/100mL at 20 oC) 

(1) Sources: Canadian Centre for Occupational Health & Safety (2005); Merck (1989); Sax 

and Lewis (1989); Syracuse Research Corp. (2004). 

C. Sources and Emissions of Formaldehyde 

Formaldehyde gas is released into the environment from a variety of sources. 

There are directly emitted sources and there are indirect sources. Direct sources 

include motor vehicles, aircraft, boats, chemical plants, and fireplaces (see 
Chapter III Page 15 

subsection III.C.1). Indirect sources include atmospheric photooxidation 

processes, which is the dominant source of HCHO in the lower atmosphere. The 

photochemical oxidation of hydrocarbons in polluted atmospheres that contain 

ozone and nitrogen oxides results in formation of HCHO. This is the largest 

source of HCHO in ambient air in California (CARB, 1992). 

Formaldehyde is the most commercially important aldehyde and it is an essential 

component of many resin technologies. More than half of all HCHO is used 

primarily to make urea-, phenol-, melamine-formaldehyde and polyacetal resins 

(Formaldehyde Council, Inc., 2005). Formaldehyde-based resins are used as 

adhesives for composite wood products including HWPW, PB, and MDF. 

Formaldehyde is widely used in mobile and conventional home construction, and 

in the garment industry. It can be found in products such as antimicrobial agents 

and it is also used in fumigants and soil disinfectants (USDHHS, 1999). As a 

result, these activities emit significant amounts of HCHO into surrounding air. 

Some of the uses of HCHO are summarized in Table III-2. 

Table III-2. Product Distribution for Formaldehyde in the U.S. (2003)1

Product Percentage of consumption 

Urea Formaldehyde Resins* 27 

Phenolic Resins* 20 

Polyacetal Resins* 11 

Butanediol 9 

Methylene Diisocyanate (MDI) 8 

Pentaerythritol 4 

Urea Formaldehyde Concentrates 3 

Hexamethylenetetramine 2 

Melamine Resins* 3 

Miscellaneous 14 

(1) Source: Global Insight, Inc. (2006). “*” indicates products used in the manufacture of 

composite wood products. Note: Total may not add up to 100% due to rounding. 

With respect to composite wood products, HCHO is directly emitted from 

manufacturing plants during panel processing and from fabrication facilities that 

use these products to make furniture, cabinets, etc. As HCHO emissions from 

composite wood products occur over multiple year periods, and throughout their 

distribution and use, substantive amounts of emissions occur during: 

• Truck, rail, and ship transportation during product distribution;

• Use in new home construction and remodeling construction; 

• Stockpiles in lumberyards and wood product warehouses; and 
Chapter III Page 16 

• Exchange processes from indoors to outdoors through windows, doors, 

and ventilation systems in homes and other buildings. 

1. Outdoor Sources 

Among the principal, directly-emitted sources of HCHO is the combustion of 

fossil fuels from mobile sources, which comprises nearly 76% of direct HCHO 

emissions (Table III-3). Of this total, nearly 26% of total statewide HCHO 

emissions originate from automotive exhaust (CARB, 2006a; Canadian Centre 

for Occupational Health & Safety, 2005). The remaining 50% can be attributed to 

airplanes, recreational boats, construction, and mining equipment (CARB, 

2006a). Stationary sources comprise approximately 13% and area-wide 

sources, such as wood burning add approximately 11% to the overall statewide 

HCHO emissions. Other important, direct outdoor sources include power plants, 

agricultural burns, oil refineries, incinerators, and tobacco smoke. 

Table III-3. Formaldehyde – 2005 Statewide Emission Inventory1

Emission Source Tons/Year Percent of Total 

Stationary 2,474 12 

Area-wide 2,014 10 

On-Road Mobile 4,999 25 

Gasoline 3,076 15

Diesel 1,922 10

Other Mobile 9,590 48 

Gasoline 2,979 15

Diesel 4,526 23

Other 2,085 10

Composite Wood 900 5 

Natural Sources 0 0 

Total Statewide 19,978 100 

(1) Source: CARB (2006a) for all tons/year values except “Composite Wood.” The 

tons/year value for composite wood is a preliminary estimate based on Appendix 

B. Note: Totals may not add up due to rounding.

Other anthropogenic sources of HCHO include industrial releases of HCHO at 

any given stage of the production, use, storage, transport, or disposal of products 

with residual HCHO (Liteplo et al., 2002). 

2. Indoor Sources 

Generally, indoor HCHO concentrations are higher than outdoor concentrations 

due to the wide spectrum of building materials and consumer products in 
Chapter III Page 17 

workplaces and residential areas that emit HCHO (CARB, 1992; USDHHS, 

1999). Formaldehyde resins are used in many materials and these resins slowly 

give off HCHO over time. Off-gassing from construction and building materials, 

especially composite wood products made with urea-formaldehyde (UF) resins 

and spray-on insulating foam are primary sources of indoor HCHO emissions. 

Other potentially significant sources of HCHO in indoor areas are tobacco 

smoke, wood-burning stoves, fireplaces, and furnaces (CARB, 1992). Textile 

products, carpet, pads and tape, drapes, and a vast number of consumer 

products also contribute to indoor HCHO concentrations (CARB, 2005b). While 

these emissions originate in indoor environments, the major portion of these 

emissions are removed to outside, ambient air by normal ventilation processes 

(e.g., when air moves through windows or doors, or mechanical ventilation 

systems), within a few hours. 

a. Composite Wood Products

Newly manufactured composite wood products such as HWPW, PB, and MDF 

are the most significant sources of HCHO inside of homes (CARB, 2005b). 

Particleboard is used as sub-flooring, shelving material, as well as in cabinetry 

and furniture. Hardwood plywood paneling is commonly utilized for decorative 

wall coverings. Hardwood plywood is used in cabinets, furniture, and flooring. 

Medium density fiberboard is used for drawer fronts, cabinets, and furniture tops. 

Emission rates of selected indoor sources of HCHO are presented in Table III-4. 

The products tested were those used most commonly in the California market. 

The results showed that bare urea-formaldehyde composite wood products were 

the highest dry product emitters. The adhesive component of composite wood 

products (UF resin) is primarily responsible for the off-gassing of HCHO into the 

air. When these wood products are pressed in the manufacturing process, some 

unreacted UF resin and other volatiles are trapped within the boards, and 

released to air over time. Typically HCHO concentrations in the core of a 

composite wood panel are twice as high as that at the surface (USDHHS, 1999). 

Unreacted hydroxy-methyl groups that are inherently present in UF resins can 

also produce HCHO by hydrolytic cleavage. 
Chapter III Page 18 

Table III-4. Emission Rates of Selected Indoor Sources of 

Formaldehyde (μg/m2/hr)1

Source of Formaldehyde Emission Rate 

Bare Urea-Formaldehyde Wood Products 8.6 to 1,580 

Coated Urea-Formaldehyde Products < 2.7 to 460 

Permanent Press Fabrics 42 to 215 

Decorative Laminates 4 to 51 

Fiberglass Products 16 to 32 

Bare Phenol-Formaldehyde Wood Products 4.1 to 9.2 

Paper Grocery Bags and Towels < 0.6 

Latex Paint 502 

Fingernail Hardener 215,500 

Nail Polish 20,700 

Base Coat Floor Finish 1,050,000 

Top Coat Floor Finish 421,000 

(1) Source: Battelle (1996). “μg/m2

/hr” = microgram per square meter per hour. Values 

for wet products are average initial emissions. 

Principally, the release of HCHO is highest from newly manufactured wood 

products; however, the emission is strongly dependent on the nature of the 

material. As the products age, emissions of HCHO decrease over time to lower 

rates, thus older homes generally have lower indoor HCHO levels (CARB, 1992; 

Sexton et al., 1989). Formaldehyde emissions from composite wood materials 

have been measured in mobile homes and found to be greater than in 

conventional homes as a result of higher loading ratios (i.e., the ratio of the 

surface area of a source, such as a PB panel, to the volume of the enclosed area 

where the source is present). Meyer and Hermanns (1985) found that mobile 

homes have minimal ventilation and poorly insulated features, and thus, 

experience elevated HCHO levels due to the higher ambient temperatures where 

they are located. 

b. Insulation Products

Urea-formaldehyde foam insulation (UFFI) previously was a major source of 

HCHO emissions that was addressed in the 1980’s. In the early 1970’s, UFFI 

was injected into wall cavities to improve the energy efficiency of older homes 

(Meek et al., 1985). Due to continuous health concerns, adverse acute and 

chronic health problems arose from the HCHO emissions that occurred during 

this time, and the U.S. Consumer Products Safety Commission placed a ban on 

UFFI in 1982. Although this ban was overturned, this action significantly 

contributed to a reduction in HCHO emissions and the residential use of UFFI 
Chapter III Page 19 

products. The California Energy Commission adopted insulation standards in 

1982, which granted the use of UFFI only if its emissions were below 0.01 % by 

weight in a standard test protocol (CARB, 1992). This rule effectively prohibits 

the use of UFFI in California. Studies have shown that HCHO released from 

UFFI products decreased rapidly in the first few months and progressively 

declines with time. Thus, HCHO concentrations in older homes from insulation 

materials are likely to be low after several decades of product off-gassing. 

c. Furnishings 

There are many furnishing products that contain HCHO resins, and thus, have 

the potential to emit HCHO. Furniture constructed with PB and wood veneer 

emits HCHO. Formaldehyde polymers are used in the manufacture of floor 

coverings. Pre-pasted wall paper and papers that consist of fibers or layers that 

are bonded with HCHO resins also have HCHO-emitting potential (Gammage 

and Gupta, 1984). Formaldehyde-based resins are commonly used in the textile 

industry; they are used to produce crease-resistant and flame-retardant fabrics, 

and fabrics that withstand shrinking. Formaldehyde-releasing agents also 

provide dimensional stability and serve as binders in textile printing. 

d. Cigarette Smoke

Sterling et al. (1987) measured HCHO in office buildings where smoking was 

permitted and found levels to be as high as 0.60 ppm. In comparison, nonsmoking office buildings had levels as high as 0.22 ppm. Although composite 

wood products contribute to the majority of HCHO emissions in indoor air 

(Battelle, 1996), environmental tobacco smoke may also be a source of 10 to 

25% of the noxious exposure (Sterling et al., 1987). 

e. Consumer Products

Formaldehyde is also found in varying quantities in selected consumer products 

such as nail care products, adhesives, and paper products. Fabrics can be 

treated with HCHO-containing compounds, where it is used to add permanent 

press qualities to clothing and draperies. Paper products, such as grocery bags, 

napkins, paper towels, and disposable sanitary products are often treated with 

HCHO-containing resins which improve strength and water resistance 

(Gammage and Gupta, 1984). These consumer products contribute minimally to 

the HCHO concentrations of indoor air. 

D. Emissions from Composite Wood Products 

Prior to this rulemaking, HCHO emissions from composite wood products were 

not specifically estimated due to a scarcity of information on HCHO emission 

rates, rates of decay in emissions over time, and the amount of product sold 

each year into the California marketplace. Based on efforts to quantify the extent 

of emissions from composite wood products in the state, staff identified 
Chapter III Page 20 

composite wood products as a separate category of area-wide sources of HCHO 

(Appendix B). 

1. Emissions Inventory

Area-wide sources are source categories associated with human activity that 

take place over a wide geographic area (CARB, 2004). For purposes of the 

statewide emissions inventory for toxic air contaminants, composite wood 

products (i.e., HWPW, PB, and MDF) were classified as an “aggregated point 

source,” which consists of many small point sources, which are not inventoried 

individually, but rather are estimated as a group and reported as a single source 

category. The emission estimation technique used to develop the statewide 

HCHO emissions inventory for composite wood products required knowledge of 

two fundamental elements: (1) rates of HCHO emission from HWPW, PB, and 

MDF, and (2) the amount of composite wood panels in use in California (CARB, 

2006c). Rates of HCHO emission were estimated from measured air 

concentrations (Myers, 1984; Myers and Nagaoka, 1981). For uncoated panels, 

decreases in HCHO emission over time were estimated in consideration of 

published emission decay studies (e.g., Zinn et al., 1990). Emissions of HCHO 

from uncoated panels were projected to occur over an 11-year time period when 

emission rates stabilize to about 2% of a newly manufactured panel. For coated 

panels, it was assumed that the initial rate of decrease in HCHO emission would 

be moderated by the coating, and that it would take longer for unbound HCHO in 

the panel to be released to air (i.e., 20-years). Estimates of the total amount of 

composite wood products in California that could potentially emit HCHO to air 

were developed from annual product summaries prepared by the USDA (e.g., 

Howard, 2004). 

For 2002, total statewide HCHO emissions from PB, MDF, and HWPW were 

estimated to be about 450, 190, and 240 tons per year, respectively. Thus, the 

total amount of HCHO emissions from this area-wide source category was about 

900 tons per year. 

E. Natural Occurrences 

Formaldehyde occurs naturally in the environment and it is a product of many 

natural processes. The primary sources of release from natural sources include 

biomass combustion, such as forest and brush fires (Howard, 1989). Other 

natural sources of HCHO include animal wastes, microbial by-products of 

biological systems, and plant volatiles (USDHHS, 1999). Photochemical 

oxidation of naturally emitted hydrocarbon precursors also account for HCHO 

emissions (Zhang et al., 2004). In water, HCHO is also formed by the irradiation 

of humic substances by sunlight (Kieber et al., 1990; WHO, 2001). 

Formaldehyde is present as a metabolic intermediate and exists at low levels in 

most living organisms (WHO, 2001). The basic pathway for cellular metabolism 
Chapter III Page 21 

of HCHO involves formic acid formation, catalyzed by formaldehyde 

dehydrogenase and glutathione, which is quickly removed by the supporting 

blood supply (Heck et al., 1982). The extent of exposure to HCHO other than by 

inhalation is very small under normal circumstances. In California, HCHO is 

present in drinking water in very low amounts. Except for accidental water 

contamination with HCHO, concentrations in drinking water are < 0.1 mg/L 

(WHO, 2001). Formaldehyde levels in food are higher, but the majority of HCHO 

present in food is not absorbed; rather it is rapidly converted to harmless 

metabolites in the body (CARB, 1992). Fruits and vegetables typically contain 

3 to 60 mg/kg, milk and milk products approximately 1 mg/kg, meat and fish 6 to 

20 mg/kg, and shellfish 1 to 100 mg/kg (WHO, 2001).

Reaction of HCHO with primary and secondary amines, thiols, hydroxyls and 

amides to form methylol derivatives is virtually instantaneous (WHO, 2001). 

During chemical reactions, HCHO acts as an electrophile and reacts with 

macromolecules, such as proteins, DNA, and RNA to form reversible adducts or 

irreversible cross-links. When HCHO is absorbed it can be oxidized to formate (a 

salt or ester of formic acid) along three different pathways, and exhaled as 

carbon dioxide (USDHHS, 1999). In the human body, HCHO is produced in 

small quantities as a normal metabolite and as well as in the oxidative 

demethylation of xenobiotics (i.e., foreign materials to the body), thus it 

accumulates in the liver. Removal of HCHO from blood plasma occurs with a 

half-life of approximately 1 to 1.5 minutes, with most of it being converted to 

carbon dioxide and exhaled via the lungs. Smaller amounts of HCHO are 

excreted in urine as formate salts and several other metabolites (WHO, 2001). 

F. Measured Formaldehyde Concentrations 

Formaldehyde concentrations range considerably depending on where 

measurements are made. This section provides an overview of measured and 

modeled concentrations in a range of microenvironments. 

1. Outdoor Concentrations

Formaldehyde is the most common aldehyde in the environment and it is usually 

present in the highest concentration of all the major aldehydes and ketones in 

ambient air (Finlayson-Pitts and Pitts, 2000). Since HCHO in outdoor air has the 

potential to enter buildings, schools, and residential areas, measured indoor 

concentrations must be gauged against outdoor levels of HCHO (3 to 4 μg/m3

; 

see Table III-5). The natural background concentration of HCHO is < 1 μg/m3 (1 

ppb = 1.23 μg/m3), with a mean = 0.5 μg/m3 (IARC, 1995). Concentrations in 

unpopulated areas, rural-urban interfaces and large-urban areas are reported to 

range from 0.4 to 2.5, 0.1 to 12.3, and 1.2 to 73.8 μg/m3

, respectively (FinlaysonPitts and Pitts, 2000). 
Chapter III Page 22 

In late 1984, CARB established a statewide air toxic monitoring network to 

facilitate the identification of air toxics which pose an inhalation risk to the largest 

number of people in the state. Ambient levels of HCHO are routinely monitored 

in the CARB toxics network, and the data are used to support human exposure 

and health risk assessments, assess temporal trends, changes in the 

environmental quality, and impacts on the environment. 

The CARB’s HCHO sampling network encompasses 15 air basins across 

California, including the eight most populous, which reflect the highest priority 

locations in the state (Figure III-2 – labeled as Figure 10). The ambient 

monitoring network consists of 17 air monitoring stations, where 24-hour samples 

are collected on a one day in 12 day schedule. Formaldehyde is continuously 

extracted from ambient air to silica cartridges coated with acidified 2, 4-

dinitrophenylhydrazine (DNPH) (CARB, 2001). An ozone scrubber is installed 

upstream from the sampling cartridge in order to eliminate interference by ozone. 

During sampling, HCHO reacts with DNPH to form hydrazone derivatives which 

are eluted from the cartridges and quantified by reverse-phase high performance 

liquid chromatography with ultraviolet absorption detector at 360 nm. 

Outdoor HCHO concentrations were obtained from the Annual Statewide Toxics 

Summary (Table III-6) for 1996 through 2005 (CARB, 2006b). The mean 

ambient HCHO concentration was 3.69 μg/m3

 and the maximum was 18.45 

μg/m3

. Trends for California have shown a steady mean level for the past 

decade, with annual HCHO concentrations ranging from 3.14 to 4.31 μg/m3. The 

highest mean values measured were 4.23 and 4.31 μg/m3 in 1996 and 2002, 

respectively. Minimum HCHO concentrations ranged from 0.06 μg/m3 (recorded 

in multiple years) to 0.4 μg/m3 in 2002. Maximum values ranged from 9.7 μg/m3 

in 2000 to 32.0 μg/m3 in 2001. While maximum values have been fairly 

consistent in 2002-2005, minimum values are higher than in the late 1990’s. 

Table III-5. Statewide Annual Average Formaldehyde 

Concentrations (μg/m3): 1996-20051

Year Range Mean (± SD) 

2005 0.2 to 17.2 3.52 ± 2.52 

2004 0.1 to 18.5 3.31 ± 2.35 

2003 0.2 to 14.8 3.87 ± 2.46 

2002 0.4 to 22.1 4.31 ± 2.80 

2001 0.06 to 32.0 3.91 ± 3.51 

2000 0.2 to 9.7 3.14 ± 1.82 

1999 0.06 to 16.0 3.94 ± 2.61 

1998 0.06 to 12.3 3.25 ± 2.19 

1997 0.06 to 14.8 3.55 ± 2.03 

1996 0.06 to 27.1 4.23 ± 2.85 

(1) Source: CARB (2006b). “μg/m3

” = micrograms per cubic meter; “SD” = 

standard deviation. Detection limit = 0.123 μg/m3.
Chapter III Page 23 

The standard deviation in statewide annual average HCHO concentration has 

been fairly consistent from year-to-year (Figure III-1). The maximum standard 

deviation was recorded in 2001 (3.51 μg/m3) and the lowest in 2000 (1.82 μg/m3). 

This is consistent with our understanding of regional-scale ambient HCHO 

concentrations which are largely determined by rates of photochemical 

processes. 

Figure III-1. Annual Statewide Summary for Ambient Formaldehyde1

Annual Statewide Toxics Summary of Formaldehyde

-4

-2

0

2

4

6

8

10

12

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

year

μg/m3

Mean

(1) Source: CARB (2006b). 

The statewide characterization of ambient HCHO in 2005-2006 was 

accomplished by measuring levels at selected locations across the state. 

Summary data for each of the monitoring sites is presented in Table III-7. These 

data were collected from January 2005 through April 2006; the most recent 

quality-assured data from the CARB network. Concentrations of HCHO varied 

across air basins, where in southern California, concentrations tended to be 

higher (≥ 4.0 μg/m3

) than in northern California (< 3.0 μg/m3). Intermediate 

concentrations (2.0 to 2.9 μg/m3), were observed in inland basins, South Central 

Coast, and the San Diego Basin. 
Chapter III Page 24 

Figure III-2. Mean Ambient Formaldehyde Concentrations by Air Basin. 
Chapter III Page 25 

At individual monitoring sites, mean annual concentrations ranged from 1.3 

μg/m3 (San Francisco) to 7.5 μg/m3 (Los Angeles) (Table III-6), while basin 

averages ranged from 1.6 μg/m3 in San Francisco Bay Area to 4.6 μg/m3 in the 

South Coast. The wide variation in HCHO concentration may have been due to 

a number of factors. Variations in ambient HCHO may be influenced by the 

number and types of sources located in a region, areas of heavy traffic, elements 

of climate, vegetation, varying terrain and geographical characteristics (near the 

coast versus inland), local meteorological patterns, and photochemical activity. 

Table III-6. Summary of Ambient Formaldehyde Concentrations 

(μg/m3): 1 January 2005 through 30 April 20061

Air Basin/Site Location Range Mean ± SD 

A. Southern California 

South Coast Air Basin 

Azusa 0.5 to 8.4 4.1 ± 2.4 

Burbank 0.5 to 9.1 4.9 ± 2.4 

Los Angeles 2.5 to 17.2 7.5 ± 3.6 

North Long Beach 0.5 to 7.5 3.1 ± 1.5 

Riverside 0.9 to 8.0 3.6 ± 2.2 

South Central Coast Air Basin 

Simi Valley 0.5 to 4.8 2.6 ± 1.6 

San Diego Air Basin 

Chula Vista 0.5 to 5.0 2.4 ± 1.0 

El Cajon 0.6 to 6.2 3.0 ± 1.4 

Salton Sea Air Basin 

Calexico 0.5 to 12.5 4.0 ± 2.4 

B. Northern California 

San Francisco Bay Area Air Basin 

Freemont 0.4 to 3.8 1.5 ± 0.9 

San Francisco 0.4 to 3.1 1.3 ± 0.7 

San Jose 0.5 to 5.2 2.0 ± 1.3 

San Joaquin Valley Air Basin 

Bakersfield 0.6 to 6.5 2.9 ± 1.7 

Fresno 0.9 to 8.5 3.3 ± 2.2 

Stockton 0.5 to 4.6 2.1 ± 1.2 

Sacramento Valley Air Basin 

Chico 0.4 to 12.3 3.5 ± 3.1 

Roseville 0.7 to 5.9 2.3 ± 1.4 

(1) Source: CARB (2006b).
Chapter III Page 26 

Table III-7 shows countywide HCHO emissions data (tons/year) from the 2005 

emissions inventory. The high ambient HCHO levels in the South Coast Air 

Basin follow from the presence of four of the top ten HCHO emitting counties, 

particularly Los Angeles County (CARB, 2006a). The six other counties in the 

state’s top ten accounted for approximately 25% of statewide HCHO emissions. 

Table III-7. Formaldehyde Emissions in the Top Ten California Counties1

Formaldehyde Emissions County Air Basin Tons/Year % of State 

Los Angeles South Coast 2,664 14 

San Diego San Diego 1,240 6 

Kern San Joaquin Valley 1,184 6 

Orange South Coast 908 5 

Alameda San Francisco Bay 711 4 

Santa Clara San Francisco Bay 647 3 

Santa Barbara South Central Coast 585 3 

Fresno San Joaquin 558 3 

Riverside South Coast 529 3 

San Bernardino South Coast 522 3 

(1) Source: CARB (2006b). 

Urban environments, such as Los Angeles (and large cities within other major air 

basins), commonly experience unhealthy air quality and high HCHO emissions. 

The most dominant source of HCHO in the troposphere is the oxidation of 

biogenic and anthropogenic hydrocarbons. Formaldehyde is also an important 

intermediate in the oxidation of hydrocarbons to carbon monoxide (CO); it is an 

ozone precursor and thus plays an important role in tropospheric ozone 

chemistry. Direct HCHO emissions also contribute to ambient HCHO, which are 

primarily derived from motor vehicles (CARB, 2006a). In future years, the 

adoption of increasingly stringent exhaust emission standards for motor vehicles 

will further reduce HCHO from this source category.

2. Indoor Concentrations

Generally, indoor HCHO concentrations are several times higher, and sometimes 

one or two orders of magnitude higher, than levels in ambient air, due to a higher 

concentration of sources in a confined space with reduced air mixing. As 

discussed, the major sources of HCHO are composite wood products in 

structural or finished product applications, permanent press clothing, some 

consumer products, upholstery, combustion sources, and environmental tobacco 

smoke. Many factors influence indoor HCHO concentrations, among them are 
Chapter III Page 27 

the emission rate and pattern, age of the sources, the ratio of source surface 

area to the indoor air volume, the indoor-outdoor air exchange rate, humidity, and 

temperature. Mobile homes contain significant amounts of high-emitting 

materials in a relatively small air space, and newer homes generally have greater 

amounts of new building materials that have the highest HCHO emission rates. 

Table III-8. Measured Indoor Formaldehyde Concentrations (μg/m3)

1

Environment Average Maximum 

Manufactured Homes 46 279 

Classrooms (Inside) 22 135 

Conventional Homes 17 285 

Office Buildings 16 32 

(1) Source: CARB (2005b). “Average” or “Maximum” values are the average or maximum 

values calculated from the data or reported in the one to four studies referenced for each 

environment. 

The current estimates of indoor HCHO levels in California span a broad spectrum 

of values. Estimates of average HCHO concentrations are useful in order to 

illustrate relative levels among the different environments, and to understand how 

Californian’s exposures compare to health benchmarks. Manufactured homes 

have the highest estimated average HCHO levels of 46 μg/m3 (CARB, 2005b, 

based on Sexton et al. (1986) and others). As manufacturing practices have 

changed since the early 1980’s, HCHO emissions from new composite wood 

products are lower today than what they were, as evidenced by an average 

reduction of about 50% measured by Kelly et al. (1999) compared to Pickrell et 

al. (1983). 

Data from the California Portable Classrooms Study collected in 2001 and 2002 

were used to estimate school-year average and maximum HCHO concentrations. 

A large statewide data set was collected across four seasons using both active 

and passive sampling methods. The calculated school-year average HCHO 

concentration, including both warmer and cooler season values, was 22 μg/m3

(CARB, 2005a). The statewide maximum mean was 135 μg/m3

; however, this 

value excluded extreme values measured in the study population. Results from 

the Portable Classrooms Study showed that HCHO concentrations in 4% of 

California’s classrooms (i.e., 10,720 classrooms housing 200,000 to 300,000 

children) exceeded OEHHA’s 8 hour reference exposure level for acute eye, 

nose, and lung irritation, and all of the classrooms in the study exceeded a one in 

a million excess lifetime cancer risk level. 
Chapter III Page 28 

Estimates for current conventional home concentrations of HCHO were 

estimated from two studies from the 1990’s (CARB, 2005b). In the National 

Human Exposure Assessment Survey (NHEXAS) conducted in 189 Arizona 

homes over several years, HCHO levels were measured using passive badges 

(Gordon et al., 1999). The NHEXAS utilized a probability-based sampling 

scheme to obtain data representative of the entire state. The second study, 

conducted in southern California, examined a population that resided in older 

homes in a mild climate (Avol, 1996). Results from the two studies were 

weighted by sample size to calculate estimates for conventional California 

homes. The estimated average HCHO concentration was 17 μg/m3 and the 

maximum was 285 μg/m3. 

The USEPA Building Assessment Survey and Evaluation (BASE) study, 

conducted in 100 large office buildings across the country from 1994 to 1998, 

found that pollutant levels in office buildings, including HCHO, were variable. 

The average and 95th percentile levels for HCHO were 16 and 32 μg/m3

 (USEPA, 

2007). 

All of these studies reflect the continuously elevated exposures that Californians 

experience throughout their day. Concentrations in all of these major indoor 

environments exceed acceptable health benchmarks for excess cancer risk, and 

even those for prevention of acute impacts. 

a. Portion of Formaldehyde Emitted Indoors that Moves Outdoors

Nearly all HCHO directly emitted indoors from indoor sources moves to the 

outdoors. Most such indoor-emitted HCHO moves outdoors within hours, 

primarily through indoor-outdoor air exchange from mechanical and natural 

ventilation and building leakage. Some HCHO is reversibly sorbed onto surfaces 

in the indoor space at a rate dependent on the indoor air concentration (vapor 

pressure) of HCHO, the actual surface area of the indoor surfaces, air 

movement, and other factors, with subsequent desorption at a future time. A 

small portion may be irreversibly lost through oxidative decomposition and other 

processes when uptake occurs in a surface water film, but this has not been 

quantified. A very low percentage of HCHO – from < 1% up to 7%, depending on 

the air exchange rate and other factors – is estimated to be removed through 

homogeneous chemical reactions that result in permanent removal of HCHO. 

Thus, a conservative estimate for the portion of HCHO emitted indoors that 

eventually makes its way outdoors is 90 to 100%, with the vast majority of the 

HCHO moving outdoors within hours of being released indoors. 

i. Release to the Outdoors through Air Exchange

Formaldehyde is a very volatile chemical that is readily transported to the 

outdoors as indoor air is replaced by outdoor air. All indoor spaces exchange air 

with the outdoors through mechanical or natural ventilation, or both, as well as 
Chapter III Page 29 

through infiltration due to building leakage, such as through construction 

interfaces and utility penetrations. Most homes in California are ventilated by 

infiltration and through opening of windows and doors (natural ventilation). A 

small percent of newly constructed homes have mechanical ventilation systems 

that actively draw outdoor air into the indoor space. Most medium and large 

public and commercial buildings are mechanically ventilated with a system that 

moves large quantities of air through the building over time in order to meet 

building ventilation requirements. Smaller public and commercial buildings are 

more variable in the type of ventilation they use; some have small mechanical 

systems that actively exchange air, while others are more similar to residential 

buildings and rely on natural ventilation and leakage for air exchange. 

Consequently, public and commercial buildings have a more variable range of air 

exchange rates than residences. 

The air exchange rate (AER) of a building is typically expressed as the number of 

building volumes of air that enter each hour, also called air changes per hour. 

Due to airflow patterns, incomplete mixing of air in some indoor spaces, and nonuniform distribution of indoor pollutant sources, ventilation efficiency is typically 

less than 100%. Ventilation efficiency generally refers to the effectiveness of the 

ventilation system or conditions in reducing such aspects as air pollutant 

concentrations, odors, and excessive heat, relative to the feasible theoretical 

maximum reduction (Bearg, 1993). In indoor spaces with reasonably well-mixed 

air, the decrease in the concentration of an indoor contaminant can be expressed 

based on the time constant of the ventilation process, or 1/N (in units of hours), 

where N is the air exchange rate (Bearg, 1993; Maroni et al., 1995). For an AER 

of 0.5 per hour, then, 1/N = 1/0.5 = 2 hours. After one time constant, or 2 hours, 

63% of the original body of indoor air would be released outdoors, based on an 

exponential decay function, and 37% would remain; after two time constants (4 

hours in this example) only 13.5% of the original body of air would remain. 

Air exchange rates (AERs) in California homes range from about 0.10 to 3.0 air 

changes per hour, averaging about 0.5 to 1 in the winter, and about 1 to 3 in the 

summer (Ozkaynak et al., 1996; Sheldon et al., 1993; Wilson et al., 1993; 

Berkeley Solar Group and Xenergy, 1990; Pellizzari et al., 1989; Wilson et al., 

1986; Koontz 1998; Pandian et al., 1993, 1998). In light of the various 

improvements in energy efficiency in California homes required through 

regulation or encouraged through rebates and other utility programs over the 

past decade, current average air exchange rates are likely closer to the lower 

ends of these ranges, or about 0.5 AER in the winter and 1 to 1.5 in the summer. 

Thus, based on the discussion above, the volume of air indoors is moved to the 

outdoors within a matter of hours under typical residential conditions. This 

several hour residence time of HCHO indoors may allow the opportunity for 

permanent loss of a very small portion of the HCHO through chemical reaction 

and some temporary loss through sorption onto surfaces (discussed below). 

However, most of the HCHO emitted indoors would be lost to the outdoors within 

several hours due to the exchange with outdoor air.
Chapter III Page 30 

Air exchange rates in public and commercial buildings range from about 0.2 to 9, 

averaging about 1 to 2.5 (Grot, 1995; Persily, 1989; Turk et al., 1987). Based on 

the time constant discussion above, the volume of air in these buildings would 

typically be replaced within a few hours. Thus, with the exception of areas of 

poor air mixing in the building, nearly all of the HCHO in a building at a given 

point in time would be expected to be moved to the outdoors within several 

hours. 

ii. Sorption to Indoor Surfaces and Materials 

Like other VOCs, HCHO displays sorption to and subsequent desorption from 

indoor materials (sink effects) such as carpet, walls, and furnishings. The rates 

of sorption and desorption are dependent on the air concentration (vapor 

pressure) in the room, temperature and humidity, the actual surface area (“fleece 

factor” – accounting for roughness and porosity), the indoor-outdoor air exchange 

rate and the efficiency of air mixing, and characteristics of the pollutant and the 

specific surface material (Weschler, 2003; Zhang et al., 2002; Won et al., 2001; 

Van der Wal et al., 1997; Tichenor et al., 1991; Nazaroff and Cass, 1989). 

However, sorption has generally been found to result in little or no permanent 

loss of HCHO and other very volatile compounds. Matthews et al. (1987) found 

that common gypsum board used for interior walls sorbed and released HCHO 

based on its vapor concentration in the air surrounding the board, with sorption 

highest with high air concentrations and desorption highest with low air 

concentrations, and very little loss of HCHO. In a study of ventilation and VOC 

concentrations in a call center, Hodgson et al. (2003) found that emissions of 

HCHO were elevated at higher ventilation rate conditions; the authors speculated 

that this association was attributable to re-emission from the indoor material 

sinks. Smedje and Norback (2001) found that after adjusting for season and air 

exchange rate, an increase in fleece factor of 0.1 m

2

/m3 was associated with an 

increase in HCHO of 4 μg/m3, and they concluded that furnishings and textiles 

acted as significant pollutant reservoirs in the classrooms studied. Van der Wal 

et al. (1998) did not test HCHO but found that other very volatile compounds 

exhibited a weak sorption effect, even when tested with the strongest sink 

(woollen carpet). 

Based on formaldehyde’s hydrophilic nature and possible reactivity with amino 

groups, a small portion of indoor-emitted HCHO may be permanently lost through 

oxidative decomposition and other processes when uptake occurs in a surface 

water film, but this has not been quantified. The limited data on HCHO to date 

generally indicate higher levels of HCHO associated with increased ventilation 

rates, which is consistent with substantial re-emission of HCHO from indoor 

sinks. 
Chapter III Page 31 

iii. Estimated Reactivity Losses

Indoor HCHO reactions appear to differ from those outdoors. The half-life of 

HCHO in the outdoor environment is estimated to range from about 4 to 10 hours 

(Kao, 1994; Atkinson, 1990). However, this relatively short lifespan is largely 

attributable to photolysis, which generally does not occur in indoor environments 

(or is very much reduced) due to lack of sunlight, and to reactions with 

atmospheric chemical species not normally present in large quantities indoors. 

Indoor reactivity loss of HCHO is believed to be largely attributable to 

homogeneous decomposition dominated by attack by the hydroxyl (OH) radical 

(Weschler and Shields 1996; Nazaroff, 2006). Ozone/alkene reactions can 

produce hydroxyl radicals indoors, resulting in “typical” OH levels indoors 

estimated at about 7 x 105 molecules/cm3 (or 2.8 x 10-5 ppb) by Weschler and 

Shields (1997). The reaction of hydroxyl with HCHO has a second order rate 

constant of 0.24 per ppb per second, or 860 per ppb per hour (Weschler and 

Shields, 1996). From this information, Nazaroff (2006) has estimated a first order 

loss rate coefficient of 0.024 per hour (R), and a fractional degree of reduction in 

the indoor concentration of HCHO from homogeneous chemical reaction equal to 

approximately 1 – [A/(A + R)], where A equals the AER. Thus, for an AER of 0.5, 

the HCHO concentration would be reduced by 1 – [(0.5)/(0.5 + 0.024)], or about 

5%. For an air exchange rate of 3 it would be reduced by about 0.8%, and for an 

AER of 0.3, it would be reduced by about 7.4%. These results are consistent 

with Weschler and Shields (2000) who found that concentrations of products 

generated from reactions among indoor pollutants increased as ventilation rates 

decreased. Thus, permanent loss due to reaction indoors might range from less 

than 1% up to 7%. However, because most buildings experience AERs of 0.5 

and higher, the percent reduction in HCHO levels would generally be very low, 

less than 5%. 

Few other indoor HCHO reactions have been reported or studied. Formaldehyde 

loss from reaction with ozone indoors has been found to be negligible, due to the 

exceedingly low rate constant of this reaction (Weschler 2000). Other reactions 

likely occur, but at levels too low to be readily evident. Consequently, reactivity 

losses indoors are estimated to total 1 to 7% of HCHO, but typically less than 

5%, and total permanent loss of HCHO indoors due to any cause is estimated 

conservatively at no more than 10% total. 

3. In-vehicle Concentrations

Pollutant concentrations were measured in-vehicles in simulated two-hour 

commutes in Los Angeles and Sacramento (Research Triangle Institute, 1998). 

The measured pollutants included particulate matter, metals, and selected 

organic compounds, including HCHO. In-vehicle HCHO levels were generally 

higher in Los Angeles than in Sacramento, where average in-vehicle 

concentrations ranged from 10 to 22 μg/m3

 and 5 to 14 μg/m3, respectively. In 
Chapter III Page 32 

two “maximum concentration” commutes designed to achieve the highest invehicle pollutant concentration possible, concentrations of 62 to 68 μg/m3

 were 

recorded. Compared to concentrations at roadside or ambient air monitoring 

stations (i.e., 2 to 4 μg/m3 in Sacramento and 7 to 19 μg/m3 in Los Angeles), 

average in-vehicle HCHO levels were typically two to four times higher. While 

factors such as roadway condition, congestion level, and time-of-day were found 

to variably influence in-vehicle pollutant levels, the effects of vehicle type and 

ventilation settings were found to be minimal. 

G. Modeled Formaldehyde Concentrations 

A near-source air dispersion modeling approach was used to estimate HCHO 

concentrations in outdoor air in two scenarios. This section describes the HCHO 

concentrations that may result near a warehouse store or downwind of a PB 

plant and associated cancer risks. 

1. Near-source Modeling

Near-source air dispersion modeling was conducted to estimate the outdoor air 

concentrations of HCHO resulting from emissions of HCHO from composite 

wood products. Two scenarios were modeled: (1) a warehouse-size home 

repair store with a large amount of composite wood products stored inside, with 

emissions exiting the building through a large roll-up door, and (2) bundles of 

particleboard stacked outdoors under a pole barn. In both scenarios, the nearest 

receptor, a resident, was assumed to be located approximately 30 meters from 

the point of emissions. Emissions were estimated for the different types of 

composite wood products based on emission factors summarized in Appendix C 

that are based on studies conducted by Battelle (1996). The USEPA Industrial 

Source Complex Short Term (ISCST3) air dispersion model was used to model 

HCHO concentrations downwind of the sites (USEPA, 1995). Because 

meteorological conditions vary throughout California, meteorological data from 

the following five cities were used: Burbank, Fresno, Oakland, Pasadena, and 

San Diego. An annual average air concentration was estimated for both 

scenarios at a distance of 30 meters from the emission source. The results of 

the modeling are contained in Appendix C. 

Cancer risk estimates can be calculated by using modeling results and the 

cancer unit risk factor for HCHO developed by the Office of Environmental Health 

Hazard Assessment (OEHHA, 2005) of 6.0 x 10-6 per μg/m3. The modeled 

annual average HCHO concentration for both scenarios corresponded to a 

cancer risk ranging from about 0.1 to 0.3 excess cancer cases per million people 

exposed, assuming a 70-year lifetime exposure. This modeling analysis 

demonstrates that composite wood products contribute to outdoor cancer risk. 

 
Chapter III Page 33 

2. Near-source Modeling of a Particleboard Plant

Similar to the near-source modeling described in subsection III.G. above, worstcase assumptions were made about what near-source HCHO concentrations 

could be downwind of a particleboard manufacturing plant. The Occupational 

Safety & Health Administration’s (OSHA) permissible 8-hour exposure level for 

HCHO is 937.5 μg/m3

 (0.75 ppm) (OSHA, Not Dated). This concentration was 

assumed to be uniform throughout a large manufacturing plant of 100 meters by 

100 meters with a 5 meter high ceiling. The following calculation was used to 

estimate an emission rate: 

 (937.5 μg/m3)(100 m)(100 m)(5 m) = 5.86 x 106 μg/hr 

 (8 hr) 

This emission rate is 42-times higher than in the warehouse-size home repair 

store scenario described in subsection III.G.1. In air dispersion modeling, 

downwind concentrations are directly proportional to the emission rate. Hence, 

the downwind air concentration could be as high as 42 times higher than 

downwind of the warehouse-size home repair store, or as high as 0.0225 μg/m3

 x 

42, for an estimated annual average concentration of 0.94 μg/m3. This 

corresponds to a risk of about six excess cancer cases per million people 

exposed, assuming a 70-year lifetime exposure. 

H. Atmospheric Persistence 

Formaldehyde can be present in the atmosphere in two ways: it can be directly 

emitted into the atmosphere or it can be formed in the atmosphere from methane 

and non-methane hydrocarbons through photochemical degradation. In 

California, photochemical degradation is the largest source of HCHO in ambient 

air (CARB, 2006a). The dominant atmospheric removal process for HCHO in the 

lower troposphere occurs primarily by photolysis and oxidation by hydroxyl 

radicals and by wet deposition, which leads to the incorporation of HCHO into the 

rain, cloud and fog water (CARB, 1992). In the absence of nitrogen dioxide, the 

half-life of HCHO is estimated to be 50 minutes during the daytime, but only 35 

minutes when nitrogen dioxide is present (Bufalini et al., 1972). With photolysis 

as the principal removal mechanism, atmospheric lifetimes of approximately 7 

and 4 to 10 hours, were calculated by Atkinson (1990) and Kao (1994), 

respectively. Episodic removal by wet deposition (e.g., rain, snow, or fog) can 

also occur, resulting in shorter atmospheric lifetimes on an event-basis. 

I. Risk Characterization 

A “toxic air contaminant” is defined in H&SC §39655(a) as: 

“...an air pollutant which may cause or contribute to an increase in 

mortality or in serious illness, or which may pose a present or potential 

hazard to human health.” 
Chapter III Page 34 

Presently, there are approximately 200 compounds that have been designated 

as top ten TACs in California (CARB, 1999), and HCHO is one of the most 

harmful TACs based on its potential public health risk (CARB, 2006a). In terms 

of estimated chances per million of developing cancer over a 70-year lifetime 

(i.e., 20 chances per million), exposure to ambient annual average 

concentrations of HCHO rank third behind diesel particulate matter (540 chances 

per million) and benzene (43 chances per million). While statewide efforts to 

control mobile source exhaust emissions have led to major reductions in 

emissions of diesel particulate matter, benzene, and HCHO, efforts to reduce 

other sources of HCHO have been limited. 

Studies show that Californians spend close to 90% of the day indoors (University 

of California, Berkeley, 1991), where HCHO concentrations are reported to be 

four- to ten-times higher than outdoors (CARB, 2005b). Estimates of the lifetime 

cancer risk from total daily exposure to HCHO are provided in section VII.D. 

J. References 

Atkinson R. 1990. Lifetimes and Fates of Toxic Air Contaminants in California’s 

Atmosphere. Appendix E: Atmospheric Lifetime and Fate of Formaldehyde. 

Final Report, CARB Contract No. A732-107, Research Division, Sacramento, 

CA. 28 pp. 

Avol E. 1996. Residential Microenvironmental and Personal Sampling Project 

for Exposure Classification. Final Report, CARB Contract No. 92-317, Research 

Division, Sacramento, CA. 

Battelle. (1996). Determination of Formaldehyde and Toluene Diisocyanate 

Emissions from Indoor Residential Sources. Final Report, CARB Contract No. 

93-315, Research Division, Sacramento, CA. 

Bearg DW. 1993. Ventilation Characterization. In: Indoor Air Quality and HVAC 

Systems. Lewis Publishers, CRC Press, Boca Raton, FL. Chapter 7, p. 125-

142. 

Berkeley Solar Group and Xenergy. 1990. Occupancy Patterns and Energy 

Consumption in New California Houses (1984-1988). California Energy 

Commission Consultant Report, P400-90-009, Sacramento, CA. 

 

Bufalini JJ, BW Gay Jr, and KL Brubaker. 1972. Hydrogen peroxide permeation 

from formaldehyde photooxidation and its presence in urban atmospheres. 

Environmental Science & Technology, 6(9): 816-821. 
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California Air Resources Board (CARB). 1992. Identification of Formaldehyde 

as a Toxic Air Contaminant. Part A. Exposure Assessment. Technical Support 

Document, Stationary Source Division, Sacramento, CA. 103 pp. 

CARB. 1999. Update to the Toxic Air Contaminant List. Staff Report, Stationary 

Source Division, Sacramento, CA. 23 pp. 

CARB. 2001. Standard Operating Procedure for the Determination of Carbonyl 

Compounds in Ambient Air. SOP MLD 022. Northern Laboratory Branch, 

Monitoring and Laboratory Division, Sacramento, CA. 10 pp. 

CARB. 2004. More information on areawide source categories. From: 

http://www.arb.ca.gov/ei/areasrc/moreareainfo.htm Accessed: 13 February 

2007. 

CARB. 2005a. State and Local Air Monitoring Network Plan. From: 

http://www.arb.ca.gov/aqd/namslams/namslams.htm Accessed: 10 October 

2006. 

CARB. 2005b. Indoor Air Pollution in California. Report to the Legislature, 

Pursuant to Health & Safety Code §39930. Research Division, Sacramento, CA. 

248 pp (plus appendices). 

CARB. 2006a. The California Almanac of Emissions and Air Quality, 2006. 

Planning & Technical Support Division, Sacramento, CA. 506 pp. 

CARB. 2006b. Annual Statewide Toxics Summary. Accessed: 14 October 

2006. From: http://www.arb.ca.gov/adam/toxics/statepages/hchostate.html

CARB. 2006c. Estimation of 2002 Formaldehyde Emission Inventory from 

Composite Wood Products. Planning & Technical Support Division, Sacramento, 

CA. 30 pp. 

Canadian Centre for Occupational Health and Safety. 2005. Formaldehyde gas. 

Cheminfo. Accessed: 11 May 2006. From: 

http:intox.org/databank/documents/chemical/formalde/cie422.htm 

Finlayson-Pitts BJ and JN Pitts Jr. 2000. Chemistry of the Upper and Lower 

Atmosphere: Theory, Experiments, and Applications. Academic Press, San 

Diego. 969 pp. [QC879.6 F5] 

The Formaldehyde Council, Inc. 2005. Formaldehyde: A Brief History and Its 

Contributions to Society and the U.S. and Canadian Economics. From: 

http://formaldehyde.org/EconomicBackground.pdf Accessed: 8 February 2007. 
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Gammage R and K Gupta. 1984. Formaldehyde. In: Walsh PJ CS Dudney and 

ED Copenhaver. Indoor Air Quality, p. 109-142. CRC Press, Boca Raton, FL. 

Gerberich HR and GC Seaman. 1994. Formaldehyde. Kirk-Othmer 

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Chapter IV Page 42 

IV. Manufacturing of Composite Wood Products 

This chapter describes how the composite wood products subject to this ATCM 

are manufactured and the fundamental chemistry of commonly used 

formaldehyde-containing and no added HCHO resins (see Chapter V for details). 

A. Background 

Hardwood plywood is made by gluing together hardwood plies, and used to 

make paneling, flooring, cabinets and furniture. Particleboard is made of wood 

fragments or particles glued together, and used to make countertops, cabinets, 

and floor underlayments. Medium density fiberboard is made of wood fibers 

glued together, and used to make furniture, cabinets, moldings, and door skins. 

While there are many other types of composite wood products (e.g., oriented 

strandboard, hardboard, etc.), the ATCM applies to HWPW, PB, and MDF. 

B. Composite Wood Product Manufacturing Plants 

1. Hardwood Plywood Plants

Plywood is made out of wood veneers and an inner core, where the core may be 

a wood veneer, lumber, PB, MDF, or a combination of materials (Figure IV-1). 

The proposed ATCM would apply to HWPW made with either a veneer core or 

with a composite core composed of PB, MDF, or a combination of PB, MDF, and 

wood veneers (e.g., combination core). The primary uses of HWPW are for 

interior wall panels, furniture, flooring, and cabinets. In 2003, HWPW production 

in the U.S. was estimated to be 1.9-million m3

 (Howard, 2005). 

Figure IV-1. Types of Hardwood Plywood 

Source: Cognard (2005).

Logs are steamed, then peeled to form a continuous ribbon of thin veneer. The 

veneer is cut and dried. Processed veneers are stacked onto a assembly line 

and adhesives applied. Stacked veneers are cold pressed and then hot pressed. 

After the panels cool, they are trimmed, resized, or sanded. 
Chapter IV Page 43 

Figure IV-2. Plywood Manufacturing Process 

Source: Cognard (2005). 

Plywood panels of 3⁄8” or thinner typically contain one double glue-line; panels 

with thicknesses of 1⁄2”, 5⁄8”, and 3⁄4” contain two double glue-lines (Spelter, 1989). 

A single glue-line application rate is 30-40 lbs per 1,000 ft2 (Industry Canada, 

2005a; 2005b). As such, thicker panels require twice as much glue as thin 

panels. The glue used may contain HCHO. 

2. Particleboard Plants

Particleboard (PB) is typically made in three layers: two face layers and a core. 

The faces of the board consist of finer wood particles than the core. This layered 

construction promotes more consistent heat transfer during the curing process. 

In 2003, PB production in the U.S. was 7.1-million m

3

 (Composite Panel 

Association, 2006; Howard, 2005; Industry Canada, 2005a). It is principally used 

in furniture manufacturing, underlayments, or substrates for countertops. 

The five main steps in PB manufacturing are: (1) furnish preparation (i.e., wood 

particles), (2) resin application, (3) mat formation, (4) hot pressing, and (5) 

finishing. The furnish is prepared by refining logs and other raw materials into 

small particles, and drying them to achieve a moisture content of 2 to 7% 

(Cognard, 2005). Drying the furnish to a specific moisture content is key to 

ensuring that the proper amount of resin is added prior to manufacturing, which is 

fundamental to controlling surface HCHO emissions and desired structural 

properties. As addition of the resin provides moisture to the furnish, it is a critical 

step insofar as achieving an optimal moisture content at the start of the 

manufacturing process. 

During resin application, resin is mixed with the furnish. In PB, the resin 

accounts for 5 to 12% of the total weight of the panel depending on the size of 

the wood particles and the required properties of the panel (e.g., moisture 

resistance) (Cognard, 2005; Goldboard, 2000). After a UF resin is thoroughly 

Log Yard Log Conditioning Peeling 

Lay up Line 

(Cold Press) 

Apply 

Adhesive 

(Hot Press) 

Panel Trimming 

& Sanding 

Finished 

Panel 

Drying 
Chapter IV Page 44 

mixed with the furnish, the mixture is cold-pressed to form a mat, then hotpressed at cure temperatures ranging from 130 to 150 oC (Cognard, 2005). In 

comparison, PB made with PF resin requires hot-pressing at temperatures 

ranging from 180 to 230 oC (Pizzi, 1994). In the finishing process, PB panels are 

trimmed, cut, and sanded to produce panels of a desired thickness. Figure IV-3 

depicts a typical production line for PB manufacturing. 

Figure IV-3: Schematic of a Particleboard Manufacturing Line 

Source: Wikipedia Contributors, 2006.

3. Medium Density Fiberboard (MDF) Plants

In 2003, MDF production was 2.7-million m3 in the U.S., where it is primarily used 

in the manufacture of furniture, shelving, molding, and kitchen cabinets 

(Composite Panel Association, 2006; Howard, 2005). The manufacturing 

process for MDF is similar to that for PB, except that additional processing is 

required to prepare the fibers in the furnish (McCallum, 1996; Tetlow, Not Dated). 

Logs used in the manufacture of MDF are debarked before being chipped with a 

disk chipper to produce chips of the desired size. After washing, the chips are 

compacted using a screwfeeder and then fed into a defibrator (or digester) to 

produce a fine, light-weight pulp. From the defibrator, the pulp enters a blowline, 

where it mixed with wax and resin before being stored for making panels. This is 

the main factor contributing to the difference in density between MDF (600 to 800 

kg m-3) and PB (160 to 450 kg m-3). 
Chapter IV Page 45 

C. Resins Currently Used in Composite Wood Products 

1. General Properties of Resins 

The role between resins and wood surfaces is a very complex interaction and 

entails many different theories regarding bond formation and thermodynamic 

processes. First, we must define some terms in order to describe some of the 

interactions that occur (USDA, 1999): 

• Adhesive is a substance capable of holding materials together by surface 

attachment. 

• Adherend is a substrate held to another substrate by an adhesive. 

• Adhesion is defined as “the state in which two surfaces are held together 

by interfacial forces, such as valence forces, interlocking action, or both. 

o Valence forces are the interactions of atoms, ions, and molecules

by the adhesive and the adherend. 

o Interlocking action means surfaces are held together by an 

adhesive that has penetrated the porous wood surface. 

The primary mechanism by which adhesives fasten to porous wood surfaces is 

mechanical interlocking (Frihart, 2004), which takes place below the surface of 

the wood. The adhesive penetrates beyond the damaged fibers of the wood 

surface into the next two to six wood cell layers. The deeper the adhesive can 

penetrate into the wood, the more effective the mechanical interlocking. Also, if 

the adhesive is able to diffuse into the cell walls of the wood while curing takes 

place, the strength of the bond can exceed the strength of the wood itself. 

Three intermolecular attraction forces are important to the bond formation 

between adhesive and the molecular structure of wood (Vick, 1999). They are: 

1. Dipole-dipole forces – positively and negatively charged polar molecules 

that have powerful attractions toward other polar molecules; 

2. London forces – a weaker attraction of polar and non-polar molecules. 

These forces are weaker than dipole-dipole forces but increase as the 

number of atoms or molecules increase; and 

3. Hydrogen bonds – a strong attraction between a positively charged atom 

from a polar molecule and the electronegative atom of another molecule. 

Hydrogen bonds are usually stronger than dipole-dipole forces. Hydrogen 

bonds are probably the most important intermolecular force due to the 

number of hydroxyl groups on cellulosic surfaces. 

Adhesion is nearly completed after the transformation of the adhesive from liquid 

to solid form. There are two mechanisms in which an adhesive changes from 

liquid to a solid form (Connor, 2001). This transformation may be a physical 

change (thermoplastics) or a chemical change (thermosettings). In 

thermoplastics, the solid form may occur by a loss of solvent from the adhesive 
Chapter IV Page 46 

through evaporation or diffusion into the wood, or cooling of molten adhesive on 

a cooler surface. For thermosets, the mechanism is through a chemical 

polymerization to form crosslinked structures. 

2. Formaldehyde-containing Resins

The most prevalent types of resin used in composite wood products contain 

HCHO (Frihart, 2005). Compounds such as urea, phenol, and melamine are 

combined with HCHO to develop different formulations of resins for PB, MDF, 

plywood, and other composite wood products. The chemical reaction involves a 

nucleophile (electron-rich compound), such as urea, phenol, and melamine, with 

an electrophile (electron-poor compound), such as HCHO. There are three 

reaction steps involved with HCHO adhesives (Frihart, 2005): 

1. Formaldehyde reacting with a nucleophile to form a hydroxymethyl 

derivative (Figure IV-4); 

2. Condensation of two hydroxymethyl groups to form a bismethylene ether 

group, with loss of a water molecule; and 

3. Elimination of HCHO from the bismethylene ether to form a methylene 

bridge. 

The rate of reaction depends on the pH of the environment, the nucleophile, 

temperature, and the addition of catalysts or retarders. 

Figure IV-4. Reaction between a Nucleophile (Nu) and Formaldehyde 

 

 

O

H

H

N u:

E le c tro p h ile

OH

N

N

N

H2N NH2

NH2

NH2

O

H2N

Nucleophiles

 Phenol Urea Melamine 

The majority of formaldehyde-containing resins are waterborne. The amount of 

water in the resin is very critical for the polymerization of the resin. Too much 

water hinders the reaction; too little water reduces the mobility of the resin and 

limits the polymerization process. For resin formulation, the mole ratio of HCHO 

needs to be greater than that of the co-reactant (Frihart, 2005), which is needed 
Chapter IV Page 47 

to bring about the required reactions to form a crosslink-type solid. All 

formulations are also adjusted to decrease the amount of HCHO emissions and 

to insure good curing times and fast set rates. 

a. Urea-Formaldehyde Resins

Urea-formaldehyde (UF) resins have been around since the early 1920’s and 

have been the most dominant adhesive for PB, MDF, and HWPW (Meyer and 

Hermanns, 1986). In the U.S. alone, it is estimated that the demand for UF 

resins will reach over 2.4 billion pounds in 2007. Approximately 89% of the UF 

produced in North America is used for wood adhesives (Kennedy, 2005). Ureaformaldehyde resins are used for interior applications and need a dry 

environment. They cure fast and are relatively inexpensive. There are many 

advantages and disadvantages concerning the use of UF resins (Table IV-1). 

Table IV-1. Advantages and Disadvantages of Urea-formaldehyde Resins1

Advantages Disadvantages 

• Low cost 

• Rapid cure rate 

• Light color 

• Non-flammable 

• Resistant to microorganisms 

• Not water-resistant 

• Continuation of HCHO 

emissions 

• Combination of moisture and 

heat depolymerizes resin 

(1) Source: Frihart (2005). 

i. Manufacturing Urea-formaldehyde (UF) Resins

Urea and HCHO are the building blocks for UF resins. Urea is synthesized by 

combining ammonia (NH3) and carbon dioxide (CO2) under heat and pressure. 

Formaldehyde, with the addition of a catalyst, is manufactured from methanol 

(CH3OH) (Orica, 1999). There are two main steps involved in the manufacturing 

of UF resins (Connor, 1996). The first stage involves the addition of HCHO with 

urea. Under basic conditions (pH 8 to 9), urea is hydroxymethylated to form 

mono-, di-, and trihydroxymethylureas (Figure IV-5). 
Chapter IV Page 48 

Figure IV-5. Addition of Urea and Formaldehyde to Form Hydroxymethylureas 

O

H2N NH2

O

H H

N

HOH2C

CH2OH

N

H

O

CH2OH

+

3

Addition

The second stage involves a condensation reaction under acidic conditions 

(about pH 5) to generate oligomers that will polymerize until a target viscosity is 

obtained (Figure IV-6). Polymerization is slowed by raising the pH and cooling 

the reaction. Water is then removed by vacuum distillation to achieve a desired 

solids content (i.e., 60 to 65%). Urea is often added to the resin to reduce HCHO 

emissions and obtain the desired formaldehyde-to-urea mole ratio. 

Figure IV-6. Condensation Reaction and Polymerization of UF Resins 

N

HOH2C

CH2OH

N

H

O

CH2OH

N

HOH2C

CH2OH

N

H

O

C

H2

O

C

H2

N

CH2OH

N

H

O

C

H2

O

C

H2

N

CH2OH

N

H

CH2OH

O

n

Condensation

acid

-H2O

The reactions that occur during UF resin synthesis are reversible. During the 

forward reaction, water is eliminated. However, if moisture interacts with the UF 

resin, depolymerization may occur, leading to hydrolysis or the release of HCHO. 

ii. Curing Urea-formaldehyde (UF) Resins

During the hot pressing of a composite wood product, polymerization and 

condensation of the resin is completed and the release of free HCHO occurs. 

Hot-press temperatures for UF resins usually range between 100 to 120 °C. This 

is a critical step in the manufacturing process since too much heat can hydrolyze 

the UF resin into urea and HCHO, which degrades the bond and releases even 

more HCHO (Conner, 2001). Table IV-2 displays some of the characteristics of 

UF resins: 
Chapter IV Page 49 

Table IV-2. Characteristics of Urea-formaldehyde (UF) Resins1

Category Summary 

Form Available as a dry powder or liquid(s) 

Properties High in dry strength; moderately durable under damp conditions; 

low resistance to temperatures > 49 °C; white or ta n in color 

Preparation Liquid use as received; powder form mix with water; hardeners, 

extenders, and fillers may be added; hot press at 100 to 120 °C. 

Uses HWPW for interior use and furniture; interior PB and MDF for 

cabinets, underlayment, flush doors, and furniture core stock 

(1) Source: Eckelman (1997). 

b. Phenol-formaldehyde (PF) Resin

Phenol-formaldehyde (PF) resins were first introduced and commercially 

developed in the early 20th century by Leo Baekeland (Society of the Plastics 

Industry, 1997). They are one of the oldest classes of synthetic polymers used in 

composite wood products. Phenol-formaldehyde resins are used mainly for 

exterior applications because of their high water resistance and higher strength 

retention after water soaking. They also have outstanding durability and high 

polymer strength due to good adhesion to wood surfaces. Approximately 32% of 

the total 1.78 metric tons of resin solids is consumed in North America (Zheng, 

2002). The primary composite wood products that use PF resins are oriented 

strandboard and softwood plywood, which are mainly used for exterior sidings. 

They may be unsuitable for decorative applications, such as paneling and 

furniture, because of the inherent dark color of the resin. Although PF resins 

have many advantages, some of their disadvantages are longer press times and 

higher press temperatures, which results in higher energy consumption and 

lower productivity. However, by altering reaction temperature, reaction time, 

catalyst type, and formaldehyde-to-phenol ratio, some disadvantages may be 

overcome (Frihart, 2005). 

There are two main types of phenolic resins: resole and novolac. Novolac resins 

are produced using an acid catalyst and excess phenol; whereas, resole resins 

are produced with a base catalyst and excess formaldehyde (Durez, Not Dated). 

Most wood adhesive applications use resole resins because they provide a 

soluble adhesive that has good wetting properties and the cure is delayed until 

activated by heat, allowing additional time for product assembly. 
Chapter IV Page 50 

i. Phenol-formaldehyde (PF) Resin Chemistry

Phenolic resins are developed through a polycondensation reaction of phenol 

and HCHO (Frihart, 2005). Phenols may react with HCHO in both the ortho- and 

para- positions of the hydroxyl group in either a basic or acidic environment 

(Figure IV-7). 

Figure IV-7. Addition Reaction for Phenol and Formaldehyde 

OH

O

H H

OH

HOH2C CH2OH

CH2OH

+

3 Addition

base or acid

The second stage of resin development involves the formation of linear phenolformaldehyde oligomers through heat and condensation. The oligomers are 

created by reaction of the methylol groups with other phenol or methylol phenol 

compounds (Figure IV-8). 

Figure IV-8. Phenol-formaldehyde (PF) Resin: Condensation Reaction 

OH

HOH2C

CH2OH

C

H2

CH2OH

OH

C

H2

CH2OH

OH

CH2OH

n

OH

HOH2C CH2OH

CH2OH

Condensation

heat

-H2O

After the formation of the linear oligomers, polymerization occurs to create a 

phenol-formaldehyde crosslinked polymer network (Figure IV-9). 
Chapter IV Page 51 

Figure IV-9. Phenol-Formaldehyde Cross-linked Polymer 

Ch

OH

OH OH

OH

Ch

OH

OH OH

Ch

Ch

Ch

Phenol Form aldehyde Crosslinked Polym er

Unlike UF resins, PF reactions are not reversible and are pressed at a higher 

temperature (190 °C or higher) (Eckelman, 1997). T able IV-3 lists some of the 

characteristics involved with PF resins. 

Table IV-3. Characteristics of Phenol-formaldehyde (PF) Resins1

Category Summary 

Form Available as a dry powder or liquid(s) 

Properties High in dry and wet strength; very resistant to moist conditions 

and high temperatures; dark red color 

Preparation 

Liquid form use as received; powder form mixed with alcohol or 

water; extenders and fillers usually added to liquid form; press 

temperatures are higher (up to 200 °C) 

Uses Exterior use in softwood plywood, OSB, hardboard 

(1) Source: Eckelman (1997). 

c. Melamine-containing Formaldehyde (MF) Resins

Like PF resins, melamine-formaldehyde (MF) and melamine-urea-formaldehyde 

(MUF) resins are resistant to moist conditions (Marra, 1992). They are most 

commonly used for exterior and semi-exterior plywood and PB. In addition, MF 
Chapter IV Page 52 

is used for decorative laminates, paper treating, and paper coating. One 

drawback of MF resins is the cost of melamine (e.g., $63 to $68 per pound) (ICIS 

Pricing, 2006). This contributed to the development of MUF resins, which still 

have water resistance, but at a lower cost. The MUF resins can be viewed as a 

less expensive MF resin that has lower durability, or as a more expensive UF 

resin that has better water resistance. The MF and MUF resins are also lighter in 

color compared to PF resins. 

i. Melamine Chemistry

The formation of melamine-based resins is very similar to that of an UF resin 

(Frihart, 2005). However, the addition of HCHO to the amino groups of 

melamine is faster and more complete than to urea because melamine is a 

stronger nucleophile than urea (Figure IV-10). 

Figure IV-10. Addition Reaction for Formaldehyde and Melamine 

N

N

N

H2N NH2

NH2

O

H H

N

N

N

HN NH

HN

CH2OH

CH2OH CH2OH

+

3

Addition

Melamine Formaldehyde Adduct

Melamine can potentially react with six HCHO molecules to form two methylol 

groups on each exocyclic amine group. This condensation reaction can occur 

under acidic, neutral, and slightly basic conditions (Figure IV-11). 

Figure IV-11. Condensation Reaction of Hydroxymethylated Melamines 

N

N

N

HN NH

HN

CH2OH

CH2OH CH2OH

N N

N N

H

HN

HN

CH2OH

CH2OH

C

H2

N

H

N N

N

HN

CH2OH

N

H

C

H2

N

H

N N

N

HN

HN

CH2OH

n

Condensation

heat

-H2O

Furthermore, the release of HCHO during the condensation reaction is less 

prominent than for UF resins. During polymerization, pH is lowered and 

temperature is raised to insure a complete reaction. In addition, melamine 
Chapter IV Page 53 

significantly reduces HCHO emissions (Dijkman, 2004). Table IV-4 lists some of 

the properties and uses for melamine-based resins. 

Table IV-4. Summary of Melamine-based Resin Properties and Uses1

Category Summary 

Form Powder with blended catalyst; may use up to 40% melamine 

with urea; white to tan; colorless bondline 

Properties High dry and wet strength; very resistant to water and damp 

conditions 

Preparation Powder mixed with water and applied at room temperature; 

cured in hot press (120°C - 150°C) 

Uses Typically a fortifier in UF resins; used in HWPW and MDF 

(1) Source: Eckelman (1997). 

3. No added Formaldehyde Resins

For the past 70-years, HCHO has been an essential solvent in composite wood 

product resins. In fact, greater than 95% of wood adhesives are formaldehydebased (Dunky, 2005). However, there are “no added” HCHO resins that are 

currently in the composite wood products market that are developing into a 

feasible option for manufacturers. Examples of “no added” HCHO resins are 

polydiphenylmethane diisocyanate (pMDI), soy-based, polyvinyl acetate (PVA), 

and tannin resins. 

a. Polydiphenylmethane Diisocyanate (pMDI) Resins

Isocyanate-based adhesives have been commercially available since the 1940’s, 

but their use increased substantially in the 1970’s (Eckelman, 1997). 

Polydiphenylmethane diisocyanate (pMDI) is primarily used in oriented 

strandboard production and applications for strawboard products, but has been 

commercially available for other wood composites, such as MDF and PB 

(Ecology Action, 2004). The cost of pMDI is considerable; however, these resins 

have a high reactivity and efficiency in bonding to wood surfaces or adhering to 

difficult surfaces (Frihart, 2005). The chemical bonds in pMDI are stronger and 

more stable than the condensation reactions of UF or PF (Pizzi, 1994). There is 

even more demand for pMDI-bonded products where increased water resistance 

is required since pMDI resins are resistant to hydrolysis. Table IV-5 lists the 

advantages and disadvantages of pMDI. 
Chapter IV Page 54 

Table IV-5. Advantages and Disadvantages of Polydiphenylmethane 

Diisocyanate (pMDI) Resins1

Advantages Disadvantages 

• Tolerance for higher moisture 

content in wood 

• Less MDI is needed on a weight 

basis to form bonded material 

• Faster press cycles 

• Lower press temperatures 

• No formaldehyde emissions 

• Higher cost 

• Use of mold releases for metal 

press platens 

• Health risks to workers 

(isocyanates) 

• Must be stored away from 

moisture to prevent precure 

(1) Source: Marra (1992). 

i. Polydiphenylmethane Diisocyanate (pMDI) Chemistry 

The first reaction for the polymerization of MDI that occurs is the combination of 

the isocyanate and water to form a urethane bridge (Figure IV-12). Once 

isocyanate reacts with water, the rest of the process proceeds rapidly if there is 

enough isocyanate for the reaction. The result is an unstable carbamic acid 

product that decomposes to form an amine and carbon dioxide (Pizzi, 1994). 

Figure IV-12. Isocyanate and Water React to Produce a Urethane 

N

H

O

R N C O + H R C O R' 2O

The amine formed by this reaction will react immediately with additional 

isocyanates to form a substituted urea compound (Figure IV-13). 

Figure IV-13. Reaction of an Amine and Isocyanate to Form a Substituted Urea 

N O N N

O

R H2 + C R R H C NH R
Chapter IV Page 55 

Cross-linking and hardening occur when amine groups from the urethane react 

with the substituted urea to form allophenate and biuret bridges (Figure IV-14). 

Figure IV-14. Urethane Bridge and Substituted Ureas React with Isocyanates 

to Produce Allophenate and Biuret Bridges 

R N C O NH C

O

N C

O

R O

R

N C R'

O

+ O

allophenate

R H R'

R N C O NH C

O

N C

O

R NH

R

N C R

O

+ R H NH R

biuret

This rapid polymerization and ability to form bonds in the presence of higher 

moisture content gives MDI advantages in several applications. When used in 

core areas that might have higher moisture contents, MDI bonds to wet lumber. 

Another use of MDI is the manufacturing of strawboard. Because of the low 

polarity of MDI, it is able to penetrate through the waxy coating of straw and cure 

readily (Frihart, 2005). Table IV-6 lists some of the MDI resin characteristics. 

Table IV-6. Characteristics of MDI Resins1

Category Summary 

Form Liquid resin or water emulsions; can create wide variety of 

adhesives; light brown liquid and clear bondline 

Properties 

Excellent adhesion to wood and other materials, such as metals 

and plastics; resistant to high moisture and temperatures; 

excellent chemical aging resistance 

Preparation One-part adhesive cures by heat or moisture; two-parts resins 

cure upon mixing; very rapid cure 

Uses Used mainly in OSB, PB, MDF or flakeboards 

(1) Source: Eckelman (1997). 
Chapter IV Page 56 

b. Soy-based Resins

Soy-based resins have been used in the manufacture of plywood for more than 

70-years (United Soybean Board, 2004). However, early soy resins had low 

solids, slow press times, and, most importantly, poor water resistance (Wescott 

et al., 2006). This limited the use of soy resins to only interior applications. 

Since the introduction of petroleum derived resins (e.g., UF or PF), soy-based 

resins rapidly diminished from the market because they were inferior in 

performance and more expensive. In the last 40-years, UF and PF have been 

the most popular resins used in composite wood products. In recent years, 

environmental concerns from volatile organic compounds, such as freeformaldehyde from UF resins and the constant increase of petroleum prices, 

have revitalized interests in developing soy-based resins (Lorenz et al., 1999). 

The primary ingredient in soy-based resins is soy flour, which is produced by 

grinding the meal that remains after removing soybean oil (Wescott and Frihart, 

2004). Soy flour is high in protein and contains many side-chain reactive amino 

acid groups and is believed to have the ability to react with other cross-linking 

agents to create a water-resistant resin. 

i. Soy-based Resin Preparation

In a study by Wescott and Frihart (2004), soy resins were prepared in a lowtemperature environment. They are formulated with water, sodium hydroxide 

(8% to 12%), and a solubilizing agent (e.g., a glycol), along with soy flour. The 

ingredients were combined and heated to 70 °C. Wat er durability was modified 

by the addition of a copolymer or synthetic resin to engage the polymerization 

process. 

New soy resins are beginning to show promise in both performance and 

economics compared to the UF and PF resins. Soy resins are also safer to 

handle and reduce the amount of free HCHO that can be emitted from composite 

wood products. Chapter V describes a range of different soy-based resins that 

are being explored today for composite wood products. 

c. Polyvinyl Acetates (PVA)

Polyvinyl acetate (PVA) is known throughout as your common “white glue” used 

mainly for HWPW veneers and wood bonding in furniture. This resin sets quickly 

at room temperature and has a high dry strength, but is less resistant to 

moisture, humidity, or high temperatures (Eckelman, 1997). Because PVA loses 

bonding capacity at temperatures over 70 °C, it is used mainly for interior 

applications. However, cross-linking agents, such as chromium complexes, may 

be added to the resin to withstand higher moisture contents and temperatures 

(Connor, 2001). 
Chapter IV Page 57 

Polyvinyl acetate is a linear polymer that is flexible in nature and exhibits good 

flow on the surface of wood (Frihart, 2005). Since PVA has a high content of 

acetal groups, the resin is able to form hydrogen bonds with wood for a good 

interfacial adhesion. The polymer flexibility of PVA provides a conformable bond 

if the wood expands or contracts (Marra, 1992). 

i. Polyvinyl Acetate (PVA) Chemistry 

Polyvinyl acetate is a self-polymerizing resin that is initiated under free radical 

conditions of the monomer vinyl acetate. By adding ethylene, the polymer chains 

can be modified to form a PVA copolymer which creates a more flexible resin 

(Figure IV-15). 

Figure IV-15. Polymerization of PVA 

H2C CH

CH3

O

C

H2

CH

O

Ch

Ch

O

CH3

n

Free Radical

Homopolymerization

Poly(vinyl acetate) Homopolymer

Cross-linking PVA with other resin additives such as glyoxal, HCHO resins, or 

isocyanates, can convert the PVA from a thermoplastic to a thermoset (see 

subsection IV.C.1). This improves resistance to high moisture and higher 

temperatures (Frihart, 2005). Table IV-7 lists some characteristics of PVA. 

Table IV-7. Characteristics of Polyvinyl Acetate (PVA) Resins1

Category Summary 

Form Several brands available; vary in properties; sold in liquid forms 

Properties High dry strength; low resistance to moisture and elevated 

temperatures; white or yellow in color 

Preparation Ready to use liquid; applied at room temperature 

Uses HWPW; furniture assembly 

(1) Source: Eckelman (1997). 
Chapter IV Page 58 

d. Tannin-based Resins

Attempts have been made to depart from the use of petroleum derived products, 

such as phenol, to using natural resources instead of synthetic resins. Tannins, 

as a natural substitute for phenols, are a natural phenolic-type material that is 

extracted from the bark or heartwood of many plant species (Roffael et al., 2000) 

(Figure IV-16). Mangrove and mimosa bark contain comparably high levels of 

extractives, while the amount from spruce bark is relatively low. Commercially 

available tannin extracts that are used in manufacturing include: Acacia sp. 

(wattle or mimosa), Schinopsis sp. (quebracho), Tsuga sp. (hemlock), Rhus sp. 

(sumac), and Pinus sp. (Pizzi, 2006). 

Figure IV-16. Average Yield of Extractives from Different Woods and Barks 1 

0% 10% 20% 30% 40% 50%

Chestnut Wood

Oak Wood

Oak Bark

Spruce Bark

Pinus radiata Bark

Sumach

Valonea

Quebracho Wood

Mimosa Bark

Mangrove Bark

Tannins

Non Tannins

(1) Source: Roffael et al., 2000. 

Tannins are categorized as either hydrolyzable or condensed. Hydrolyzable 

tannins are used more for medicinal purposes and not in adhesive research. 

Condensed tannins, which are used in the preparation of resin adhesives, 

constitute more than 90% of the total world production (Sellers and Miller, 2004). 

Tannins are more reactive than phenol resulting in water-resistant bonds when 

polymerized with HCHO (Santana et al., 1997). This reactivity is due to their “Aring,” which is resorcinolic in nature (Figure IV-17). The A-ring ensures the rate 

of reaction to be 10 to 50 times faster than phenol (Kim et al., 2003). 
Chapter IV Page 59 

Figure IV-17. The A-Ring Unit of a Tannin Compound 

HO

OH

Tannins have their limitations compared to synthetic resins. They have a high 

viscosity, restrictions on availability, and are highly reactive (Frihart, 2005). This 

causes a short pot-life for tannin resins. However, other hardeners may be 

added to prolong tannin pot-life (Trosa and Pizzi, 2001). Reactions involving 

tannin compounds are very complex, but studies have shown that HCHO reacts 

with the free C6 and C8 sites on the A-ring to form the adhesive (Kim et al., 

2003). This characteristic results in HCHO emissions comparable to the wood 

itself. Research in tannin adhesives has continued to discover more lowformaldehyde resins. 

D. References 

Cognard P. 2005. Woodworking and furniture adhesives. Part 5: Applications 

and end uses. Accessed: 20 September 2006. From: 

http://www.specialchem4adhesives.com/resources/articles/printarticle.aspx?id=1

235 

Composite Panel Association (CPA). 2006. 2005 North American Shipments 

Report: Particleboard, Medium Density Fiberboard, Hardboard. CPA, 

Gaithersburg, MD. 18 pp. 

Connor AH. 1996. Urea-formaldehyde adhesive resins. In: Salamone JC (ed). 

Polymeric Materials Encyclopedia, Volume 11, T-Z, p. 8496-8501. CRC Press, 

Inc., Boca Raton. ISBN: 0-8493-2470-X. 

Connor AH. 2001. Wood: Adhesives. In: Buschow KHJ (ed). Encyclopedia of 

Materials: Science and Technology, p. 9583-9599. Elsevier Science Ltd., 

Amsterdam. ISBN: 0-08-0431526. 

Dijkman H. 2004. DSM Melamine: Growing a profitable business. From: 

http://www.dsm.com/en_US/downloads/invest/dijkman_24_sept.pdf Accessed: 4 

February 2007. 

Dunky M. 2005. Resins for ultra low formaldehyde emission according to the 

Japanese F**** quality. From: http://www.forestprod.org/adhesives05dunky3.pdf 

Accessed: 4 February 2007. 
Chapter IV Page 60 

Durez Corporation. Not Dated. Phenolic molding composites. From: 

http://www.durez.com/product.pdfs/phen.mold.comp/pmc.tech.overview.pdf 

Accessed: 4 February 2007. 

Eckelman CA. 1997. Brief survey of wood adhesives. FNR 154, Forestry & 

Natural Resources, Purdue University, Cooperative Extension Service, West 

Lafayette, IN. 10 pp. 

Ecology Action. 2004. Wood panels: Plywood, OSB, MDF, and Ag Waste 

Boards. Accessed: 2 February 2007. From: 

http://www.ecoact.org/Programs/Green_Building/green_Materials/wood_panels.h

tm 

Frihart CR. 2004. Adhesive interactions with wood. In: Forest Products 

Laboratory. Fundamentals of Composite Processing: Proceedings of a 

Workshop. General Technical Report FPL-GTR-149, p. 29-38. USDA, Forest 

Service, Forest Products Laboratory, Madison, WI. 

Frihart CR. 2005. Wood adhesion and adhesives. In: Rowell RM (ed). 

Handbook of Wood Chemistry and Wood Composites. Chapter 9, p. 215-278. 

CRC Press, Inc., Boca Raton. 

Goldboard Development Corporation. 2000. Gluing: Urea-formaldehyde (UF) 

resin. From: http://www.goldboard.com/products/gluing_uf.html Accessed: 12 

December 2001. 

Howard JL. 2005. U.S. Forest Products Annual Market Review and Prospects, 

2001-2005. Research Note FPL-RN-0299, USDA, Forest Service, Forest 

Products Laboratory, Madison, WI. 11 pp. 

ICIS Pricing. 2006. Melamine (USA): 9th August 2006. Accessed: 2 February 

2007. From: 

http://www.icispricing.com/il_shared/Samples/SubPage10100043.asp 

Industry Canada. 2005a. Wood-based panel products: Technology roadmap. I. 

Introduction and overview. From: http://strategis.ic.gc.ca/epic/internet/infiif.nsf/en/oc01504e.html Accessed: 13 April 2006. 

Industry Canada. 2005b. Wood-based panel products: Technology roadmap. II. 

Panels in perspective. From: http://strategis.ic.gc.ca/epic/internet/infiif.nsf/en/oc01505e.html Accessed: 13 April 2006. 

Kennedy HJ. 2005. The North American Wood Adhesives Market. Accessed: 4 

February 2007. From: http://www.forestprod.org/adhesives05kennedy.pdf 
Chapter IV Page 61 

Kim S, Y-K Lee, H-J Kim, and HH Lee. 2003. Physico-mechanical properties of 

particleboards bonded with pine and wattle tannin-based adhesives. Journal of 

Adhesion Science & Technology, 17(14): 1863-1875. 

Lorenz LF, AH Conner, and AW Christiansen. 1999. The effect of soy protein 

additions on the reactivity and formaldehyde emissions of urea-formaldehyde 

adhesive resins. Forest Products Journal, 49(3): 73-78. 

Marra AA. 1992. Technology of Wood Bonding: Principles in Practice. Chapter 

4, p. 61-101. Van Nostrand Reinhold Company, New York. 454 pp. ISBN: 

0442007973. 

McCallum D. 1996. The manufacturing process: Medium density fibreboard. 

From: http://sres-associated.anu.edu.au/fpt/mdf/manufacture.html Accessed: 23 

February 2007. 

Meyer B and K Hermanns. 1986. Formaldehyde release from wood products: 

An overview. In: Meyer B, BA Kottes Andrews, and RM Reinhardt (eds). 

Formaldehyde Release from Wood Products. ACS Symposium Series, 316: 1-

16. 

Orica Limited. 1999. Urea formaldehyde resin. Accessed: 4 February 2007. 

From: 

http://www.pacia.org.au/_uploaditems/docs/3.urea_formaldehyde_resin.pdf 

Pizzi A. 1994. Advanced Wood Adhesives Technology. Chapter 8, p. 273-282. 

Marcel Dekker, Inc., New York. 

Pizzi A. 2006. Recent developments in eco-efficient bio-based adhesives for 

wood bonding: Opportunities and issues. Journal of Adhesion Science & 

Technology, 20(8): 829-846. 

Roffael E, B Dix, and J Okum. 2000. Use of spruce tannin as a binder in 

particleboards and medium density fiberboards (MDF). Holz als Roh- und 

Werkstoff, 58: 301-305. 

Santana MAE, MGD Baumann, and AH Connor. 1997. Utilization of black wattle 

bark and tannin liquefied in phenol in the preparation of resol-type adhesives. 

From: http://www.fpl.fs.fed.us/documnts/pdf1997/santa97a.pdf Accessed: 4 

February 2007. 

Sellers T Jr and GD Miller Jr. 2004. Laboratory manufacture of high moisture 

southern pine strandboard bonded with three tannin adhesive types. Forest 

Products Journal, 54(12): 296-301. 
Chapter IV Page 62 

(The) Society of the Plastics Industry, Inc. 1997. The phenolic advantage. 

From: http://www.phenolics.org/products/PhenolicNL.htm Accessed: 11 April 

2001. 

Spelter H. 1989. Plywood Manufacturing Cost Trends, Excluding Wood, in 

Western U.S. Mills: 1975-1988. General Technical Report FPL-GTR-64. USDA, 

Forest Service, Forest Products Laboratory, Madison, WI. 12 pp. 

Tetlow K. Not Dated. Composite Panels: Particleboard and Medium-density 

fiberboard. Accessed: 28 February 2007. From: 

http://archrecord.construction.com/resources/conteduc/archives/0512weyerhaeu

ser-1.asp

Trosa A and A Pizzi. 2001. A no-aldehyde emission hardener for tannin-based 

wood adhesives for exterior panels. Holz als Roh- und Werkstoff, 59: 266-271. 

United Soybean Board. 2004. Soy-based composites technical research. From: 

http://www.omnitechintl.com/pdf/Composites%20-%20T.pdf Accessed: 4 

February 2007. 

U.S. Department of Agriculture (USDA). 1999. Glossary. In: Forest Products 

Laboratory. Wood Handbook – Wood as an Engineering Material. General 

Technical Report FPL-GTR-113. USDA, Forest Service, Forest Products 

Laboratory, Madison, WI. 

Vick CB. 1999. Adhesive bonding of wood materials. In: Forest Products 

Laboratory. Wood Handbook – Wood as an Engineering Material. General 

Technical Report FPL-GTR-113, Chapter 9. USDA, Forest Service, Forest 

Products Laboratory, Madison, WI. 

Westcott JM and CR Frihart. 2004. Competitive soybean flour/phenolformaldehyde adhesives for oriented strandboard. In: Tichy RJ and V Yadama 

(eds). 38th International Wood Composites Symposium Proceedings, p. 199-206. 

Washington State University, Pullman, WA. 

Westcott JM, CR Frihart, and AE Traska. 2006. High-soy-containing waterdurable adhesives. Journal of Adhesion Science & Technology, 20(8): 859-873. 

Wikipedia contributors. 2006. Particle board. Accessed: 5 September 2006. 

From: http://en.wikipedia.org/wiki/particle_board 

Zheng J. 2002. Studies of PF Resole/Isocyanate Hybrid Adhesives. Ph.D. 

Dissertation, Virginia Polytechnic Institute and State University, Blacksburg, VA. 

213 pp. Accessed: 4 February 2007. From: 

http://scholar.lib.vt.edu/theses/available/etd-01072003-

200607/unrestricted/Jun_Zheng_Dissertation.pdf 
Chapter V Page 63 

V. Assessment of Best Available Control Technology 

In this chapter, the technical basis for the proposed Phase 1 and Phase 2 

standards for HWPW, PB, and MDF are presented in consideration of BACT. 

For this ATCM, BACT is defined as HWPW, PB, and MDF meeting the proposed 

Phase 2 emission limits in Tables V-21, V-23, and V-25, respectively, through a 

combination of process- and resin-related modifications. The candidate resin 

systems for meeting BACT are listed below: 

• HWPW -- Phase 2 Standard (0.05 ppm) 

° UF (mole ratio ≈ 1.2 to 1.4) + 15% Melamine 

° PVA 

° PVA-Soy 

• PB -- Phase 2 Standard (0.09 ppm) 

° UF (mole ratio ≈ 0.8 to 1.1) + 8% Melamine 

° UF (mole ratio ≈ 0.8 to 1.1) + Scavengers 

° PF 

• MDF – Phase 2 Standard (0.11 ppm) 

° UF (mole ratio ≈ 0.9 to 1.2) + 12% Melamine 

° UF (mole ratio ≈ 0.9 to 1.2) + Scavengers 

° pMDI 

The above resin systems reflect staff’s assessment of BACT, which recognizes 

that manufacturers that choose to use UF resins have one or more options for 

reducing their HCHO emissions to meet the proposed Phase 2 standards. 

In section C, we summarize the results of studies on resins used to make 

HWPW, PB, and MDF. In section D, we summarize the results of studies on 

candidate low-formaldehyde resin systems. In section E, the technical basis for 

the proposed Phase 2 limits is described. In general, staff projects that BACT 

will be based on reformulated UF resins. However, the proposed regulation 

provides an incentive for panel manufacturers to convert to no added HCHO 

resins early by not having to comply with the requirement to perform quarterly 

emission tests of their products under a third party certification program. 

A. Introduction 

The range of resin systems that may presently or with some degree of 

modification be used to manufacture products that comply with the proposed 

emission standards is discussed in the remainder of this chapter. 
Chapter V Page 64 

1. Legal Requirements

According to H&SC §39666, CARB is required to adopt ATCMs to reduce 

emissions of TACs. For TACs without a Board-specified threshold exposure 

level, H&SC §39666 requires the ATCM to be designed to reduce emissions to 

the lowest level achievable through the application of BACT, or a more effective 

control method. With respect to BACT for the present ATCM, there are two 

elements identified in H&SC §39665(a)(4) and §39665(a)(6) that need to be 

evaluated: 

(4) The availability and technological feasibility of airborne toxic control 

measures to reduce or eliminate emissions, the anticipated effect of 

airborne toxic control measures on levels of exposure, and the degree 

to which proposed airborne toxic control measures are compatible 

with, or applicable to, recent technological improvements or other 

actions, which emitting sources have implemented or taken in the 

recent past to reduce emissions. 

(6) The availability, suitability, and relative efficacy of substitute 

compounds of a less hazardous nature. 

To determine BACT, staff evaluated the proposed control measure and 

alternatives to the proposed control measure by gathering pertinent information 

from a variety or sources, as described in the following subsections. For this 

ATCM, BACT is defined as HWPW, PB, and MDF meeting the proposed Phase 2 

emission limits in Tables V-21, V-23, and V-25, respectively. 

2. Best Available Control Technology Assessment Process

To ascertain BACT, staff collected information by exploring patents, scientific 

literature, consultations with academia, resin researchers and manufacturers, 

and examining the data collected in a CARB survey of composite wood products 

manufactured in 2002. 

a. Patents on Resins Used in Composite Wood Products

Staff researched the patents regarding resins used in composite wood products 

listed on the U.S. Patent & Trademark Office website (http://www.uspto.gov/) 

listed in 2001 through 2006, and found over 80 patents and 34 applications. 

Examples of resins included: 

• Soybean flour and a cross-linking agent adhesive; 

• Liquid melamine-urea-formaldehyde (MUF) resin that includes using a 

catalyst, thickener, and hardener; 

• Water resistant polyvinyl acetate (PVA) aqueous emulsion; 

• Tannin-based resins; 

• Protein-modified urea-formaldehyde (UF) resin; 
Chapter V Page 65 

• Soy protein portion and modifying ingredient portion; 

• Glutaraldehyde co-solvent urea resins; 

• Formaldehyde-free lignocellulosic adhesive, and 

• Hydrolyzates of soybeans as components of thermosetting resins. 

b. Scientific Literature

Several search engines were used to locate articles in the peer-reviewed 

literature. The primary websites that were accessed include:

• Science Direct: lists handbooks, book series’, and journal collections -- 

over 6.75 million articles; 

• APT Online: lists current and archived journals, issues, and authors; 

• Thomson Scientific: provides access to complete bibliographic information 

from over 8,000 leading journals and more than 2,000 books; and 

• Google: enables users to search the web, usenet, and images. 

c. Consultations

Through phone calls and emails, staff contacted resin researchers, resin 

manufacturers, and academia to discuss resin technology used in manufacturing 

composite wood products. Table V-1 lists the contacts made to date relative to 

resin technology. 

Table V-1. List of Researchers, Manufacturers, and Academia Contacted 

Contact Affiliation 

Bailey, Mr. Chris Collins Company (Portland, OR) 

Gardner, Dr. Doug University of Maine (Orono, ME) 

Harmon, Dave Hexion Specialty Chemicals (Springfield, OR) 

Holloway, Tom Dynea Adhesives (Springfield, OR) 

Johns, Dr. William Washington State University (Pullman, WA)

Kelly, Dr. Myron North Carolina State University (Raleigh, NC) 

Kim, Dr. Moon Mississippi State University (Starkville, MS) 

Li, Dr. Kaichang Oregon State University (Corvallis, OR) 

Matuana, Dr. Laurent Michigan State University (East Lansing, MI) 

Moriarty, Mr. Chris Huntsman International, LLC (Salt Lake City, UT) 

Odda, Mr. Ulf Akzo Nobel (Sweden) 

Pizzi, Dr. Antonio ENSTIB, University of Nancy I FR (France) 

Rosengarth, Mr. T.J. Flakeboard Company, Ltd. (Canada) 

Shupe, Dr. Todd Louisiana Forest Prod. Dev. Ctr. (Baton Rouge, LA) 

Sun, Dr. Susan Kansas State University (Manhattan, KS) 

Tang, Dr. R.C. Auburn University (Auburn, AL) 

Taylor, Mr. Mike States Industries (Eugene, OR) 

Wescott, Dr. James Heartland Resource Technologies, LLC (Pasadena, CA) 

Wolcott, Dr. Michael Washington State University (Pullman, WA) 
Chapter V Page 66 

In conjunction with public workshops and stakeholder meetings held over the 

years, staff has also made contact with a number of U.S. and overseas 

manufacturers, including: 

• Columbia Forest Products (Portland, OR) 

• Flakeboard (Canada) 

• Georgia-Pacific (Decatur, GA) 

• Masisa (Chile) 

• Roseburg Forest Products (Roseburg, OR) 

• SierraPine, Ltd. (Roseville, CA) 

• States Industries (Eugene, OR) 

• Timber Products (Springfield, OR) 

• Weyerhauser (Eugene, OR) 

d. 2003 California Air Resources Board Survey

The CARB staff distributed a composite wood products survey to manufacturers 

across the U.S. in March 2003 to collect information regarding engineered wood 

products, such as plywood, particleboard, fiberboard, and other composite wood 

products. The survey, hereafter referred to as the “2003 CARB Survey”, 

consisted of four questionnaires pertaining to manufacturer, product, resin, and 

process information. Over 250 surveys were mailed out, in which respondents 

were asked to provide information pertaining to products manufactured in 2002. 

From the 250 surveys distributed, ARB received 57 responses. Staff categorized 

the responses by composite wood type and entered all information into an 

AccessTM database. 

Based on an analysis of the survey results, the highest formaldehyde-emitting 

composite wood products were hardwood plywood, particleboard, and medium 

density fiberboard for interior applications. The majority of these products are 

made with urea-formaldehyde resins, which are inexpensive, and emit more 

HCHO than products made with other resins. For this ATCM, controlling the 

HCHO emissions from hardwood plywood, particleboard, and medium density 

fiberboard was the focus of this BACT assessment. 

3. Overview of Existing Formaldehyde Standards and Regulations 

During the 1970’s, HCHO emissions from PB and HWPW led to numerous 

complaints in newly constructed homes. In 1985, the U.S. Housing and Urban 

Development Agency (HUD) implemented a regulation that limited the HCHO 

concentration in mobile homes to 0.4 parts per million (ppm) (Spelter, 1992). 

This would be achieved by lowering HCHO emissions from PB and HWPW to 0.3 

and 0.2 ppm, respectively. This action triggered a need for many HWPW and PB 

manufacturers to modify their products in order to comply with the standard. 

However, absent any new regulations since 1985, industry has continued to 
Chapter V Page 67 

produce products that comply with the HUD standard (Turner et al., 1996) with 

modest reductions in average HCHO emissions. Products specifically covered 

under the HUD standard are not subject to the proposed ATCM. 

Similar concerns relative to the health effects of HCHO emissions from 

composite wood products and HCHO in indoor air were also being raised in 

Europe. This led to a guideline from the German health ministry in 1980 to limit 

HCHO emissions from particleboards, fiberboards, and plywood to 0.1 ppm in a 

steady state climate chamber test, which is also known as the E1 classification 

(Deutsches Institut fur Bautechnik, 1994). In 2000, Australia adopted the same 

standards as those used in Europe. Compliance with European regulations is 

based on the quantity of free-formaldehyde in a product rather than the actual 

emissions from the product; the presumption for this is that any freeformaldehyde in a wood product will be emitted at a later time. The E1 standard 

is an “average” standard that allows for panels to be produced with HCHO 

contents higher than the numerical value of the standard, so long as an equal 

amount of product is produced at a comparable HCHO content below the 

standard. In terms of HCHO contents, Europe allows multiple grades of panels 

to be sold for consumer use. As such, not all panels sold to Europe meet the E1 

standard; a portion is made to comply with the E2 standard, which approximates 

the stringency of the 1985 HUD standards in the U.S. 

The most stringent HCHO regulation implemented today is the Japanese 

Building Standard Law (BSL) (Takabatake, 2003). The BSL has a “sick house” 

regulation which regulates the amount of chemical products, such as HCHO, that 

can be emitted from building materials. As noted above for Europe, multiple 

grades of products are allowed in Japan, in terms of HCHO content. There are 

15 kinds of HCHO-emitting building materials subject to the regulation, which 

include plywood, PB, and MDF. The regulation requires suppliers of building 

materials to determine HCHO emission levels from their products and comply 

with applicable JIS (Japan Industrial Standards) or JAS (Japan Agriculture 

Standards), or obtain approval from the Ministry of Land, Infrastructure and 

Transport (MLIT). All building materials are classified by HCHO emission rate 

into four formaldehyde-emitting categories: Type I, F, F, and F. 

Table V-2 describes the four Japanese formaldehyde-emission standards for 

building materials. The emission standards are expressed as an emission rate 

as determined by testing with the Japanese desiccator test. 
Chapter V Page 68 

Table V-2. Japanese Building Standard Law Classifications for Building Material 

Formaldehyde (HCHO) Emissions1

Classification HCHO Emission Rate (mg/m2/hr) Board Usage 

Type I 0.12 < x Prohibited in use 

F 0.02 < x < 0.12 Tighter area restriction 

F 0.005 < x < 0.02 Area restriction 

F x < 0.005 No restrictions 

(1) Source: Takabatake (2003). “mg/m2

/hr” = milligrams HCHO per square meter per hour. 

The use of Type 1 building materials as interior finishing materials in habitable 

rooms is prohibited. The use of F and F building materials in habitable 

rooms is limited, depending on total area of the room(s). The amount of F

and F building materials is adjusted based on the number of ventilators and 

floor area of each habitable room. Use of F building materials is without 

any limitations. 

To meet these demanding HCHO standards, resins must be modified to reduce 

HCHO emissions levels to a significant extent. Low HCHO resins have been 

developed by engaging one or more technological methods, such as: 

• Lowering the formaldehyde:urea (F:U) ratio of the UF resin; 

• Adding formaldehyde-scavenger materials directly to the UF resin; 

• Post-treating panels with a formaldehyde scavenger; or 

• Changing to a new resin system. 

From this list of options, the primary method used to decrease HCHO emissions 

is by lowering the F:U ratio. In the 1980’s, F:U ratios were generally between 1.4 

to 1.6. Today, F:U ratios in resins used in the U.S. range from 1.05 to 1.2 

(Bauman, 1997). To an extent, the results of the CARB 2003 survey suggest 

that more stringent HCHO emission standards in Europe and Japan have 

prompted U.S. manufacturers to lower the F:U ratios in the resins that they use. 

Some UF resins with F:U ratios of 0.8 to 0.9 have been developed. However, 

complications in the mechanical and physical performance of wood panels may 

arise when HCHO levels are lowered. This is usually compensated for by adding 

a substitute compound in place of HCHO, or by fortification with chemicals 

intended to reinforce the glue bonds. 

Another option to significantly lower HCHO emissions is adding HCHO 

scavengers directly to UF resins before press time. These scavengers are 

usually nitrogen-based compounds that bind to free-formaldehyde in the resin. 

Urea scavengers have been used for many years and are very effective in 

reducing HCHO emissions without influencing the physical characteristics of the 
Chapter V Page 69 

wood panel. Another type of scavenger is a scavenger wax emulsion, which 

reduces HCHO emissions in two ways: it scavenges free-formaldehyde and also 

hinders water absorption by the wood panel. Most HCHO scavengers are cost 

effective and widely used in North American plants. 

There are also a variety of post-pressing board treatments used to reduce HCHO 

emissions from UF resins (Myers, 1986). While post-pressing treatments are 

used to a lesser extent than pre-pressing treatments, both are very effective. 

The most common post-pressing treatment used to reduce HCHO emissions is 

to fumigate wood panels with anhydrous ammonia. Significant HCHO emission 

reductions, two to 10 times less, can be achieved by exposure to anhydrous 

ammonia. Other post-press treatments include adding liquid ammonia or 

ammonia salt solutions to the board surface. Ammonium bicarbonate and 

ammonium carbonate have been used as solid powders, while solutions of 

ammonium salts, alkali metal salts, and other compounds having amine 

functionality have been found to be effective. 

Breakthroughs in resin chemistry have led to the development of new resin 

systems that are either low-emitting or zero-added HCHO, to meet the more 

stringent European E1 and Japan F standards. Table V-3 compares the 

different HCHO emission standards for composite wood products in the U.S., 

Europe, and Japan. In the U.S., separate standards are established for PB, 

plywood, and MDF (i.e., voluntary standards set by ANSI) based on surface 

HCHO emissions (ASTM E1333). In Europe, the standards for PB and plywood 

are based on surface HCHO emissions (EN 717-1), but compliance with the 

standard is determined by the amount of free-formaldehyde in PB (EN 120) or by 

the HCHO emission rate in plywood (EN 717-2). In Japan, all building materials 

subject to the Building Standard Law are based on HCHO emission rate (JIS 

A1901). Because these various standards are applied differently, target different 

health related goals, and tested using different analytical methods, they are not 

directly comparable to the proposed Phase 1 and Phase 2 standards developed 

by staff. An analysis of the relative stringency of the standards in the proposed 

ATCM is contained in Appendix H. In Appendix H, the approximate ASTM 

E1333-equivalent values for E1 products are estimated to be 0.14 ppm for 

HWPW and PB, and 0.10 ppm for MDF. For the F and F, the 

approximate ASTM E1333-equivalent values are estimated to be 0.07 and 

0.04 ppm, respectively. 
Chapter V Page 70 

Table V-3. Formaldehyde (HCHO) Emission Standards for Composite Wood 

Products in the U.S., Europe, and Japan1

Standard Product HCHO Limit Test Method 

Particleboard 0.30 ppm 

Med. Density Fiberboard 0.30 ppm 

Plywood Wall Panels 0.20 ppm U.S. 

Industrial Plywood 0.30 ppm 

ASTM 

E1333 

Particleboard, Plywood 0.10 ppm EN 717-1 

Europe – E1 Particleboard 6 to 10 mg/100 g EN 120 

Plywood ≤ 3.5 mg/m2

/hr EN 717-2 

All Products -- F 0.02 to 0.12 

mg/m2

/hr 

All Products -- F 0.005 to 0.02 

mg/m2

/hr 

Japan – F 

Standards 

All Products -- F ≤ 0.005 mg/m2

/hr 

JIS A1901 

(1) Sources: ASTM (1996); Building Center of Japan (2004); Groah et al. (1991); National 

Particleboard Association (1994). The U.S. standard for MDF is the voluntary ANSI standard. 

“ANSI” = American National Standards Institute; “ppm” = parts per million; “mg/100g” = milligrams 

per 100 grams of dry board; “mg/m2/hr” = milligrams per square meter per hour; “ASTM E1333” = 

American Large Chamber Test Method; “EN 717-1” = European Institute Large Chamber Test 

Method; “EN 120” = European Perforator Test; “EN 717-2” = European Gas Analysis Method; 

“JIS A1901” = Japanese Small Chamber Test. 

B. Product Descriptions and Survey Results 

This section provides information on how the selected products are 

manufactured, the results of analyses of the “CARB 2003 Survey,” and for 

HWPW, an evaluation of supplemental data submitted by the Hardwood Plywood 

& Veneer Association to CARB. 

1. Hardwood Plywood 

a. Description and Properties 

Hardwood plywood (HWPW) consists of thin wood veneers (or plies) glued 

together so that the grain direction of each layer of veneer is perpendicular to 

that of its adjacent layers (Youngquist, 1999). This cross-lamination provides 

excellent two-way strength for a suite of stiffness (e.g., dry shear test) and water 

resistance properties (e.g., three-cycle soak test) (American National Standards 

Institute, 2000). Hardwood plywood is always constructed with an odd number of 

plies, where the outside and inside plies are referred to as the faces and core, 
Chapter V Page 71 

respectively. There are several types of HWPW differentiated by the thickness 

and composition of the core, which is commonly made with either veneer, 

lumber, MDF, or PB. The outermost layer or face layer is finely finished wood 

surface made from a hardwood species such as oak or maple. 

With respect to water resistance, there are four grades of HWPW: Technical, 

Type I, Type II, and Type III, where Technical grade HWPW is the most waterresistant and Type III the least (Youngquist, 1999). To our knowledge, in order to 

produce HWPW for exterior applications (i.e., Technical or Type 1), resins other 

than urea-formaldehyde (UF) resins are used (e.g., phenol-formaldehyde), which 

typically have HCHO emission rates that are 90% or more below that of HWPW 

made with a UF resin (Battelle, 1996). In comparison, HWPW designated as 

either Type II or III are interior-grade products that are largely used as decorative 

wall paneling, and the construction of cabinets and furniture (Norbord Inc., Not 

Dated). The resin most commonly used in these products is UF resin, which has 

been found to produce HWPW with ASTM E1333 values ranging from 0.05 to 

0.19 ppm (Hardwood Plywood & Veneer Association, 2006). 

b. Analysis of Responses to the CARB 2003 Survey 

To learn more about the HCHO emission characteristics of HWPW produced in 

the U.S., a survey (CARB, 2003) was mailed to domestic manufacturers. The 

intent of the CARB 2003 Survey was to learn about the types of equipment used 

to manufacture composite wood products and to determine the characteristics of 

HWPW, PB, and MDF produced in the U.S. in 2002. A total of 10 responses 

were received with information on HWPW, representing approximately 73% of 

total U.S. production (in 2002, total U.S. production was estimated to be 

approximately 1.5 x 109 ft2, based on 3⁄8” thickness). The range of reported 

ASTM E1333 values from the 10 respondents was 0.07 to 0.75 ppm, and the 

production-weighted grand mean was 0.09 ppm. All 10 companies reported 

using an ammonia-UF resin to manufacture their HWPW, where the lowest 

ASTM E1333 values were achieved by manufacturers that added catalysts (e.g., 

ammonium chloride or hexamethylentetramine (hexamine)). The HWPW that 

was reported to have an ASTM E1333 value of 0.75 ppm was an architectural 

plywood product, which is produced in very low volumes for highly specialized 

applications (e.g., curved objects). 

c. Supplemental Data from the Hardwood Plywood & Veneer 

Association 

 

In fall 2006, various stakeholders in the HWPW industry asked if consideration 

had been given to establishing separate HCHO emission standards for HWPW 

made with a veneer core (HWPW-VC) vs. HWPW made with a composite core 

(HWPW-CC) (i.e., core material is either PB or MDF). As this distinction had not 

been specified previously, there were no plans at the time to establish separate 

standards for the two products. To clarify the need for separate standards and to 

supplement analyses of the CARB 2003 Survey data, the Hardwood Plywood & 
Chapter V Page 72 

Veneer Association (HPVA) offered to submit HCHO emission data from HWPWVC and HWPW-CC manufactured in 2001-06 from several companies (Note: 

Statutes governing manufacturer confidentiality prohibit the disclosure of actual 

company names). The HCHO emission data for HWPW-VC from six companies, 

measured using either ASTM D5582 (desiccator test) or ASTM E1333 (large 

chamber test) were provided for two to five years of production (Table V-4). 

Table V-4. Measured or Estimated ASTM E1333 Average Data for Hardwood 

Plywood-Veneer Core from Selected U.S. Manufacturers1

Company Year No. Samples ASTM E1333 (ppm) 

HPVA #1 2004-05 20 0.12 

HPVA #2 2001-05 40 0.13 

HPVA #3 N/A 11 0.10* 

HPVA #4 – Mill F 2003-05 18 0.12* 

HPVA #4 – Mill G 2001-05 56 0.09* 

HPVA #4 – Mill H 2001-04 15 0.09* 

HPVA #4 – Mill I 2001-05 103 0.13* 

HPVA #4 – Mill J 2004-05 6 0.15* 

HPVA #5 – Mill A 2001-05 6 0.17 

HPVA #5 – Mill B “ 11 0.08 

HPVA #5 – Mill C “ 16 0.09 

HPVA #5 – Mill D “ 6 0.19 

HPVA #5 – Mill E “ 9 0.10 

HPVA #6 2004-06 32 0.09 

Grand Mean (n = 14) ----- ----- 0.12

(1) Data provided by the Hardwood Plywood & Veneer Association; ASTM E1333 data followed by 

an asterisk indicate values estimated by multiplying measured ASTM D5582 data by 0.4. 

In consideration of the variation in numbers of samples, reported years, and 

company/mill information, multiple-year means were calculated for each mill that 

could be identified. For data that could not be assigned to a specific mill, data for 

the entire company were averaged. In 2001-06, facility mean ASTM E1333 

values ranged from 0.09 to 0.19 ppm, and the grand mean was 0.12 ppm (n = 

14). Relative to the data from the CARB 2003 Survey, the range of reported 

ASTM E1333 values was smaller, but the grand mean was 25% higher (i.e., 0.12 

ppm vs. 0.09 ppm in the CARB 2003 Survey). 

Less data were provided for HWPW-CC (i.e., three companies vs. six for HWPWVC) (Table V-5), which in part reflects lower production volumes for HWPW-CC 

than HWPW-VC. As for the HWPW-VC data, multiple-year means were 

calculated for each company, and the company means averaged to calculate a 

grand mean. Compared to HWPW-VC, the range in ASTM E1333 values was 
Chapter V Page 73 

smaller, as was the grand mean (0.08 ppm for HWPW-CC vs. 0.12 for HWPWVC), which may have been influenced by the difference in sample sizes. These 

data, in light of the lower grand mean and inter-company range in ASTM E1333 

values for HWPW-CC, does not support the need for emission standards with 

different ASTM E1333 values for HWPW-VC and HWPW-CC at this time. 

Table V-5. Measured or Estimated ASTM E1333 Data for Hardwood PlywoodComposite Core from Selected U.S. Manufacturers1

Company Core Year No. Samples ASTM E1333 

(ppm) 

HPVA “A” PB 2005 1 0.05 

HPVA “B” PB 2001-04 11 0.08 

HPVA “C” PB NA 8 0.10* 

HPVA “B” MDF 2001-03 5 0.09 

HPVA “C” MDF NA 9 0.09* 

Grand Mean (n = 5) ----- ----- ----- 0.08

(1) Data provided by the Hardwood Plywood & Veneer Association; ASTM E1333 data with an 

asterisk indicate values estimated by multiplying ASTM D5582 data by 0.4. NA = not available. 

2. Particleboard

a. Description and Properties 

Particleboard is made of wood fragments, such as chips or shavings, that are 

dried and mechanically pressed with heat into sheet form, and bonded together 

with resin (Youngquist, 1999). There are typically three layers in a PB panel -- 

the two outer faces of the board, which consist of finely ground wood particles, 

and the core which consists of more coarse material. Particleboard (85% or 

more) is used for furniture, flooring systems, underlayment, manufactured 

housing, and other products in conventional homes (e.g., cabinets) (Milton, 

2006). 

b. Analysis of Responses to the CARB 2003 Survey

A total of 20 responses were received with information on PB, representing 

approximately 53% of total U.S. production (in 2002, total U.S. production was 

estimated to be approximately 2.9 x 109 ft2, based on 3⁄4” thickness). The range 

of reported ASTM E1333 values from the 20 respondents was 0.13 to 0.24 ppm, 

and the production-weighted grand mean was 0.18 ppm. In all, the 20 

respondents reported using two UF and one phenol-formaldehyde (PF) resin to 

manufacture the products they offered for sale in 2002. One of the UF resins, 

used in approximately 51% of reported production volume, was a straight UF 
Chapter V Page 74 

polymer with a F:U mole ratio of 1.1 to 1.3 (Note: For UF resins, the mole amount 

of HCHO is typically greater than for urea. As such, if a UF resin is reported to 

have a mole ratio greater than 1, this reflects the F:U mole ratio and not the U:F 

mole ratio). 

To reduce surface emissions of HCHO from PB made with a UF resin of this 

kind, manufacturers may include one or more additives to the resin such as 

catalysts (sodium chloride, sodium sulfate, ammonium sulfate), scavengers (low 

mole ratio urea solution), and/or wax emulsions (for moisture retention). The 

other UF resin was a methanol-UF resin that was used to produce approximately 

48% of the reported volume of production. As for the straight polymer UF resin, 

surface emissions of HCHO may be reduced by use of the same additives 

mentioned above, as well as magnesium chloride-hexahydrate. The remaining 

1% of reported production was manufactured with a blended PF-UF resin. 

3. Medium Density Fiberboard (MDF)

a. Description and Properties 

Medium density fiberboard (MDF) is made of wood fibers and has stronger 

physical properties than PB (Youngquist, 1999). Fiberboard is classified by 

board density -- MDF has a specific gravity of 0.5 to 0.8 or a density of 31 to 50 

lbs/ft3 (Keidel Supply Co., Inc., 2001-06). The surfaces of MDF are smooth, 

uniform, and free of knots, and it can undergo a variety of finishing steps 

depending on the final product. The primary uses for MDF include furniture, 

cabinets, molding, door skins, and industrial packaging (Mithra, 2007). 

b. Analysis of Responses to the CARB 2003 Survey 

A total of 12 responses were received with information on MDF, representing 

approximately 83% of total U.S. production (in 2002, total U.S. production was 

estimated to be approximately 1.6 x 109 ft2, based on 3⁄4” thickness). The range 

of reported ASTM E1333 values from the 12 respondents was 0.03 to 0.31 ppm, 

and the production-weighted grand mean was 0.25 ppm. In all, the 12 

respondents reported using three UF and one methylene diisocyanate (MDI) 

resin to manufacture the products offered for sale in 2002. Similar to PB, a major 

portion of manufacturers reported using a straight polymer UF (approximately 

40% of reported production) or methanol-UF resin (approximately 20%), while 

others used a melamine-UF resin (approximately 39%) with sodium chloride as a 

catalyst. Although the same additives listed for PB may be used to control 

surface emissions of HCHO from MDF (i.e., catalysts, scavengers, and wax 

emulsions), the specific additives used to manufacture MDF are considered to be 

proprietary information. Of the reported volume of production, approximately 1% 

was made using a MDI resin. 
Chapter V Page 75 

C. Present-day Resin Technologies 

In this BACT assessment of present-day resin technologies, an evaluation of 

currently used and laboratory tested resins, and production processes that may 

be used to achieve the maximum feasible HCHO emission reductions from 

HWPW, PB, and MDF was conducted. Staff’s review of the literature concludes 

that generally speaking, resin technologies can be applied to all three regulated 

products (HWPW, PB, and MDF), although adjustments in resins may be 

necessary to accommodate the different manufacturing processes. In addition, 

the assessment also considers the results of the CARB 2003 Survey, patent 

searches, a literature review, and consultations with resin suppliers, panel 

manufacturers, and academia. In this analysis, resin systems were evaluated in 

consideration of the need to meet selected structural properties. 

1. Urea-formaldehyde (UF) Resins

Presently, UF resins are the most widely used adhesives in the manufacture of 

HWPW, PB, and MDF, which produces boards with the highest HCHO surface 

emissions (i.e., ASTM E1333 values). The basic chemical reaction in UF resins 

involves bond formation between amine and hydroxyl groups on the resin 

components. New technologies seek to find alternative components that are 

able to form irreversible bonds with HCHO to reduce the amount of free HCHO 

that remains in the final product. To produce HWPW, PB, and MDF with a UF 

resin that would achieve lower HCHO emissions, manufacturers may choose to 

use resins with lower F:U mole ratios (i.e., less than 1.0), add different amounts 

or mixtures of scavengers and hardeners, and/or apply decreased press times 

and temperatures (Wolcott et al., 1996). Limited studies indicate the potential to 

meet the F standards, but it is not clear as to how low an ASTM E1333 

value can be achieved using a UF resin, as efforts made to date to lower surface 

HCHO emissions from HWPW, PB, and MDF are not well documented in the 

open literature. 

2. Melamine-urea-formaldehyde (MUF) Resins

The most widely used approach for decreasing surface HCHO emissions from 

boards made with a UF resin is to lower the F:U mole ratio of the base resin. 

Presently, mole ratios are reported to range from 1.05 to 1.2, depending on the 

specific formulation of the resin (Baumann, 1997). However, when the F:U mole 

ratio is lowered below 1.0 (i.e., more moles of urea than HCHO), adjustments 

must be made to the resin to moderate unwanted changes in the physical and 

structural properties of the board. The addition of melamine during resin 

synthesis is often used to improve the durability and stability of a board, and its 

addition can also decrease surface HCHO emissions by acting as cross-linking 

agent. 

Cremonini and Pizzi (1999) measured the effects of adding melamine acetate 

(Mac) on the tensile strength of plywood made with a UF resin (F:U mole ratio = 
Chapter V Page 76 

1.5). Measurements of tensile strength were made before and two-years after 

exposure to the weather in northern Italy (Table V-6). While plywood made with 

a “UF + 15% Mac” resin had a lower initial tensile strength than plywood made 

with commercially available Phenol-MUF resin, it had a higher tensile strength 

after two-years of weather exposure (1.27 vs. 1.05 N/mm2). In comparison, 

plywood made with commercially available MUF resin exhibited both higher initial 

and post-exposure tensile strength than plywood made with PMUF or any “UF + 

Mac” resin combinations. Overall, the durability of plywood made with 15% or 

more Mac would allow manufacturers to produce panels that comply with 

European tensile strength requirements, comparable to plywood made with a 

MUF resin with 33 to 40% melamine. This suggests that the addition of Mac to 

UF resins may be equally as effective in maintaining plywood tensile strength as 

MUF resins with higher melamine contents. Pizzi (2000) also reported that 

equivalent tensile strengths were measured in plywood bonded with a 40:60 

weight ratio MUF resin and plywood bonded with a 10:90 weight ratio melaminesalt UF resin. 

Table V-6. Effect of Melamine Acetate (Mac) on Plywood Tensile Strength1

---------- Tensile Strength (N/mm2) ---------- Resin (M:U weight ratio) Initial Post-exposure 

PMUF Control (33:66) 1.48 1.05 

MUF Control (47:53) 2.07 1.91 

UF + 10% Mac (7:93) 0.52 0 

UF + 15% Mac (10:90) 1.33 1.27 

UF + 20% Mac (13:87) 1.10 1.07 

EN 314 Requirement > 1.0 NA 

(1) Source: Cremonini and Pizzi (1999). PMUF = phenol melamine urea-formaldehdye; MUF = melamine 

urea-formaldehyde; UF = urea-formaldehyde. The base UF resin had a F:U mole ratio of 1.5. Postexposure tensile strength is the value after two-years of weather-exposure in northern Italy. NA = not 

applicable. 

Relative to lowering HCHO emissions, Dunky (1995) developed a MUF resin 

using a very low mole ratio UF resin (F:U = 0.75 to 0.90) and adding 15 to 23% 

melamine by weight to achieve very low HCHO concentrations. With respect to 

HCHO content, the panels exhibited DIN EN 120 values less than 2.0 mg/100 g 

(approximate ATSM E1333 value of 0.025 ppm). 

Akzo Nobel (2005; 2006) is currently conducting laboratory trials on a MUF resin 

made with a low mole ratio UF resin (F:U = 1.05 to 1.15), melamine, and a 

“catcher” compound. The catcher is specifically formulated to decrease HCHO 

emissions from PB produced with the MUF resin. Particleboard, ranging in 

thickness from 16 to 28 mm, has been produced at a press temperature of 185 

°C and a 10.8 s/mm press time. While the resin system is still in laboratory trials, 

it has shown good success in terms of producing PB with low JIS A1460 

(Japanese desiccator test) values (less than 0.3 mg/L ≈ ASTM E1333 value of 
Chapter V Page 77 

0.04 ppm) and improving durability when applied at a 10% by weight resin 

dosage. This resin system has the potential to be used to make PB with very low 

HCHO emissions. 

3. Melamine-formaldehyde (MF) Resins

Melamine-formaldehyde resins are excellent exterior wood adhesives because of 

their water resistance. Frihart and Chandler (2006) found that MF resins could 

reduce wood swelling by entering into the walls of wood cells and strengthening 

them. 

Kim and Kim (2005) conducted a range of HCHO emission tests (e.g., DIN EN 

120, JIS A1460) on 8-mm MDF made from Korean pine (4% moisture content) 

and bonded with a MF resin. The resin had a F:M mole ratio of 1.75. Before the 

MDF was pressed, three-parts (to resin) of 25% ammonium chloride (hardener) 

and 13 parts of 44% wax solution (for waterproofing) were added to the base MF 

resin. The MDF made with the MF resin displayed a JIS A1460 value of 0.6 ppm 

and a DIN EN 120 value of 2.88 mg/100 g dry board, which complies with the 

Japanese F and nearly the F standard. 

Pizzi et al. (1996) examined the strength and HCHO emission properties of PB 

made under laboratory conditions with either a 0.5 or 1.1 mole ratio MF resin 

containing ammonium chloride (i.e., 15-parts by weight of a 20% solution). 

Hexamine (i.e., 38-parts by weight of a 40% solution) was added to the 0.5 mole 

ratio MF resin to determine if hexamine addition could compensate for the resin’s 

lower melamine content. Observed differences in dry internal bond strength and 

DIN EN 120 results are shown in Table V-7 for PB made with the two MF resins. 

These results confirm that the addition of hexamine to a low mole ratio MF resin 

allows for the production of PB with similar internal bond strengths as PB made 

with higher mole ratio MF resins. In addition, the DIN EN 120 value of the PB 

made with the hexamine-hardened MF resin was approximately 50% lower than 

the value of the higher mole ratio MF resin without hexamine. Overall, it appears 

that adding hexamine as a hardener to MF resins may be an effective way to 

lower HCHO emissions and maintain internal bond strength in PB. Further 

research is needed to identify the optimal amount of hexamine to add to MF 

resins for the manufacture of PB with acceptable internal bond strengths and low 

HCHO emissions. 

The findings from these studies demonstrate the potential for using MF resins to 

produce PB or MDF with low HCHO emission properties. 
Chapter V Page 78 

Table V-7. Comparison of Strength and HCHO Emission Properties of 

Particleboard Made with Two Melamine-formaldehyde (MF) Resins1

-------------------- Resin -------------------- Resin or Particleboard Parameter MF Alone MF + Hexamine 

MF Mole Ratio (Parts by Weight) 1.1 (174) 0.5 (154) 

Dry Internal Bond Pressure (MPa) 0.77 0.65 

DIN EN 120 (mg HCHO/100 g) 6.9 3.5 

(1) Source: Pizzi et al. (1996). MPa = megapascals; mg = milligrams; g = grams. DIN EN 120 

refers to the European perforator test. The press time for PB made with either resin was 4-

minutes. 

4. Phenol-formaldehyde (PF) Resins

Phenol-formaldehyde resins are commonly used in PB for exterior applications 

that must be durable under wet and/or humid conditions. They typically exhibit 

low HCHO emission rates (Battelle, 1996), and selected commercially available 

products would likely comply with the proposed Phase 2 standards that would 

take affect in 2011 to 2012 (Appendix A). Industry representatives have 

expressed concern over the longer press times and higher press temperatures 

required for producing products with PF versus UF resins, as these changes 

result in higher energy consumption and decreased productivity. However, 

recent studies have shown that adding compounds such as esters, lactones, or 

organic carbonates to PF resins can reduce cure times (Conner et al., 2002; 

Lorenz and Conner, 2000; Pizzi et al., 1997). 

5. Methlylene Diisocyanate (MDI) Resins

Since the 1970’s, MDI has been increasingly used in the manufacture of MDF 

(Eckelman, 1997). As a non-polar, low viscosity liquid that wets the wood 

surface and penetrates deep into the wood structure, MDI resins penetrate 

further than PF resins, thus creating one of the most durable adhesive networks. 

While more expensive than any other resin discussed in this section, there are no 

HCHO emissions associated with its use, enabling PB and MDF made with this 

adhesive to meet the proposed Phase 2 standards that would take effect in 2011 

to 2012. A number of other properties that make MDI a desirable adhesive for 

composite wood products include: 

• Fast polymerization rate (making it suitable for use as core resin) and 

ability to form bonds with wood with a high moisture content, including 

green wood (Connor, 2001; Frihart, 2005); 

• Low volatility – less resin is used to manufacture products with 

comparable structural properties (Marra, 1992); and 
Chapter V Page 79 

• Lower energy-related production costs due to the use of lower press 

temperatures, faster press cycles, and shorter drying times (Connor, 

2001). 

At the industrial-scale, research on isocyanates is presently focused on their use 

as a copolymerization agent in existing resins, which have led to the creation of 

hybrid resin systems (e.g., UF-MDI, PF-MDI, PUF-MDI, PMUF-MDI, and PUFTMDI) that outperform traditional wood resins (Lei et al., 2006). 

6. Methylene Diisocyanate (MDI) Hybrid Resins

a. Urea-formaldehyde-MDI (UF-MDI) Resins

Composite wood products made with UF resins are only used for interior 

applications because they have very low water resistance properties. However, 

researchers working with MDI hybrids have recently created an exterior-grade 

UF-MDI hybrid resin for use in a range of applications (Mansouri et al., 2006). By 

using a UF-MDI resin made by adding MDI (10 to 15% by weight) to a UF resin, 

the water resistance of plywood was substantially upgraded. Wieland et al. 

(2006) found that adding ammonium sulfate (approximately 2% by weight) could 

further accelerate plywood curing times. In plywood, the strength of the bondlines made with a UF/MDI hybrid resin are much improved relative to those made 

with a UF resin due to the greater number of urethane crosslinks that form 

between isocyanate and UF methylol groups. 

Mansouri et al. (2006) examined the changes to structural properties in plywood 

made with UF-MDI hybrid resins ranging from 5 to 15% MDI by weight (Table V8). The test material was a three-layer beech veneer plywood bonded with a 

base UF resin (F:U mole ratio = 1.6 to 1.8) that was modified by the addition of 

ammonium sulfate (2% solution), wheat flour (30% by weight), and MDI. The 

results show that as the amount of MDI is increased, the boiling water 

performance of the plywood improved (e.g., after 11-minutes the tensile strength 

of the control was four- to five-times lower than the plywood made with any of the 

UF-MDI hybrid resins). While the selected measures of tensile strength were all 

improved by the addition of MDI to the UF resin, the extent of improvement is 

much greater when 10 to 15% MDI is added vs. only 5%. To produce plywood 

with exterior-grade properties using a UF resin, greater amounts of MDI would 

need to be added to achieve the required level of water resistance. 

Nevertheless, the tensile strength and water resistance properties of plywood 

made with a UF resin can be considerably improved by the addition of 10 to 15% 

MDI by weight. 
Chapter V Page 80 

Table V-8. Selected Measures of Tensile Strength (N/mm2) in Plywood Made 

with Urea-formaldehyde (UF) and UF-Methylene Diisocyanate (UF-MDI) Hybrid 

Resins1

------------ Tensile Strength (N/mm2) ------------ Test UF UF-MDI (5%) UF-MDI (10%) UF-MDI (15%)

Dry Internal Bond 2.00 2.07 2.13 1.89 

24-hour Cold Soak 1.91 2.00 2.00 2.26 

Boiling Water: 3-min 2.27 2.88 2.49 2.57 

Boiling Water: 5-min 1.96 2.41 2.52 2.32 

Boiling Water: 7-min 1.87 2.02 2.21 2.18 

Boiling Water: 11-min 0.42 1.84 1.70 1.90 

Boiling Water: 15-min 0 0 1.28 1.95 

Boiling Water: 19-min 0 0 1.25 1.49 

Boiling Water: 23-min 0 0 0 0.71 

Boiling Water: 27-min 0 0 0 0.61 

Boiling Water: 30-min 0 0 0 0 

(1) Source: Mansouri et al. (2006). For the UF-MDI headings, values in parentheses indicate the 

amount of MDI in the resin on a weight-basis. “min” = minutes. Glue-spread = 300-320 g/m2; 

press time = 5 min; press temperature = 120 °C; pre ss pressure = 11 kg/cm2. 

b. Phenol-formaldehyde-MDI (PF-MDI) Resins

Phenol-formaldehyde and MDI resins have been used to manufacture plywood 

and oriented strand board (OSB) for exterior applications outside the U.S. 

because of their excellent water resistance. Presently, PF resins dominate the 

market for exterior and marine-grade plywood (Pizzi et al., 1995); however, PF 

resins are less effective when used to bind wood veneers with high moisture 

contents. This limitation may be overcome by adding MDI to a PF resin (as in a 

PF-MDI hybrid), as it raises the moisture tolerance of the resin, promotes resin 

curing, and enables a stronger bond-line to develop between the plywood 

veneers (Figure V-1). When used alone, full curing of a MDI resin requires 

veneer moisture contents to be above 10% and curing time is not affected until 

the veneer moisture content is greater than 18% (Zheng, 2002). Compared to 

PF resins, MDI resins have a faster cure rate at lower press temperature and 

better resin network stability at lower adhesive spread levels (Conner, 2001), and 

are currently used in industrial applications to upgrade the performance of 

traditional wood resins (Lei et al., 2006). 
Chapter V Page 81 

Figure V-1. Polyurethane Cross-linking in a PF-MDI Hybrid Resin 

OH

CH2 CH2

OH

n n

CH2

OH

CH2 O NH NH O

O

C

O

OH

CH2

CH2 R C

c. Phenol-urea-formaldehyde-MDI (PUF-MDI) Resins

Phenol-urea-formaldehyde (PUF) resins have been used for exterior applications 

since the early 1990’s (Pizzi, 1994). To reduce resin cost, increasing amounts of 

urea have been added, which affects a number of structural properties in PB, 

especially water resistance (Osman et al., 2005). To counterbalance the effects 

of urea, MDI can be added to improve the performance of the board and to 

accelerate the curing process. 

Table V-9. Effect of MDI and/or Urea Additions on Selected Resin and Panel 

Properties in Particleboard Made with Phenol-urea-formaldehyde (PUF) Resins1

-------------------- PUF Resin -------------------- 

Resin or Panel Property Control 10% MDI 10% MDI 

+ 15% Urea

10% MDI 

+ 20% 

Urea 

Viscosity (MPa · s) 570 570 210 164 

Board Density (kg/m3) 693 706 708 705 

Wet Internal Bond (MPa) 0.16 0.25 0.19 0.16 

(1) Source: Osman et al. (2005). “MPa · s” = megapascals-second; “g/cm3

” = grams per cubic 

centimeter; “MPa” = megapascals. Particleboard press temperature = 195°C, press time = 11 

s/mm, and pressure = 28 kg/cm2

. Wet internal bond strength was measured after the PB was 

boiled in water for two-hours and dried for 16-hours (DIN 68763). 

Osman et al. (2005) examined the properties of 16-mm PB made with four PUF 

resins, to evaluate the changes resulting from additions of MDI and urea. The 

control PUF resin had a solids content of 59% and contained approximately 40% 

urea by weight. The test resins were “PUF + 10% MDI,” “PUF + 10% MDI + 15% 

urea,” and “PUF + 10% MDI + 20% urea.” With respect to resin viscosity, 

addition of MDI alone had no effect relative to the PUF control, but urea additions 

resulted in sizable reductions (Table V-9). While only minor changes were 

observed in PB density (i.e., 1 to 2% higher than the PUF control), the addition of 

10% MDI to the PUF resin dramatically increased the wet internal bond strength 
Chapter V Page 82 

of PB compared to the PUF control, except with addition of 20% urea. With 

further research, it is conceivable that a cost-competitive PUF-MDI hybrid resin 

may be developed to allow manufacturers to produce PB with the desired 

structural properties and low HCHO surface emissions. 

d. Phenol-melamine-urea-formaldehyde-MDI (PMUF-MDI) Resins

Phenol-melamine-urea-formaldehyde (PMUF) resin is used to manufacture 

exterior-grade composite wood panels. The resin is made by co-reaction of a 

PMUF resin with 5 to 10% phenol (Cremonini et al., 1996). 

Lei et al. (2006) evaluated the effects of adding small increments of MDI to a 

PMUF resin on PB performance. The base PMUF resin had P:M:U:F mole ratio 

of 0.11 phenol, 0.33 melamine, 1.18 urea, and 2.15 formaldehyde, plus 

ammonium sulfate (3% by weight). Small additions of MDI did not appear to 

affect PB dry internal bond strength, as the value for PB made with 100% MDI 

was only 14% higher than for the PB made with 100% PMUF resin (Table V-10). 

Table V-10. Dry and Wet Internal Bond (IB) Strength and Density in 

Particleboard Made Phenol-melamine-urea-formaldehyde (PMUF)-MDI Resins1

PMUF Resin --------------- Internal Bond (IB) or Density --------------- 

% MDI Added Dry IB 

(MPa) 

Dry Density 

(kg/m3

) 

Wet IB 

(MPa) 

Wet Density 

(kg/m3) 

0 1.00 711 0.09 727 

5 0.95 693 0.21 675 

10 1.05 726 0.23 713 

15 1.08 697 0.29 720 

25 0.94 701 0.46 714 

50 1.00 702 0.48 694 

75 1.01 702 0.46 689 

85 1.02 681 0.36 708 

90 1.05 698 0.45 674 

95 0.98 681 0.48 700 

100 1.14 653 0.58 660 

(1) Source: Lei et al. (2006). “MPa” = megapascals; “kg/m3

” = kilograms per cubic meter. The 

total resin solid content of the PB was 10%. Particleboard press temperature = 195 oC, press 

time = 11 s/mm, and maximum pressure = 33 kg/cm2

. Wet internal bond strength was measured 

after the PB was boiled in water for two-hours and dried for 16-hours. 

Far greater changes were observed in wet internal bond strength where additions 

of 5 or 10% MDI raised values by more than two fold (i.e., 0.21 to 0.23 vs. 0.09 

MPa). When the amount of MDI was 25% or more, wet internal bond strength 

was increased by four or five fold relative to the PMUF control. Densities of the 
Chapter V Page 83 

PB ranged from 653 to 727 kg/m3 in measurements made before or after the wet 

internal bond test. While lower densities were measured in PB made with 85% 

or more MDI before the wet internal bond test, the reductions were not 

consistently observed after the wet internal bond test. At lower MDI additions 

(e.g., 10 to 25%), PB density appeared to be consistently higher relative to PB 

made with the PMUF resin without added MDI. In conclusion, as for the other 

MDI hybrid resins discussed previously (e.g., UF-MDI, PF-MDI, PUF-MDI) adding 

small amounts of MDI to a PMUF resin was also found to dramatically increase 

the performance of PB. For PMUF resins, the largest improvement was 

observed for wet internal bond strength, where additions of 5 to 10% MDI are 

likely to result in only a small increase in resin cost. 

D. Candidate Low-formaldehyde Resin Systems 

In this section, the resin systems that have been used to produce panels with 

low-formaldehyde emissions are discussed. While interior-grade HWPW, PB, 

and MDF are all presently being made with UF resins, in future years, it may be 

necessary to consider an array of low HCHO resins given the manufacturing 

differences between HWPW, PB, and MDF. This is partly due to the stringency 

of present HWPW, PB, and MDF emission standards in the U.S., which have not 

kept pace with efforts in Europe and Japan, where the bulk of the research 

concerning low-formaldehyde resin technology is occurring. 

While the commercial viability of soy resins for HWPW has been demonstrated in 

the U.S., staff expects that manufacturers will opt to use UF resins because of its 

low cost and versatility. To date, domestic efforts to lower HCHO emissions 

have been a consequence of work aimed at improving water resistance in 

composite wood products. As such, despite not being discussed in detail here, 

modified UF resins are likely to be the primary choice of manufacturers to 

achieve low HCHO emissions. Following optimization of plant-level operations 

and wood preparation, it is projected that the use of additives such as hexamine 

and melamine will be examined closely. Should these options prove to be too 

costly, the use of cost-effective non-UF resins might then be considered. 

1. Hardwood Plywood (HWPW) Resins

a. Soy-based Resins for Low-formaldehyde Hardwood Plywood

Soy-based resins have been used since the early 20th Century (United Soybean 

Board, 2004), and research efforts have continuously focused on the 

development of resins with near-zero HCHO emissions, competitive pricing, and 

improved water resistance. In recent years, the use of soybeans (which are 

approximately 40% protein and approximately 34% carbohydrate), as a 

component in adhesives for plywood has grown, due in part to the abundance of 

key functional groups that all resins must have (Li et al., 2004). Proteins provide 

amine and amide functional groups, and carbohydrates provide hydroxyl groups 
Chapter V Page 84 

for high reactivity with a range of cross-linking agents (Heartland Resource 

Technologies, Not Dated). 

Figure V-2. Cationic Polyamidoamine-epichlorohydrin (PAE) 

N

O

H

N

OH

+

-

Cl

Li et al. (2004) prepared a soy-based resin for plywood by combining soy protein 

isolate (SPI) with Kymene® 557H, a commercially available cationic 

polyamidoamine-epichlorohydrin (PAE) resin used in the paper industry (Figure 

V-2). Soy protein isolate is a soy product with a higher protein (86% vs. 40% by 

weight) and lower carbohydrate (14% vs. 34% by weight) content than soybeans. 

A plywood adhesive was prepared by mixing SPI and Kymene®

 at a dry weight 

ratio of 1.33:1. The maximum shear strength and water resistance were then 

determined on 1 x 10 cm plywood strips. Measurements of shear strength were 

made on dry plywood and plywood subject to a water-soaking-and-drying 

(WSAD) test, where the test materials were soaked in water at room temperature 

for 24-hours, and dried for 24-hours, prior to being measured (Figure V-3). No 

significant differences were observed in dry and WSAD shear strength at any 

reaction time. This indicated that plywood shear strength was not reduced after 

a WSAD test, and none of the plywood samples delaminated. 
Chapter V Page 85 

Figure V-3. Effect of Reaction Time on the Dry and Water-Soaking-and Drying 

(WSAD) Shear Strength of Plywood Made with a Soy Protein Isolate-Kymene® 

Resin1 

0

1

2

3

4

5

6

7

8

9

5 30 60 90 120 150

Reaction Time (min)

Shear Strength (MPa)

Dry

WSAD

(1) Source: Li et al. (2004). Shear strengths are the mean of 10 or more replicate measurements. 

Plywood was made with 1 x 10 cm strips of sugar maple veneer; press temperature = 120 °C, 

press time = 5 min; press pressure = 200 psi. 

 

The SPI-Kymene® adhesive developed by Li et al. (2004) produced plywood with 

comparable shear strength properties to plywood made with a PF resin. 

However, SPI is very expensive, and at present-day prices, is not costcompetitive with PF. In comparison, soy flour is an inexpensive alternative that 

may have utility for plywood made for interior applications, which have lower 

interior strength and water-resistance requirements than exterior-grade plywood. 

As such, soy flour-Kymene®

 adhesives may be a cost-competitive no added 

HCHO replacement for UF resins in interior grade plywood. The use of a soybased adhesive for HWPW was initiated by Columbia Forest Products, which 

markets its trademark PurebondTM product line as HWPW made with a no added 

HCHO resin (Columbia Forest Products, 2005). In 2006, Columbia Forest 

Products began converting their HWPW-VC plants, which previously made 

HWPW-VC with a UF resin, to manufacturing PurebondTM. Columbia Forest 

Products has stated that the use of PurebondTM is cost-neutral to UF resin and 

meets the F standard, and its utility as a resin for PB and MDF is 

currently being tested. 

Heartland Resource Technologies has also developed a promising soy-based 

adhesive for HWPW called Soyad®

. In this resin formulation, soy flour is 

combined with a PF resin (Heartland Resource Technologies, Not Dated). In 

their resin, soy flour is denatured in an alkaline environment to expose all 
Chapter V Page 86 

available amine and hydroxyl functional groups to make them accessible to 

crosslinking with the PF resin. When the soy flour is added to the PF resin for 

crosslinking, the bonds formed with HCHO are irreversible. In their experience, 

the manufacturing process is more user-friendly with soy-based resins, since no 

vacuum processing or high-pressure steps are involved (Westcott and Frihart, 

2004). Heartland Resource Technologies has overcome many of the difficulties 

that were encountered in other efforts to develop a soy adhesive for HWPW 

(Table V-11). 

Table V-11. Soy-based Adhesives: Problems and Solutions1

Problems Solutions 

Biologically Unstable Proper denaturing and copolymerizing with small 

amount of reactant improves product biological stability. 

Low Solids 

A new method for denaturing and copolymerizing with 

viable crosslinking agents was developed, allowing for 

soy resins with solids contents ranging from 30 to 45%. 

Slow Press Times Copolymerizing with reactive crosslinking agents allows 

for tailoring cure rates to meet a variety of applications. 

Poor Water 

Resistance 

Soy resins become water-resistant thermoset resins 

after copolymerizing with reactive crosslinking agents. 

Very Short Shelf Life Through innovative processing, the soy resin shelf life 

ranges from two weeks (similar to PF) to one year. 

(1) Source: Wescott and Frihart (2004). 

Wescott and Frihart (2004) examined the properties of oriented strand board 

(OSB) made with a commercially available PF resin and soy-PF resins. Table V12 lists the physical properties of the resins that were tested. The soy-PF resins 

were made using a soy:phenol ratio of either a 1:1 or 3.4:1 by weight. While the 

viscosity of the soy-PF resins were three- to four-times higher than the PF resin, 

the soy-PF resins could still be applied as a spray. This is because the soy-PF 

resins are thixotropic; their viscosity lowers when stress or high shear is applied, 

such as in the spraying process. As such, the viscosity of these soy-PF resins is 

lowered when it is sprayed, then it returns to its original viscosity after pressing 

and cooling. This property makes the resins easier to work into the 

manufacturing process and may have applications to PB and MDF. While the 

soy-PF resins had lower solids contents than the PF resin, values for percent 

extractables were similar for the 1:1 soy-PF resins and higher for the 3.4:1 soyPF resin. 
Chapter V Page 87 

Table V-12. Physical Properties of Phenol-formaldehyde (PF) and Soy-PF 

Resins1

----------------------------- Resin ------------------------------ Property PF Soy-PF 1 Soy-PF 2 Soy-PF 3 Soy-PF 4 

Soy:Phenol 0:1 1:1 1:1 1:1 3.4:1 

Viscosity (mPa·s) 244 1,200 1,100 750 1,100 

pH 11.2 10.2 11.3 11.3 10.3 

% Solids 53.3 39.0 34.4 39.5 35 

% Extractable 24 16 22 22 32 

(1) Source: Westcott and Frihart (2004). “mPa·s ” = millipascal-second. 

In their OSB study, Westcott and Frihart (2004) used the soy-PF resins as a face 

resin, which they applied by air atomization. The 7

/16” OSB was formed on a 16” 

x 16” mat from yellow poplar strands with 5.6% moisture content to a target 

density of 42 lbs/ft3 (674 kg/m3). The OSB made with a 1:1 soy:phenol ratio (i.e., 

Soy-PF 1-3), displayed dry internal bond strengths that were comparable to OSB 

made with the PF resin (Figure V-4). The OSB made with soy-PF 4 required a 

longer press time due to its higher soy content (data not shown). Further 

research is needed to optimize the crosslinking in soy-PF resins at soy:phenol 

ratios greater than 1:1. 

Figure V-4. Dry Internal Bond Strengths for Oriented Strand Board made with PF 

and Soy-PF Resins1

 

0

10

20

30

40

50

60

70

80

90

100

PF Control Soy 1 Soy 2 Soy 3

Internal Bond (lb./in

2

)

210 sec

150 sec

(1) Source: Westcott and Frihart (2004). Oriented Strand Board press temperature = 200 oC. 
Chapter V Page 88 

Wet internal bond strength was evaluated after applying the aggressive 2-hour 

boil test, where OSB is boiled for 2-hours and then oven-dried (Westcott and 

Frihart, 2004). As for the results of the dry internal bond test, OSB made with the 

1:1 soy:phenol resins exhibited comparable results to OSB made with a PF resin 

(Figure V-5), indicating that soy resins can used to produce OSB with excellent 

durability. 

Figure V-5. Wet Internal Bond Strengths for Oriented Strand Board Made with 

Phenol-formaldehyde (PF) and Soy-PF Resins1

0

1

2

3

4

5

6

7

8

9

10

PF Soy 1 Soy 2 Soy 3

Internal Bond (lb./in

2

)

210 sec

150 sec

(1) Source: Westcott and Frihart (2004). 

In conclusion, soy resins are an option for HWPW, and there are other 

researchers working to develop soy-based resins. For example, at Kansas State 

University, Dr. X. Susan Sun is developing a HCHO-free soy resin that is water 

resistant (K-State Media Relations & Marketing, 1998). The United Soybean 

Board is currently involved with soy binder research for large manufacturers of 

composite wood products (United Soybean Board, 2004). 

b. Polyvinyl Acetate (PVA) Resins for Low-formaldehyde Hardwood 

Plywood

Polyvinyl acetate (PVA) is used to manufacture HWPW-VC for internal 

applications. It is a water-soluble adhesive that does not contain HCHO, and is 

one of the more flexible resins used to make plywood. Plywood made with PVA 

cures at lower temperatures than UF resins, thus allowing for reduced product 

cycle times (Steenbergen, 2000). The pot-life for PVA ranges from two to three 
Chapter V Page 89 

days after mixing compared to three or four hours for UF resins (Steenbergen, 

2000). Under high moisture settings, PVA it does not bind as well as UF (Frihart, 

2005). 

Franklin International (1999), among others, sells PVA that meets the 

requirements for the Hardwood Plywood & Veneer Association’s HP-1 Type I and 

Type II plywood under several brand names (e.g., Multibond®

, Titebond®, 

Advantage®). Polyvinyl acetate adhesives can be obtained as either one-part 

systems that come pre-mixed, or as a two-part system that utilizes a catalyst. 

Because PVA is a no added HCHO resin (i.e., does not use HCHO as part of the 

cross-linking structure), it could be used to make HWPW that would achieve low 

HCHO emission levels. 

c. Tannin-based Resins for Low-formaldehyde Hardwood Plywood

The use of tannins, as a substitute for petroleum-based resins, has been studied 

for quite some time. Tannins are naturally phenolic and have been used 

commercially as a replacement for phenol or resorcinol in PF or phenolresorcinol-formaldehyde (PRF) resins in Brazil, South Africa, and Australia 

(Santana et al., 1996). Different hardwood tannins, such as wattle and 

quebracho, have been produced and used commercially (Li and Maplesden, 

1998). As a naturally occurring compound in trees, there is a real potential for 

tannins to be used in an aldehyde-free and no added HCHO adhesive for 

plywood, PB, and MDF. Three new tannin-based technologies, tannin-hexamine 

hardening, tannin autocondensation, and methylolated nitroparaffin hardening, 

are ready for use at the industrial-scale, and are presently being considered for 

use by a number of international manufacturers (Pizzi, 2006). 

Hexamine (Figure V-6) is a nitrogen-containing compound that can be used as a 

tannin hardener (Kamoun et al., 2003). It readily reacts with the nucleophilic 

sites on tannins, resorcinol, and melamine. Under alkaline conditions, hexamine 

intermediates react with tannins before decomposition to HCHO. Tanninhexamine resins are environmental-friendly; composite wood products made with 

these resins exhibit near-zero HCHO concentrations when measured using the 

JIS A5908 desiccator test (Pichelin et al., 2006). Pizzi et al. (1994) found that 

faster press times for products made with tannin-hexamine resins could be 

achieved by adding accelerators, such as zinc salts. 
Chapter V Page 90 

Figure V-6. Chemical Structure of Hexamine 

N

N

N N

CH2 CH2

CH2

CH2

CH2

CH2

Tannin autocondensation is a reaction that takes place between polyflavonoid 

tannins that consist of 5 to 11 monoflavonoid units. Monoflavonoid units consist 

of two phenolic rings joined by a heterocyclic ring (i.e., one or more atoms in the 

ring are atoms other than carbon) (Figure V-7). Under alkaline or acidic 

conditions, polyflavonoid tannins can autocondense in the absence of HCHO – 

the functional groups on a monoflavonoid in a tannin molecule can react with 

another monoflavonoid unit on a different tannin molecule. While the viscosity of 

the tannin increases, gelling does not occur (Pizzi, 2006). In order to control 

viscosity, increase pot-life, and avert gelation in tannins, methanol is usually 

added. Overall, tannin autocondensation reactions improve the dry strength of 

composite wood panels with little or no HCHO emissions. 

Figure V-7. Chemical Structure of a Monoflavonoid Unit 

O O

O

O

O

H

H

H

H

Trosa and Pizzi (2001) compared the breaking loads and HCHO contents of 

plywood made with a quebracho tannin-based resin amended with a 

methylolated nitroparaffin (i.e., tris(hydroxymethyl)nitromethane or TN). The 10-

mm plywood (5-ply okoume veneer) had an initial moisture content of 4%. 

Compared to plywood made with a MUF resin (M:U = 1), breaking loads in 

plywood made with tannin-TN resins were 22 to 67% lower (Table V-13). 
Chapter V Page 91 

However, when TN additions were 8% by weight or higher, measured breaking 

loads exceeded the minimum requirement of European Norm EN 314 Method 

5.5.3. for exterior-grade plywood. In terms of HCHO content, the plywood made 

with the tannin-based resin with 10% TN had a DIN EN 120 value of 0.5 mg/100 

g dry board, well below the European E1 standard of 8 mg/100 g dry board. 

These results show that the addition of TN, and potentially other methylolated 

nitroparaffins, to tannin-based resins, can both improve plywood strength and 

lower HCHO content. 

Table V-13. Effect of Tris(hydroxymethyl)nitromethane (TN) Addition on the 

Breaking Loads and Formaldehyde Contents of Plywood Made with Quebracho 

Tannin Resin1

Resin or Standard Breaking Load 

(MPa) 

HCHO Emissions 

(mg/100 g panel) 

MUF Control 2.7 6 

Quebracho + 6% TN 0.9 NA 

Quebracho + 8% TN 1.7 NA 

Quebracho + 10% TN 2.1 0.5 

EN 314 Standard > 1.0 < 6.5 

(1) Source: Trosa and Pizzi (2001). “MPa” = megapascals; “mg” = milligram(s); “g” = gram(s); 

“NA” = not available. Plywood press temperature = 120 °C; total press time = 6 minutes; press 

pressure = 8 kg/cm2

; glue spread = 250 g/m2. EN 314 Standard refers to the European Standard 

for Class 3, Marine-grade plywood. 

Tannin-based adhesives have also been used to manufacture various grades of 

HWPW in Brazil and China. To produce exterior-grade plywood, adhesives are 

fortified with other polymer systems, such as PF, RF, PRF, and MDI (Santana et 

al., 1997). Copolymerization with resol PF may also provide cost savings 

(approximately 20 to 40%) in that industrial applications allow for the use of 250 

g/m2 adhesive instead of 400 g/m2, as required for PF resin. 

d. Phenol-urea-formaldehyde-Tannin (PUFT) Resins for Lowformaldehyde Hardwood Plywood

Tannins, which are phenolic in nature, can be used to replace phenol in PF 

resins. Vasquez et al. (2004) created a PUFT resin using PUF prepolymers and 

Pinus pinaster bark tannins, and compared the chemical characteristics of the 

resulting PUF and PUFT adhesives. The PUF and PUFT resins were prepared 

in two stages. The first stage involved reacting HCHO and phenol under acidic 

conditions for one or two hours, and the second involved reacting HCHO with 

urea under alkaline conditions for 40 or 80-minutes. The two-stage synthesis 

allowed the viscosity of the resin to be comparable to PUF resins used in 

commercial plywood facilities (1,300 to 3,000 mPa·s); however, the viscosity of 
Chapter V Page 92 

the PUFT resins increased over the 16 to 18 hour period between resin synthesis 

and chemical analysis. The PUFT resins displayed lower free-phenol contents 

than the PUF prepolymers and longer pot-lifes (4 to 7 days) than other tanninmodified adhesive systems that were deemed unsuitable for use in plywood 

manufacturing. For the PUF resins, lower free-formaldehyde:phenol ratios were 

observed in resins with 80-minute stage two reaction times (Figure V-8). The 

PUFT resins, containing 5 to 17% tannin by weight, had 40 to 65% lower ratios of 

free-formaldehyde:phenol than comparable PUF resins. The PUFT resins with 

the highest tannin concentrations exhibited the lowest free-formaldehyde:phenol 

ratios. Spectral data indicated that the decrease in free-formaldehyde was due 

to methylolation reactions between Pinus pinaster bark tannin and freeformaldehyde in the resin. 

Figure V-8. Mole Ratios of Free Formaldehyde:Phenol in Phenol-ureaformaldehyde (PUF) and PUF-Tannin Resins1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

PUF

(1,40)

PUFT

(1,40)

17%

PUF

(1,80)

PUFT

(1,80)

5%

PUF

(2,40)

PUFT

(2,40)

17%

PUF

(2,80)

PUFT

(2,80)

10%

Moles Free-HCHO/mol phenol

(1) Source: Vasquez et al. (2004). The numbers in parentheses are the number of hours and 

minutes required for stage 1 and stage 2 resin synthesis, respectively. For PUFT resins, the % 

value is the tannin concentration on a weight basis. 

2. Particleboard (PB) Resins

a. Phenol-urea-formaldehyde (PUF) Resins for Low-formaldehyde 

Particleboard 

For the past 40-years, PB manufacturers have primarily used UF and PF resins. 

The use of low-cost UF resins has been dominant for interior applications, while 

PF resins are principally used to make exterior-grade products. The 

development of PUF resins was undertaken as a cost-control approach to 
Chapter V Page 93 

improving the durability and reducing HCHO emissions from interior-grade 

products (Tomita and Hse, 1998). 

Zhao et al. (1999) examined the gel times for PF resins co-reacted with urea (up 

to 42%) under alkaline conditions, which promotes reactions between the 

hydroxyl groups on PF resins and amine groups on urea, as shown in the 

following: 

PF–CH2OH + NH2CONH2 ↔ PF–CH2–NHCONH2

Tests were conducted on samples of PB prepared in their laboratory made with a 

9% PF resin solids content. The gel times of the PF resins with different F:P 

mole ratios and mole percentages of co-reacted urea are displayed in Table V14. These results indicate that at the F:P mole ratios tested, increasing the 

amount of urea leads to faster gel times. The decrease in gel times with urea 

addition was thought to be due to an increase in molecular size of the polymer. 

Table V-14. Gel Times (minutes) for Particleboard Made with Phenolformaldehyde (PF) Resins Co-reacted with Urea1

F:P Mole -------------------- Urea (Mole % of Phenol) -------------------- 

Ratio 0 6 12 18 24 

1.5 64.9 53.4 46.1 37.2 29.5 

1.7 46 35.5 30.2 23.4 21.5 

2.5 25.4 23.3 19.5 18.1 18.0 

(1) Source: Zhao et al. (1999). Particleboard press temperature = 190 to 195 °C; maximum 

pressure = 28 kg/cm2. 

These workers also examined the effects of urea addition on dry and wet internal 

bond strength of softwood PB bonded with a PF resin (F:P mole ratio = 1.7) 

(Table V-15). Their results showed that the dry and wet internal bond strengths 

are highest for softwood PB made a PUF resin with 12 to 24 mole-percent urea 

(i.e., dry strength > 1 MPa and wet strength ≥ 0.27 MPa). Spectral data 

confirmed that the greatest proportion of urea co-reaction with phenol occurs at 

18 mole-percent urea, and that at urea mole-percentages greater than 12, there 

is virtually no free-formaldehyde in the PB. 
Chapter V Page 94 

Table V-15. Effect of Urea Addition on Dry and Wet Internal Bond Strengths in 

Softwood Particleboard Bonded Phenol-formaldehyde (PF) Resin1

Resin Dry Internal Bond (MPa) Wet Internal Bond (MPa) 

PF Control 0.88 0.20 

+ 6% urea 0.91 0.26 

+ 12% urea 1.07 0.30 

+ 18% urea 1.09 0.31 

+ 24% urea 1.12 0.28 

+ 30% urea 0.98 0.25 

+ 36% urea 0.94 0.24 

+ 42% urea 0.96 0.25 

(1) Source: Zhao et al. (1999). Wet internal bond strength was measured after the particleboard 

was boiled for two-hours and dried. The F:P mole ratio of the PF control resin = 1.7.

The process throughput of PB made with PF resins is typically slower than that 

for PB made with UF resins, where the fastest press times for PB made with a 

commercial PF resin is reported to be 12 to 13 s/mm at a press temperature of 

190 °C (Zhao et al., 1999). To achieve faster pres s times, manufacturers can 

either use higher press temperatures or add carbonate accelerators. The 

effectiveness of glycerol triacetate or triacetin (Figure V-9) has been tested in 

PUF resins as an means to accelerate PUF resin crosslinking and increase the 

board strength. 

Figure V-9. Chemical Structure of Triacetin 

O

O

O

O

O

O

Zhao et al. (1999) found that the press time for hardwood PB bonded with a PUF 

resin (i.e., F:P mole ratio = 1.7, urea = 24 mole-percent) could be reduced from 

21.4 to 8.5 s/mm without decreasing dry or wet internal bond strength, by 

addition of triacetin (Table V-16). The press times they achieved were 

comparable to those of a catalyzed UF resin. The hardwood PB made using an 

8.5 s/mm press time, exhibited dry and wet internal bond strengths that would 
Chapter V Page 95 

readily comply with the European Norm (EN 300, 1996) or German DIN 

standards (DIN 68763) of 0.35 MPa or greater and 0.15 MPa or greater, 

respectively. At a 7.1 s/mm press time, dry and wet internal bonds were 

markedly lower than at 21.4 s/mm, but the resulting dry and wet internal bond 

strengths would still comply with European and German standards. Similar 

reductions in press times may also be achieved by raising press temperatures to 

200 to 220 °C without reducing internal bond streng th to levels below the 

standard(s). Board densities ranged only slightly, from 729 to 753 kg/m3, over 

the range of press times tested. 

Table V-16. Effect of Press Time on Dry and Wet Internal Bond Strength in 

Hardwood Particleboard Bonded with a Phenol-urea-formaldehyde (PUF) Resin 

with Triacetin1

Press Time 

(s) 

Press Time 

(s/mm) 

Dry Internal 

Bond (MPa) 

Board Density 

(kg/m3) 

Wet Internal 

Bond (MPa) 

300 21.4 0.85 753 0.23 

240 17.1 0.93 758 0.28 

180 12.9 0.95 729 0.29 

150 10.7 0.95 732 0.30 

120 8.5 0.81 751 0.22 

100 7.1 0.52 735 0.15 

90 6.4 0.49 741 0.11 

(1) Source: Zhao et al. (1999). Wet internal bond strength was measured after the PB was boiled 

for two-hours and dried. Particleboard was bonded with PUF resin with a F:P mole ratio = 1.7; 24 

mole-percent urea, and 10% triacetin by weight. “s” = seconds; “s/mm” = seconds per millimeter; 

“MPa” = megapascals; “kg/m3” = kilograms per cubic meter. 

b. Tannin-based Resins for Low-formaldehyde Particleboard

The effort to decrease or eliminate surface HCHO emissions from PB using 

tannin-based resins is a work-in-progress. There are tannin technologies that 

are viable for commercial use in Australia, New Zealand, Chile, Brazil, Argentina, 

and South Africa (Frihart, 2005). Interest in using tannin-based resins is growing 

in Japan and Europe. In this regard, tannin autocondensation, an environmentalfriendly technology previously described subsection IV.A.3. for HWPW, can also 

be used for manufacturing PB. 

Pizzi et al. (1995) measured the HCHO content of PB made with resin produced 

by pecan nut (Carya illinoensis) tannin autocondensation. Over a range of press 

times from 10 to 37.5 s/mm, HCHO contents in PB ranged from 0.01 to 0.03 

mg/100 g dry board (by the DIN EN 120 test). These data demonstrate the 

potential utility of tannin-based resins for producing PB with low HCHO contents. 

To determine if the structural properties of PB made with tannin-based resins 
Chapter V Page 96 

were adversely affected, these workers measured the internal bond strength of 

PB made with four commercial flavonoid tannin-based resins (i.e., pecan nut (C. 

illinoensis), pine bark (Pinus radiata), mimosa bark (Acacia mollissima), and 

quebracho wood (Schinopsis balansae)). The 12-mm PB used in the study was 

made by pressing wood particles with 3% moisture content for 7.5 minutes at 

190 oC. Board densities ranged from 680 to 700 kg/m3

. While the internal bond 

strengths for PB made with pine and pecan resins were as high as 0.8 MPa, the 

values for PB made with mimosa or quebracho resins were 0.3 MPa or less. 

However, when pecan nut tannin (40% by weight) was added to the mimosa or 

quebracho resins, internal bond strengths increased by four- to five-fold. The 

increase in internal bond strength was thought to be due the presence of more 

reactive tannin “A-rings” in pecan nut and pine bark than in mimosa bark or 

quebracho wood. Press times could also be improved by the addition of finely 

powdered silica. 

In comparison, Kim et al. (2003) measured the mechanical and physical 

properties of PB made with two tannin-hexamine resins (subsection IV.A.3.). 

Ttwo other hardeners besides hexamine were tested, but only the results for 

hexamine are discussed here. Commercial tannin extracts from wattle (or 

mimosa (Acacia mearnsii)), and radiata pine (Pinus radiata) were provided by 

Bondtite (New South Wales, Australia) and DITECO (Punta Arenas, Chile), 

respectively. Hexamine (i.e., 6.5, 8, and 10% by weight of dry tannin extract) 

was added to each tannin extract. The PB was pressed a temperatures ranging 

from 160 to 190 oC for 5-minutes at a pressure of 30 kg/cm2

, and released in 

(two) one-minute steps. The 8-mm PB was preconditioned at 25 °C and 65% 

relative humidity for two weeks before testing. The HCHO contents of the PB 

were measured by the DIN EN 120 test. Particleboard produced with either 

tannin-hexamine resin had very low HCHO content; the values for wattle and 

pine were 0.85 and 1.75 mg HCHO/100 g dry board, respectively. By 

extrapolation, PB with these DIN EN 120 values would have ASTM E1333 values 

less than 0.03 ppm, which may meet the Japanese F standard. In 

comparison, the proposed Phase 2 standard for PB is 0.08 ppm. 

Kim et al. (2003) also examined changes in bending (modulus of rupture) and 

internal bond strength in PB made with the wattle and pine tannin-hexamine 

resins. The two tannins differ with respect to their A-ring reactivity, which affect 

their curing properties. The resin made with wattle tannin is more of a 

thermosetting resin, in which functional group cross-linking increases with press 

temperature, whereas the resin made with pine tannin is fast-reacting, and cures 

at lower press temperatures. As projected, PB made with the wattle tanninhexamine resin exhibited a stronger modulus of rupture and internal bond 

strength as press temperature was raised from 160 to 190 °C, while the 

responses of PB made with the pine tannin-hexamine resin decreased with 

increasing press temperature. Overall, PB made with either tannin-hexamine 

resin exhibited strength properties that exceeded the minimum requirements for 

Grade M-3 industrial or shelving PB (Table V-17; ANSI, 1999). 
Chapter V Page 97 

Table V-17. Minimum American National Standards Institute (ANSI) Strength 

Requirements for Medium (M) Industrial and Shelving Grade Particleboard1

------------ Minimum Strength Requirement (MPa) ----------- 

Grade Modulus of 

Rupture Modulus of Elasticity Internal Bond 

M1 11.0 1,725 0.40 

MS 12.5 1,900 0.40 

M2 14.5 2,250 0.45 

M3 16.5 2,750 0.55 

(1) Source: ANSI (1999). Listed values are those specified for the ANSI A208.1 standard. 

In other studies to identify additives that would both lower HCHO contents and 

strengthen the physical properties of PB, Trosa and Pizzi (2001) added a 

methylolated nitroparaffin (i.e., tris(hydroxymethyl)nitromethane or TN) to a 

tannin-based resin and produced PB with satisfactory structural properties for dry 

internal bond and 2-hour boil test strengths, and low HCHO emissions (DIN EN 

120 = 0.3 to 0.6 mg/100 g dry board). Ballerini et al. (2005) used a tannin-glyoxal 

adhesive to produce PB with very low HCHO contents (i.e., DIN EN 120 = 0.6 

mg/100 g dry board). Glyoxal is a simple di-aldehyde that has a low toxicity and 

can be substituted for HCHO. Either of the above additives, TN or glyoxal, could 

be used to produce PB that would comply with the proposed Phase 2 standard 

(0.08 ppm). 

c. Cashew Nut Shell Liquid (CNSL) Resins for Low-formaldehyde 

Particleboard

Cashew nut shell liquid (CNSL) is a naturally occurring product that chemically 

has phenolic nuclei with unsaturated fatty acid chains (Figure V-10), and has 

potential utility as an additive for improving water-resistance in PB, and possibly 

other composite wood products (Pizzi, 2006). Presently, the major source 

continents of CNSL are South America and Asia; however, there are a number of 

cashew plantations in Mozambique (Kanji et al., 2004). At BC (formerly the 

BioComposites Center, Bangor, Wales), reactive aldehyde monomers were 

prepared by ozonolysis of CNSL. As an additive to PB resin, the aldehyde 

monomers react with the aromatic groups of cardanol (i.e., anacardic acid) and 

produce a phenol/aldehyde crosslinking network. As these monomers are very 

reactive, self-condensation occurs and no crosslinking agent needs to be added 

to the mixture. 
Chapter V Page 98 

Figure V-10. Chemical Composition of Cashew Nut Shell Liquid 

OH

R1

R2

R3

C15H31-n

R1 = H or CH3

R2 = H or OH

R3 = H or COOH

Anacardic acid (R1 = H, R2 = H, R3 = COOH)

Cardanol (R1 = H, R2 = H, R3 = H)

Cardol (R1 = H, R2 = OH, R3 = H)

Methyl cardol (R1 = CH3, R2 = OH, R3 = H)

The CNSL-based resin technology is in early stages of development, thus, it is 

difficult to evaluate its economical feasibility. However, strength tests of PB 

made in a laboratory with CNSL-based resins are promising (Table V-18). 

Compared to PB made with PF resin, PB made with a CNSL-based resin had 

higher lap-shear bond and dry internal bond strengths. These findings provide 

support for the use of CNSL-based resins in PB manufacturing (Pizzi, 2006), but 

additional information on press time and board density is needed to fully assess 

its cost-effectiveness in industrial applications. 

Table V-18. Strength Responses in Particleboard Made with Phenolformaldehyde (PF) and Cashew Shell Nut Liquid (CNSL) Resins1

-------------------- Strength (MPa) -------------------- Resin Lap-shear Bond Dry Internal Bond Wet Internal Bond 

PF Control 5.55 0.69 NR 

CNSL 6.77 1.05 0.58 

(1) Source: Pizzi (2000). “MPa” = megapascals; “NR” = not reported. Wet internal bond strength 

was measured after the particleboard was boiled for two-hours and dried. 

d. Soy-based Resins

Work continues to develop soy resins that can be used to produce PB (Heartland 

Resource Technologies, Not Dated). Recently, Columbia Forest Products 

announced the availability of a PurebondTM PB, which is being used as the 

platform for its composite core plywood products. 
Chapter V Page 99 

3. Medium Density Fiberboard (MDF) Resins

a. Tannin-based Resins for Low-formaldehyde Medium Density 

Fiberboard 

Three tannin-based technologies (i.e., hexamine addition, autocondensation, and 

methylolated nitroparaffin addition; see subsection IV.A.3.) that have potential 

utility in the manufacture of HWPW and PB, have also been found to be 

applicable to MDF. 

Trosa and Pizzi (2001) found that exterior/marine-grade HWPW, PB, and MDF, 

with very low HCHO emissions, could be made with a tannin-based resin by 

adding an inexpensive methylolated nitroparaffin (i.e., tris(hydroxymethyl)-

nitromethane or TN). In their study, the addition of TN prolonged the pot-life of 

the tannin-based resin, and HCHO emissions only occurred when the wood was 

heated – at lower temperatures, the resin appeared to depress HCHO emissions 

originating from wood used to make the boards. Comparison of HCHO content 

and measures of strength and swell were conducted on 3-mm MDF made from 

pine wood fibers in plant trials with either UF or quebracho tannin-based resin 

(i.e., total tannin solids, TN, and wax emulsion contents were 14%, 16%, and 2%, 

respectively). Relative to the MDF made with UF resin, the MDF made with the 

tannin-based resin had a higher bending strength and lower free-HCHO content 

(Table V-19), but no differences were observed in cold water swell, board 

density, or dry internal bond strength. The free-HCHO content of the MDF was 

low enough to meet the requirement for E0 boards, which is lower than the 

proposed Phase 2 standard for MDF of 0.08 ppm. Similar results were also 

obtained for HWPW and PB made with the tannin-based resin. As an additive to 

tannin-based resins, TN could be added with other HCHO-based resin hardeners 

(e.g., methylolureas, paraformaldehyde) over a broad range without loss of 

effectiveness. 

Table V-19. Density, Swell, Strength, and Formaldehyde Content in Medium 

Density Fiberboard Made with Urea-formaldehyde (UF) and Quebracho Tanninbased Resins1

-------------------- Resin -------------------- Parameter Quebracho Tannin UF Control 

Density (kg/m3) 870 870 

Cold Water Swell (20 °C for 24-hours) 14% 14% 

Bending Strength (MPa) 38 30 

Dry Internal Bond Strength (MPa) 1.8 1.8 

HCHO Content (mg/100 g dry board) 0.0 0.9 

(1) Source: Trosa and Pizzi (2001). “kg/m3

” = kilograms per cubic meter; “oC” = degrees Celsius; “MPa” = 

megapascals; “mg” = milligrams. Medium density fiberboard (3-mm thickness) press temperature = 180 °C , 

press time = 22 s/mm; maximum press pressure = 170 Bar. The quebracho tannin-based resin contained 

16% tris(hydroxymethyl)nitromethane and 2% wax emulsion by weight. 
Chapter V Page 100 

b. Phenol-urea-formaldehyde-Tannin (PUFT) Resins for Lowformaldehyde Medium Density Fiberboard

As the cost of petrochemical-based resin components rise (e.g., phenol), the 

search for lower cost alternatives is of increasing concern to resin manufacturers. 

For HWPW and MDF, phenol-urea-formaldehyde-tannin (PUFT) resins have 

been tested with promising results, in which increasing amounts of tannins can 

be added in place of phenol. 

Lopez-Suevos and Riedl (2003) measured the dry and wet internal bond 

strengths of MDF made with three PUFT resins. The PUFT resins were made by 

adding 35% Pinus pinaster bark tannin solution to a PUF resin (40% solids 

content by weight). Three PUFT resins were prepared: PUFT-10, PUFT-12, and 

PUFT-15 (the numbers indicate the % tannin content by weight). The MDF was 

made with 90% black spruce and 10% Douglas-fir fibers with an initial moisture 

content of 3%. Relative to dry or wet internal bond strength, only MDF made with 

PUFT-10 had values comparable to MDF made with a PF resin (Table V-20). 

The MDF made with PUFT-15 or PUFT-12, even when pressed for 8.83 minutes, 

exhibited markedly lower dry and wet internal bond strengths, that may be due to 

a higher degree of resin condensation (i.e., when larger resin molecules form, 

which do not bond as tightly to wood fibers as smaller molecules). While all of 

the MDF tested exhibited dry internal bond strengths above the European 

standard for interior-grade MDF (0.6 MPa; EN 319), only the MDF made with the 

PF or PUFT-10 resins would comply with the dry and wet internal bond strength 

standards for exterior-grade MDF (0.8 and 0.15 MPa, respectively). The PUFT10 resin, which has a 44% phenol replacement by tannins, could conceivably be 

a cost-competitive resin for MDF, which may also have a low HCHO content. 

Table V-20. Dry and Wet Internal Bond Strengths of Medium Density Fiberboard 

Made with Phenol-formaldehyde (PF) and Phenol-urea-formaldehyde-tannin 

(PUFT) Resins1

--------------- Strength (MPa) --------------- Resin (Press Time) Density 

(kg/m3

) Dry Internal Bond Wet Internal Bond 

PF Control (5.33 min) 727 1.18 0.58 

PUFT-15 (5.33 min) 771 0.74 0.09 

PUFT-15 (6.83 min) 706 0.62 0.07 

PUFT-15 (8.83 min) 710 0.68 0.08 

PUFT-12 (5.33 min) 734 0.72 0.13 

PUFT-10 (5.33 min) 732 1.10 0.20 

PUFT-10 (8.83 min) 728 1.42 0.44 

(1) Source: Lopez-Suevos and Riedl (2003). “MPa” = megapascals; “kg/m3

” = kilograms per cubic 

meter. Medium density fiberboard press temperature = 215 oC. 
Chapter V Page 101 

E. Technical Basis for the Proposed Emission Standards 

1. Proposed Emission Standards for Hardwood Plywood 

Appendix A contains the regulation order for the proposed ATCM. For HWPW, 

made with a veneer core (HWPW-VC) or with a composite core (HWPW-CC), the 

numerical values of the proposed Phase 1 and 2 HCHO emission standards are 

based on analyses of manufacturer responses to the CARB 2003 Survey, data 

supplied by the Hardwood Plywood & Veneer Association (HPVA), reports or 

articles in the open literature, commercial brochures, and other published 

materials or websites, and stakeholder meetings, concerning resin technologies 

that are either commercially available or laboratory tested to display low or nearzero HCHO emissions. The proposed standards and effective dates for HWPWVC and HWPW-CC are shown in Table V-21. 

Table V-21. Proposed Phase 1 (P1) and Phase 2 (P2)

Formaldehyde (HCHO) Emission Standards for Hardwood

Plywood1

HCHO Emission Standard Effective Date HWPW-VC HWPW-CC 

January 1, 2009 P1: 0.08 ppm ----- 

July 1, 2009 ----- P1: 0.08 ppm 

January 1, 2011 P2: 0.05 ppm ----- 

July 1, 2012 ----- P2: 0.05 ppm 

(1) “ppm” = parts per million; “HWPW-VC” = hardwood plywood with a veneer 

core; “HWPW-CC” = hardwood plywood with a composite core. Compliance 

with the HCHO Emission Standards is demonstrated by producing HWPW-VC 

and HWPW-CC with an ASTM E1333 test value less than or equal to the 

listed P1 or P2 HCHO concentration in ppm. 

From the CARB 2003 Survey, approximately 20% of the HWPW-VC or HWPWCC produced for sale in 2002 achieved, on average, an ASTM E1333 test value 

that would meet the proposed Phase 1 standard of 0.08 ppm. However, as the 

survey respondents did not distinguish if the information they provided was for 

decorative wall panels or industrial panels, industry representatives are 

concerned that the above estimate may not be accurate. Note that the survey 

was conducted before Columbia Forest Products switched to using PurebondTM 

and now about 40% of the HWPW in the U.S. meets the Phase 2 standard. In 

the ASTM E1333 test, decorative wall panels are tested at a higher loading rate 

(0.29 ft2/ft3) than industrial panels (0.13 ft2/ft3). Thus, unless it can be determined 

which type of HWPW-VC or HWPW-CC was measured, an accurate analysis of 

industrial panel emissions cannot be made with certainty. From the survey, all of 

the HWPW-VC or HWPW-CC that achieved an ASTM E1333 value of 0.08 ppm 
Chapter V Page 102 

was made with an ammonia-UF (AUF) resin with added catalysts or hardeners to 

reduce surface HCHO emissions. These AUF resins were reported to have high 

F:U mole F:U ratios ranging from 1.7 to 1.98. Absent clear information regarding 

the need to develop a new standard for decorative wall panels, no change is 

proposed with respect to the loading rates presently used for ASTM E1333 

testing. 

To produce HWPW-VC or HWPW-CC that would meet the proposed Phase 1 

emission standard (a 0.08 ppm cap), manufacturers that choose to use UF resins 

could use resins with lower F:U mole ratios (e.g., 1.05 to 1.20; Baumann, 1997) 

to lower their emissions below their present ASTM E1333 levels. Further 

reductions could be achieved through the use of additives such as ammonium 

chloride or hexamine, which act as hardeners or catalysts, in amounts ranging 

from 1 to 4% by weight. The combined use of a lower F:U mole ratio resin and 

addition of hardeners should enable manufacturers to produce HWPW-VC or 

HWPW-CC that complies with the proposed Phase 1 standard. However, as 

none of the reported HWPW-VC or HWPW-CC was able to comply, on average, 

with the proposed Phase 2 standard (a 0.05 ppm cap), manufacturers may need 

to utilize a reformulated resin system or another resin system than UF. While 

laboratory studies indicate that reductions in HCHO emissions can be achieved 

by the addition of melamine and/or MDI, it will be up to manufacturers to 

determine how best to manufacture HWPW-VC or HWPW-CC that meets the 

proposed Phase 2 standard. 

From analysis of the data provided by the Hardwood Plywood & Veneer 

Association, the issue of whether to establish separate HCHO emission 

standards for HWPW-VC and HWPW-CC was clarified. Previously, stakeholders 

requested that CARB staff consider setting separate standards because the core 

material in HWPW-CC was typically either PB or MDF, which has higher 

allowable emissions than HWPW. In calculating mean ASTM E1333 values for 

HWPW-VC and HWPW-CC from the data provided by the HPVA, the means for 

HWPW-VC and HWPW-CC were 0.12 ppm (n = 14) and 0.08 ppm (n = 5), 

respectively (Tables V-4 and V-5). Moreover, the range in ASTM E1333 values 

for HWPW-VC was 0.08 to 0.19 ppm vs. 0.05 to 0.10 ppm for HWPW-CC. As 

this was counterintuitive to the justification offered by stakeholders from the 

HWPW industry for separate standards, the numerical values of the proposed 

Phase 1 and Phase 2 standards, which apply to HWPW-VC and HWPW-CC, are 

the same. Additional time is provided for HWPW-CC to allow for the availability 

and use of lower emitting core materials. 

In evaluating BACT for HWPW, an internet search uncovered products from 

three U.S. sources, either HWPW panels or resin used to manufacture HWPW, 

that could be used immediately to produce HWPW that complies with the 

proposed Phase 2 standard (Table V-22). 
Chapter V Page 103 

Table V-22. Low-formaldehyde Hardwood Plywood (HWPW) or HWPW-Resins1

Product Company HCHO Emissions Resin System 

PurebondTM Columbia Forest Products Near-zero Soy-based 

Multibond® Franklin Adhesives Near-zero PVA 

Purekor® Collins Pine Company Near-zero MDI 

(1) “Near-zero” emissions indicates measured ASTM E1333 test values = 0.03 ppm or less. 

From the literature and stakeholder discussions, there are resins that have the 

potential to be used to manufacture HWPW to meet the proposed Phase 1 and 

Phase 2 standards, such as soy-based, PVA, MUF, PUF, PUF-tannin, and 

several MDI hybrid systems, and the resin preparation and application methods 

are well documented. As such, staff proposes that the numerical value of the 

Phase 1 standard for HWPW, regardless of core composition, be a cap of 0.08 

ppm measured by the ASTM E1333 test, with effective dates of January 1, 2009 

for HWPW-VC and July 1, 2009 for HWPW-CC. For Phase 2, the proposed 

standard would be a cap of 0.05 ppm measured by the ASTM E1333 test, 

regardless of core composition, with effective dates of January 1, 2011 for 

HWPW-VC and July 1, 2012 for HWPW-CC. 

For Phase 2, careful consideration was given to the absolute value of the 

proposed standard, requirements of the present ASTM E1333 test and the 

potential for higher emitting products in core materials (e.g., PB or MDF) to raise 

measured HCHO concentrations in the ASTM E1333 test. 

2. Proposed Emission Standards for Particleboard

As for HWPW, the numerical values for the proposed Phase 1 and Phase 2 

HCHO emission standards are also based on analyses of the CARB 2003 

Survey. In addition, a review of the literature and expert opinions provided by 

industry and stakeholders on the range of resin and wood preparation 

technologies that could be used to manufacture PB with low to near-zero surface 

HCHO emissions were considered. The proposed standards and effective dates 

for PB are shown in Table V-23. 
Chapter V Page 104 

Table V-23. Proposed Phase 1 (P1) and 2 (P2) Emission 

Standards for Particleboard1

Effective Date HCHO Emission Standard 

January 1, 2009 P1: 0.18 ppm 

January 1, 2011 P2: 0.09 ppm 

(1) “ppm” = parts per million. Compliance with the HCHO Emission Standards 

is demonstrated by producing particleboard with an ASTM E1333 test value 

less than or equal to the listed P1 or P2 HCHO concentration in ppm. 

Analysis of the CARB 2003 Survey data for PB found that approximately 55% of 

the PB produced in 2002, on average, would comply with the proposed Phase 1 

standard of 0.18 ppm. The predominant resins used were UF or methanol-UF 

resins, and PB manufacturers that reported the lowest average ASTM E1333 

values (i.e., less than 0.18 ppm) achieved those levels by adding low mole ratio 

urea solutions (which act as a HCHO scavenger) and/or a variety of catalysts, 

such as ammonium sulfate, sodium chloride, and sodium sulfate. 

Table V-24. Low-formaldehyde Particleboard (PB) and PB-Resin Systems1

Product Company ASTM E1333 

Value Resin Chemistry 

Low-formaldehyde Particleboard 

Purekor® Collins Pine Near-zero MDI 

Skyblend® Roseburg < 0.01 ppm PF 

Low-formaldehyde Particleboard Resin Systems 

Ecobind® Hexion ≤ 0.03 ppm 

MUF + Co-reactants 

PF 

Soy/PVA blend 

Kenocatch® Akzo Nobel ≤ 0.03 ppm MUF + catcher 

Rubinate® Huntsman Near-zero Polyurethane 

(1) “MDI” = methylene diisocyanate; “PF” = phenol-formaldehyde; “MUF” = melamine-ureaformaldehyde; “PVA” = polyvinyl acetate; “ppm” = parts per million. “Near-zero” refers to an 

extrapolated ASTM E1333 value less than 0.03 ppm. 

No manufacturer reported producing PB with an average ASTM E1333 value that 

would meet the proposed Phase 2 standard of 0.09 ppm, although after an 

internet search, a short-list of commercially available low-formaldehyde PB or 
Chapter V Page 105 

resins used to manufacture PB was developed (Table V-24). Both PB products 

are made for niche markets (e.g., Green Building Programs) that specify the use 

of low- or no added HCHO materials. These resin systems, if used in 

combination with additives or low-formaldehyde resins developed outside the 

U.S., may potentially be used meet the proposed Phase 2 standard. 

3. Proposed Emission Standards for Medium Density Fiberboard 

As for HWPW and PB, analysis of the data from the CARB 2003 Survey, 

information in the open literature and expert opinions on low- and no added 

HCHO resin technologies, were the main data considered with respect to 

selecting the numerical values of the proposed Phase 1 and 2 emission 

standards for MDF. The proposed standards and their effective dates are shown 

in Table V-25 for MDF. 

Table V-25. Proposed Phase 1 (P1) and Phase 2 (P2) Standards for 

Medium Density Fiberboard1

Effective Date HCHO Emission Standard 

January 1, 2009 P1: 0.21 ppm 

January 1, 2011 P2: 0.11 ppm 

(1) “ppm” = parts per million. Compliance with the HCHO Emission Standards 

is demonstrated by producing MDF with an ASTM E1333-96 test value less 

than or equal to the listed P1 or P2 HCHO concentration in ppm. 

(2) Thin MDF Phase 1 standard is 0.21 ppm (January 1, 2009), and Phase 2 

standard is 0.13 ppm (January 1, 2012) 

From the CARB 2003 Survey, approximately 25% of MDF reported for sale in 

2002, on average, would comply with the proposed Phase 1 standard (0.21 

ppm). All of the manufacturers that reported producing MDF at an average 

ASTM E1333-96 of 0.21 ppm or less made their products with a UF resin. In our 

view, MDF manufacturers would be able to consistently meet the Phase 1 

standard by using low mole ratio urea solutions (which act as a scavenger), 

and/or a variety of catalysts, such as melamine, ammonium sulfate, sodium 

chloride, and sodium sulfate, or proprietary scavengers. Making MDF with a MDI 

resin would also be a viable approach for meeting the Phase 1 and 2 standards, 

but at present, MDI use is typically limited to the production of products for niche 

applications (e.g., hospitals). These resin systems are just a few of the ways that 

MDF manufacturers could meet the proposed Phase 2 standard (0.11 ppm cap) 

(Table V-26). 
Chapter V Page 106 

Table V-26. Available Low-formaldehyde Medium Density Fiberboard (MDF) or 

MDF-resins1

Product Company HCHO 

Emissions Resin Chemistry 

Low-formaldehyde Medium Density Fiberboard 

• Arreis®

• Medite II®

• Medex®

Sierra Pine ≤ 0.05 ppm MDI 

Purekor® Collins Pine Near-zero MDI 

Low-formaldehyde MDF-resins 

Ecobind® Hexion ≤ 0.03 

• MUF + Coreactants 

• PF 

• Soy/PVA Blend 

Kenocatch® Akzo Nobel ≤ 0.03 MUF + Catcher 

Rubinate® Huntsman Near-zero Polyurethane 

(1) “MDI” = methylene diisocyanate; “PF” = phenol-formaldehyde; “MUF” = melamine-ureaformaldehyde; “PVA” = polyvinyl acetate; “ppm” = parts per million. “Near-zero” refers to an 

extrapolated ASTM E1333 value less than 0.03 ppm. 

4. Thin Medium Density Fiberboard (MDF) (Thickness ≤ 8-mm)

“Thin MDF” is defined as MDF with thicknesses of 8 mm (≈

5

/16 inch) or less. 

While the amount of thin MDF production is not known with certainty, to our 

knowledge, it represents a small percentage of total MDF production in the U.S. 

Thin MDF, at thicknesses starting at 1.8 mm, is being manufactured and used as 

a substitute for hardboard and thin plywood due to its being smooth on both 

surfaces and free from the grain features of plywood substrates (European Panel 

Federation, Not Dated). Fabricators use these materials in furniture (e.g., drawer 

bottoms, cabinet backs, and center panels in framed doors) and as wall and 

ceiling panels, skins in flush doors, partitioning, lightweight doors, and exhibition 

paneling for inside-building applications (e.g., offices, reception areas, 

classrooms, and exhibition displays). 

From CARB’s 2003 Survey, only two MDF manufacturers listed thin MDF as a 

product that they offer for sale. One manufacturer reported ASTM E1333 values 

ranging from 0.17 to 2.5 ppm for MDF ranging in thickness from 8 mm to 5⁄8”; 

however, none of the reported ASTM E1333 values could be specifically 

assigned to thin MDF. The second manufacturer reported ASTM E1333 values 
Chapter V Page 107 

ranging from 0.20 to 0.37 ppm for their thin MDF made with a UF resin (exact 

thickness was not provided). A web-search for manufacturers of thin MDF found 

Fibrex®

 manufactured by Flakeboard Company Limited (Flakeboard, 2005), 

which is described as a high density, thin MDF. As the average ASTM E1333 

values for this product were reported to be less than 0.2 ppm, it would presently 

comply with the proposed Phase 1 standard for MDF (i.e., 0.21 ppm). From the 

Composite Panel Association (CPA) website (CPA, 2006), one other 

manufacturer indicated the availability of thin MDF, that presumably complies 

with the HUD standard (0.3 ppm). 

Recently, a U.S. manufacturer reported that the thin MDF they produce exhibited 

ASTM E1333 values of 0.7 ppm or higher, consistent with one of the 

manufacturers that responded to the CARB 2003 Survey. As such, they contend 

that it is unlikely that thin MDF can be made to comply with the proposed Phase 

1 (0.21 ppm) and Phase 2 standards (0.11 ppm), and consideration be given to 

setting a separate standard for MDF of thicknesses less than 8 mm. While the 

specific application for the 0.7 ppm product is not known, given the existence of 

Flakeboard’s Fibrex®

 and the prospects for a full range of no added ureaformaldehyde MDF products from CalAg (Sustainable Design Resources, 2003), 

there is a reasonable basis for projecting that thin MDF could be manufactured to 

comply with the proposed Phase 1 standard of 0.21 ppm for thin MDF in January 

2009 and the proposed Phase 2 standard of 0.13 ppm in January 2012. 

5. ASTM E1333 Background Concentration 

The large chamber test method (ASTM E1333) is the industry recognized test 

method for measuring surface emissions of HCHO from composite wood 

products in the U.S. In the ASTM E1333 test, boards are pre-conditioned for 

approximately seven days in a controlled chamber prior to emission testing. The 

test chamber is purged of HCHO by running tests without boards or with the use 

of filters designed to lower the background HCHO concentration in air, or both. 

To run an emission test, the test material is placed inside the conditioned 

chamber at 25 °C, 50% relative humidity, and an air exchange of 0.5/hr. The 

sample remains in the chamber for 16 to 20 hours prior to measuring the HCHO 

concentration of the air in the chamber. In consideration of the proposed 

numerical values of the Phase 2 standards, manufacturers will likely need to 

ensure the use of intake air with very low HCHO levels and use the DNPH 

method to accurately measure HCHO levels in quality control testing. 

6. Technical Basis for Consumer Products

Health & Safety Code §41712 requires all consumer product regulations adopted 

by the Board to be technologically and commercially feasible. Also, 1996 

revisions to H&SC §41712 added a constraint that consumer product regulations 

not eliminate a product form. These statutory criteria were followed in setting the 

proposed limits for PB and MDF. As discussed in Chapter 1, PB and MDF meet 

the statutory definition of a “consumer product” under H&SC §41712. 
Chapter V Page 108 

For PB and MDF, there are products already on the market that would comply 

with the proposed Phase 1 and Phase 2 standards. In this regard, the proposed 

emission standards for PB and MDF are considered to be technologically 

feasible as the limit is already being met by at least one product designated as 

PB or MDF, and that the limit can reasonably be expected to be met in the time 

frame provided in the proposed ATCM through additional development efforts. 

In setting the proposed limits for PB and MDF, staff made an effort, wherever 

possible, to ensure that multiple resin technologies exist or are anticipated to 

exist through additional development efforts, which would allow products to 

comply by the proposed effective dates. 

The term “commercially feasible” is not defined in State law. In interpreting this 

term, staff has utilized the reasoning employed by the U.S. Court of Appeals for 

the District of Columbia in interpreting the federal Clean Air Act. In the leading 

case of International Harvester Company v. Ruckelshaus, (D.C. Cir. 1973) 478 F. 

2d 615, the Court held that the USEPA could promulgate technology-forcing 

motor vehicle emission limits which might result in fewer models and more limited 

choice of engine types for consumers so long as as the basic market demand for 

new passenger automobiles could be generally met. 

Following this reasoning, staff has concluded that a regulation is “commercially 

feasible” as long as the “basic market demand” for a particular consumer product 

can be met. “Basic market demand” is the underlying need of consumers for a 

product to fulfill a basic, necessary function. Applying this reasoning to the 

proposed Phase 2 standards for PB and MDF allows for the basic market 

demand to be met for each product. 

In meeting the criteria for technological and commercial feasibility, we believe 

that the proposed standards for PB and MDF meet the requirements of 

H&SC §41712. 

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Chapter VI Page 116 

VI. Proposed Airborne Toxic Control Measure (ATCM) 

This chapter describes the proposed ATCM and its basis, including a discussion 

of alternatives to the proposed ATCM. The staff’s proposed regulation order is 

found in Appendix A. 

A. Summary of the Proposed Airborne Toxic Control Measure (ATCM) 

The proposed ATCM would reduce HCHO emissions from HWPW, PB, MDF, 

and finished goods containing those materials, that are sold, offered for sale, 

supplied, used, or manufactured for sale in California. This would be achieved 

by requiring manufacturers for the HWPW, PB, and MDF products they produce 

for use in California, to meet new stringent HCHO emission standards introduced 

in two phases. The measure applies not only to manufacturers, but also to 

distributors, importers, fabricators, and retailers that sell or supply HWPW, PB, or 

MDF, or finished goods containing those materials, for use in California. The 

proposed ATCM does not apply to composite wood products and finished goods 

that are manufactured or sold for shipment and use outside of California. 

The proposed ATCM also does not apply to PB and HWPW installed in 

manufactured homes used as dwelling units. Formaldehyde emission standards 

for PB and plywood installed in manufactured homes have been promulgated by 

the U.S. Department of Housing and Urban Development (24 Code of Federal 

Regulations section 3280 et seq., section 3280.308). Federal law generally 

preempts State and local regulations regarding construction and safety standards 

for manufactured homes, such as the formaldehyde standards specified in the 

HUD regulations (see 42 U.S. C.A section 94503(d)). To comply with federal 

law, the proposed ATCM exempts products covered by the HUD regulations. 

The HUD regulations do not apply to plywood and particleboard used in 

applications other than manufactured homes (e.g., residential and office 

buildings, furniture, etc.) and finished products made with these materials. The 

HUD regulations also do not apply to MDF used in manufactured homes, which 

would be covered by the proposed ATCM. 

Furthermore, the proposed ATCM would not apply to architectural plywood, 

military specification plywood used in airplane construction, or composite wood 

products used in motor vehicles. Military plywood and composite wood use in 

motor vehicles is very limited and inclusion in the regulation would create difficult 

compliance issues for these mobile sources. Finally, the proposed ATCM also 

exempts finished windows containing less than five volume percent of HWPW, 

PB or MDF combined in relation to the total volume of the finished window 

product. 

On January 1, 2009, the proposed ATCM establishes a suite of new emission 

standards that would take effect, beginning with the Phase 1 (P1) emission 

standards for HWPW made with a veneer core (HWPW-VC), PB, MDF, and thin 
Chapter VI Page 117 

MDF (Table VI-1). Subsequently, on July 1, 2009, the remaining P1 standard for 

HWPW made with a composite core (HWPW-CC) would become effective. The 

Phase 2 (P2) standards for HWPW-VC, PB, MDF, thin MDF, and HWPW-CC 

become effective in the 2011-2012 timeframe, as specified in the following table. 

Table VI-1. Proposed Phase 1 and Phase 2 Standards for Hardwood Plywood 

(HWPW), Particleboard (PB), and Medium Density Fiberboard (MDF)1Error! 

Bookmark not defined.

-------------------- ASTM E1333-96 Value (ppm) -------------------- Effective Date HWPW-VC HWPW-CC PB MDF tMDF 

January 2009 P1: 0.08 ----- P1: 0.18 P1: 0.21 P1: 0.21 

July 2009 ----- P1: 0.08 ----- ----- ----- 

January 2011 P2: 0.05 ----- P2: 0.09 P2: 0.11 ----- 

January 2012 ----- ----- ----- ----- P2: 0.13 

July 2012 ----- P2: 0.05 ----- ----- ----- 

(1) Abbreviations: P1 = Phase 1, P2 = Phase 2, HWPW-VC = HWPW with a veneer core, HWPWCC = HWPW with a composite core, PB = particleboard, MDF = medium density fiberboard; 

tMDF = thin MDF. 

Finally, the proposed ATCM contains “sell-through” provisions that allow 

noncomplying products manufactured before the effective dates of the Phase 1 

and Phase 2 emission standards to be sold for certain specified time periods 

after these effective dates. Differing sell-through periods apply depending on 

whether the product is sold by a manufacturer, distributor, importer, fabricator, or 

retailer. All of the sell-through provisions of the ATCM are contained in 

Appendix 1 of section 93120.12. 

1. Section 93120.3- Requirements for Manufacturers of Composite 

Wood Products

The requirements for manufacturers are contained in section 93120.3 and 

Appendix 2 of section 93120.12. In general, manufacturers of HWPW-VC, 

HWPW-CC, PB, MDF, or thin MDF, whether foreign or domestic, would be 

required to: 

• Meet the applicable emission standards; 

• Provide independent verification of the emissions performance of the 

composite wood product they manufacture; 

• Have quality assurance programs; 

• Comply with labeling and recordkeeping requirements. 

To independently verify the emissions performance of their composite wood 

products, manufacturers using formaldehyde based resin systems would be 
Chapter VI Page 118 

required to be monitored by independent groups known as “third party certifiers.” 

Manufacturers would work with third party certifiers to initiate quality control and 

emission testing programs in order to demonstrate ongoing compliance with the 

applicable emission standards in Table VI-1. All testing will be correlated to 

product emission tests using the “large chamber test method,” hereafter referred 

to as ASTM E1333-96. 

Under the provisions of section 93120.12, Appendix 2, manufacturers would also 

be required to develop and follow a quality assurance program. Basic elements 

of the quality assurance program include development of a quality control 

manual, verification of quality control personnel, establishment of a correlation 

between the manufacturing plant test method and ASTM E1333-96, and ongoing 

quarterly emissions correlation verification testing. In addition, Appendix 2 also 

provides guidance on the disposition of manufactured panels that do not meet 

the regulatory emission standards. 

Generally speaking, the proposed regulation primarily affects composite wood 

products made with formaldehyde based resin systems. As mentioned 

throughout this staff report, however, several examples exist today of alternative 

resin systems that contain no added formaldehyde and result in only de minimus 

formaldehyde emissions from composite wood products. Therefore, under 

section 93120.3(b) manufacturers using these resins would be allowed to follow 

an alternative compliance option that does not require third party certification. 

To qualify for the “no added formaldehyde resin” compliance option, 

manufacturers must apply to and obtain written approval from CARB. The 

application must contain the resin chemical formulation, a demonstration of the 

emissions performance of the candidate “no added formaldehyde” resin system, 

and a statement to indicate the manufacturer’s intent to use the candidate resin 

exclusively in the manufacturing of identified products. Upon approval, CARB 

will notify the manufacturer in writing. CARB approval would exempt the 

manufacturer only from the third party certification requirements of the proposed 

ATCM; all other ATCM requirements would still apply. 

Because composite wood panels are a commonly traded commodity, there are 

many potential distribution routes within commerce. So, to facilitate enforcement 

of the emission standards the proposed ATCM requires all manufacturers that 

supply products for sale or use in California to label these products in a manner 

that clearly identifies their third party certifier, the name of their company, product 

lot number or batch produced, and a marking to denote that the product meets 

the applicable Phase 1 or Phase 2 emission standard. Manufacturers are also 

required to maintain records for two years so composite wood products can be 

traced back to individual manufacturers and to specific emissions performance 

tests under third party certification program. 
Chapter VI Page 119 

Because manufacturers are the only group who can determine the formaldehyde 

levels in composite wood products, it is vital that downstream customers have 

some way of knowing whether the products they purchase are legal to sell in 

California. Therefore, the proposed ATCM specifies the information that must 

be passed from manufacturers to downstream customers. In addition to the 

labeling requirements discussed above, manufacturers are required to state on 

the product bill of lading or invoice that the product complies with the applicable 

Phase 1 or Phase 2 emission standard. Manufacturers are also required to 

maintain specified records at their production facilities. These records will allow 

individual panels sold in commerce to be traced back to specific lot or batch of 

product that was manufactured. 

The proposed ATCM allows a one-month sell-through period for noncomplying 

products manufactured before the effective dates of the Phase 1 and Phase 2 

standards. The specific sell-through dates for manufacturers are set forth in the 

following table (Table VI-2): 

Table VI-2. Schedule of Composite Wood Product Sell-through for 

Manufacturers1

Event HWPWVC 

HWPWCC PB MDF tMDF 

Effective Date: P1 Jan ‘09 Jul ‘09 Jan ’09 Jan ’09 Jan ’09 

Date When Only P1 

Products Can Be Sold Feb ‘09 Aug ‘09 Feb ‘09 Feb ‘09 Feb ‘09 

Effective Date: P2 Jan ‘11 Jul ‘12 Jan ‘11 Jan ‘11 Jan ‘12 

Date When Only P2 

Products Can Be Sold Feb ‘11 Aug ‘12 Feb ‘11 Feb ‘11 Feb ‘12 

(1) All effective dates begin on the 1st day of the specified month-year. Manufacturers have a onemonth sell-through period following the effective date of the applicable P1 or P2 standard. 

Abbreviations: P1 = Phase 1, P2 = Phase 2, HWPW-VC = HWPW with a veneer core, HWPWCC = HWPW with a composite core, PB = particleboard, MDF = medium density fiberboard, 

tMDF = thin MDF. 

Relative to enforcement, section 93120.3(f) notifies manufacturers that they may 

be inspected by CARB or local air district personnel (as well as third party 

certifiers as specified in Appendices 2 and 3 of section 93120.12). Inspections 

would be focused on facility inspections, auditing of records, and securing of 

samples for enforcement testing. 
Chapter VI Page 120 

2. Section 93120.4- Requirements for Third Party Certifiers 

Third party certifiers have an important role in ensuring that manufacturers of 

composite wood products can demonstrate that their production facilities are 

producing products that comply with the applicable emission standards in 

Table VI-1. Requirements for third party certifiers are contained in section 

93120.12, Appendix 3. The application process to become an ARB-approved 

third party certifier is specified in section 93120.4. 

The proposed ATCM requires routine quality assurance emissions testing by 

manufacturers of newly produced composite wood products. The quality 

assurance manufacturing testing program is developed in collaboration with, and 

is independently validated by, third party certifiers. All third party certifiers are 

required to be approved by CARB as provided in section 93120.4. 

To be approved as a third party certifier, an organization must submit an 

application in writing to the Executive Officer for approval. Applicants must 

demonstrate that they have actual field experience in the certification of 

laboratories and wood products, have the ability to train and supervise 

inspectors, possess product inspection agency certification, and large chamber 

ASTM E1333-96 certification by the International Accreditation Service or by 

another signatory to the International Laboratory Accreditation Cooperation 

Mutual Recognition Arrangement, and must list which products they are qualified 

to certify. If the criteria specified in the ATCM are met, the Executive Officer will 

issue an executive order approving them as an third party certifier. The 

Executive Officer will also assign an identifying number to each third party 

certifier. As described previously, manufacturers will display this number on 

each panel or bundle of composite wood products. 

The proposed ATCM requires third party certifiers to take part in quarterly 

validation of correlations between manufacturers’ small scale testing and the 

ASTM E1333-96 large chamber. All large chambers must be certified by the 

International Accreditation Service, Inc., or by another signatory to the 

International Laboratory Accreditation Cooperation Mutual Recognition 

Arrangement. Third party certifiers must also conduct periodic inspections of 

manufacturing facilities and maintain records for two years, including a list of 

manufacturers certified by the third party certifier, results of inspection audits, 

and proof of certification for ASTM E1333-96 large chambers used. 

Third party certifiers are also subject to enforcement audits by CARB. Executive 

orders granted to third party certifiers will contain conditions allowing CARB to 

verify that third party certifiers are complying with all regulatory requirements. A 

provision is also included whereby the Executive Officer may review and, for 

good cause, modify or revoke an executive order approving a third party certifier. 

In order to provide due process protections, an executive order cannot be 
Chapter VI Page 121 

modified or revoked unless the third party certifier is first provided an opportunity 

for a hearing. 

3. Section 93120.5- Requirements for Distributors 

Distributors are the “goods movers” within the marketplace supply chain. The 

proposed ATCM requires that all products and finished goods sold by distributors 

must comply with the applicable emission standards. The proposed ATCM also 

requires that distributors must take reasonable prudent precautions to ensure 

that the composite wood products and finished goods they acquire are in 

compliance with the applicable emission standards in Table VI-1. To accomplish 

this, distributors would need to establish a procurement policy that requires them 

to obtain and keep a record of written documentation from their suppliers that the 

products they acquire meet the applicable emission standards. Records must be 

kept for a minimum of two years for enforcement purposes. 

Typically distributors only sell products in commerce and do not modify the 

products they sell. But, if a distributor modifies the composite wood products or 

finished goods that they acquire, then the regulation requires distributors to follow 

the labeling and sell-through requirements for fabricators (see section VI.A.5). 

Under section 93120.5(d), distributors are also required to provide a written 

statement on the bill of lading or invoice that states that the composite wood 

product or finished goods they sell meet the emission standards. 

Because distributors may purchase HWPW-VC, HWPW-CC, PB, MDF or tMDF 

panels from manufacturers during the sell-through periods in Table VI-2, an 

additional period of time is provided to distributors to sell-through products that 

do not comply with the new standards. In total, distributors would have a sellthrough period of five-months after the effective date of the applicable Phase 1 or 

Phase 2 standards in Table VI-1 (see Table VI-3). The sell-through period for 

finished goods would be the same as that for composite wood products. 

Table VI-3. Schedule of Composite Wood Product Sell-through for Distributors1 

Event HWPWVC 

HWPWCC PB MDF tMDF 

Effective Date: P1 Jan ‘09 Jul ‘09 Jan ‘09 Jan ‘09 Jan ‘09 

Date When Only P1 

Products Can Be Sold Jun ‘09 Dec ‘09 Jun ‘09 Jun ‘09 Jun ‘09 

Effective Date: P2 Jan ‘11 Jul ‘12 Jan ‘11 Jan ‘11 Jan ‘12 

Date When Only P2 

Products Can Be Sold Jun ‘11 Dec ‘12 Jun ‘11 Jun ‘11 Jun ‘12 

(1) All effective dates begin on the 1st day of the specified month-year. Distributors have a five-month sellthrough period following the effective date of the applicable P1 or P2 standard. Abbreviations: P1 = Phase 

1, P2 = Phase 2, HWPW-VC = HWPW with a veneer core, HWPW-CC = HWPW with a composite core, 

PB = particleboard, MDF = medium density fiberboard, tMDF = thin MDF. 
Chapter VI Page 122 

Regarding enforcement, section 93120.5(e) notifies distributors that they may be 

inspected by CARB or local air district personnel. Inspections would be focused 

on facility inspections, auditing of records, and securing of samples for 

enforcement testing. 

4. Section 93120.6- Requirements for Importers

The proposed ATCM requires that all products and finished goods sold by 

importers must comply with the applicable emission standards. The proposed 

ATCM also requires that importers must take reasonable prudent precautions to 

ensure that the composite wood products and finished goods they acquire are in 

compliance with the applicable emission standards in Table VI-1. To accomplish 

this, importers would need to establish a procurement policy that requires them 

to obtain and keep a record of written documentation from their suppliers that the 

products they acquire meet the applicable emission standards. Records must be 

kept for a minimum of two years for enforcement purposes. 

Typically, importers do not modify goods they market, so for unmodified 

composite wood products or finished goods, no additional labeling would be 

required on the part of importers. However, if an importer modifies the composite 

wood products or finished goods that they purchase, they would subject to the 

labeling and sell-through requirements for fabricators (see section VI.A.5). 

Under section 93120.6(d), importers are also required to provide a written 

statement on the bill of lading or invoice that states that the composite wood 

product or composite wood products contained in finished goods comply with the 

emission standards in Table VI-1. 

 

Because importers may purchase HWPW-VC, HWPW-CC, PB, MDF, or tMDF 

panels and finished goods from an overseas manufacturer during the sellthrough periods allowed for manufacturers, an additional period of time is 

provided to importers to sell-through products that do not comply with the new 

standards. In total, importers would have a sell-through period of five months 

(the same as distributors) after the effective date of the applicable Phase 1 or 

Phase 2 standards in Table VI-1 (see Table VI-3). The sell-through period for 

finished goods would be the same as that for composite wood products. 
Chapter VI Page 123 

Table VI-4. Schedule of Composite Wood Product Sell-through for Importers1 

Event HWPWVC 

HWPWCC PB MDF tMDF 

Effective Date: P1 Jan ‘09 Jul ‘09 Jan ‘09 Jan ‘09 Jan ‘09 

Date When Only P1 

Products Can Be Sold Jun ‘09 Dec ‘09 Jun ‘09 Jun ‘09 Jun ‘09 

Effective Date: P2 Jan ‘11 Jul ‘12 Jan ‘11 Jan ‘11 Jan ‘12 

Date When Only P2 

Products Can Be Sold Jun ‘11 Dec ‘12 Jun ‘11 Jun ‘11 Jun ‘12 

(1) All effective dates begin on the 1st day of the specified month-year. Importers have a fivemonth sell-through period following the effective date of the applicable P1 or P2 standard. 

Abbreviations: P1 = Phase 1, P2 = Phase 2, HWPW-VC = HWPW with a veneer core, HWPWCC = HWPW with a composite core, PB = particleboard, MDF = medium density fiberboard, 

tMDF = thin MDF.

Regarding enforcement, section 93120.6(e) notifies importers that they may be 

inspected by CARB or local air district personnel. Inspections would be focused 

on facility inspections, auditing of records, and securing of samples for 

enforcement testing. 

 

5. Section 93120.7- Requirements for Fabricators

The proposed ATCM defines “fabricator” as any person that uses composite 

wood products to make finished goods. Examples of fabricators are companies 

that use composite wood panels to produce furniture or cabinets. While such 

companies might be referred to as “manufacturers” in ordinary conversation, they 

are not “manufacturers” under the ATCM. The proposed ATCM uses the term 

“manufacturer” to refer only to persons who manufacturer or produce the actual 

composite wood products (i.e., HWPW, PB or MDF), as opposed to persons who 

use panels of HWPW, PB or MDF to make finished goods. A person can be both 

a “fabricator” and a “manufacturer” if they produce both composite wood products 

and make finished goods from these products. Such a person would have to 

comply with both the provisions of the ATCM that apply to manufacturers (for the 

HWPW, PB or MDF that they produce) and the provisions that apply to 

fabricators (for the finished goods that they produce). 

Like distributors and importers, the proposed ATCM requires that all products 

and finished goods sold by fabricators must comply with the applicable emission 

standards. The proposed ATCM also requires that fabricators must take 

reasonable prudent precautions to ensure that the composite wood products and 

finished good components they acquire are in compliance with the applicable 

emission standards in Table VI-1. To accomplish this, fabricators would need to 
Chapter VI Page 124 

establish a procurement policy that requires them to obtain and keep a record of 

written documentation from their suppliers that the products they acquire meet 

the applicable emission standards. Records must be kept for a minimum of two 

years for enforcement purposes. 

Among finished goods produced with composite wood products, window 

assemblies typically utilize only small amounts of HWPW, PB or MDF. 

Therefore, exposure from composite wood products used in windows is expected 

to be insignificant and enforcement testing would also be complex and 

expensive. Therefore, section 93120.7(b) provides an exemption for windows. 

The exemption applies only to windows that contain more than five percent by 

volume of any composite wood product. 

To denote that the finished goods produced by a fabricator for the California 

market were made with complying products, fabricators must label every finished 

good, or on every box containing finished goods. Fabricators may label finished 

goods with a stamp, tag, sticker, or bar code. Under the proposal, fabricators 

would also be required to designate their goods as being made with HWPW, PB 

or MDF in compliance with the emission standards on the bill of lading or invoice 

provided to retailers or other entities that sell those composite wood products or 

finished goods to the public. 

Because fabricators may purchase HWPW-VC, HWPW-CC, PB, MDF, or tMDF 

from distributors and importers during the sell-through periods allowed for these 

entities, an additional period of time is provided to fabricators to sell-through 

products that do not comply with the new standards. In total, fabricators would 

have a sell-through period of 12 months after the effective date of the applicable 

Phase 1 or Phase 2 standards (see Table VI-5). The longer sell-through period 

reflects that fact that it takes time for fabricators to produce finished goods from 

the composite wood products they purchase. 

Table VI-5. Schedule of Composite Wood Product Sell-through for Fabricators1 

Event HWPWVC 

HWPWCC PB MDF tMDF 

Effective Date: P1 Jan ‘09 Jul ‘09 Jan ‘09 Jan ‘09 Jan ‘09 

Date When Only P1 

Products Can Be Sold Jan ‘10 Jul ‘10 Jan ‘10 Jan ‘10 Jan ‘10 

Effective Date: P2 Jan ‘11 Jul ‘12 Jan ‘11 Jan ‘11 Jan ‘12 

Date When Only P2 

Products Can Be Sold Jan ‘12 Jul ‘13 Jan ‘12 Jan ‘12 Jan ‘13 

(1) All dates begin on the 1st day of the specified month-year. Fabricators are provided a 12-

month sell-through period following the effective date of the applicable P1 or P2 standard. 

Abbreviations: P1 = Phase 1, P2 = Phase 2, HWPW-VC = HWPW with a veneer core, HWPWCC = HWPW with a composite core, PB = particleboard, MDF = medium density fiberboard, 

tMDF = thin MDF.
Chapter VI Page 125 

Regarding enforcement, section 93120.7(e) notifies fabricators that they may be 

inspected by CARB or local air district personnel. Inspections would be focused 

on facility inspections, auditing of records, and securing of samples for 

enforcement testing. 

6. Section 93120.8- Requirements for Retailers 

The proposed ATCM requires that all products and finished goods sold by 

retailers must comply with the applicable emission standards. The proposed 

ATCM also requires that retailers must take reasonable prudent precautions 

(such as communicating with their suppliers) to ensure that the composite wood 

products and finished goods they purchase are in compliance with the applicable 

emission standards in Table VI-1. To accomplish this, retailers would need to 

establish a procurement policy that requires them to obtain and keep a record of 

written documentation from their suppliers that the products they acquire meet 

the applicable emission standards. Records must be kept for a minimum of two 

years for enforcement purposes. 

Because retailers may purchase HWPW-VC, HWPW-CC, PB, MDF or tMDF 

products or finished goods from manufacturers, importers, distributors, or 

fabricators during the sell-through periods for these entities, an additional period 

of time is provided to retailers to sell-through products that do not comply with the 

new standards. In total, retailers would have sell-through periods of 12 months 

and 18 months, after the effective date of the applicable Phase 1 or Phase 2 

standards in Table VI-1 (see Table VI-6), for HWPW-VC, HWPW-CC, PB, MDF, 

and tMDF panels and finished goods containing those products, respectively. 
Chapter VI Page 126 

Table VI-6. Schedule of Composite Wood Panel Sell-through for Retailers1 

Event HWPWVC 

HWPWCC PB MDF tMDF 

A. Composite Wood Products 

Effective Date: P1 Jan ‘09 Jul ‘09 Jan ‘09 Jan ‘09 Jan ‘09 

Date When Only P1 

Products Can Be Sold Jan ‘10 Jul ‘10 Jan ‘10 Jan ‘10 Jan ‘10 

Effective Date: P2 Jan ‘11 Jul ‘12 Jan ‘11 Jan ‘11 Jan ‘12 

Date When Only P2 

Products Can Be Sold Jan ‘12 Jul ‘13 Jan ‘12 Jan ‘12 Jan ‘13 

B. Finished Goods 

Effective Date: P1 Jan ‘09 Jul ‘09 Jan ‘09 Jan ‘09 Jan ‘09 

Date When Only P1 

Products Can Be Sold Jul ‘10 Jan ‘11 Jul ‘10 Jul ‘10 Jul ‘10 

Effective Date: P2 Jan ‘11 Jul ‘12 Jan ‘11 Jan ‘11 Jan ‘12 

Date When Only P2 

Products Can Be Sold Jul ‘12 Jan ‘14 Jul ‘12 Jul ‘12 Jul ‘13 

(1) All effective dates begin on the 1st day of the specified month-year. Retailers have a 12-

month or 18-month sell-through period following the effective date of the applicable P1 or P2 

standard for panels or finished products, respectively. Abbreviations: P1 = Phase 1, P2 = 

Phase 2, HWPW-VC = HWPW with a veneer core, HWPW-CC = HWPW with a composite core, 

PB = particleboard, MDF = medium density fiberboard, tMDF = thin MDF.

Regarding enforcement, section 93120.8(c) notifies retailers that they may be 

inspected by CARB or local air district personnel. Inspections would be focused 

on facility inspections, auditing of records, and securing of samples for 

enforcement testing.. 

7. Section 93120.9- Test Methods 

The regulation includes various test methods to be used to demonstrate 

compliance with the emissions standards specified in section 93120.2. 

Under section 93120.9(a), the emission standards will be based on the industry 

standard large chamber test method, as specified in American Standards for 

Testing and Materials (ASTM) E1333-96. The ASTM E1333-96 test method was 

developed by the ASTM through a consensus process and is recognized as the 

“gold standard” among formaldehyde test methods. Furthermore, the current 

federal HUD standards regarding particleboard and plywood in manufactured 

homes specify the ASTM E1333-96 as the applicable test method. 
Chapter VI Page 127 

Sections 93120.9(a)(1)-(3) allows for the use of equivalent alternate test methods 

in lieu of ASTM E1333-96, if approved by the Executive Officer. An application 

process is also specified for obtaining ARB approval. This section allows 

alternative test methods to be used that may prove to be more applicable to 

particular products. 

Sections 93120.9(b) and (c) describe the test method to be used for enforcement 

purposes. These provisions reference the use of ASTM D6007-02 for testing of 

HWPW, PB or MDF, or finished goods made from these materials. The ASTM 

D6007-02 is a standardized small chamber industry-developed test method. 

When properly calibrated, test results from a small chamber are known to have a 

very high correlation to large chamber test results. The use of the small chamber 

is included in the regulation to allow CARB to conduct compliance verification 

testing using smaller sample sizes and to obtain faster results. 

The small chamber method will also allow CARB to test pieces of composite 

wood products in finished goods that are bare or partially covered (e.g. one side 

laminated). To test fully covered or laminated finished products, CARB will 

follow the method development plan shown in Table VI-7. 

Table VI-7. Development Plan for Fully Covered Finished Products 

Timeframe Action/Activity 

Spring 2007 

• Purchase lab equipment 

• Purchase/build small testing chambers 

• Begin evaluating field equipment 

Summer 2007 

• Develop draft lab analytical methods and begin 

testing composite wood samples, starting with raw 

boards 

• Begin certification process for small chambers 

Fall 2007 • Begin evaluating finished product sample preparation 

approaches 

Late 2007 

• Complete certification of small chambers against a

large chamber 

• Begin round robin testing with other labs 

Spring 2008 • Complete round robin testing, make refinements to 

lab methods as necessary 

Summer 2008 • Complete lab analytical protocols, including finished 

product testing (sampling, preparation and analysis
Chapter VI Page 128 

B. Alternatives to the Proposed Airborne Toxic Control MeasureError! 

Bookmark not defined.

1. Alternative 1: No Action

Taking no action would allow the continued sale of high HCHO-emitting 

composite wood products that have detrimental impacts on public health. 

Without stricter HCHO emission limits it will continue to be legal for high HCHOemitting composite wood products and finished goods to be sold in California that 

cannot currently be sold to many other countries. Because there is no safe 

threshold for exposure to HCHO, taking no action perpetuates the existing public 

health risks described in this staff report. 

2. Alternative 2: Establish Less Stringent Emission Limits 

a. Applicability

The principal entities that would be affected by this alternative are manufacturers 

of HWPW-VC, HWPW-CC, PB, MDF, and tMDF, resin manufacturers, 

businesses that use those materials to fabricate other products, distributors, 

importers and retailers of HWPW-VC, HWPW-CC, PB, MDF, tMDF, or finished 

goods containing those materials. 

b. Effectiveness

This alternative would not provide as great a public health benefit as the 

proposed ATCM. For example, if emission standards equal to the 1985 HUD 

standards are promulgated, there would be no public health benefit relative to 

current conditions because the major portion of U.S. manufacturers already 

produce composite wood products in voluntary compliance with the HUD 

standard. Some reductions may be achieved with respect to emissions from 

MDF, which is currently an unregulated product. 

c. Enforceability

This alternative would require the same level of enforcement as the proposed 

ATCM. 

d. Resource Considerations

Minor modifications may be needed to incorporate a greater compliance margin 

to ensure that only products meeting an emission standard equal to the HUD 

standard are distributed to California. Tighter tolerances on manufacturing lines 

may need to be established by some manufacturers in order to avoid potential 

violations resulting from the sale of non-complying products. 
Chapter VI Page 129 

3. Alternative 3: Establish More Stringent Emission Limits – Zero 

Emission Products

This alternative would require composite wood manufacturers to use no added 

HCHO resins in the production of HWPW-VC, HWPW-CC, PB, MDF, and thin 

MDF. 

a. Applicability

Manufacturers of HWPW-VC, HWPW-CC, PB, MDF, thin MDF; resin producers; 

businesses that use composite wood products to fabricate other products; 

distributors; importers; and retailers of HWPW-VC, HWPW-CC, PB, MDF, thin 

MDF, or finished goods containing those materials, would be the principal entities 

affected. 

b. Effectiveness

This alternative is not feasible at present, as we believe that cost-effective, no 

added HCHO resins would not be commercially available for all three products in 

the 2011-2012 timeframe. Setting a “zero emission” cap standard is also 

technically impractical because some HCHO is emitted from wood itself, and the 

air used to measure HCHO emissions from composite wood panels also contains 

trace amounts of HCHO. As such, even if the product were made with a no 

added HCHO resin, there could be enough HCHO emitted from wood or present 

in the test intake air to result in a non-zero emission test value. 

c. Enforceability

This alternative would require the same level of enforcement as the proposed 

ATCM. 

d. Resource Considerations

Major breakthroughs in manufacturing and resin technology would be needed to 

consistently produce HWPW, PB, and MDF that would comply with a zero 

emission standard. The costs for developing these products would far exceed 

the estimated cost increases resulting from the proposed ATCM, possibly as 

much as 135% higher in the case of zero emission MDF made with pMDI. 

C. Conclusion 

We evaluated each of the alternatives and determined that the alternatives did 

not meet the objective of H&SC §39666 to reduce emissions to the lowest level 

achievable through the application of BACT, or a more effective control method, 

in consideration of cost, health risk, and environmental impacts. 
Chapter VII Page 130 

VII. Health Impacts of the Proposed Airborne Toxic Control Measure 

This chapter presents an overview of the health risk assessment process, 

potential health impacts from exposure to HCHO in selected scenarios, 

information on alternative wood adhesives, and the benefits of the proposed 

ATCM in terms of reducing statewide emissions and potential health impacts. 

A. Overview of the Health Risk Assessment 

 

A health risk assessment (HRA) is a report prepared by a risk assessor that 

describes the potential for an individual or population to experience adverse 

health impacts as a result of being exposed to the emissions released from a 

pollution-generating facility. Adverse health effects may include cancer, 

developmental effects, and/or respiratory illness. In a HRA, estimates of total 

pollutant exposure are calculated by cumulating pollutant uptake via inhalation of 

gaseous and/or particulate compounds, ingestion of contaminated water and 

food, and dermal absorption. For HCHO emitted by building materials and 

consumer products, the principal pollutant uptake pathway is inhalation of 

gaseous HCHO. In the following HRA, HCHO uptake via inhalation was the only 

exposure pathway evaluated to assess potential cancer or non-cancer health 

impacts. 

 The following four steps are followed to prepare a HRA: 

• Step 1 -- Hazard Identification 

First, a determination is made as to whether or not a hazard exists. If a hazard is 

deemed to exist, an analysis is performed to identify which pollutant(s) is/are 

involved and what types of health effects may result (i.e., cancer or non-cancer). 

As HCHO has been identified as a toxic air contaminant (CARB, 1992), there is 

no threshold exposure level below which adverse health effects are not 

anticipated. 

• Step 2 -- Dose-response Assessment 

Next, the relationship, if any, between an individual’s exposure to a pollutant and 

the incidence of adverse health effects is characterized. For cancer and noncancer effects, OEHHA provides cancer potency or unit risk factors (URF) and 

reference exposure levels (REL), respectively. The following citations contain 

lists of the URFs or RELs used in California: 

OEHHA. 2005a. Appendix A: Hot Spots Unit Risk and Cancer Potency Values. 

In: OEHHA. Air Toxics Hot Spots Program Risk Assessment Guidelines. Part II. 

Technical Support Document for Describing Available Cancer Potency Factors. 
Chapter VII Page 131 

OEHHA. 2000. All acute reference exposure levels adopted by OEHHA as of 

May 2000. From: http://www.oehha.ca.gov/air/acute_rels/allacrels.html 

OEHHA. 2005b. All chronic reference exposure levels adopted by OEHHA as of 

February 2005. From: http://www.oehha.ca.gov/air/chronic_rels/allchrels.html

• Step 3 – Exposure Assessment 

Public exposure is estimated by evaluating representative and elevated exposure 

scenarios, relevant exposure pathways (e.g., inhalation), and the magnitude of 

exposure. For exposure to HCHO, daily time-weighted average exposures were 

calculated for children and adults, by estimating the time spent either outdoors, 

indoors, or and in-vehicles, and multiplying by an applicable representative or 

elevated HCHO concentration from the literature. 

• Step 4 – Risk Characterization 

To calculate potential cancer risk in adults and children, the Hot Spots Program 

equation (OEHHA, 2003) was used to determine an inhalation dose (Doseinh) for 

HCHO: 

Doseinh = [(Cair) x (DBR) x (A) x (EF) x (ED) x 10-6] ÷ AT 

Where: 

Doseinh = Dose through inhalation (mg/kg body weight-day) 

Cair = HCHO concentration in air (μg/m3) 

DBR = Daily breathing rate (liter/kg body weight-day) 

A = Inhalation absorption factor (dimensionless adjustment) 

EF = Exposure frequency (days/year) 

ED = Exposure duration (years) 

10-6 = Constant: (10-3 x 10-3) for (μg to mg) and (liter to m3), respectively 

AT = Averaging time period (70-years) in days (25,550 days) 

The numerical values of the components in the above equation were chosen 

based on OEHHA (2003), except for the calculation of Cair. For this component, 

a daily time-weighted average (TWA) formaldehyde concentration was 

calculated, consistent with the scenario-based guidelines for exposure 

assessment developed by USEPA (Federal Register, 1992). A daily TWA 

formaldehyde concentration was calculated separately for adults and children. In 

general terms, daily TWA HCHO concentration is: 

Daily TWA = [(Tind x Cind) + (Tout x Cout) + (Tinv x Cinv)] ÷ 24 
Chapter VII Page 132 

Where: 

Daily TWA = Daily time-weighted average HCHO concentration (μg/m3

) 

Tind = Time spent indoors (hr) 

Cind = Indoor HCHO concentration (μg/m3) 

Tout = Time spent outdoors (hr) 

Cout = Outdoor HCHO concentration (μg/m3

) 

Tinv = Time spent in-vehicles (hr) 

Cinv = In-vehicle HCHO concentration (μg/m3) 

24 = Constant (24 hr/day) 

A reference exposure level or “REL” is used as an indicator of the potential for a 

compound to cause adverse, non-cancer health effects (e.g., respiratory illness). 

For a given TAC, its REL is the pollutant concentration at or below which no 

adverse health effects are anticipated. To incorporate a margin of safety into 

RELs, they are designed to protect the most sensitive individuals in a population 

from acute and chronic exposures to a TAC. An acute exposure is defined as 

one or a series of short-term exposures generally lasting less than 24 hours (i.e., 

a one hour exposure is used to assess acute non-cancer impacts). Chronic 

exposures are defined as exposures lasting from one year to an entire lifetime. 

B. Total Daily Formaldehyde Exposure as the Basis for Risk 

Assessment 

To assess the potential health impacts of HCHO emissions from composite wood 

products, quality assured data are needed on HCHO concentrations that people 

are exposed to, and health effect values (i.e., URFs and RELs). For this 

rulemaking, a persons’ total daily exposure to HCHO was estimated; this is a 

measure of cumulative HCHO exposure from the air they breathe in indoor, 

outdoor, and in-vehicle microenvironments, rather than outdoor air alone. This 

requires estimates to be calculated of average HCHO concentrations in three 

microenvironments that people spend time in. As studies have found that 

Californians spend 90% or more of their time indoors, a principal focus was the 

development of estimates for HCHO concentrations in new and existing homes. 

Brief descriptions are provided in the following subchapters concerning the 

estimates of indoor HCHO concentrations and health effects values. 

1. Average and Elevated Formaldehyde Concentrations

Average and elevated HCHO concentration data were primarily obtained from a 

CARB report prepared for the Legislature on indoor air pollution in California 

(CARB, 2005). In Appendix III of the report, average and maximum HCHO 

concentrations in selected indoor and outdoor microenvironments were 

estimated (Table VII-1) and served as the principal basis for calculating daily 

TWA concentrations of HCHO. For conventional homes, the elevated 

concentration represents the average concentration measured in newly built 
Chapter VII Page 133 

homes (Sherman and Hodgson, 2003). The average and elevated HCHO 

concentrations for time spent in vehicles were estimated from the data in 

Research Triangle Institute (1998). 

Table VII-1. Average and Elevated Formaldehyde Concentrations (μg/m3) 

in Selected Indoor and Outdoor Microenvironments 

Microenvironment Average (μg/m3) Elevated (μg/m3) 

Conventional Home 17.2 46.7 

In-vehicle 9.6 12.0 

Outdoors 3.7 15.0 

(1) Sources: CARB (2005); Research Triangle Institute (1998); Sherman and Hodgson (2003). 

2. Health Effects Values for Formaldehyde 

Pollutant exposure-response relationships are characterized by a variety of 

health effects values that describe the incidence of adverse health effects relative 

to the degree of pollutant exposure. A unit risk factor or “URF” is used as an 

estimate of potential cancer risk, and RELs are used as estimates of potential 

non-cancer impacts. The health values for HCHO, determined by OEHHA, are 

listed in Table VII-2. For non-cancer effects, the RELs (acute and chronic) were 

established to protect against eye irritation, and associated impacts to the 

respiratory and immune systems (OEHHA, 1999; 2000).

Table VII-2. Health Effects Values for Formaldehyde

1

Unit Risk Factor 

(μg/m3)

-1

Acute Reference 

Exposure Level (μg/m3) 

Chronic Reference 

Exposure Level (μg/m3) 

6 x 10-6 94 3 

(1) Sources: OEHHA (2000); (2005a); (2005b). 

a. Health Effects in Humans 

Numerous acute controlled human exposure studies, as well as observational 

studies in occupational settings, have been conducted to investigate 

formaldehyde’s irritative and pulmonary effects (Sheppard et al., 1984; Sauder et 

al., 1986; Schachter et al., 1986; Kulle et al., 1987; Sauder et al., 1987; 

Schachter et al., 1987; Witek et al., 1987; Uba et al., 1989; Harving et al., 1990; 

Akbar-Khanzadeh et al., 1994). Both irritation and significant decrements in 

pulmonary function have been observed in occupational studies of carpentry, 
Chapter VII Page 134 

wood and wood product, chemical plant, and formaldehyde production plant 

workers exposed to formaldehyde (Alexandersson et al., 1982; Alexandersson 

and Hedenstierna, 1988; Holmstrom and Wilhelmsson, 1988; Horvath et al., 

1988; Alexandersson and Hedenstierna, 1989; Malaka and Kodama, 1990; 

Wilhelmsson and Holmstrom, 1992). Formaldehyde exposures in the home and 

school environment have also been associated with irritation and pulmonary 

function effects in children (Wantke et al., 1996; Smedje et al., 1997; Garrett et 

al., 1999; Smedje and Norback, 2001a; 2001b; Delfino et al., 2003). 

i. Respiratory Effects and Irritation – Acute Exposure

Formaldehyde vapor produces immediate local irritation in mucous membranes, 

including eyes, nose, and the upper respiratory tract (Arts et al., 2006). 

Formaldehyde exposures of 0.25-1.39 ppm (1 ppm = 1.24 mg/m3) evoked 

numerous complaints of upper respiratory tract and eye irritation among 

embalmers at different funeral homes (Kerfoot and Mooney, 1975). Anatomy 

class students exposed to an average of 1.1 ppm (standard deviation = 0.56 

ppm) for 2 hours per week over 14 weeks experienced eye, nose and throat 

irritation (Kriebel et al., 2001). Exposure to low or moderate levels of 

formaldehyde (<1-3 ppm) can result in eye and upper respiratory tract irritation, 

headache, and rhinitis (inflammation of the mucous membrane of the nose) 

(Weber-Tschopp et al., 1977; Kulle et al., 1987). This has been observed in 

occupants of houses insulated with urea-formaldehyde foam insulation (UFFI), 

residents of mobile homes, and employees of mobile day-care centers (Olsen 

and Dossing, 1982; Ritchie and Lehnen, 1987), and noted in occupational 

settings. 

Most people cannot tolerate exposures to more than 5 ppm formaldehyde in air, 

and above 10-20 ppm symptoms become severe and shortness of breath occurs. 

For example, 13.9 ppm formaldehyde for 30 minutes caused considerable nasal 

and eye irritation and continued mild lacrimation (abnormal or excessive 

secretion of tears) in human volunteer subjects (Sim and Pattle, 1957). 

High concentrations of formaldehyde may result in severe mucous membrane 

irritation, burning, and lacrimation, nasal obstruction, choking, labored breathing, 

and chest tightness (Porter, 1975; Solomons and Cochrane, 1984a). Inhalation 

exposures to high concentrations can cause significant inflammation of the lower 

respiratory tract, resulting in swelling of the throat, inflammation of the windpipe 

and bronchi, narrowing of the bronchi, inflammation of the lungs, and 

accumulation of fluid in the lungs. Pulmonary injury may continue to worsen for 

12 hours or more after exposure. 

Rhinitis and a wide range of asthma-like conditions can result from exposure to 

formaldehyde. Even fairly low concentrations of formaldehyde can produce rapid 

onset of nose and throat irritation, causing coughing, chest pain, shortness of 

breath, and wheezing. Persons who are sensitized to formaldehyde may also 
Chapter VII Page 135 

experience headaches, minor eye and airway irritation, asthma, and dermatitis 

(inflammation of the skin), even at very low doses. Previously sensitized 

individuals can develop severe constriction of the bronchi at very low 

concentrations (e.g. 0.3 ppm). Bronchial constriction may begin immediately or 

can be delayed for 3 to 4 hours; effects may worsen for up to 20 hours after 

exposure and can persist for several days. Lower respiratory effects can include 

bronchitis (acute or chronic inflammation of the bronchial tubes), pulmonary 

edema (abnormal accumulation of fluid in the lungs), or pneumonia. 

Exposure to 3 ppm formaldehyde for 1 hour in a controlled exposure study 

resulted in clinically significant reductions in respiratory rates in both asthmatic 

and normal subjects (Green et al., 1987). Exposure to formaldehyde adversely 

affects pulmonary functioning with decreases in peak expiratory flow (PEF) of 1% 

per ppm of formaldehyde (Kriebel et al., 2001). The effects of formaldehyde on 

asthmatics may be dependent on previous, repeated exposure in worker studies 

(Burge et al., 1985). Some studies indicate that asthmatics may not be more 

sensitive than non-asthmatics to the respiratory effects of formaldehyde unless 

specifically sensitized to formaldehyde, such as occurs in occupational settings. 

However, as noted below, chronic low level exposure may be associated with 

asthma development in children. 

Formaldehyde provocation of human subjects occupationally exposed to 

formaldehyde at concentrations of 1.5 to 20.6 ppm and suffering from asthmalike symptoms such as wheezing, shortness of breath, or rhinitis, also resulted in 

pulmonary function decrements consistent with immediate and/or delayed 

bronchoconstriction (constriction of the bronchial air passages) (Hendrick and 

Lane, 1977; Wallenstein et al., 1978; Burge et al., 1985; Nordman et al., 1985). 

Workers exposed to low concentrations may develop severe prolonged asthma 

attacks after prior exposure; this suggests that they may have become sensitized 

(Feinman, 1988). Histology technicians exposed to formaldehyde volatilized 

from formalin at concentrations of 0.2 to 1.9 ppm were shown to have reduced 

pulmonary function, compared with controls (Kilburn et al., 1989). Furthermore, 

3 out of 15 occupationally exposed workers challenged with formaldehyde vapors 

at concentrations from 1.5 ppm to 20.6 ppm for a brief duration, exhibited late 

asthmatic reactions (Burge et al., 1985). Six other subjects had immediate 

asthmatic reactions likely due to irritant effects. Asthmatic responses were also 

observed in 12 occupationally-exposed workers challenged with 1.67 ppm 

formaldehyde (Nordman et al., 1985). 
Chapter VII Page 136 

ii. Chronic Human Exposure 

Formaldehyde exposure primarily affects the mucous membranes of the upper 

airways and eyes. Chronically exposed populations that have been studied 

include embalmers, residents in houses insulated with urea-formaldehyde foam, 

anatomy class students, histology technicians, wood and pulp mill workers, and 

asthmatics. The literature describing these effects is briefly summarized below. 

iii. Exposure to Residents

Occupants of houses insulated with urea formaldehyde foam insulation (UFFI) 

(1726 subjects) were compared with control subjects (720 subjects) for 

subjective measures of irritation, pulmonary function (FVC, FEV1, FEF25-75, 

FEF50), nasal airway resistance, odor threshold for pyridine, nasal cytology, and 

hypersensitivity skin-patch testing (Broder et al., 1988). The mean length of time 

of exposure to UFFI was 4.6 years. A significant increase in symptoms of eye, 

nose and throat irritation was observed in subjects from UFFI homes (average 

exposure 0.043 ppm), compared with controls (average exposure 0.035 ppm). 

No other differences from control measurements were observed (Broder et al., 

1988). 

Doctor-diagnosed asthma and chronic bronchitis have been found to be more 

prevalent in houses with elevated formaldehyde (Krzyzanowski et al., 1990). 

Compared with children exposed in their homes to less than 8 ppb, children in 

homes with formaldehyde levels greater than 49 ppb had a 39% higher risk of 

asthma after adjusting for common asthma risk factors (Rumchev et al., 2002). 

Exposure concentrations as low as 0.09 ppm formaldehyde exacerbated chronic 

respiratory and allergy problems in residents living in mobile homes (Liu et al., 

1991). 

Ritchie and Lehnen (1987) reported a dose-dependent increase in health 

complaints (eye and throat irritation, and headaches) in 2000 residents living in 

397 mobile and 494 conventional homes, that was demonstrated by logistic 

regression. Complaints of symptoms of irritation were noted at concentrations of 

0.1 ppm formaldehyde or above. Similarly, Liu et al. (1991) found that exposure 

to 0.09 ppm (0.135 mg/m3) formaldehyde exacerbated chronic respiratory and 

allergy problems in residents living in mobile homes. 

Employees of mobile day-care centers (66 subjects) reported increased 

incidence of eye, nose and throat irritation, unnatural thirst, headaches, abnormal 

tiredness, menstrual disorders, and increased use of analgesics as compared to 

control workers (Olsen and Dossing, 1982). The mean formaldehyde 

concentration in these mobile units was 0.29 ppm (0.43 mg/m3

) (range = 0.24 - 

0.55 mg/m3). The exposed workers were exposed in these units a minimum of 3 

months. A control group of 26 subjects in different institutions was exposed to a 

mean concentration of 0.05 ppm (0.08 mg/m3) formaldehyde. 
Chapter VII Page 137 

iv. Occupational Exposures 

Kerfoot and Mooney (1975) reported that estimated formaldehyde exposures of 

0.25-1.39 ppm evoked numerous complaints of upper respiratory tract and eye 

irritation among seven embalmers at six different funeral homes. Three of the 

seven embalmers in this study reportedly had asthma. Levine et al. (1984) 

examined the death certificates of 1477 Ontario undertakers. Exposure 

measurements taken from a group of West Virginia embalmers were used as 

exposure estimates for the embalming process, ranging from 0.3-0.9 ppm 

(average 1-hour exposure) and 0.4-2.1 ppm (peak 30-minute exposure). 

Mortality due to non-malignant diseases was significantly elevated due to a twofold excess of deaths related to the digestive system. The authors suggest 

increased alcoholism could have contributed to this increase. 

An increase in severity of nasal epithelial histological lesions, including loss of 

cilia and goblet cell hyperplasia (11%), squamous metaplasia (78%), and mild 

dysplasia (8%), was observed in 75 wood products workers exposed to between 

0.1 and 1.1 mg/m3 (0.08-0.89 ppm) formaldehyde for a mean duration of 10.5 

years (range = 1 - 39 years), compared to an equal number of control subjects 

(Edling et al., 1988). Only three exposed men had normal mucosa. A high 

frequency of symptoms relating to the eyes and upper airways was reported in 

exposed workers. Nasal symptoms included mostly a runny nose and crusting. 

The histological grading showed a significantly higher score for nasal lesions 

when compared with the referents (2.9 versus 1.8). Exposed smokers had a 

higher, but non-significant, score than ex-smokers and non-smokers. When 

relating the histological score to duration of exposure, the mean histological 

score was about the same regardless of years of employment. In addition, no 

difference in the histological scores was found between workers exposed only to 

formaldehyde and those exposed to formaldehyde and wood dust. 

Chronic occupational exposure to formaldehyde concentrations estimated to be 

0.025 ppm for greater than six years resulted in complaints by 22 exposed 

workers of respiratory, gastrointestinal, musculoskeletal, and cardiovascular 

problems, a higher incidence of abnormal chest x-rays, and elevated formic acid 

excretion in the urine (Srivastava et al., 1992). A control group of 27 workers 

unexposed to formaldehyde was used for comparison. A significantly higher 

incidence of abnormal chest x-rays was observed in formaldehyde-exposed 

workers compared with controls. 

Alexandersson et al. (1982) compared the irritant symptoms and pulmonary 

function of 47 carpentry workers exposed to a mean concentration of 

formaldehyde of 0.36 ppm (range = 0.04 - 1.25 ppm) with 20 unexposed controls. 

The average length of employment for the exposed workers was 5.9 years. 

Symptoms of eye and throat irritation as well as airway obstruction were more 

common in exposed workers. In addition, a significant reduction in FEV1, 
Chapter VII Page 138 

FEV1/FVC, and MMF was observed in exposed workers, as compared with 

controls. 

Alexandersson and colleagues studied workers (38 total) exposed for a mean 

duration of 7.8 years to 0.11 - 2.12 ppm (mean = 0.33 ppm) formaldehyde for 

symptomatology, lung function, and total IgG and IgE levels in the serum 

(Alexandersson and Hedenstierna, 1989). The control group consisted of 18 

unexposed individuals. Significant decrements in pulmonary function (FVC and 

FEV1) were observed, compared with the controls. Eye, nose, and throat 

irritation was also reported more frequently by the exposed group, compared with 

the control group. No correlation was found between duration of exposure, or 

formaldehyde concentration, and the presence of IgE and IgG antibodies. 

Chemical plant workers (70 subjects) exposed to a mean of 0.17 ppm (0.26 

mg/m3) formaldehyde for an unspecified duration were compared with 36 control 

workers not exposed to formaldehyde (Holmstrom and Wilhelmsson, 1988). The 

exposed subjects exhibited a higher frequency of eye, nose, and deep airway 

discomfort. In addition, the exposed subjects had diminished olfactory ability, 

delayed mucociliary clearance, and decreased FVC. 

Horvath et al. (1988) compared subjective irritation and pulmonary function in 

109 workers exposed to formaldehyde with similar measures in a control group of 

254 subjects. The formaldehyde concentrations for the exposed and control 

groups were 0.69 ppm (1.04 mg/m3) and 0.05 ppm (0.08 mg/m3), respectively. 

Mean formaldehyde concentration in the pre-shift testing facility and the state 

(Wisconsin) ambient outdoor - formaldehyde level were both 0.04 ppm 

(0.06 mg/m3). Duration of formaldehyde exposure was not stated. Subjects 

were evaluated pre- and post work-shift and compared with control subjects. 

Significant differences in symptoms of irritation, FEV1, FEV1/FVC ratio, FEF50, 

FEF25, and FEF75 were found when comparing exposed subjects’ pre- and post 

work-shift values. However, the pre-workshift values were not different from 

controls. 

Significant increase in symptoms of irritation were reported for 66 workers 

exposed for 1 - 36 years (mean = 10 years) to a mean concentration of 0.17 ppm 

(0.26 mg/m3

) formaldehyde (Wilhelmsson and Holmstrom, 1992). Controls (36 

subjects) consisted of office workers in a government office and were exposed to 

a mean concentration of 0.06 ppm (0.09 mg/m3

) formaldehyde. The significant 

increase in symptoms of irritation in exposed workers did not correlate with total 

serum IgE antibody levels. However, two exposed workers, who complained of 

nasal discomfort, had elevated IgE levels. 

v. Immunological Effects in Humans

The binding of formaldehyde to endogenous proteins creates haptens that can 

elicit an immune response. This underlies sensitization of formaldehyde exposed 
Chapter VII Page 139 

individuals and may explain the induction of asthma in occupationally exposed 

individuals as well as the indications of increased asthma in children exposed at 

home. Chronic exposure to formaldehyde has been associated with 

immunological hypersensitivity as measured by elevated circulating IgG and IgE 

auto-antibodies to human serum albumin (Thrasher et al., 1987). In addition, a 

decrease in the proportion of T-cells was observed, indicating altered immunity. 

Thrasher et al. (1990) later found that long-term exposure to formaldehyde was 

associated with auto-antibodies, immune activation, and formaldehyde-albumin 

adducts in patients occupationally exposed, or residents of mobile homes and 

homes containing particleboard sub-flooring (Thrasher et al., 1990). 

Gorski et al. 1992 evaluated the production of active oxygen species by 

neutrophils in 18 persons exposed to 0.5 mg/m3

 (0.3 ppm) formaldehyde for two 

hours (Gorski et al., 1992). All 13 subjects who had allergic contact dermatitis 

(tested positive to formaldehyde in skin patch) exhibited significantly higher 

chemiluminescence of granulocytes isolated from whole blood 30 minutes and 24 

hours post-exposure than the individuals who were not formaldehyde sensitive. 

Thus, the immune cellular response of skin-sensitized individuals to an inhalation 

exposure to formaldehyde indicates increased production of active oxygen 

species, and demonstrates that inhalation exposures can elicit immune and 

inflammatory reactions in sensitized individuals. 

vi. Reproductive and Developmental Effects in Humans

There are no conclusive data showing that formaldehyde is toxic to the 

reproductive system or to developing fetuses in humans. Epidemiological 

studies of occupationally exposed individuals showed no clear evidence of either 

maternal or paternal inhalation exposure to formaldehyde associated with 

increased risk of spontaneous abortion (Hemminki et al., 1985; Lindbohm et al., 

1991; John et al., 1994; Taskinen et al., 1994). 

In humans there are few data on the association of teratogenicity or adverse 

reproductive effects with formaldehyde exposure. Existing data do not suggest 

that formaldehyde, by inhalation or oral routes, produces significant teratogenic 

or reproductive effects (ATSDR, 1999). 

vii. Infants and Children

There are a number of physiological and behavioral factors that influence 

response to toxicants and differ between children and adults (OEHHA, 2001). 

Pharmacokinetic differences between children and adults include factors that 

influence absorption, distribution, metabolism, and excretion of toxicants. In 

addition, infants and children may have qualitatively different responses due to 

different target tissue sensitivities during windows of susceptibility in the 

developmental process. 
Chapter VII Page 140 

There is evidence that following acute exposure to formaldehyde, asthmatics and 

others previously sensitized to formaldehyde may be more likely to show asthmalike symptoms such as wheezing, shortness of breath, rhinitis, and/or 

decrements in pulmonary function consistent with immediate and/or delayed 

bronchoconstriction (Hendrick and Lane, 1977; Wallenstein et al., 1978; Burge et 

al., 1985; Nordman et al., 1985). Furthermore, some asthmatics may respond 

with significant reductions in lung function due to the irritant effects on asthma, 

sensitized or not. The potential association between formaldehyde exposure and 

asthma is of special concern for children because they have higher prevalence 

rates of asthma than adults, and their asthma episodes can be more severe due 

to their smaller airways, which may result in more hospitalizations of children, 

especially for the first four years of life (Mannino et al., 1998). In several studies, 

asthma symptoms in secondary school children were more common in schools 

with higher concentrations of formaldehyde (Harving et al., 1990; Smedje et al., 

1997; Smedje and Norback, 2001b). In addition, the incidence of new asthma 

diagnosis was more common in children whose classrooms had higher 

concentrations of formaldehyde (Smedje and Norback, 2001a). Thus children, 

particularly asthmatic children, may be at greater risk from acute exposure to 

formaldehyde. 

There are few chronic studies that compare the effects of formaldehyde on 

children versus adults. Among those that do, there is evidence that children are 

more susceptible to the adverse effects of chronic formaldehyde exposure. 

Krzyzanowski et al. (1990) assessed chronic pulmonary symptoms and function 

in 298 children (6-15 years of age) and 613 adults (> 15 years of age) in relation 

to measured formaldehyde levels in their homes (Krzyzanowski et al., 1990). 

Information on pulmonary symptoms and doctor-diagnosed asthma and chronic 

bronchitis was collected by questionnaire. Pulmonary function was assessed as 

peak expiratory flow rates (PEF) measured up to four times a day. The 

prevalence of chronic respiratory symptoms in children was not related to 

formaldehyde levels measured in tertiles (< 40, 41-60, > 60 ppb). However, 

doctor-diagnosed asthma and chronic bronchitis were more prevalent in houses 

with elevated formaldehyde (p for trend < 0.02). This effect was driven by the 

high disease prevalence observed in homes with kitchen formaldehyde levels 

>60 ppb, and was especially pronounced among children with concomitant 

exposure to environmental tobacco smoke. By comparison, in adults, while the 

prevalence rates of chronic cough and wheeze were somewhat higher in houses 

with higher formaldehyde, none of the respiratory symptoms or diseases was 

significantly related to formaldehyde levels (Krzyzanowski et al., 1990). 

In a random effects model, Krzyzanowski et al. (1990) found that lung function 

(measured as peak expiratory flow (PEF) in children, but not adults, was 

significantly decreased by formaldehyde (coefficient for household mean 

formaldehyde ± SE: -1.28 ± 0.46 vs 0.09 ± 0.27) (Krzyzanowski et al., 1990). 

Measurements of PEF in the morning suggested that children with asthma were 

more severely affected than healthy children (coefficient ± SE: 1.45 ± 0.53 p 
Chapter VII Page 141 

<0.05) vs 0.09 ± 0.15 (p >0.10)). The authors note no threshold was found for 

formaldehyde effects on ventilatory function in the children, and that a 10% 

decrease in PEF was associated with exposures as low as 30 ppb in nonasthmatic children with an even larger effect in asthmatic children at 30 ppb. 

Compared to children, the effects of formaldehyde on pulmonary function in 

adults were smaller, transient, limited to morning measurements, and generally 

most pronounced among smokers exposed to the higher levels of formaldehyde. 

These studies suggest that children may be more susceptible to the effects of 

chronic formaldehyde exposure on lung function than are adults. 

Among studies of children only, a case-control study examined risk factors for 

asthma among young children (6 mo- 3 yr) (Rumchev et al., 2002). Cases 

included children with clinically-diagnosed asthma, and controls were children of 

the same age group without such a diagnosis. Formaldehyde levels were 

measured in the homes, once in summer and once in winter. Questionnaires 

were used to assess potential risk factors for asthma and collect parental reports 

of respiratory symptoms characteristic of asthma (cough, shortness of breath, 

wheeze, runny nose, trouble breathing, and hay fever in their children) (Rumchev 

et al., 2002). Formaldehyde levels were higher in the homes of children 

exhibiting asthma symptoms. Estimates of the relative risk for asthma (odds 

ratios) were adjusted for measured indoor air pollutants, relative humidity, 

temperature, atopy (hereditary allergy), family history of asthma, age, gender, 

socioeconomic status, pets, smoke exposure, air conditioning, and gas 

appliances. Compared with children exposed to < 8 ppb, children in homes with 

formaldehyde levels > 49 ppb had a 39% higher risk of asthma (p < 0.05) after 

adjusting for common asthma risk factors (Rumchev et al., 2002). 

Franklin et al. (2000) measured exhaled nitric oxide levels in 224 children 6-13 

years of age as an indicator of inflammation of the lower airways following 

chronic low-level formaldehyde exposure in the home (Kitaeva et al., 1990; 

Franklin et al., 2000). While there was no effect of formaldehyde on lung function 

measured by spirometry, eNO was significantly higher in children from homes 

with average formaldehyde levels ≥ 50 ppb compared with those from homes 

with levels ≤ 50 ppb (15.5 ppb eNO vs 8.7; p = 0.02) (Franklin et al., 2000). 

Garrett et al. (1999) examined the association between formaldehyde levels at 

home (median 15.8 μg/m3; maximum 139 μg/m3) and atopy and allergic 

sensitization in 148 children, 7-14 years of age (Garrett et al., 1999). The risk of 

atopy increased by 40% with each 10 μg/m3 increase in formaldehyde measured 

in the bedroom. Two measures of allergic sensitization to 12 common 

environmental allergens, the number of positive skin prick tests and maximum 

wheal size, both showed linear associations with increasing maximum 

formaldehyde exposure levels. After adjusting for parental asthma and allergy, 

there was no evidence of an association between asthma in the children and 

formaldehyde levels. However, these data do suggest that formaldehyde levels 
Chapter VII Page 142 

commonly found in homes can enhance sensitization of children to common 

aeroallergens (Garrett et al., 1999). 

Of the numerous, primarily occupational, studies in adults, the NOAEL and 

LOAEL are 32 μg/m3 (26 ppb) and 92 μg/m3 (75 ppb), respectively, after 

adjustment for exposure continuity to formaldehyde. These data are based on 

nasal and eye irritation observed in Wilhelmsson and Holstrom (1992), and 

histological lesions in the nasal cavity documented in Edling et al. (1988). 

However, studies in children, including the Krzyzanowski study above, indicate 

adverse health impacts in children at concentrations as low as 30 ppb. 

Wantke et al. (1996) reported that formaldehyde-specific IgE and respiratory 

symptoms were reduced when children transferred from schools with 

formaldehyde concentrations of 43 to 75 ppb to schools with concentrations of 23 

to 29 ppb (Wantke et al., 1996). However, the prevalence of IgE sensitization in 

Japanese school children was not significant whether or not they had asthma 

(Doi et al., 2003). Formaldehyde in indoor air was significantly related to 

bacterial-specific IgG among Hungarian asthmatic children (Erdei et al., 2003). 

While these human studies are not entirely consistent with each other, and there 

is potential for confounding in each, nevertheless, taken together, they suggest 

that children are more sensitive to formaldehyde toxicity than adults. Findings by 

Delfino et al. (2003) also support the view that toxic air contaminants, such as 

formaldehyde, in communities in proximity to major emission sources, including 

both industrial and traffic sources, have adverse effects on asthma in children 

(Delfino et al., 2003). The odds ratio for more severe asthma symptoms per 

interquartile range (3.16 ppb formaldehyde) were 1.37 (95% CI 1.04-1.80). 

b. Health Effects in Experimental Animals

i. Acute Animal Studies

Studies of the acute effects of formaldehyde exposure in experimental animals 

with exposure durations ranging from 30 minutes to 10 hours resulted in irritation, 

decrements in respiratory functioning, respiratory distress, and lethality. In rats 

exposed to formaldehyde vapor 500-1,400 ppm (1 ppm = 1.24 mg/m3

) for 30 

minutes, the lethal concentration to 50% of the exposure group (LC50) was 800 

ppm (Skog, 1950). The first deaths did not occur until 6 hours after cessation of 

exposure; respiratory difficulty lasted several days after exposure; and several 

died after 15 days of bronchitis and diffuse bronchopneumonia. Three weeks 

following exposure, histological examinations of the surviving animals revealed 

bronchitis, pulmonary micro-hemorrhages, and edema. The report stated that 

formaldehyde exposure resulted in delayed lethality (Skog, 1950). 

Exposure of mice to high concentrations of formaldehyde (726 ppm) for 2 hours, 

resulted in deaths from massive pulmonary hemorrhage and edema, but 2-hr 

exposure to 113 ppm did not produce signs of “substantial distress” (Horton et 
Chapter VII Page 143 

al., 1963). Alarie (1981) determined the 10-minute LC50 for formaldehyde in mice 

to be 2,162 ppm (95% CI, 1,687-2,770 ppm) (Alarie, 1981). In an acute lethality 

study , 125 or 250 ppm formaldehyde for 4 hours resulted in deaths of albino rats 

(Carpenter et al., 1949). In another lethality study, the LC50 in rats and mice for a 

4-hour formaldehyde exposure was 474 ppm and 407 ppm, respectively 

(Nagornyi et al., 1979). A multi-species study showed that a 10-hr exposure to 

15.4 ppm formaldehyde vapor killed 3 of 5 rabbits, 8 of 20 guinea pigs, and 17 of 

50 mice (Salem and Cullumbine, 1960). 

Amdur notes that exposure of guinea pigs to formaldehyde for one hour 

increases resistance and decreases compliance relative to the control level at 

0.31 ppm and above (p<0.05) (Amdur, 1960). 

Swiecechowski et al. exposed guinea pigs to 0.86, 3.4, 9.4, or 31.1 ppm 

formaldehyde for 2 hours, or to 0.11, 0.31, 0.59, or 1.05 ppm formaldehyde for 8 

hours (Swiecichowski et al., 1993). An 8-hour exposure to > 0.3 ppm 

formaldehyde was sufficient to produce a significant increase in airway reactivity. 

Similar effects occurred after > 9 ppm (>11 mg/m3) formaldehyde for the 2-hour 

exposure group. Formaldehyde exposure also heightened airway smooth 

muscle responsiveness to acetylcholine (or carbachol) ex vivo. 

Riedel et al. studied the influence of formaldehyde exposure on allergic 

sensitization in the guinea pig (Riedel et al., 1996). Exposure to formaldehyde 

concentrations (0.13 and 0.25 ppm) over 5 consecutive days, followed by 

sensitization to ovalbumin (OA) resulted in enhanced sensitization relative to 

filtered air controls (P < 0.01). Furthermore, compressed air measurements of 

specific bronchial provocation were significantly higher in the 0.25 ppm 

formaldehyde group than in controls (p< 0.01), indicating increased bronchial 

obstruction. Histological examination found edema of the bronchial mucosa, but 

there was no sign of inflammation of the lower airways in formaldehyde-exposed 

guinea pigs. The investigators concluded that short-term exposure to a low 

concentration of formaldehyde (0.25 ppm) can significantly enhance sensitization 

to inhaled allergens in the guinea pig. 

 

Mice exposed to 0.2 to 13 ppm formaldehyde showed a concentration-dependent 

decrease in respiratory rate, which was attributable to sensory irritation at 0.3 to 

4.0 ppm, and, above 4 ppm, also to bronchoconstriction (Nielsen et al., 1999). 

Taken together, these acute animal studies show that formaldehyde is a 

respiratory irritant at low exposures, and can aggravate asthma-like conditions. 

ii. Reproductive and Developmental Toxicity 

A developmental toxicity study on formaldehyde was conducted on pregnant rats 

(25 per group) that were exposed to 0, 2, 5, or 10 ppm formaldehyde for 6 

hours/day, during days 6-15 of gestation (Martin, 1990). Although exposure to 
Chapter VII Page 144 

10 ppm formaldehyde resulted in reduced food consumption and body weight 

gain in the maternal rats, no effects on the number, viability or normal 

development of the fetuses were seen. In addition, pregnant rats (25 per group) 

were exposed to 0, 5, 10, 20, or 40 ppm formaldehyde from days 6 - 20 of 

gestation (Saillenfait et al., 1989). Maternal weight gain and fetal weight were 

significantly reduced in the 40 ppm exposure group. No significant fetotoxicity or 

teratogenic defects were observed at formaldehyde levels that were not also 

maternally toxic (Saillenfait et al., 1989). 

Evidence of embryotoxicity was reported in embryos of rats that had been 

exposed to formaldehyde by inhalation 4 h/d, 5 d/wk for 4 months (Kitaeva et al., 

1990). At 1.5 mg/m3

, but not at 0.5 mg/m3, there was a significant increase in the 

proportion of degenerate embryos. By comparison, the bone marrow cells of the 

mothers appeared to be more sensitive to formaldehyde as shown by significant 

increases in the numbers of cells with aberrations, and the numbers of 

chromosomes with aberrations and aneuploidy at both dose levels (Kitaeva et al., 

1990). 

iii. Sub-chronic Animal Studies 

Sub-chronic studies in rats and mice exposed to formaldehyde have shown 

histopathological changes (tissue changes characteristic of disease) in the nasal 

respiratory epithelium and nasal lesions in a dose-dependent manner (MonteiroRiviere and Popp, 1986). In the nasal respiratory epithelium of adult male rats 

with exposure to 0.5 or 2 ppm formaldehyde, effects were limited to altered cilia 

(minute short hair-like processes, capable of lashing movement) with occasional 

wing-like projections on the ends of the ciliary shafts. Loss of microvilli 

(microscopic projections of tissues, cells, or cell organelles) in ciliated cells was 

noted at all exposure concentrations (Monteiro-Riviere and Popp, 1986). 

Intermittent exposures (8 hours/day, 5 days/week) of rats to 4 ppm formaldehyde 

for 13 weeks resulted in significant histological changes in the nasal septum and 

turbinates; however, 2 ppm did not produce significant lesions (Wilmer et al., 

1989). This study revealed the concentration-dependent nature of the nasal 

lesions caused by formaldehyde exposure. 

When male and female Wistar rats were exposed to 0.3 to 3 ppm formaldehyde 

vapor (6 hours/day, 5 days/week) for 13 weeks, histopathological nasal changes 

varying from epithelial disarrangement to epithelial hyperplasia (abnormal or 

unusual increase in epithelial cells composing a tissue) and squamous 

metaplasia (abnormal replacement of cells of one type by cells of another) were 

found in the 3 ppm group, and were restricted to a small area of the anterior 

respiratory epithelium (Zwart et al., 1988). In another subchronic study, rats 

were exposed to formaldehyde 0 to 20 ppm (6 hours/day, 5 days/week) for 13 

weeks (Woutersen et al., 1989). Rats exposed to 20 ppm displayed retarded 

growth, yellowing of the fur, and significant histological lesions in the respiratory 

epithelium. Exposure to 10 ppm did not affect growth, but resulted in significant 
Chapter VII Page 145 

histological lesions in the respiratory tract. No significant adverse effects were 

seen at the 1.0 ppm exposure level (Woutersen et al., 1989). 

Mice exposed subchronically to 0 to 40 ppm formaldehyde (6 hours/day, 5 

days/week) for 13 weeks had histological lesions in the upper respiratory 

epithelium (≥10 ppm) and exposure to 40 ppm was lethal (Maronpot et al., 1986). 

iv. Chronic Animal Studies

Nasal lesions of the respiratory and olfactory epithelium have been observed 

after chronic inhalation exposure of mice and rats to formaldehyde (Kerns et al., 

1983; Rusch et al., 1983; Appelman et al., 1988; Woutersen et al., 1989; Kamata 

et al., 1997; Kimbell et al., 1997). Fischer-344 rats and B6C3F1 mice were 

exposed to 0 to 14.3 ppm formaldehyde vapor (6 hours/day, 5 days/week) for 24 

months (Kerns et al., 1983). The exposure period was followed-up by 6 months 

of non-exposure with interim sacrifices conducted at 6, 12, 18, 24, 27, and 30 

months. Both male and female rats in the 5.6 and 14.3 ppm groups 

demonstrated decreased body weights over the 2-year period. At the 6 month 

sacrifice, the rats exposed to 14.3 ppm formaldehyde had non-neoplastic lesions 

of epithelial dysplasia (abnormal growth or development) in the nasal septum and 

turbinates (Kerns et al., 1983). As the study progressed, epithelial dysplasia, 

squamous dysplasia, mucopurulent discharge (containing mucus and pus), and 

rhinitis increased in severity and distribution in all exposure groups (Kerns et al., 

1983). In B6C3F1 mice, cumulative survival decreased in males from 6 months 

to the end of the study. Serous rhinitis was detected at 6 months in the 14.3 ppm 

group of mice. Metaplastic and dysplastic changes were noted at 18 months in 

most rats in the 14.3 ppm group and in a few mice in the 5.6 ppm exposure 

group. By 24-months, the majority of mice in the 14.3 ppm group had 

metaplastic and dysplastic changes associated with serous rhinitis, in contrast to 

a few mice in the 5.6 ppm group and a few in the 2 ppm group (Kerns et al., 

1983). 

At a similar dose of 10 ppm, compound-related nasal lesions of the respiratory 

and olfactory epithelium in male Wistar rats exposed 6 hours/day, 5 days/week to 

0 to 10 ppm formaldehyde vapor for 28 months were observed (Woutersen et al., 

1989). In the respiratory epithelium, the lesions consisted of rhinitis, squamous 

metaplasia and basal cell/pseudoepithelial hyperplasia. In the olfactory region, 

the lesions included epithelial degeneration and rhinitis. In a parallel study, male 

Wistar rats were exposed to 0 to 10 ppm formaldehyde for 3 months followed by 

a 25-month observation period. As with the previous studies, compound-related 

histopathological changes were found in the noses of the 10 ppm group and 

were comprised of increased incidences of squamous metaplasia of the 

respiratory epithelium and rhinitis (Woutersen et al., 1989). 

Similar results were observed when male F-344 rats were exposed to 

formaldehyde vapor at 0 to 15 ppm (6 hours/day, 5 days/week) for up to 28 
Chapter VII Page 146 

weeks (Kamata et al., 1997). Animals from each group were randomly selected 

at the end of 12, 18, and 24 months, and surviving animals at 28 months were 

sacrificed for full pathological evaluation. Behavioral effects related to sensory 

irritation were evident in the 15 ppm group. Abnormal histopathological findings 

were confined to the nasal cavity. Inflammatory cell infiltration, erosion or edema 

of the nasal cavity was evident in all groups, including controls. Significantly 

increased incidence of non-proliferative (squamous cell metaplasia without 

epithelial cell hyperplasia) and proliferative lesions (epithelial cell hyperplasia 

with squamous cell metaplasia) were observed in the nasal cavities beginning at 

2 ppm. In the 0.3 ppm group, a non-significant increase in proliferative nasal 

lesions was observed in rats that were either sacrificed or died following the 18th

month of exposure. Note that respiratory tract lesions also occur in 

occupationally exposed workers at lower formaldehyde concentrations. 

Also using male F-344 rats exposed to 0 to 15 ppm formaldehyde (6 hours/day, 5 

days/week) for up to 6 months, squamous metaplasia was not observed in any 

regions of the nasal cavity in the control, 0.7, or 2 ppm groups (Kimbell et al., 

1997). However, the extent and incidence of squamous metaplasia in the nasal 

cavity increased with increasing dose beginning at 6 ppm (Kimbell et al., 1997). 

In a different study, significant nasal lesions were found in rats exposed to 10 

ppm formaldehyde (6 hours/day, 5 days/week) for 52 weeks, but exposure to 1.0 

ppm or less for this period did not result in nasal histological lesions (Appelman 

et al., 1988). However, Apfelbach and Weiler determined that rats (5 exposed, 

10 controls) exposed to 0.25 ppm (0.38 mg/m3) formaldehyde for 130 days lost 

the olfactory ability to detect ethyl acetate odor (Apfelbach and Weiler, 1991). 

Groups of 6 male cynomolgus monkeys, 20 male or female rats, and 10 male or 

female hamsters were exposed to 0 to 3.0 ppm formaldehyde vapor (22 

hours/day, 7 days/week) for 26 weeks (Rusch et al., 1983). There was no 

treatment-related mortality during the study. In monkeys, the most significant 

findings were hoarseness, congestion and squamous metaplasia of the nasal 

turbinates in 6/6 monkeys exposed to 2.95 ppm. There were no signs of toxicity 

in the lower exposure groups (0.19 and 0.98 ppm). In the rat, squamous 

metaplasia and basal cell hyperplasia of the nasal epithelia were significantly 

increased in rats exposed to 2.95 ppm. The same group exhibited decreased 

body weights and decreased liver weights. In contrast to monkeys and rats, 

hamsters did not show any signs of response to exposure, even at 2.95 ppm. 

More than 90% of inhaled formaldehyde gas is absorbed in the upper respiratory 

tract of rats and monkeys (Conolly et al., 2002). In rats, it is absorbed in the 

nasal passages; in monkeys, it is also absorbed in the nasopharynx, trachea and 

proximal regions of the major bronchi. In mice exposed to high concentrations of 

formaldehyde, minute ventilation is decreased by 50% throughout exposure, 

resulting in a lower effective dose. This occurs only transiently in rats, as the 

minute ventilation is rapidly restored. 
Chapter VII Page 147 

Acute or subacute exposure of rats to a concentration of 2 ppm appears to cause 

no detectable damage to the nasal epithelium and does not significantly increase 

rates of cell turnover. Cell turnover rates in rat nose during subchronic or chronic 

exposures to formaldehyde do not increase at 2 ppm, increase marginally at 

concentrations of 3 to 6 ppm and increase substantially at concentrations of 10-

15 ppm. Therefore, concentration is more important than length of exposure in 

determining the cytotoxicity of formaldehyde (Conolly et al., 2002). In a different 

study rats were exposed for six months to 0, 0.5, 3, and 15 ppm formaldehyde, 

which resulted in significantly elevated total lung cytochrome P450 in all 

formaldehyde-exposed groups (Dallas et al., 1989). The degree of P450 

induction was highest after 4 days exposure and decreased slightly over the 

course of the experiment. 

c. Human Carcinogenicity

i. Genotoxicity

Formaldehyde is genotoxic (damaging to genetic material) to humans. Increased 

numbers of DNA–protein crosslinks have been found in peripheral blood 

lymphocytes of exposed workers (Shaham et al., 1997; Shaham et al., 2002; 

Shaham et al., 2003). Formaldehyde induces DNA-protein crosslinks, DNA 

single-strand breaks, chromosomal aberrations, sister chromatid exchanges and 

gene mutations in human cells in vitro (Grafstrom et al., 1984; U.S.EPA, 1987; 

Shaham et al., 1996; IARC, 2004a; 2004b).

ii. Nasopharyngeal Cancer 

Many studies in the epidemiological literature support a link between 

formaldehyde and elevated risk of cancers of the upper respiratory tract in 

workers and in the general population. According to the International Agency for 

the Research on Cancer (IARC), nasopharyngeal cancer mortality was 

statistically significantly increased in a cohort study of United States industrial 

workers exposed to formaldehyde in comparison with the U.S. national 

population, with statistically significant exposure–response relationships for peak 

and cumulative exposure (IARC, 2004a; 2004b). The individual studies used as 

the basis of this conclusion are described in further detail below. 

Among the industrial cohort studies, Stayner et al. (1988) reported a relative risk 

of 3.4 (90% CI: 1.2-7.9) for buccal cancer (Stayner et al., 1988), and Blair et al.

(1986) reported a relative risk of 3.00 (90% CI: 1.30-5.92) for nasopharyngeal 

cancer (Blair et al., 1986). Among industrial proportional mortality studies, 

Liebling et al.(1984) reported a relative risk of 8.70 (90% CI: 1.50-27.33) for 

buccal/pharyngeal cancer (Liebling et al., 1984) and Stayner et al. (1985) 

reported a relative risk of 7.5 (90% CI: 2.0-19) for buccal cancer (Stayner et al., 

1985). In all of these studies the elevated risk was statistically significant. The 

population-based case control studies reported statistically significant 
Chapter VII Page 148 

relationships between formaldehyde exposure and upper respiratory cancers in 

three studies (Olsen and Dossing, 1982; Hayes et al., 1986; Vaughan et al., 

2000), although these cancers can appear in any of several sites. Studies of 

embalmers, who used formaldehyde, have shown increased rates of 

nasopharyngeal cancer, brain cancer and leukemia. A significant incidence of 

nasopharyngeal cancer was found among workers in fiberboard plants and 

among book binders, both being subject to formaldehyde exposure (Malker et al., 

1990). 

IARC (2004) has reviewed available cohort studies including those of 

embalmers, industrial workers, and British chemical workers (IARC, 2004a; 

2004b). An excess of nasopharyngeal cancer was observed in a proportionate 

mortality analysis for the largest U.S. cohort of embalmers (Hayes et al., 1990) 

and in a Danish study of proportionate cancer incidence among workers at 

companies which used or manufactured formaldehyde (Hansen and Olsen, 

1995). 

In a more recent study, evidence of an exposure-response relationship with 

mortality from nasopharyngeal cancer was found in a large cohort of 

formaldehyde-exposed workers, but not for cancers of the pancreas, brain, lung, 

or prostate (Hauptmann et al., 2004). 

The relation of nasopharyngeal cancer with exposure to formaldehyde has also 

been investigated in seven case control studies (Olsen et al., 1984; Vaughan et 

al., 1986a; 1986b; Roush et al., 1987; West et al., 1993; Armstrong et al., 2000; 

Vaughan et al., 2000; Hildesheim et al., 2001), five of which found elevations of 

risk for overall exposure to formaldehyde, or in higher exposure categories, 

including one in which the increase in risk was statistically significant, and three 

that found higher risks in subjects with the highest probability, level or duration of 

exposure. The Working Group considered it improbable that all of the positive 

findings for nasopharyngeal cancer that were reported from the epidemiological 

studies, and particularly from the large study of industrial workers in the USA, 

could be explained by bias or unrecognized confounding effects. The Working 

Group concluded that these studies provide “sufficient epidemiological evidence 

that formaldehyde causes nasopharyngeal cancer in humans” (IARC, 2004a; 

2004b). 

Blair et al. (1987) presented further analysis resulting in a significant association 

between nasopharyngeal cancer and simultaneous exposure to formaldehyde 

and to particulate, indicating that such exposure may be a risk factor (Blair et al., 

1987). 

Recent occupational studies have investigated the relationship of formaldehyde 

exposure to histological changes, some of which are potentially precancerous 

lesions, in the nasal mucosa. Holmstrom et al. (1989) found that workers 

exposed to well-defined levels of formaldehyde developed significant changes in 
Chapter VII Page 149 

the middle turbinate, while those exposed to both formaldehyde and wood dust 

did not (Holmstrom et al., 1989). Boysen et al. (1990) found in nasal biopses that 

workers exposed to formaldehyde showed a significantly higher degree of 

metaplastic alterations (Boysen et al., 1990). Edling et al.(1988) found significant 

histological differences in the nasal mucosa of formaldehyde workers compared 

to unexposed workers, but found no histological differences between those 

exposed to formaldehyde and those exposed to formaldehyde and wood dust 

(Edling et al., 1988). Berke (1987) found no statistical relationship between 

exfoliated nasal cells in formaldehyde-exposed workers and control groups. 

Thus, these studies provide some indication of possible histological changes due 

to formaldehyde exposure in humans, consistent with results in animals. 

iii. Leukemia

Leukemia mortality, primarily of the myeloid-type, was increased in six of seven 

cohorts of embalmers, funeral-parlor workers, pathologists, and anatomists 

(Walrath and Fraumeni, 1983; Levine et al., 1984; Walrath and Fraumeni, 1984; 

Logue et al., 1986; Stroup et al., 1986; Hayes et al., 1990; Hall et al., 1991) as 

reviewed by IARC 2004a; IARC 2004b. Recent evidence indicates a greater 

incidence of leukemia in two cohorts of U.S. industrial workers and U.S. garment 

workers, but not in a third cohort of United Kingdom chemical workers. 

Therefore, IARC concluded that there is “strong but not sufficient evidence for a 

causal association between leukemia and occupational exposure to 

formaldehyde” (IARC, 2004a; 2004b). 

Until recently, the findings for leukemia in studies of professional workers 

appeared to be contradicted by the lack of such findings among industrial 

workers. However, some evidence for an excess of leukemia has been reported 

in the recent updates of two of the three major cohort studies of industrial 

workers. A statistically significant exposure–response relationship was observed 

between peak exposures to formaldehyde and mortality from leukemia in the 

study of industrial workers in the USA (Blair et al., 1990; Hauptmann et al., 

2003). A recent meta-analysis found that, overall the relative risk for leukemia in 

these workers was increased and did not vary significantly among studies 

(Collins and Lineker, 2004). 

Mortality from leukemia was also found to be in excess in the recent update of 

the study of garment workers exposed to formaldehyde in the U.S. (Pinkerton et 

al., 2004). A small and statistically non-significant excess was observed for the 

entire cohort in comparison with rates from the general population. This excess 

was somewhat stronger for myeloid leukemia, which is consistent with the 

findings from the study of industrial workers in the U.S. and several of the studies 

of medical professionals and embalmers. In contrast, the updated study of 

industrial workers in the U.K. did not find excess mortality from leukemia 

(Coggon et al., 2003). 
Chapter VII Page 150 

Linos et al. reported elevated rates of follicular non-Hodgkin’s lymphoma and of 

acute myeloid leukemia among embalmers and funeral directors in a populationbased case control (Linos et al., 1990). The excess was also stronger among 

workers with long duration of exposure and long follow-up, and who had been 

employed early in the study period when exposures to formaldehyde were 

believed to be the highest. This pattern of findings is generally consistent with 

what might be expected if, in fact, exposure to formaldehyde were causally 

associated with risk for leukemia. 

The IARC Working Group concluded, “In summary, there is strong but not 

sufficient evidence for a causal association between leukemia and occupational 

exposure to formaldehyde.” This conclusion, falling between sufficient and limited 

evidence, was based on a consistently increased risk in studies of embalmers, 

funeral parlor workers, pathologists, and anatomists and was present in two of 

the three most informative studies of industrial workers (IARC, 2004a; 2004b). 

iv. Lung Cancer

The three largest - and therefore potentially most sensitive - industrial cohort 

studies reported an elevated rate of lung cancer. The largest study with 26,561 

U.S. workers, reported a statistically elevated death rate due to lung cancer, 

equivalent to 35% above the national average (Blair et al., 1986). Several other 

studies reported elevated death rates due to lung cancer (Acheson et al., 1984a; 

1984b; 1984c) in 7,680 British male workers, mostly young, and in 11,030 US 

workers, mostly female (Stayner et al., 1988). Some of the categories in the 

Acheson study showed statistically significant increases of lung cancer (Acheson 

et al., 1984a; 1984b). The Stayner (1988) study found lung cancer to be 

elevated 14% overall, which was not statistically significant, but the exposures 

were well below those of the other two studies. 

In Blair et al. (1986), the investigators concluded that a causal relationship 

between formaldehyde exposure and lung cancer was unlikely because of a lack 

of dose gradient for those tumors. Sterling and Weinkam (1988; 1989) 

performed a reanalysis on the basis that Blair et al. (1986) failed to account for a 

“healthy-worker” effect in the original report. These corrected results showed 

that lung cancer was related to formaldehyde exposure in a dose-dependent 

manner which was statistically significant (Sterling and Weinkam, 1988; 1989). 

Recent epidemiological studies contribute to the conclusions only marginally. 

Gerin et al.(1989) presented the results of a large case control study with 3,726 

cancer patients (Gerin et al., 1989). The odds ratio for the highest exposure 

group with adenocarcinoma of the lung was nearly significant at the 95% 

confidence level, and there was an apparent trend of incidence of this cancer 

with exposure. Bertazzi et al. (1989) presented an extension of a previous study 

(Bertazzi et al., 1986), that had detected elevated lung cancer among 1,332 

workers in a resin B-289 manufacturing plant subject to formaldehyde exposure 
Chapter VII Page 151 

(Bertazzi et al., 1989 as cited in IARC, 2004a; 2004b). In the extended study 

with more accurate estimates of exposure, the lung cancer rate was not elevated 

above expected for those exposed to formaldehyde (Bertazzi et al., 1989 as cited 

in IARC, 2004a; 2004b). Coggon et al. (2003) noted an increase in the risk of 

lung cancer, but not a significant association with mortality (Coggon et al., 2003). 

Based on the current data alone, a definitive relationship between formaldehyde 

exposure and lung cancer mortality could not be made by the IARC Working 

Group (IARC, 2004a; 2004b). 

v. Sinonasal Cancer

The association between exposure to formaldehyde and risk for sinonasal cancer 

has been evaluated in six case–control studies with a primary focus on 

formaldehyde. Four of these studies also contributed to a pooled analysis that 

collated occupational data from 12 case–control investigations. After adjustment 

for known occupational confounders, this analysis showed an increased risk for 

adenocarcinoma in both men and women and also (although on the basis of only 

a small number of exposed cases) in the subset of subjects who were thought 

never to have been occupationally exposed to wood or leather dust. Moreover, 

there was a dose–response trend in relation to an index of cumulative exposure 

(Luce et al., 2002). One other case-control study (Olsen and Asnaes, 1986) and 

a proportionate incidence study (Hansen and Olsen, 1995) showed an increased 

risk of sinonasal cancer, particularly squamous cell carcinoma. Against these 

largely positive findings, the three most informative cohort studies of industrial 

and garment workers showed no excess of sinonasal cancer (Coggon et al., 

2003; Hauptmann et al., 2004; Pinkerton et al., 2004). 

The IARC Working Group noted that most of the epidemiological studies did not 

distinguish tumors as originating in the nose or sinuses, thus an increased risk of 

nasal cancer would be diluted if there were no corresponding effect on the 

sinuses. In the case-control studies, the Working Group also noted the potential 

for confounding by wood dust exposure, which is associated with 

nasopharyngeal adenocarcinoma. The Working Group concluded that there is 

limited evidence that formaldehyde causes sinonasal cancer in humans (IARC, 

2004a; 2004b). 

vi. Cancer at Other Sites

A number of studies have found associations between exposure to formaldehyde 

and cancer at other sites, including the oral cavity, oro- and hypopharynx, 

pancreas, larynx, lung and brain. However, the IARC 2004 Working Group 

considered that the overall balance of epidemiological evidence did not support a 

causal role for formaldehyde in relation to these other cancers (IARC, 2004a, 

IARC 2004b). 
Chapter VII Page 152 

d. Animal Carcinogenicity

i. Genotoxicity

Formaldehyde is comprehensively genotoxic in a variety of experimental 

systems, ranging from bacteria to rodents, in vivo. Administration of 

formaldehyde in the diet to Drosophila melanogaster induced lethal and visible 

mutations, deficiencies, duplications, inversions, translocations and crossing-over 

in spermatogonia (Auerbach et al., 1977; Swenberg et al., 1983). 

In rodent cells in vitro, formaldehyde induced cell transformation, chromosomal 

aberrations, sister chromatid exchange, DNA strand breaks, DNA-protein 

crosslinks and gene mutation (Cosma et al., 1988; Casanova et al., 1994; Merk 

and Speit, 1998; Speit and Merk, 2002). Inhalation of formaldehyde leads to the 

formation of DNA-protein cross-links in the nasal respiratory mucosa of rats and 

monkeys (Conaway et al., 1996). The formation of DNA-protein cross-links is a 

sublinear function of the formaldehyde concentration in inhaled air from 0.69 to 

15 ppm, and the yield of DNA-protein cross-links at a given inhaled concentration 

is approximately an order of magnitude lower in monkeys than in rats. About 

50% of formaldehyde-induced tumors in the nasal mucosa of rats have a point 

mutation in the p53 tumor suppressor gene. 

ii. Nasopharyngeal Cancer

In experimental animals, several studies have shown that inhalation exposure 

induces squamous cell carcinomas of the nasal cavities in rats (Albert et al., 

1982; Kerns et al., 1983; Sellakumar et al., 1985; Morgan et al., 1986; Feron et 

al., 1988; Woutersen et al., 1989; Monticello et al., 1996; Kamata et al., 1997), 

although single studies in mice (Kerns et al., 1983) and hamsters (Dalbey, 1982) 

showed no carcinogenic effects. Several studies in which formaldehyde was 

administered to rats by inhalation showed evidence of carcinogenicity, 

particularly induction of squamous-cell carcinomas of the nasal cavities, usually 

only at the highest exposure. A chronic exposure study that primarily 

investigated aspects of nasal tumor development, examined rat nasal cavities 

following exposure to 0 - 15 ppm of formaldehyde for 6 hours/day, 5 days/week 

for 24 months (Monticello et al., 1996). Nasal lesions developed at 6, 10, and 15 

ppm. The two highest doses included epithelial hypertrophy and hyperplasia, 

squamous metaplasia, and a mixed inflammatory cell infiltrate, but the lesions of 

the 6 ppm group were minimal to absent and limited to focal squamous 

metaplasia in the anterior regions of the nasal cavity (Monticello et al., 1996). 

A study sponsored by the Chemical Industry Institute for Toxicology (CIIT) has 

provided the most quantitatively useful evidence for the carcinogenicity of 

formaldehyde (Swenberg et al., 1980a; Swenberg et al., 1980b; Kerns et al., 

1983). This study used 120 male and 120 female Fischer-344 rats in each dose 

group, including a clean air group. The adjusted tumor incidences (adjusted for 
Chapter VII Page 153 

competing causes of death, including scheduled interim sacrifices) for squamous 

cell carcinomas in the nasal passages of males and females combined, when 

exposed to 0 to 14.3 ppm formaldehyde (6 hours/day, 5 days/week) for up to 24 

months, were 0/156, 0/159, 2/153 and 94/140 for the highest dose group (14.3 

ppm) (USEPA, 1987). 

In an analogous study on mice, two mice in the high dose group (14.3 ppm) 

developed squamous cell carcinomas, a finding that was not statistically 

significant, but was thought to be biologically significant due to the absence of 

this tumor in control animals and due to concurrence with the rat studies. Kerns 

et al. (1983) also reported benign tumors, including polypoid adenomas and 

squamous cell papillomas (Kerns et al., 1983). Swenberg et al. (1980) described 

a number of additional lesions in the nasal turbinates of rats exposed to 

formaldehyde for 18 months, including rhinitis, epithelial dysplasia and 

hyperplasia, squamous hyperplasia, and cellular atypia that occurred in a doserelated manner (Swenberg et al., 1980a; Swenberg et al., 1980b). Other 

inhalation studies (Albert et al., 1982; Tobe et al., 1985) have also provided 

positive evidence for the carcinogenicity of formaldehyde. 

iii. Leukemia

The IARC Working Group concluded, “The current data indicate that both 

genotoxicity and cytotoxicity play important roles in the carcinogenesis of 

formaldehyde in nasal tissues.” On the other hand, with respect to the potential 

for formaldehyde to induce leukemia, the Working Group was not aware of any 

good rodent models for acute myeloid leukemia in humans (IARC, 2004a; IARC 

2004b). Several possible mechanisms were considered, such as clastogenic 

damage to circulating stem cells. There is a single study reporting cytogenetic 

abnormalities in the bone marrow of rats inhaling formaldehyde (Kitaeva et al., 

1990). The Working Group concluded, “Based on the data available at this time, 

it was not possible to identify a mechanism for the induction of myeloid leukemia 

in humans” (IARC 2004a; IARC 2004b). 

iv. Other Routes of Exposure

Four studies of formaldehyde administered to rats in drinking-water gave varying 

results: one showed an increased incidence of forestomach papillomas in male 

rats (Takahashi et al., 1986), a second showed an increased incidence of 

gastrointestinal leiomyosarcomas in female rats and in both sexes combined 

(Soffritti et al., 1989), a third showed increased incidences of total malignant 

tumors, lymphomas and leukemias, and testicular interstitial-cell adenomas in 

male rats (Soffritti et al., 2002), while a fourth did not show a carcinogenic effect 

(Til et al., 1989). 
Chapter VII Page 154 

Recent investigations of chronic toxicity have shown formaldehyde administered 

orally for 24 months to be carcinogenic in Sprague-Dawley rats. Six exposure 

groups each of 50 male and 50 female Sprague-Dawley rats, with drinking water 

concentration of 8 ppm to 1210 ppm formaldehyde, reported increases in the 

percent of B-290 animals bearing leukemias and gastrointestinal neoplasias at 

the higher exposures. Til et al. (1989), using three exposure groups, of 70 male 

and 70 female Wistar rats each, with drinking water concentrations of 16 to1 532 

ppm, reported numerous pathological changes at the highest exposure level, but 

no evidence of carcinogenicity at any level. Tobe et al. (1989), using three 

exposure groups, of 20 male and 20 female Wistar rats each, with drinking water 

concentrations of 161 to 4032 ppm, also reported pathological changes at the 

highest exposures level but no significant increases in the incidence of any tumor 

in these small treatment groups (Tobe et al., 1989). In a letter to the editor, 

Feron et al. (1990) questioned the conclusions and some methods of Soffritti et 

al. (1989) (Feron et al., 1990). 

Other types of exposures have produced a spectrum of results. Watanabe et al.

(1954) presented a brief preliminary report of experimentally inducing sarcomas 

by repeated injections of an aqueous solution of formaldehyde in rats (Watanabe 

et al., 1954 as cited in IARC (2004)). Muller et al. (1978) induced a preneoplastic 

lesion of the oral mucosa by repeated exposure to formalin solution in rabbits. 

(Muller et al., 1978). Homma et al. (1986) found that formalin solution repeatedly 

administered in transplanted rat bladders did not promote the formation of tumors 

(Homma et al., 1986). Takahashi et al. (1986) found that formalin solution in the 

diet promoted stomach tumors in Wistar rats (Takahashi et al., 1986). Iversen et 

al. (1988) found that topical skin application of formaldehyde solution in mice did 

not promote the formation of skin tumors (Iversen et al., 1988). 

v. Co-carcinogenicity

Formaldehyde has shown co-carcinogenic effects by inhalation, ingestion, and 

dermal exposure to rodents (Dalbey, 1982; Takahashi et al., 1986; Iversen et al., 

1988). In additional studies in mice, rats and hamsters, modification of the 

carcinogenicity of known carcinogens was tested by administration of 

formaldehyde in drinking-water, by application on the skin or by inhalation. Oral 

administration of formaldehyde concomitantly with N-nitrosodimethylamine to 

mice increased the incidence of tumors at various sites. Exposure of hamsters to 

formaldehyde by inhalation increased the multiplicity of tracheal tumors induced 

by subcutaneous injections of N-nitrosodiethylamine (Morgan et al., 1986). Skin 

application of formaldehyde concomitantly with 7,12-dimethylbenz[a]anthracene 

reduced the latency of skin tumors in mice (Homma et al., 1986). In rats, 

concomitant administration of formaldehyde and N-methyl-N ́-nitro-Nnitrosoguanidine in the drinking-water increased the incidence of 

adenocarcinoma of the glandular stomach (Tobe et al., 1989). 
Chapter VII Page 155 

vi. Overall IARC Conclusion

The IARC Working Group concluded that formaldehyde is carcinogenic to 

humans (Group 1), on the basis of sufficient evidence in humans and sufficient 

evidence in experimental animals. Based on the information now available, this 

classification is higher than those of earlier IARC evaluations (IARC 1982, 1987, 

1995)(IARC 2004a; IARC 2004b). 

C. Factors that Affect the Outcome of a Health Risk Assessment 

Estimates of the potential health effects of HCHO emissions from composite 

wood products could be affected by: 

• HCHO concentrations in indoor microenvironments; 

• Rate of decrease in product-specific HCHO emissions with time; 

• Initial product-specific HCHO emission rates; 

• Air exchange rates in indoor microenvironments; 

• Product-specific HCHO compensation points; 

• Number and total surface area of HCHO-emitting products; and 

• Practices utilized, if any, to reduce indoor HCHO exposure. 

Variations in the numerical value of these factors will have substantive impacts 

on estimates of potential cancer risk and extent of non-cancer effects. For 

example, maintaining high air exchange rates and using air filtration systems 

could greatly reduce indoor exposures in homes, schools, and workplaces. 

D. Summary of Potential Health Impacts 

In this chapter, the results of the total daily HCHO exposure analyses are 

presented. As Californians spend 90% or more of their day indoors (University of 

California, Berkeley, 1991a), total daily HCHO exposure is predominantly 

determined by indoor air quality. Based on the exposure analysis, significant 

reductions in lifetime cancer risk may be realized by reducing HCHO emissions 

from composite wood products used as building materials and to fabricate 

finished products, such as furniture. 

To calculate total daily exposure to HCHO requires data on activity patterns (i.e., 

time spent in different microenvironments; Table VII-3) and typical HCHO 

concentrations (μg/m3

) in the selected microenvironments (Table VII-1). A daily 

TWA was calculated for an average and elevated exposure for adults and 

children (i.e., four scenarios – current-average and current-elevated for children 

and adults). 
Chapter VII Page 156 

Table VII-3. Age-group Specific and Average Child and Adult Activity Patterns1

Age Tind (hr) Tout (hr) Tinv (hr) Ttotal (hr) 

0-2 21.43 1.57 1.01 24.00 

3-5 20.47 2.38 1.15 23.99 

6-8 20.34 2.83 0.83 24.00 

9-11 19.69 3.28 1.03 24.01 

12-17 21.23 1.00 1.78 23.99 

18-24 20.55 1.23 2.22 24.01 

25-34 20.98 1.21 1.83 23.99 

35-44 20.65 1.36 1.98 23.96 

45-54 20.95 0.98 2.03 23.96 

55-64 20.64 1.73 1.63 23.99 

65+ 21.57 1.15 1.3 24.02 

Child – Average 20.55 2.45 1.00 24.00 

Adult – Average 20.82 1.47 1.71 24.00 

(1) Sources: University of California, Berkeley, 1991a and 1991b. Tind = time spent indoors; Tout = 

time spent outdoors, Tinv = time spent in-vehicles, and Ttotal = (Tind + Tout + Tinv). Averages for 

children and adults are the average from age 0-9 and 0-70 years, respectively. 

Summary data in two technical reports were used to calculate the average time 

spent indoors, outdoors, or in a vehicle (University of California, Berkeley, 1991a; 

1991b). For children from age 0-11, average time spent was calculated as the 

mean for boys and girls for age groups 0-2, 3-5, 6-8, and 9-11 (University of 

California, Berkeley, 1991b). Activity patterns for adolescents and adults were 

calculated as the mean for men and women for age groups 12-17, 18-24, 25-34, 

35-44, 45-54, 55-64, and 65+ (University of California, Berkeley, 1991a). Over a 

conceptual 70-year lifetime, the standard exposure duration for health risk 

assessments (OEHHA, 2003), Tind ranged from 19.69 to 21.57 hr/day, Tout from 

0.98 to 3.28 hr/day, and Tinv from 0.83 to 2.22 hr/day (Table VII-3). 

Using the data in Tables VII-1 and VII-3, estimates of total daily HCHO exposure 

(μg/m3-hr) and daily time-weighted average HCHO concentration (μg/m3) were 

calculated (Table VII-4). Although adults spend more time indoors or in-vehicles, 

there are only slight differences in exposure and daily TWA compared to 

children. 
Chapter VII Page 157 

Table VII-4. Estimates of Total Formaldehyde (HCHO) Exposure and Daily Timeweighted Average (TWA) Formaldehyde Concentration1

----- HCHO (μg/m3) ----- Exposure (μg/m3-hr) Environment Time (hr) Average Elevated Average Elevated 

Child: Total Exposure and Daily TWA 

Indoors 20.65 17.2 46.7 355 964 

In-vehicle 1.25 9.6 12 12 15 

Outdoors 2.10 3.7 15 8 32 

Total 24 ----- ----- 375 1,011 

Daily TWA ----- ----- ----- 15.6 42.1 

Adult: Total Exposure and Daily TWA 

Indoors 20.82 17.2 46.7 358 972 

In-vehicle 1.71 9.6 12 16 21 

Outdoors 1.47 3.7 15 6 22 

Total 24 ----- ----- 380 1,015 

Daily TWA ----- ----- ----- 15.8 42.3 

(1) Sources: Refer to Tables VII-1 and VII-3. “HCHO” = formaldehyde; “μg/m3

” = micrograms per 

cubic meter; “μg/m3-hr” = μg/m3)-hour. Exposure was calculated by multiplying “time” by average 

or elevated HCHO concentration. Daily TWA was calculated by dividing “Exposure” by 24-hours. 

E. Multi-pathway Health Risk Assessment 

To evaluate the potential health effects of a TAC all the routes by which an 

individual may be exposed to the TAC need to be identified. The pathways or 

routes of pollutant exposure may include inhalation, dermal exposure, and 

ingestion of soil particles and food. For purposes of this HRA and rulemaking, 

inhalation is the principal pathway of HCHO exposure (95% or more), with small 

amounts of uptake by dermal exposure from disinfectant use. Therefore, 

analysis of impacts is based on exposure via inhalation only. 

F. Statewide Emission and Risk Reduction Benefits 

The proposed ATCM would reduce emissions of HCHO from HWPW, PB, and 

MDF by approximately 20% in Phase 1 and approximately 57% in Phase 2, 

resulting in an estimated annual statewide emissions reduction of 180 and 500 

tons per year, respectively. Because these emissions would substantially reduce 

indoor HCHO exposures, where HCHO levels are highest and where people 

spend approximately 90% of their time, the reduction in potential excess cancer 
Chapter VII Page 158 

cases in children is estimated to range from 3 to 9 after Phase 1, and 9 to 26 

after Phase 2 (Table VII-5). 

Table VII-5. Estimated Cancer Risk in Children and Adults After Implementation 

of the Phase 1 and Phase 2 Emission Standards1

Childhood Exposure: 9-year Exposure to Formaldehyde (HCHO) 

Exposure Scenario TWA HCHO 

(μg/m3) 

Cancer Risk 

Per Million 

Cancer Cases 

Reduced 

Current-average 16 23 ----- 

• Post Phase 1 13 20 3 

• Post Phase 2 9 14 9 

 

Current-elevated 42 63 ----- 

• Post Phase 1 36 54 9 

• Post Phase 2 25 37 26 

Lifetime Exposure: 70-year Exposure to Formaldehyde (HCHO) 

Exposure Scenario TWA HCHO 

(μg/m3

) 

Cancer Risk 

Per Million 

Cancer Cases 

Reduced 

Current-average 16 86 ----- 

• Post Phase 1 14 74 12 

• Post Phase 2 9 51 35 

 

Current-elevated 42 231 ----- 

• Post Phase 1 36 196 35 

• Post Phase 2 25 134 97 

(1) “TWA HCHO” = Daily time-weighted average HCHO concentration. Changes in Phase 1 and 

Phase 2 TWA HCHO levels were calculated based on 16% and 44% reductions in HCHO levels 

in a home (Appendix E). Cancer risk was calculated according to OEHHA (2005c). 

For adults, reductions in cancer risk, based on a 70-year lifetime exposure, would 

be reduced by 12 to 35, and 35 to 97, after Phase 1 and Phase 2, respectively 

(Table VII-5). 

Non-cancer chronic inhalation impacts were calculated by dividing the daily TWA 

exposure concentrations by the chronic inhalation REL for HCHO (i.e., 3 μg/m3

for eye irritation) to derive a hazard quotient (OEHHA, 2003). Thus the hazard 

quotient based on the current-average TWA exposure concentration (15.8 μg/m3) 

would be 5.3 -- after Phase 1 and Phase 2, the hazard quotient would decrease 
Chapter VII Page 159 

to 4.5 and 3.1, respectively. As all of these values are greater than one, there is 

a probability of adverse eye irritation effects from HCHO at current- and future 

daily TWA exposure concentrations. The current average, post-Phase 1, and 

post-Phase 2 hazard quotients for children were 5.2, 4.4, and 3.1, respectively. 

For the current-elevated scenario, hazard quotients were approximately 2.7 times 

higher than for the current-average scenario in all time frames. 

G. Potential Adverse Health Effects from Replacement Compounds 

It is anticipated that most manufacturers will achieve the required emission 

reductions by lowering the amount of HCHO used in the UF resin systems that 

they presently use. However, greater use of existing low-formaldehyde or 

formaldehyde-free adhesives may be considered (i.e., phenol-formaldehyde, 

melamine-formaldehyde and isocyanates) in selected products. One HWPW 

manufacturer began the exclusive use of a soy flour-based adhesive in 2006. 

1. Methylene Diphenyl Isocyanate (CAS No. 101-68-8)

 

Methylene diphenyl isocyanate (MDI) is used in existing wood adhesives (Forest 

Products Laboratory, 1999). In consideration of potential respiratory effects, the 

chronic REL for MDI is 0.7 μg/m3 in California (OEHHA, 2000). Workplaces are 

the primary source of exposure to MDI, where it is handled by workers using 

respirators (Massachusetts Toxics Use Reduction Institute, Not Dated; NIOSH, 

2005). The USEPA (Not Dated) reported that there is inadequate data to classify 

MDI as a human carcinogen, consistent with a not classifiable designation by 

IARC (Massachusetts Toxics Use Reduction Institute, Not Dated). The USEPA 

(Not Dated) also reported that there was only limited data regarding animal 

carcinogenicity. It should be noted that panels made with MDI, once reacted in 

the production facility, do not continue to emit as do the current UF resin 

products. 

2. Melamine (CAS No. 108-78-1) 

Presently, melamine-HCHO resins are used in the manufacture of HWPW, and 

HCHO emissions from these products were found to be intermediate to those of 

products bonded with urea-formaldehyde (high) and phenol-formaldehyde (low) 

(CARB 2003 Survey, unpublished data). Toxicity to mammals is low – it is not 

irritating to skin or eyes (OECD, 1998). Although one study found that melamine 

exposure produced urinary bladder tumors in male rats, it has not been classified 

as a carcinogen by IARC. 

3. Phenol (CAS No. 108-95-2) 

Phenol is a hazardous air pollutant that was identified as TAC under AB 2728 

(CARB, 1993). To a limited extent, manufacturers may choose to utilize phenolHCHO resin in place of urea-formaldehyde for selected applications. Wood 
Chapter VII Page 160 

products made with phenol-formaldehyde resins have very low HCHO emissions, 

and are exempt from the U.S. Housing and Urban Development standards for 

building materials used in mobile home construction (PFS Research Foundation, 

2001). Phenol is a common industrial chemical used in a variety of 

manufacturing processes and household products (CARB, 1997c). While phenol 

is a strong eye and respiratory irritant, there are limited data concerning its 

chronic health effects in humans resulting from inhalation or oral exposure. 

Moreover, due to a lack of data, phenol has not been classified as a carcinogen 

by either USEPA or IARC. 

4. Soy Flour 

A soy flour based resin is scheduled for use in the manufacture of HWPW by 

Columbia Forest Products beginning in 2006 (McIsaac, 2005). Soy flour is a high 

protein powder generally made from dehulled, heat-processed soybeans or 

soybean flakes (Wikipedia Contributors, 2007). Soy flour is already being used 

in preparation and manufacture of a number of food products sold throughout the 

world, and its use as a wood adhesive is not expected to cause adverse noncancer or cancer health effects. 

H. Workplace Exposure 

Formaldehyde is a TAC (CARB, 1992) that is classified as a known human 

carcinogen by IARC, and is an irritant to the eyes and the respiratory system. At 

concentrations ranging from 0.5 to 1.0 ppm, most individuals will experience eye, 

nose, and/or throat irritation. At concentrations greater than 1.0 ppm, HCHO 

causes extreme discomfort (OEHHA, 1999). Various workplace standards have 

been developed in consideration of these findings: 

• U.S. Department of Labor’s Occupational Safety & Health Administration 

(OSHA) adopted “Permissible Exposure Limits” (PEL) in 1992 of 0.75-ppm 

for an 8-hr workday, and a 2-ppm Short-term Exposure Limit (STEL) 

(Formaldehyde Council Inc., 2005); 

• Australia “Worksafe Standards” are 1.0 ppm “time-weighted average” 

(TWA) for an 8-hr workday, and a 2 ppm STEL for 15-min as safe levels 

for occupational exposure (Plywood Association of Australasia, 2004); and 

• New Zealand’s “Occupational Exposure Limit” (OEL) is 1.0 ppm, not to be 

exceeded (Plywood Association of Australasia, 2004). 

Lowering the amount of HCHO used in the manufacture of MDF, PB, and HWPW 

serves to reduce workplace HCHO exposures for workers in raw board 

manufacturing and resin plants. Moreover, end-user exposure would also be 

lowered due to the reduced HCHO content of raw boards. 
Chapter VII Page 161 

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VIII. Economic Impacts of the Proposed Airborne Toxic Control 

Measure 

This chapter presents the estimated costs and economic impacts associated with 

the implementation of the proposed ATCM to control HCHO emissions from 

HWPW, PB, MDF, and finished goods that contain those materials. An overview 

of composite wood manufacturing in the U.S. is provided as a basis for assessing 

the financial ability of manufacturers to produce products that comply with the 

proposed emission standards. An explanation of the cost-basis is then 

presented where estimates of the least-costly (i.e., use of “drop-in” technology) 

and most-costly (i.e., outdated plants) options are presented, along with 

projected impacts to small producers. 

The total cost of compliance to the composite wood manufacturing industry was 

estimated by multiplying the projected per panel increases in HWPW, PB, and 

MDF by the amount sold to California. These costs would be borne by those 

manufacturers that currently do not produce products that comply with the 

proposed Phase 1 or Phase 2 standards and plan to continue to sell products 

into the California market. The projected impacts to downstream businesses 

such as distributors, importers, fabricators, and retailers are also discussed. 

A. Background 

1. Composite Wood Product Manufacturing in the U.S. 

a. Particleboard

In North America (U.S. and Canada), PB manufacturing is a billion-plus dollar 

industry (Composite Panel Association, 2006). In 2005, North American PB 

shipments (≈ production) of industrial and flooring products were approximately 

6-billion ft2 (approximately 10-million m3) with an estimated value of $1.65 billion 

(i.e., the average cost of PB was $311 per thousand ft2

). 

In North America, the interests of PB and MDF manufacturers are largely 

represented by the Composite Panel Association (Gaithersburg, Maryland). An 

affiliated organization, the 180-plus member Composite Wood Council, brings 

together PB and MDF panel producers, furniture and cabinet manufacturers, 

distributors, suppliers, and others to disseminate to a broader audience, the 

attributes of composite wood products. The Composite Panel Association’s 

current membership includes 37 of the leading U.S., Canadian, and Mexican 

manufacturers, collectively representing over 95% of total North American 

manufacturing capacity (Table VIII-1) (Composite Panel Association, Not Dated). 

This number is consistent with estimates for 1997-98, when the number of U.S. 

mills was thought to be 45 to 51 (Sellers, 2001; USEPA, 2002), which may 

account for the small percentage of manufacturers that are not members of the 

Composite Panel Association. Seven companies that manufacture PB in North 
Chapter VIII Page 179 

America also operate MDF mills (i.e., ATC Panels, Flakeboard, Georgia-Pacific, 

SierraPine, Temple-Inland, Uniboard, Weyerhaeuser). 

In the CARB 2003 Survey, responses were received from 20-mills regarding the 

manufacture of PB (CARB, 2003). The range in reported annual production 

amounts was 36- to 350-million ft2, where the median annual production of the 

20-mills was 130-million ft2

. In an attempt to classify the mills as either small, 

mid-size, or large, for purposes of this report, small manufacturers were 

designated as mills that produced less than 110-million ft2 (17%), mid-size 

manufacturers between 110- to 170-million ft2 (37%), and large manufacturers 

more than 170-million ft2 (46%). Regardless of whether a mill was small, midsize, or large, these facilities represent enterprises with a minimum of 50 or more 

employees. Similar distinctions were made for the 56-companies subject to the 

USEPA’s National Emission Standard for Hazardous Air Pollutants rulemaking 

for composite wood product manufacturing: 23% of facilities had less than 100-

employees, 54% had between 100- to 249-employees, and 23% had more than 

250-employees (USEPA, 2002). 

Besides number of employees, questions arise with respect to mill age and the 

vintage of equipment being used at present, which will likely determine the extent 

of modification needed to produce PB that complies with proposed Phase 1 and 

Phase 2 standards in 2009 to 2012. It is not clear what portion of the industry 

has already expended resources to upgrade their facilities over the past 10-

years. Seemingly, as this is an industry that is made up principally of mid-size 

and large companies, those that choose to make the necessary improvements to 

produce low-emission PB for the California market will do so after careful 

consideration of the potential economic impacts. 

Table VIII-1. Particleboard Manufacturers in the Composite Panel Association 

No. Company (No. Mills) Mill Location(s) 

1 ATC Panels, Inc. (2) Franklin, VA; Moncure, NC 

2 Boise Cascade Corp. (1) La Grande, OR 

3 CanPar Industries (1) Grand Forks, British Columbia 

4 Collins Products, LLC (1) Klamath Falls, OR 

5 Columbia Forest Products (1) Hearst, Ontario 

6 Duraplay de Parral, S.A. de C.V. (1) Parral, Chihuahua 

7 Fibratech Mfg., Inc. (1) Atikokan, Ontario 

8 Flakeboard Co., Ltd. (1) St. Stephen, New Brunswick 

9 Florida Plywoods, Inc. (1) Greenville, Florida 

10 Georgia-Pacific Corp. (5) 

Gaylord, MI; Louisville, MS; 

Russellville, SC; Taylorsville, MS; 

Vienna, GA 

11 GreenTech Panels, LLC (1) Minden, LA 
Chapter VIII Page 180 

Table VIII-1. Continued 

No. Company (No. Mills) Mill Location(s) 

12 Marshfield Door Systems, Inc. (1) Marshfield, WI

13 Merillat Industries, Inc. (1) Rapid City, SD 

14 No. Engineered Wood Products (1) Smithers, British Columbia 

15 Panolam Industries International (1) Huntsville, Ontario 

16 Potlatch Forest Products, Corp. (1) Post Falls, ID 

17 Rexcel S.A. de C.V. (2) Chihuahua, Chihuahua; 

Zitacuaro, Michoacan 

18 Roseburg Forest Products Co. (2) Dillard, OR; Missoula, MT 

19 SierraPine, Ltd. (3) Adel, GA; Martell, CA; Springfield, 

OR 

20 Tafisa Canada & Co., Ltd. (1) Lac-Megantic, Quebec 

21 Temple-Inland (4) Diboll, TX; Hope, AR; Monroeville, 

AL; Thomson, GA 

22 Timber Products Co. (1) Medford, OR 

23 Uniboard Canada, Inc. (2) Sayabec, Quebec; Val d’Or, 

Quebec 

24 Webb Furniture Enterprises, Inc. (1) Galax, VA 

25 Weyerhaeuser Co. (3) Albany, OR; Bennetsville, SC; 

Simsboro, LA 

Source: Composite Panel Association (Not Dated). 

b. Medium Density Fiberboard

In terms of total North American production, the amount of MDF produced in 

2005 was less than half of the amount of PB production (i.e., 2.6-billion vs. 5.6-

billion ft2

) (Composite Panel Association, 2006). The total value of the MDF was 

estimated to be $1-billion, about 63% of the value of PB production. Per 

thousand ft2, the average cost of MDF was about 40% higher than PB (i.e., $435 

vs. $311) in 2005. The Composite Panel Association currently lists 26-mills 

among its member companies (Table VIII-2) (Composite Panel Association, Not 

Dated). 

In the CARB 2003 Survey, responses were received from 12-mills regarding 

MDF production volume (CARB, 2003). The range in reported annual production 

amounts was 18- to 204-million ft2, where the median annual production of the 

12-mills was 107-million ft2. For the MDF cost analysis we classified the MDF 

mills as either small, mid-size, or large; in this case, small manufacturers were 

designated as mills that produced less than 100-million ft2

 (18%), mid-size 

manufacturers between 100- to 125-million ft2

 (38%), and large manufacturers 

more than 125-million ft2 (43%). Like PB-mills, small, mid-size, and large MDFmills appear to be fairly substantive facilities requiring 50-plus employees. 
Chapter VIII Page 181 

Table VIII-2. Medium Density Fiberboard Manufacturers in the Composite 

Panel Association 

No. Company (No. Mills) Mill(s) 

1 ATC Panels, Inc. (2) Clarion, PA; Pembroke, Ontario 

2 Basset Fiberboard (1) Bassett, VA 

3 CMI/CraftMaster Mfg., Inc. (1) Towanda, PA 

4 Del-Tin Fiber, LLC (1) El Dorado, AR 

5 Flakeboard Co., Ltd. (2) St. Stephen, New Brunswick; Sault 

Ste. Marie, Ontario 

6 Georgia-Pacific Corp. (2) Holly Hill, SC; Monticello, GA 

7 Great Lakes MDF, LLC (1) Lackawanna, NY 

8 Langboard, Inc. (1) Willacochee, GA 

9 Norbord Industries, Inc. (1) Deposit, NY 

10 Pan Pacific Products, Inc. (1) Broken Bow, OK 

11 Plum Creek MDF, Inc. (1) Columbia Falls, MT 

12 Sacopan, Inc. (1) Sacre-Coeur, Quebec 

13 SierraPine, Ltd. (2) Medford, OR; Rocklin, CA 

14 Temple-Inland (1) Mt. Jewett, PA 

15 Uniboard Canada, Inc. (2) La Bale, Quebec; Mont-Laurier, 

Quebec 

16 Unilin US MDF (1) Mt. Gilead, NC 

17 West Fraser Mills Ltd. (2) Quesnel, British Columbia; White 

Court, Alberta 

18 Weyerhaeuser Co. (3) Bennettsville, SC; Eugene, OR; 

Malvern, AR 

Source: Composite Panel Association (Not Dated). 

c. Hardwood Plywood

Statistics compiled by the U.S. Department of Commerce report that hardwood 

veneer products accounted for nearly 25% of the industry’s output in the early 

1990’s (Answers.com, Not Dated). In the late 1990’s, North American shipments 

(i.e., production) of hardwood veneer products were worth approximately 

$1 billion. The U.S. Department of Commerce reported that approximately 50% 

of the plywood and veneer output in the 1990’s was mainly consumed in 

residential construction, and 25% was utilized in other lumber and wood products 

industries, while 11% was used in furniture and fixtures. The U.S. Census 

Bureau estimated that there were 332 facilities in the U.S. that made hardwood 

veneer and plywood in the late 1990’s. Hardwood plywood production in 2000 

was estimated to be 2.04 million m3

 (including core material such as softwood 

plywood and OSB), in 2000 these firms shipped $3.3-billion worth of goods and 
Chapter VIII Page 182 

employed approximately 24,000 workers (Encyclopedia of American Industries, 

2007). 

In North America, Indiana, North Carolina, Wisconsin, and Michigan had the 

largest product shipments in this segment (Answers.com, Not Dated). One of the 

principal industry leaders in this category is Ply Gem Industries Inc., with 4,079 

employees, followed by two Oregon, based companies; Roseburg Forest 

Products Co., with 3,975 employees and Columbia Forest Products Inc. had 

3,500 employees. 

In North America, the interest of hardwood plywood manufacturers are largely 

represented by the Hardwood Plywood and Veneer Association (HPVA), based 

in Reston, VA (Table VIII-3). Member companies of HPVA produce 90% of the 

HWPW stock panels and hardwood veneer manufactured in North America. The 

HPVA is an international trade association, currently representing more than 150 

wood industry companies in the U.S., Canada, and abroad. 

Table. VIII-3. Hardwood Plywood Facilities in North America 

No. Company (No. Mills) Mill(s) 

1 Atlantic Veneer Corp. (1) Beaufort, NC 

2 Autumn House (1) Granite Falls, NC 

3 Besse Forest Products (1) Matoon, WI 

4 Birchland Plywood, Ltd (1) Thessalon, Ontario 

5 Buffalo Veneer & Plywood (1) Buffalo, MN 

6 Chesapeake Hardwood Prod. (1) Chesapeake, VA 

7 Columbia Forest Products (7) 

Trumann, AR; Old Fort, NC; 

Klamath Falls, OR; Chatham, VA; 

Hearst, Ontario; St. Casimir, 

Quebec 

8 Commonwealth Plywood Co. (1) Ste-Therese, Ontario

9 Darlington Veneer Co., Inc. (1) Darlington, SC 

10 Duraply De Parral (1) Parral, Chihuahua, Mexico 

11 European Panel Products (1) San Diego, CA 

12 Florida Plywoods Inc (1) Greenville, FL 

13 G/L Veneer Co., Inc. (1) Huntington Park, CA 

14 General Veneer Manufacturing (1) South Gate, CA 

15 Howell Plywood Corp (1) Dothan, AL 

16 K & L Woodworking, Inc (1) Reading, PA 

17 Mt Baker Products, Inc. (1) Bellingham, WA 

18 Murphy Plywood Co. (1) Eugene, OR 

19 Navy Island Plywood (1) West St. Paul, MN 

20 Norbord Industries (2) Toronto and Cochrane, Ontario 
Chapter VIII Page 183 

Table VIII-3. Continued 

No. Company (No. Mills) Mill(s) 

21 Nova Wood lamination Inc. (1) Kitchener, ON, Canada 

22 Panoply Corp (1) Lexington, TN 

23 PanTim Wood Products, Inc. (1) Portland, ME 

24 Panel Source International, Inc. (1) St. Albert, Alberta, Canada 

25 Pavco Industries, Inc. (1) Pascagoula, MS 

26 Perfecta Plywood Ltd. (1) St-Hyacinth, QC Canada 

27 Pittsburgh Forest Products (2) McMurray, PA; Toledo, OH 

28 Pluswood (1) Oshkosh, WI 

29 Plywood Mfg. of California, Inc. (1) Torrance, CA 

30 Pro-Ply Custom Plywood, Inc. (1) Mississauga, ON Canada 

31 Roseburg Forest Products Co. (1) Roseburg, OR 

32 States Industries, Inc. (2) Eugene, OR; Mocksville, NC 

33 South West Panel Products (1) Katy, TX 

34 Timber Products Company (4) Springfield, OR; Corinth, MS; 

Medford, OR; Grants Pass, OR 

35 Veneer One Inc. (1) Oceanside, NY 

36 Vermont Plywood (1) Hancock, VT 

37 Western Panel Mfg., Inc. (1) Eugene, OR 

38 The Wood Gallery, Inc. (1) Dallas, TX 

39 Greenline Plywood Prod., Ltd. (1) Stouffville, Ontario 

Source: Hardwood Plywood and Veneer Association (2007) 

In the CARB 2003 Survey, responses were received from ten-mills regarding 

HWPW production volume (CARB, 2003). The range in reported annual 

production amounts was 300-thousand to 218-million ft2, where the median 

annual production of the ten-mills was 69-million ft

2

. For the HWPW cost 

analysis we classified the mills as either small, mid-size, or large manufacturers; 

in this case, small manufacturers were designated as mills that produced less 

than 25-million ft2

 (3%), mid-size manufacturers between 25- to 100-million ft2

(44%), and large manufacturers more than 100-million ft2

 (53%). Unlike PB and 

MDF mills, which appear to be fairly substantial size fairly, small HWPW mills 

may be operated by 10- to 15-employees. 

The extent of modification necessary to produce hardwood plywood that 

complies with the proposed Phase 1 and Phase 2 standards in 2009 to 2012 will 

largely depend on the age of the industry (mills), equipment being used, wood 

species, and type of plywood being made. Approximately 40 to 50 percent of the 

hardwood plywood products sold in California are produced by companies that 

already expended resources to upgrade their facilities in the past several years. 

A two-tiered structure has emerged that includes plants that are newer, larger, 

and operate at low-cost while there are many older, specialized, smaller, high-
Chapter VIII Page 184 

cost plants that try to survive, however, it is not clear what portion of the industry 

is comprised by the latter. 

2. Legal Mandates

Government Code §11346.3 requires state agencies to assess the potential for 

adverse economic impacts on California businesses and individuals when 

proposing to adopt or amend any regulation, such as the proposed ATCM. The 

assessment must include an evaluation of the impact of the proposed regulation 

on jobs, business expansion, elimination, or creation, and the ability of California 

businesses to compete with comparable entities in other states. In addition, 

Government Code §11357 and guidelines adopted by the Department of Finance 

(DOF) require CARB and other state agencies to estimate the associated cost or 

savings to any local, state, or federal agency from the proposed ATCM. The 

agency proposing a regulation is also required to determine whether, as a result 

of the regulation, any cost to local agencies or school districts is reimbursable by 

the state. 

Health & Safety Code §57005 further requires CARB to perform an economic 

impact analysis of submitted alternatives to a proposed regulation before the 

adoption of any major regulation. A “major regulation” is defined as a regulation 

that would potentially cost California businesses more than $10-million per year. 

3. Affected Businesses

Any business that manufactures or markets HWPW, PB, or MDF for sale or 

supply, or finished goods containing those materials for sale or supply in 

California would potentially be affected by the proposed ATCM. This would also 

include businesses that supply or manufacture resins used in the aforementioned 

commodities and surface treatments. In this regard, the proposed ATCM is 

anticipated to directly and indirectly affect a wide range of businesses in 

California, the U.S., and other countries. The directly affected businesses 

include the following Standard Industrial Classification (SIC) codes (U.S. Census 

Bureau, 2003): 

2435: Hardwood Veneer and Plywood Manufacturing, and 

2493: Medium Density Fiberboard and Particleboard Manufacturing. 

Presently, the U.S. Census Bureau is revising the SIC coding system to the 

North American Industry Classification System (NAICS). In this system, “Wood 

Product Manufacturing” is assigned to NAICS code number 321, under which 

manufacturers of HWPW are assigned to category number 321211, and MDF 

and PB manufacturers to 321219. 

To our knowledge, the major manufacturers of HWPW, PB, or MDF are member 

companies of the Composite Wood Council and/or Composite Panel Association. 
Chapter VIII Page 185 

The Composite Wood Council membership also includes panel and finished 

good/product distributors, home furnishing and cabinet manufacturers, 

equipment manufacturers, suppliers, secondary manufacturers (including 

laminators, cut-to-size operations, and component manufacturers), transporters, 

and trade magazines in California. The Composite Panel Association represents 

over 95% of the North American manufacturing capacity for PB, MDF, hardboard, 

and other compatible products (Composite Panel Association, 2007). 

While manufacturers of HWPW, PB, or MDF are examples of directly impacted 

businesses, wood furniture and cabinet makers would be examples of indirectly 

impacted businesses. As the proposed ATCM will require downstream entities to 

purchase and use the Phase 1- and Phase 2-compliant HWPW, PB, or MDF in 

finished goods, compliance with the proposed ATCM will present different 

challenges to the various entities in the distribution chain from manufacturers to 

retailers. 

There will not be an impact on any local government agency or school district 

because the proposed ATCM specifically excludes them from the fabricator 

definition and, therefore, the fabricator requirements. 

4. Ability to Comply with the ATCM

a. Potential Business Impact

This portion of the economic impact analysis is based on a comparison of the 

return on owners’ equity (ROE) for affected businesses before and after inclusion 

of the cost to comply with the proposed requirements. The data used in this 

analysis are obtained from publicly available sources, the 2003 CARB Survey, 

the Dun and Bradstreet financial data website, and the staff’s cost analysis 

discussed later in this chapter. 

i. Affected Manufacturers

The survey identifies 25 mills nationwide that potentially will be affected by the 

Phase 2 standards of the proposed ATCM. Only nine mills owned by three 

companies are located in California. Of the 25 mills, there are 10 that 

manufacture PB which are owned by eight companies. There are nine that 

manufacture MDF owned by three companies, and six that manufacture HWPW 

that are owned by six companies. Table VIII-4 provides a range of cost per plant 

for these mills by product type. 

 
Chapter VIII Page 186 

 

Table VIII-4. Cost per Plant by Type of Affected Product 

Product Companies Mills Cost per Plant 

PB 8 10 $0.12 to 17.8 million 

MDF 3 9 $0 to 15.9 million 

HWPW 6 6 $0 to 6.6 million 

Total 17 25 $127 million 

ii. Study Approach

This study covers 14 affected companies because three of the above companies 

manufacture both PB and MDF. The approach used in evaluating the potential 

economic impact is outlined as follows: 

• Compliance cost was estimated for each of these businesses. 

• Estimated cost was adjusted for federal and state taxes. 

• The three-year average ROE was calculated, where data were available, 

for each of these businesses by averaging their ROEs for 2003 through 

2005. ROE is calculated by dividing the net profit by the net worth. The 

adjusted cost was then subtracted from net profit data. The results were 

used to calculate an adjusted three-year average ROE. The adjusted 

ROE was then compared with the ROE before subtraction of the adjusted 

cost to determine the potential impact on profitability of the business. A 

reduction of more than 10% in profitability is considered to indicate a 

potential for significant adverse economic impacts.

The threshold value of 10% has been used consistently by CARB staff to 

determine impact severity. This threshold is consistent with the thresholds used 

by USEPA and others. 

iii. Assumptions

Calculations of ROEs before and after subtraction of the adjusted compliance 

costs were based on the following assumptions: 

• All affected businesses were subject to the highest federal and state 

corporate tax rates of 35% and 9.3%, respectively; and 

• Affected businesses are not able to increase the prices of their products, 

nor can they lower their costs of doing business through short-term costcutting measures. 

We understand that this last assumption is too conservative and it is unlikely to 

occur. This assumption is made to assess the severity of impacts using static 

measures of profit. According to USEPA (2004), plywood and reconstituted 
Chapter VIII Page 187 

wood products that are used in the construction industry have a price elasticity of 

demand ranging from -0.10 to -0.27. This implies that for every 10% change in 

the price of these products, the quantity demanded for these products would 

decline from 1 to 2.7%. In other words, the affected manufacturers have a great 

ability to pass on their compliance costs to consumers. Thus, it is likely that most 

manufacturers will be able to recover the bulk of compliance costs through higher 

prices for their wood products. 

iv. Results

These businesses are affected by the proposed ATCM to the extent that the 

additional costs imposed by the proposed requirements would change their 

profitability. A detailed discussion and analysis of these costs is provided in the 

cost section of this report. According to the staff’s cost analysis, the costs of 

manufacturing a 4’ x 8’ compliant wood panel board will range from about 3 to 

$6. The Phase 2 standards of the proposed ATCM will affect about 1.2 billion ft2

of wood panel board used in California, thereby imposing approximately 127 

million in costs on composite wood manufacturers. 

Using ROE to measure profitability, we found that the average ROE of affected 

businesses declined by about 12% as shown in Table VIII-5. This represents a 

significant change in the average profitability of these businesses if they 

absorbed the entire cost of compliance. However, as stated above, these 

businesses are most likely to be able to recover the bulk of the cost increase 

from consumers because of inelastic demand for their products. In such a case, 

the maximum price increase of a 4’ x 8’ compliant wood panel to consumers 

would range from approximately $3.60 to $7.20 if manufacturers are able to 

recover the entire compliance cost of the proposed ATCM. 

Table VIII-5. Change in Return on Owner’s Equity (ROEs) for Typical 

Manufacturers in the Composite Wood Products Industry1

Product Manufactured ∆ROE 

Particleboard 1.0% 

Medium Density Fiberboard 1.1% 

Hardwood Plywood 64.1% 

Average 11.6% 

(1) “∆” = change; all ∆ROEs shown are negative (i.e., shows a decline in profitability). 

As shown in Table VIII-5, the projected change in profitability of typical 

businesses in composite wood industry varies widely. The predicted decline in 

profitability of these businesses ranged from a high of about 64% for a HWPW 

manufacturer to a low of 1.0% for a PB manufacturer. This variation in the 
Chapter VIII Page 188 

impact of the proposed ATCM can be attributed mainly to the following factors. 

First, some manufacturers incur higher costs due to the quantity of noncompliant 

wood products they manufacture or market. For instance, the estimated annual 

costs for affected businesses ranged from a high of about $55 million to a low of 

about $112,000. Second, some manufacturers operate multiple mills of different 

sizes, others operate only one mill. Finally, the performance of manufacturers 

may differ from year to year. Hence, the average 2003 through 2005 financial 

data used may not be representative of an average-year performance for some 

manufacturers. 

The estimated changes to ROEs may be high for the following reasons. First, 

annual costs of compliance are estimated using, in part, the current prices of raw 

materials. Raw material prices usually tend to fall as higher demand for these 

materials induces economy of scale production in the long run. Second, as 

stated above affected manufacturers probably would not absorb all of the 

increase in their costs of doing business. They would be able to pass some of 

the cost on to consumers in the form of higher prices. Also, they might be able to 

improve their operational efficiency, thus reducing their costs. 

b. Potential Impact on Employment 

The proposed ATCM is not expected to cause a noticeable change in California 

employment and payroll. According to the 2004 U.S. Census Bureau (U.S. 

Census Bureau, 2006a; 2006b), California employment in the composite wood 

product industry (NAICS 321211/SIC 2435 and NAICS 321219/2493, which 

includes establishments engaged in manufacturing hardwood veneer and 

plywood, and reconstituted wood products) was 1,449 in 2004, or about 3.5% of 

the national employment in the industry. This represents about 0.1% of the total 

manufacturing jobs in California in 2004. These employees working in 38 

establishments generated about $49 million in payroll (Table VIII-6), accounting 

for less than 0.1% of total California manufacturing payroll in 2004. Six 

establishments had 100 employees or more; the other 32 had less than 100 

employees each. 

Table VIII-6. Establishments, Employees, and Payroll by Industry 

NAICS SIC Establishments Employees Annual Payroll 

321211 2435 18 570 $13,794,000 

321219 2493 20 879 $34,971,000 

Total 38 1,449 $48,765,000 

The employment in the composite wood products industry accounts for a small 

portion of the California economy. The employment in the industry is unlikely to 

change significantly as a result of the proposed ATCM. This is because demand 

for affected products is price inelastic; implying that affected manufacturers or 
Chapter VIII Page 189 

marketers would be able to pass on the bulk of the cost increase to consumers in 

terms of higher prices for their products. In addition, strict enforcement of the 

proposed ATCM may enable domestic manufacturers to expand their California 

market share. Overseas manufacturers that produce low cost high emitting 

products are likely to lose some of their current price advantages over domestic 

manufacturers when the proposed ATCM goes into effect. Thus, most domestic 

manufacturers are likely to maintain their current profitability and as a result, no 

noticeable change is expected in their employment.

B. Cost of Compliance 

1. Price Trends 

In the U.S., the housing sector largely determines the demand for wood products 

(lumber and composite panels) (U.S. Department of Agriculture, Not Dated). It is 

estimated that over 55% of the engineered wood products (e.g., PB, MDF, 

plywood, oriented strand board) manufactured in the U.S. is sold to residential 

house builders, and an additional 18% to commercial and industrial buildings 

(Global Wood Trade Network, 2005). The furniture industry consumes a 22% 

share, mostly PB and MDF. Only 4% is exported (estimated valued = $1.2-

billion), with nearly 50% of exports sold to Canada. 

a. Particleboard

From 1995 to 2005, unit prices of industrial PB ($/thousand square feet ($/MSF)) 

ranged from $250 in 2003 to $328 in 2004 (Table VIII-7) (Composite Panel 

Association, 2006). Comparable unit prices were reported in Random Lengths 

(2006) for Eastern PB, where prices ranged from $214 to $291. Relative to PB 

production, the decrease in unit price coincides with a drop in production volume 

in 2001, just prior to the start of a strong upturn in housing starts in 2003 

(Random Lengths, 2006). As the number of housing starts remained high in 

2004 and 2005, there was an increase in PB production to meet demand, and 

unit prices remained above $300 per MSF. Using housing starts as an indicator 

of wood product demand in the housing sector, the fluctuations in the unit price of 

PB from 2002 to 2005 can be explained, in part, by the sufficiency of PB supplies 

(and lower prices) in 2002 and 2003, followed by temporary shortages leading to 

increased production and higher costs in 2004 and 2005. 
Chapter VIII Page 190 

Table VIII-7. Unit Cost of Industrial Particleboard: 1995-20051

------ Industrial Particleboard ($/MSF) ----- 

Year Composite Panel 

Association 

Random Lengths -- 

East 

Production 

(MSF) 

1995 306 289 4,199,735 

1996 287 285 4,367,662 

1997 288 274 5,553,339 

1998 274 269 5,836,159 

1999 297 282 6,148,748 

2000 321 286 6,113,097 

2001 279 250 5,582,154 

2002 263 214 6,016,915 

2003 250 222 5,585,105 

2004 328 291 5,851,270 

2005 311 283 5,626,080 

Mean 291 268 ----- 

(1) Source: Composite Panel Association (2006); Random Lengths (2006a). “$/MSF” = Dollars 

per million square feet. Data for industrial particleboard are estimated on a 3⁄4” basis. 

Some of the demand for PB during 2004 and 2005 may have been met by 

increasing the amount of imports or by reducing exports (Figure VIII-1). In 2002, 

total U.S. imports of PB from China were valued at approximately $56,000 (U.S. 

Department of Agriculture, Not Dated (a)). Over the ensuing four-years, the 

value of Chinese imports has risen nearly 100-fold to approximately $5-million. 

At a unit price of $300 per MSF, the represents about 16,500 MSF, less than 

0.5% of total U.S. production in 2005 (Composite Panel Association, 2006). 
Chapter VIII Page 191 

Figure VIII-1. Value ($) of U.S. Imports of Particleboard from China: 1997 to 

20061

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Particleboard Imported from China - Values in 1000 Dollars 

(1) Source: U.S. Department of Agriculture (Not Dated (a)). 

b. Medium Density Fiberboard

In 1995 to 2005, unit prices ($/MSF) of MDF ranged from $340 in 1999 to $442 

per MSF in 1995; the 10-year mean was $380 per MSF (Table VIII-8) (Composite 

Panel Association, 2006). Similar findings were reported by Random Lengths 

(2006a) for western MDF; unit prices ranged from $337 to $416 per MSF. In 

contrast to PB, MDF production has increased steadily over this period from 1.1-

million MSF in 1995 to 2.6-million MSF in 2005. However, similar to PB, unit 

prices rose substantially in 2004 and 2005, possibly due to an increased demand 

for MDF in the housing sector. 
Chapter VIII Page 192 

Table VIII-8. Unit Cost of Medium Density Fiberboard: 1995-20051

------ Medium Density Fiberboard ($/MSF) ----- 

Year Composite Panel 

Association 

Random Lengths -- 

West 

Production 

(MSF) 

1995 442 ----- 1,106,827 

1996 387 411 1,200,700 

1997 350 362 1,715,842 

1998 337 342 1,900,486 

1999 340 344 2,199,102 

2000 366 358 2,193,398 

2001 365 369 2,125,431 

2002 389 366 2,386,843 

2003 373 337 2,284,945 

2004 399 415 2,554,629 

2005 435 416 2,647,575 

Mean 380 372 ----- 

(1) Source: Composite Panel Association (2006); Random Lengths (2006a). “$/MSF” = Dollars 

per million square feet. Data for medium density fiberboard are estimated on a 3⁄4” basis. 

Imports of MDF from China, as for PB, have risen substantially since the late 

1990’s (Figure VIII-2). In 2002, total U.S. imports from China were valued at 

approximately $500,000 and in 2006, were in excess of $17-million (U.S. 

Department of Agriculture, Not Dated (a)). At a unit price of $400 per MSF, the 

present amount of imported MDF from China represents approximately 43,500 

MSF or 1 to 2% of total U.S. production. 
Chapter VIII Page 193 

Figure VIII-2. Value ($) of U.S. Imports of Medium Density Fiberboard from 

China: 1997 to 20061

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

MDF Panel Imported from China- Values in 1000 Dollars

(1) Source: U.S. Department of Agriculture (Not Dated). 

c. Hardwood Plywood

For HWPW, we were not able to find historical unit price data for panels. 

However, as shown in Table VIII-9, we found that wholesale panel prices vary 

considerably depending on the type of face species and core used in the panel. 

Table VIII-9. Unit Cost of Hardwood Plywood1

Face Species Core Price per MSF Price per Piece 

White Maple Particleboard $375 $12 

Nat. Birch Veneer $312 $10 

Cherry Particleboard $375 $12 

Hickory Veneer $469 $15 

White Maple Veneer $469 $15 

Luxcell Veneer $469 $15 

White Birch Veneer $500 $16 

Red Oak Veneer $500 $16 

Red Oak Particleboard $375 $12 

(1) Source: Pittsburgh Forest Products Company (2007). 
Chapter VIII Page 194 

Currently, the HWPW industry has been experiencing strong competition from 

foreign producers. Imports of veneer, plywood and engineered wood products 

exceed exports by a wide margin (Global Wood, 2005). In 2004, imported 

products were valued at approximately $9-billion, which represents nearly 25% of 

domestic demand. The growth in 2004 was estimated to be 51%, in spite of the 

weakening U.S. dollar. The U.S. trade deficit in veneer, plywood, and 

engineered wood products is $7.8-billion. 

Imports of HWPW from China, as for PB and MDF, have risen substantially since 

the late 1990’s (Figure VIII-3). In 2002, total U.S. imports from China were 

valued at approximately $64-million and in 2006, were in excess of $730-million 

(U.S. Department of Agriculture, Not Dated (a)). 

Figure VIII-3. Value ($) of U.S. Imports of Hardwood Plywood from China: 1997 

to 20061 

0

100000

200000

300000

400000

500000

600000

700000

800000

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Hardwood Plywood Imported from China - Values in 1000 Dollars

(1) Source: U.S. Department of Agriculture (Not Dated (a)). 

According to Wood Based Panels International (2006), the major plywood 

suppliers to the U.S. are Brazil, with 1.6-million m

3

 (30.4% market share), China 

with 1.3 million m3 (24.2%), and Canada with 700,000 m3 in 2005 (13.4%). 

Brazil, China, and Canada account for a combined market share of 

approximately 67%. 

2. Effect of Imports 

The U.S. is the world’s leading importer of wood products ($23.3 billion), followed 

by the EU-25 ($13.2-billion), and Japan ($11.8-billion) (Global Trade Atlas, Not 

Dated), where in 2004, the major U.S. suppliers were Canada (61%), China, and 

Brazil. The market leader for engineered wood products in the U.S. is 

Weyerhaeuser (10% market share); Georgia-Pacific, Boise Cascade, and 
Chapter VIII Page 195 

Louisiana-Pacific are the next largest U.S. producers, and the combined U.S. 

market share of these four companies is approximately 30% (Global Wood Trade 

Network, 2005). 

As the demand for low-cost composite wood products continues to remain high in 

the U.S., the demand is increasingly being met by imports, due in part to higher 

costs for labor, energy, raw materials, and environmental compliance in the U.S. 

In addition to panel manufacturers, furniture companies in the U.S., Europe, and 

Mexico have also commented about the increasing amount of furniture coming 

from China, where labor costs are lower (i.e., Chinese furniture exports in 1999 

and 2005 were $5-billion and $22-billion, respectively) (Bowersheim, Not dated). 

Although Canada is the leading source of imported wood products to the U.S., 

products from China are increasing in market share and may continue to rise in 

light of reported plans for production line improvements (U.S. Department of 

Agriculture, Not Dated (b)). Presently, a typical Chinese production line is 

relatively small, producing less than 50,000 m3 per year vs. 170,000 m3 per year 

in other countries (i.e., 50,000 m3≈ 29,000 MSF). While China has made regular 

purchases of four to six presses each year, it was reported that the Shanghai 

Wood-based Panel Machinery Co., Ltd. has recently developed a continuous plat 

press with an annual output capacity of 200,000 m3 that may be put into 

production beginning in 2007 (Global Wood Trade Network, 2007). 

3. Factors to Consider for Regulatory Compliance

Currently, the major centers of composite panel manufacturing in the U.S. are 

located in the Pacific Northwest, Northeast, and Southeast (USEPA, 2002). For 

the most part, large manufacturers with customers throughout the country 

operate mills in each of these regions in order to deliver their products in a timely 

and cost-competitive manner. It is estimated that California consumes roughly 

11% of the composite wood products manufactured in the U.S., and thus, 

manufacturers could choose whether or not to supply products to meet this 

sector of the U.S. Presumably, in consideration of the present way composite 

wood products are supplied to customers, the major portion of products for the 

California market would be supplied by mills in the Pacific Northwest. However, 

as a major portion of the U.S. furniture and cabinet industry is located on the 

eastern seaboard, some portion of manufacturers may choose to produce CARBcompliant products for finished goods that will be sold to California. 

Since the proposed Phase 1 and Phase 2 standards are based on emissions 

performance, several resin systems could be used. If a company determines 

that major upgrades are needed to produce CARB-compliant products at one of 

their mills, they would have the option to make “49-state” products at that mill for 

sale in other states or countries. Given the absence of HCHO emission 

standards for wood products of equal stringency to the proposed ATCM when it 

is fully implemented, in other states, Europe, and selected parts of Asia, 
Chapter VIII Page 196 

manufacturers with multiple mills would not be required to convert their entire 

operation to producing CARB-compliant composite wood products. 

In the following subsections, the projected increase in the cost of PB, MDF, and 

HWPW manufactured to comply with proposed Phase 2 standard is described. 

Understanding the incremental increase in cost on a panel-basis is fundamental 

to evaluating costs downstream, in that the costs of storing and redistributing the 

products are passed on from one level to the next. The analysis in this section 

serves to establish the incremental production cost to manufacturers, as a basis 

for assessing downstream cost to consumers. 

4. Particleboard: Estimated Increase in Panel Cost

The five main steps in PB manufacturing are: (1) preparation of the furnish (i.e., 

wood particles), (2) resin application, (3) mat formation, (4) hot pressing, and (5) 

finishing. The furnish is prepared by refining logs and other raw materials into 

small particles, and drying them to achieve a moisture content of 2 to 7% 

(Cognard, 2005). To control HCHO emissions, it is projected that selected 

manufacturers using PF resins may need to upgrade or purchase new dryers to 

more precisely control the moisture contents of the PB furnish that they use to 

make panels compliant with the proposed Phase 1 and Phase 2 standards. To 

optimize their drying operations, these manufacturers may incur a one-time 

capital investment for a new dryer. Depending on the size and energy rating of 

the new dryer, energy costs may increase, but some of these costs may be offset 

by savings due to more precise resin use. 

During resin application, resin is mixed with the furnish. In PB made with a UF 

resin, the resin accounts for 5 to 12% of the total weight of the panel depending 

on the size of the wood particles and the required properties of the panel (e.g., 

moisture resistance) (Cognard, 2005; Goldboard, 2000). Projected cost impacts 

during resin application will depend on the type of resin that manufacturers 

choose to produce panels compliant with the proposed Phase 1 and Phase 2 

standards, as the use of a new resin may require changes in mixing or 

application equipment, as well as the cost of the new additives, if any. 

After a UF resin is thoroughly mixed with the furnish, the mixture is cold-pressed 

to form a mat, then hot-pressed at cure temperatures ranging from 130 to 150 oC 

(Cognard, 2005). In comparison, PB made with PF resin requires hot-pressing at 

temperatures ranging from 180 to 230 oC (Pizzi, 1994). As greater energy costs 

will be incurred from the use of higher hot-press temperatures and longer press 

times, the increase cost per panel is expected to range on a case-by-case basis. 

The range of changes that a manufacturer chooses to make will determine the 

extent of the cost increase that they incur. 
Chapter VIII Page 197 

In the finishing process, PB panels are trimmed, cut, and sanded to produce 

panels of a desired thickness. Staff expects that any changes in the costs 

associated with the finishing process would be insignificant. 

To maintain a competitive board price, optimization of the manufacturing process 

may provide cost savings to varying degrees. For example, optimizing resin 

distribution and application systems could reduce resin waste, and lower 

manufacturing costs as well as surface HCHO emissions from the board. 

a. Drop-in Approach: Modified UF or Alternate Resin

In this subsection, the estimated cost of manufacturing a PB panel with a 

modified or alternate resin system, which does not require an upgrade to the 

existing equipment in a mill, is discussed. It is projected that to manufacture PB 

that complies with the proposed Phase 1 and Phase 2 standards, manufacturers 

will need to modify their existing UF resins or use an alternative resin system, 

which could have a measurable impact on the resin cost portion (30%) of the 

total cost of manufacturing a PB panel (Table VIII-10). 

The cost of manufacturing PB can be apportioned into six categories: adhesive, 

energy, labor, wax, wood, and miscellaneous costs (Table VIII-10). Among the 

six categories, the cost of the adhesive and wood amounts to over 50% of the 

total cost of manufacturing a panel. In future years, the cost of wood particles 

may rise significantly due to the shortage of harvestable forests in the U.S. and 

the inability to produce PB entirely from furnish made with urban wood waste. 

Moreover, the future cost of petroleum-based adhesive components (e.g., 

HCHO) is uncertain given the volatility in supply and demand that has occurred 

over the last 10-years. 

Table VIII-10. Breakdown of Costs in Particleboard

Manufacturing1

Category Percent (%) of Panel Cost 

Adhesive 30 

Electricity 9 

Labor 19 

Wax 3 

Wood Particles 24 

Miscellaneous 15 

(1) Source: Industry Canada (2005a; 2005b). 

Selected measures of the cost of PB and an estimate of the cost for the resin 

used to bind the furnish in PB ranging in thickness from 3⁄8” to 3⁄4” is presented in 
Chapter VIII Page 198 

Table VIII-11. Over this range of PB thickness, the present cost of the UF resin 

used to manufacture a PB panel ranges from $2.74 to $3.57. 

Table VIII-11. Estimated Cost of UF Resin in Particleboard of Varying 

Thickness1

------------ Board Thickness (Inches) ------------ Measure of Cost 3⁄8” 1⁄2” 5⁄8” 3⁄4” 

1,000 ft2 $286 $299 $333 $372 

4’ x 8’ Panel $9.15 $9.57 $10.66 $11.90 

Estimated Resin Cost $2.74 $2.81 $3.20 $3.57 

(1) Sources: Random Lengths (2006b); Industry Canada (2005a; 2005b). 

Urea-formaldehyde (UF) is the most commonly used resin for manufacturing 

interior grade PB in the U.S., largely because of its relatively fast curing speed 

and low cost. As the cost of the resin used to bind the wood particles in PB 

typically accounts for approximately 30% of the price of a PB panel (Industry 

Canada, 2005b), assuming that manufacturers may choose to use an alternate 

resin system to lower their HCHO emissions, our analyses indicate that the most 

likely alternates would include MF, MUF, PUF, pMDI, and PF. As the prices for 

these resins are higher than for UF resin, the cost of a PB panel compliant with 

the proposed Phase 1 or Phase 2 standards is expected to increase 

(Table VIII-12). In calculating a “final cost,” factors such as press conditions 

(e.g., press temperature, curing rate and application rate) and the use of 

additives (e.g., extenders, hardeners, scavengers), which may increase or 

decrease the final cost, were considered. 

Efficient application of extenders may reduce overall resin costs by up to 10% 

(Marutzky, 1989; Frihart, 2005) – extenders or fillers (e.g, walnut shell flour), can 

be added to resins to reduce adhesive cost by limiting the amount of resin overpenetration into wood particles. Hardeners or curing agents can be added to a 

resin to accelerate the hardening process, and could increase total production 

rates by up to 10%. Scavengers may also be added to reduce HCHO emissions 

during or after production. Commonly added scavengers include urea alone, or 

in combination with ammonium chloride or with organic amines. Panel 

manufacturers report that the application of scavengers could increase board 

prices by 1 to 5%. 
Chapter VIII Page 199 

Table VIII-12. Estimated Price Increase in Particleboard Made to Comply with 

the Phase 2 Standard with an Alternate Resin1

Resin 

Type 

Cost 

($ lbs-1) 

Cure 

Temp. 

Cure 

Rate 

HCHO 

(ppm) 

Price 

Increase (%) 

UF 0.24-0.27 NA NA 0.3 NA 

MF 0.72-0.81 Higher Slower < 0.09 60 to 70 

MUF (<12%) 0.31-0.46 Higher Slower < 0.09 10 to 30 

MUF (>12%) 0.48-0.68 Higher Slower < 0.09 30 to 55 

MUF + Catcher 0.24-0.27 Similar Similar < 0.09 < 5 

PF 0.48-0.68 Higher Slower < 0.09 30 to 55 

pMDI 0.96-1.35 Lower Slower Trace 90 to 140 

(1) “Cure Temp.” = cure temperature; “ppm” = parts per million; “NA” = not available; “UF” = ureaformaldehyde; “MF” = melamine-formaldehyde; “MUF” = melamine-UF; “PF” = phenolformaldehyde; “pMDI” = polymeric diphenylmethane diisocyanate. Cure rate and temperature are 

relative to production conditions for manufacturing particleboard (PB) with a UF resin. Values for 

“Price Increase” are relative to the cost of PB made with a UF resin; effects of cure temperature 

and rate were not considered. Resin costs are based on price information supplied at public 

workshops or in stakeholder meetings. 

Melamine-formaldehyde (MF) resin is presently used as an adhesive in exterior 

and semi-exterior grade plywood and PB, decorative laminates, paper treating 

and coating (Pizzi, 1994; Youngquist, 1999). As an alternative to UF resin, the 

use of MF resin may be cost-prohibitive in the 2010 to 2012 timeframe. It is 

estimated that PB made with a MF resin that complies with the proposed 

Phase 2 standard could cost up to 60 to 70% more than PB made with UF resin. 

Melamine Urea-formaldehyde (MUF) resin has been shown to improve the 

moisture resistance of PB while lowering surface HCHO emissions. Typically, a 

MUF resin with a melamine content of 12% or less is used to lower thickness 

swell as well as surface HCHO emissions. Conceivably, the use of a MUF resin 

with lower melamine contents could result in PB production costs comparable to 

the use of a UF resin. According to one major resin manufacturer, a 1% increase 

in the melamine content of a resin raises the cost of the resin by as much as $25 

to $30 per ton (1.2 to 1.5¢ per pound). While the cost of manufacturing PB with a 

MUF resin is expected to be higher, its superior moisture resistance may allow it 

to command a higher price than PB made with a UF resin having lesser moisture 

resistance properties, thus moderating the extent of the overall impact of the 

projected cost increase (10 to 30%). Akzo Nobel (2005) has developed a 

“catcher” which has been used in Europe to produce panels meeting the E1 

standard, and has the potential to be used as an additive that would minimally 

increase the manufacturing cost of PB made with a UF resin. 
Chapter VIII Page 200 

Phenol-formaldehyde (PF) resin is principally used in the manufacture of exteriorgrade plywood and PB, where superior water resistance is required. Blends of 

PF resins with resorcinol (i.e., PRF resins) are known to provide advantages 

insofar as lower cure temperature (Frihart, 2005). However, resorcinol is very 

expensive to use, and PRF resins would not be a cost-competitive alternative to 

UF resin. At present, it is projected that at resin application rates currently used 

to manufacture exterior-grade PB, the cost of a PB panel compliant with the 

proposed Phase 2 standard would be 30 to 55% higher due to higher resin costs 

and higher press temperatures. Further resin development to allow faster cure 

speeds could significantly lower production costs. 

Polymeric diphenylmethane diisocyanate (pMDI) resin has a low viscosity 

(Marutzky, 1989), which typically is mixed with a releasing agent to prevent 

panels from sticking to metal surfaces during hot pressing. Although pMDI resin 

is more expensive than UF resin (Table VIII-9), there are production cost-savings 

that partially offset the higher resin cost, such as the ability to use furnish with a 

higher moisture content and lower resin spread rate (Zheng, 2002). Analogous 

to MUF resins, higher prices could be afforded to PB made with pMDI owing to 

its superior water resistance relative to PB made with a UF resin. Further costsavings may also be achieved through the use of agricultural residues, such as 

wheat or rice straw in place of wood particles. At the plant-level, conversion of 

existing UF or PF facilities to pMDI should not require substantial manufacturing 

process-related capital investment (Goldboard, 2000). 

Despite its high cost, Osman et al. (1994) reported making PB with a phenolurea-formaldehyde (PUF) resin to which they added MDI alone, or in combination 

with urea. Of the three components, the cost of MDI (approximately $2,200 per 

ton) was approximately twice that of PUF (approximately $1,000 per ton) and 

ten-times more than urea (approximately $200 per ton). These workers reported 

making PB with PUF-MDI-urea resins that were comparable in cost and internal 

bond strength to PB made with the PUF resin. 

b. Plant Upgrade: New Equipment 

Sellers (2001) reported on a suite of technologies being developed to improve 

productivity in the panel manufacturing process. The list included: 

• Radio-frequency curing – to provide more precise control over adhesiverelated processes, increase production, and uniformity of curing; 

• Steam injection – to accelerate cure rates for pMDI and PF resins; 

• Foam extruders – to reduce adhesive use, trim loss, and clean-up; 

• Continuous presses – to increase production and control product surface 

roughness over that achieved by batch platen presses; and 

• Resin additives to reduce tool wear. 
Chapter VIII Page 201 

In discussions with industry representatives, the cost of equipment replacement 

is a multi-million dollar undertaking, in that equipment such as presses or dryers 

have $1-million or more price tags. As such, should a manufacturer elect to 

upgrade a plant to produce CARB-compliant products, it would likely involve an 

investment of $200,000 to $300,000 per year for ten or more years. Given the 

amount that it would cost to upgrade a plant, manufacturers would need to be 

reasonably certain of being able to recover their cost of investment. As they 

would have the option of producing products for markets other than California, it 

is not likely that manufacturers will make a major investment of this kind. Thus, 

in our view, unless manufacturers can produce CARB-compliant PB with “dropin” technology, it is more likely that the plant will be dedicated to the production of 

“49-state” wood products. 

c. Small Producers

Based on the CARB 2003 Survey, a small PB producer manufactures less than 

110-million ft2, and would be operated by less than 100-employees. For this size 

of facility, in addition to higher resin costs, consideration must also be given to 

potential cost increases due to quality control testing and documenting chain-ofcustody. If the producer is already a member of the Composite Panel 

Association or the Hardwood Plywood & Veneer Association, no additional costs 

may be anticipated for quality control testing and only minimal increases would 

be projected for labeling and chain-of-custody related activities. Likewise, 

compliance testing is tied to production volume, and therefore, smaller producers 

would conduct fewer tests over time than large producers, since they produce 

less product. 

5. Medium Density Fiberboard: Estimated Increase in Panel Cost

In 2003, MDF production was 2.7-million m3 in the U.S., where it is primarily used 

in the manufacture of furniture, shelving, molding, and kitchen cabinets 

(Composite Panel Association, 2006; Howard, 2005). Manufacturing processes 

for MDF are similar to that for PB, except that additional processing is required to 

prepare the fibers in the MDF furnish. 

a. Drop-in Approach: Modified Urea-formaldehyde or Alternate Resin

The most promising alternative resins for making MDF that complies with the 

proposed Phase 1 and Phase 2 standards are similar to those for PB 

(Table VIII-12). For MDF, the cost of resin typically accounts for 27% of the cost 

of a panel (Industry Canada, 2005a). Estimates of the cost of resin in MDF of 

varying thickness are shown in Table VIII-13. For the most common thicknesses, 

the estimated cost of UF resin alone ranges from $3 to $4 per panel. 
Chapter VIII Page 202 

Table VIII-13. Estimated Cost of Urea-formaldehyde (UF) Resin in 

Medium Density Fiberboard (MDF) of Varying Thickness

1

---------- Board Thickness ---------- Measure of Cost 3⁄8” 1⁄2” 5⁄8” 3⁄4” 

1,000 ft2 $309 $344 $402 $454 

4’ x 8’ Panel $9.89 $11.01 $12.86 $14.53 

Estimated Resin Cost $2.67 $2.97 $3.48 $3.92 

(1) Source: Random Lengths (2006b). Estimated resin cost is based on the resin 

accounting for 27% of the cost of a MDF panel. 

The estimated price increases for MDF made with an alternate resin are slightly 

less on a percentage basis than for PB. The most promising option at this time 

appears to be the addition of melamine to a UF resin (i.e., MUF), which could 

raise the price of a panel by 10 to 50% (Table VIII-14). While some 

manufacturers presently produce MDF with pMDI for specialty applications, 

unless the cost of the furnish material can be decreased significantly (e.g., fibers 

from rice straw instead of wood), the use of pMDI represents a higher cost 

option. 

Table VIII-14. Estimated Price Increase in Medium Density Fiberboard Made to 

Comply with the Phase 2 Standard with an Alternate Resin1

Resin 

Type 

Cost 

($/lbs) 

Cure 

Temp. 

Cure 

Rate 

HCHO 

(ppm) 

Price 

Increase (%) 

UF 0.24-0.27 NA NA 0.3 NA 

MF 0.72-0.81 Higher Slower <0.08 55 to 65 

MUF (<12%) 0.31-0.46 Higher Slower <0.08 10 to 25 

MUF (>12%) 0.48-0.68 Higher Slower <0.08 30 to 50 

pMDI 0.96-1.35 Lower Slower Trace 80 to 125 

(1) “Cure Temp.” = cure temperature; “ppm” = parts per million; “NA” = not available; “UF” = ureaformaldehyde; “MF” = melamine-formaldehyde; “MUF” = melamine-UF; “pMDI” = polymeric 

diphenylmethane diisocyanate. Cure rate and temperature are relative to production conditions 

for manufacturing medium density fiberboard (MDF) with a UF resin. Values for “Price Increase” 

are relative to the cost of MDF made with a UF resin; effects of cure temperature and rate were 

not considered. Resin costs are based on price information supplied at public workshops or in 

stakeholder meetings. 
Chapter VIII Page 203 

b. Plant Upgrade: New Equipment

As noted for PB, the cost of equipment replacement is a multi-million dollar 

undertaking, where presses or dryers cost $1-million a piece or more. As such, if 

a manufacturer chooses to upgrade a plant to produce CARB-compliant MDF, it 

could entail an investment of $200,000 to $300,000 per year for ten or more 

years. Given the cost to upgrade a plant, it is not likely that manufacturers will 

make a major investment of this kind, especially since they have the option to 

produce MDF for customers outside of California. Thus, in our view, unless 

manufacturers can produce CARB-compliant MDF with “drop-in” technology, it is 

more likely that a plant will be dedicated to the production of “non-California” 

wood products. 

c. Small Producers 

Based on the CARB 2003 Survey, a small MDF producer manufactures less than 

100-million ft2, and would be operated by less than 100-employees. For this size 

of facility, in addition to higher resin costs, consideration must also be given to 

potential cost increases due to quality control testing and documenting chain-ofcustody. If the producer is a member of the Composite Panel Association, no 

additional costs would be anticipated for quality control testing and only minimal 

increases would be projected for labeling and chain-of-custody related activities. 

6. Hardwood Plywood (HWPW): Estimated Increase in Panel Cost

Plywood is made out of wood veneers and an inner core, where the core may be 

a wood veneer, lumber, PB, MDF, or a combination of materials. In 2003, 

HWPW production in the U.S. was estimated to be 1.9-million m3 (Howard, 

2005). The primary uses of HWPW are for interior wall panels, furniture, flooring, 

and cabinets. 

a. Drop-in Approach: Modified Urea-formaldehyde or Alternate Resin

In a plywood panel, the cost of the resin is estimated to be about 5% of the total 

cost of the panel (Industry Canada, 2005b). In comparison, the cost of the resin 

accounts for 30% or 27% of the cost of a PB or MDF panel, respectively. For 

HWPW, the wood components (i.e., veneer and core materials) account for 50% 

or more of the cost the panel. Depending on the species and cut grade of the 

veneer, prices may range from $0.89 to $8.99 per ft2 for selected oak veneers 

(Oakwood Veneer Company, 2006a, 2006b). For this price range, a 4’ x 8’ panel 

would cost $29 to $288. To control costs, some HWPW manufacturers import 

lower-cost cores from overseas suppliers. Depending on panel thickness, the 

cost of the UF resin in a panel can be approximately $2 (Table VIII-15). 
Chapter VIII Page 204 

Table VIII-15. Estimated Cost of the Urea-formaldehyde (UF) Resin in 

Hardwood Plywood of Varying Board Thickness1

---------- Board Thickness (Inches) ---------- Measure of Cost 1⁄2” Birch 3⁄4” Birch 3⁄4” Oak 3⁄4” Maple 

4’ x 8’ Panel $33.95 $39.99 $42.99 $38.00 

Estimated Resin Cost $1.70 $2.00 $2.15 $1.90 

(1) Sources: Home Depot (2006); Industry Canada (2005b). 

The estimated price increases for HWPW made with an alternate resin are 

considerably less on a percentage basis than for PB and MDF, due to the lower 

amount of resin used to manufacture HWPW. While the use of proprietary soy or 

“MUF + Catcher” resins are essentially cost-neutral, use of PVA or a PVA/soy 

resins could raise the price of a panel by 10 to 30% (Table VIII-16). 

Table VIII-16. Estimated Price Increases in Hardwood Plywood Made with 

Alternate Resins1

Resin 

Type 

Cost 

($ lbs-1) 

Cure 

Temp. 

Cure 

Rate 

HCHO 

(ppm) 

Price 

Increase (%) 

UF 0.24-0.27 NA NA 0.3 NA 

MUF + Catcher 0.24-0.27 Similar Similar <0.08 < 5% 

PVA 0.55-1.50 Lower Shorter <0.05 10 to 30 

Soy 0.24-0.27 Similar Similar <0.05 < 5% 

PVA/Soy 0.72-0.81 Similar Similar <0.05 10 to 15 

(1) “Cure Temp.” = cure temperature; “ppm” = parts per million; “NA” = not available; “UF” = ureaformaldehyde; “MUF” = melamine-UF; “PVA” = polyvinyl acetate. Cure rate and temperature are 

relative to production conditions for manufacturing hardwood plywood with a UF resin. Values for 

“Price Increase” are relative to the cost of hardwood plywood made with a UF resin; effects of 

cure temperature and rate were not considered. Resin costs are based on price information 

supplied at public workshops or in stakeholder meetings. 

Westcott and Frihart (2004) developed a soy-PF resin that could be a candidate 

system for producing HWPW that complies with the proposed Phase 1 and 

Phase 2 standards. In trials on oriented strandboard, these workers found that 

adding soy flour, at roughly 25% the cost of phenol, could reduce unit resin cost 

by 40 to 60%, at soy:phenol weight ratios of 1 and 3.4, respectively. While this is 

data on resin use in oriented strandboard, they postulate that results for plywood 

could be similar. 
Chapter VIII Page 205 

b. Plant Upgrade: New Equipment 

For HWPW, the candidate resins that would likely be used to manufacture panels 

compliant with the Proposed Phase 1 and Phase 2 standards would not require 

new equipment for use. For example, several existing facilities that currently use 

urea formaldehyde resins also make HWPW with PVA resin in response to 

requests for “green building” compliant materials. In addition to the higher cost of 

PVA vs. UF resin, there are costs associated with cleaning the presses after 

using PVA that must be performed before returning to UF resin production. As 

such, if manufacturers produced only PVA-bonded HWPW, these cleaning costs 

would not be a consideration. In our view, manufacturers can produce CARBcompliant HWPW with “drop-in” technology, it is more a matter of whether they 

will choose to produce HWPW for California or not. 

c. Small producers

While industry representatives have stated that there are 19-mills in the U.S., 

based on the CARB 2003 Survey, some of the smaller HWPW producers 

manufacture less than 1-million ft2, and would be operated by less than 20 

employees. For this size of facility, in addition to higher resin costs, 

consideration must also be given to potential cost increases due to quality control 

testing if they continue to use UF resin and documenting chain-of-custody. If the 

producer is a member of the Hardwood Plywood & Veneer Association, the costs 

that would be anticipated for quality control testing, labeling, and chain-ofcustody related activities may be less. 

C. Cost to the Composite Wood Manufacturing Industry 

1. Calculation of Total Cost to the Industry

There are about 1,500 companies in the American engineered wood products 

industry, employing over 120,000 workers. Their combined production value 

stood at an estimated $29.5 billion in 2004. This compares to a value of 

$21.3 billion at the beginning of this century. The increase of 38.5% is partially 

due to higher prices. However, if we exclude the impact of inflation, the growth 

between 2000 and 2004 is still 30.2% (Global Wood Trade Network, 2005). 

a. Hardwood Plywood (HWPW) 

Presently, about 40% of HWPW produced for California complies with the 

proposed Phase 1 and Phase 2 standards (Columbia Forest Products, 2006). 

For the remaining 60%, we believe manufacturers could produce a panel with a 

UF resin that complies with the proposed Phase 1 standard. Manufacturers 

could do some or all of the following: 
Chapter VIII Page 206 

• Improve manufacturing process controls to increase efficiency, energy 

use, and reduce waste; 

• Use a lower mole ratio UF resin with a F:U mole ratio of approximately 1.3 

or less; 

• Use scavengers or catalysts; and/or 

• Co-blend their base UF resin with a very low mole ratio UF resin (< 1.0). 

Through application of all or some of these actions, it is reasoned that the cost of 

a Phase 1 compliant HWPW panel would be increased by about 1%, due entirely 

to the increase in resin cost (Appendix G). For example, based on the wholesale 

price of a HWPW panel presently available for sale of approximately $20 

(Pittsburgh Forest Products, 2007), the projected wholesale price of a Phase 1 

panel would be approximately $20.25. This increase would apply to both veneer 

core and composite core products. 

To meet the proposed Phase 2 standards, it is likely that manufacturers would 

have optimized their production controls and determined the essential preprocessing treatments needed to reduce manufacturing losses. To reduce 

HCHO emissions further, manufacturers could choose to use of one of three 

resin systems: MUF, PVA, or soy. In the case of Columbia Forest Products, the 

decision to develop and use a soy-based resin for their entire HWPW product 

line was not based solely on cost, and as such, cannot be considered in this 

context. The Columbia Forest Products PurebondTM is proprietary, however, if 

the soy resin technology is publicly available in the future, then another low cost 

option would be available. Rather, the estimate contained herein is based on the 

use of a MUF resin containing 15% melamine or PVA. For the MUF resin, 

hexamine addition may be another cost-competitive option (Kamoun et al., 

2003). In addition to increased resin costs over UF, it was further assumed that 

processing times would be lengthened by 10% and 20%, respectively. Through 

the use of either of these resins, it is reasoned that the cost of Phase 2 compliant 

HWPW panel would be increased by approximately 8% to 19%. As in the 

previous example, the projected wholesale price of a Phase 2 panel would be 

between $21.50 to $23.75, for either a veneer core or composite core product. 

The above estimated “per panel” increases were used to calculate the total cost 

to the HWPW industry. Using production data for 2002, where California 

consumption was estimated to be approximately 299-million ft2

 or 9.3-million 

panels (Note: a panel is 4’ x 8’ board or 32ft2

), and considering that 40% of the 

HWPW for California already complies with both the Phase 1 and Phase 2 

standards, the total cost to the HWPW industry is estimated to be approximately 

$6 million per year for Phase 1 and about $17 million per year for Phase 2. 

b. Particleboard (PB) 

Based on the CARB 2003 Survey, approximately 55% of PB produced in the 

U.S. complies with the proposed Phase 1 standard, and only a small amount of 
Chapter VIII Page 207 

specialty products (< 1%) comply with the proposed Phase 2 standard. For the 

approximately 45% of U.S. production that does not produce a panel that would 

comply with the proposed Phase 1 standard, it is projected that to produce a 

panel with a UF resin that complies with the standard, manufacturers could do 

some or all of the following: 

• Improve manufacturing process controls to increase efficiency, energy 

use, and reduce waste; 

• Use a lower mole ratio UF resin with a F:U mole ratio of approximately 1.1 

or less; 

• Use scavengers or catalysts; and/or 

• Co-blend their base UF resin with a very low mole ratio UF resin (< 1.0). 

Through application of all or some of these actions, it is reasoned that the cost of 

a Phase 1 compliant PB panel would be increased by approximately 4% to 7%, 

due almost entirely to the increase in resin cost (Appendix G). For example, 

based on the wholesale price of a PB panel presently available for sale of 

approximately $10.50 (Random Lengths, 2007), the projected wholesale price of 

a Phase 1 panel would be between $11 and $11.80. 

For the proposed Phase 2 standards, it is likely that manufacturers would have 

optimized their production controls and determined the essential pre-processing 

treatments that need to be done to reduce manufacturing losses. To reduce 

HCHO emissions further, manufacturers could choose to use of one of two resin 

systems: MUF or PF. As manufacturers will likely continue using UF resins, the 

estimate contained herein is based on the use of a MUF resin containing 8% 

melamine in combination with the use of lower mole ratio urea-formaldehyde 

resins (i.e. F:U <1). In addition to increased resin costs over UF, it was further 

assumed that processing times would be lengthened by approximately 10%. 

Through the use of MUF resin, it is reasoned that the cost of Phase 2 compliant 

PB panel would be increased by approximately 17% to 30%. As in the previous 

example, the projected wholesale price of a Phase 2 panel would be between 

$12.30 and $13.80. 

The above estimated “per panel” increases were used to calculate the total cost 

to the PB industry. Using production data for 2002, where California 

consumption was estimated to be approximately 600-million ft2

 or 19.5-million 

panels (Note: a panel is 4’ x 8’ board or 32 ft2

), and considering that 55% of 

current U.S. production already complies with the Phase 1 standard, the total 

cost to the PB industry is estimated to be approximately $4-million per year for 

Phase 1 and approximately $61-million per year for Phase 2. 

c. Medium Density Fiberboard (MDF) 

Based on the CARB 2003 Survey, approximately 25% of MDF produced in the 

U.S. complies with the proposed Phase 1 standard, and only a small amount of 
Chapter VIII Page 208 

specialty products (< 1%) comply with the proposed Phase 2 standard. For the 

approximately 75% of U.S. production that does not produce a panel that would 

comply with the proposed Phase 1 standard, it is projected that to produce a 

panel with a UF resin that complies with the standard, manufacturers could do 

some or all of the following: 

• Improve manufacturing process controls to increase efficiency, energy 

use, and reduce waste; 

• Use a lower mole ratio UF resin with a F:U mole ratio of approximately 1.1 

or less; 

• Use scavengers or catalysts; and/or 

• Co-blend their base UF resin with a very low mole ratio UF resin (< 1.0). 

Through application of all or some of these actions, it is reasoned that the cost of 

a Phase 1 compliant PB panel would be increased by approximately 4% to 6%, 

due almost entirely to the increase in resin cost (Appendix G). For example, 

based on the wholesale price of a PB panel presently available for sale of 

approximately $14.00 (Random Lengths, 2007), the projected wholesale price of 

a Phase 1 panel would be between $14.50 and $15. 

For the proposed Phase 2 standards, it was postulated that manufacturers would 

have optimized their production controls and determined the essential preprocessing treatments that needed to be done to reduce manufacturing losses. 

While pMDI hybrid resins have been found to be effective, the high cost of pMDI 

precludes its consideration in this analysis. As manufacturers will likely continue 

using UF resins, the estimate contained herein is based on the use of a MUF 

resin containing 12% melamine in combination with the use of lower mole ratio 

urea formaldehyde resin (F:U<1). In addition to increased resin costs over UF, it 

was further assumed that processing times would be lengthened by 

approximately 10%. Through the use of this MUF resin, it is reasoned that the 

production cost of a Phase 2 compliant MDF panel would be increased about 

26%. As in the previous example, the projected wholesale price of a Phase 2 

panel would be approximately $17.60. A few manufacturers produce MDF with 

pMDI, however, pMDI is much more costly than urea- formaldehyde resins (see 

Table VIII-14). The cost of an MDF panel made from pMDI would be increased 

by about 135%, due to the increase in resin cost. This increase in resin cost 

would increase the production cost of a $14.00 MDF panel to about $30. So, 

staff believes that manufacturers would opt for less expensive melamine fortified 

lower ratio urea formaldehyde resins to meet the Phase 2 emission standard. 

The above estimated “per panel” increases were used to calculate the total cost 

to the PB industry. Using production data for 2002, where California 

consumption was estimated to be approximately 280-million ft2

 or 8.7-million 

panels (Note: a panel is 4’ x 8’ board or 32 ft2

), and considering that 

approximately 25% of current U.S. production already complies with the Phase 1 

standard, the total cost to the PB industry is estimated to be approximately 
Chapter VIII Page 209 

$9-million per year for Phase 1 and approximately $49-million per year for 

Phase 2. 

d. Total Combined Cost to the Industry

For Phase 1, the total combined cost to HWPW, PB, and MDF manufacturers in 

the U.S. is estimated to be $19-million per year, and for Phase 2, $127-million 

per year (Appendix G). 

D. Distributor and Importer Costs 

Distributors and importers play an important role in the distribution of composite 

wood products to the California marketplace. While they do not typically “add 

value” to panels or finished goods that contain HWPW, PB, and/or MDF, they are 

the principal entities that resell products to fabricators and retailers. As a 

significant portion of the HWPW, PB, and MDF that is offered sale or supply in 

California is handled by distributors or importers, their adherence to the chain-ofcustody requirements of the proposed ATCM are fundamental to ensuring the 

availability and use of CARB-compliant HWPW, PB, MDF, and finished goods 

containing those materials in California. 

1. Distributors

Distributors are individuals or business entities to whom HWPW, PB, MDF, or 

finished goods containing those materials are sold or supplied to, from domestic 

sources, for the purposes of resale or distribution into commerce. In large part, 

the major portion of distributors are familiar with the wide range of composite 

wood products that are presently available for sale or supply in California, and 

understand that there is a growing demand for “green” products, that are 

environment-friendly. A growing segment of the green-products industry is 

building materials made with no added HCHO resins (Tables V-22, V-24, and V26), which are typically requested by individuals with chemical sensitivities and/or 

builders pursuing Leadership in Energy and Environmental Design (LEED) 

credits (U.S. Green Building Council, 2005). The increased availability of low 

HCHO emission PB, MDF, and HWPW, may require distributors to track some 

additional stock keeping unit (SKU) numbers for Phase 1 and Phase 2 compliant 

materials. 

Presently, with a growing interest in green building efforts focused on 

documenting the use of energy-efficient and/or products with specified 

sustainably harvested wood contents, distributors already participate in one or 

more chain-of-custody and labeling programs to assure that green-products are 

supplied to customers that request them. With respect to the use of sustainably 

harvested wood, the Forest Stewardship Council oversees one of the most 

widely recognized programs to verify the use of sustainable forest management 

practices and chain-of-custody programs (Forest Stewardship Council, 1996). 
Chapter VIII Page 210 

Through programs of this kind, a major portion of distributors are familiar with the 

level of resources (manpower and cost) that need to be expended to participate 

in a program of this kind and recognize the beneficial aspects of their 

participation. It is projected that requiring distributors to track their purchases 

and sales of CARB-compliant HWPW, PB, and MDF, would not constitute a 

significant increase in the efforts currently being done to comply with on-going 

chain-of-custody efforts, such as for the Forest Stewardship Council or the 

USEPA’s National Emission Standards for Hazardous Air Pollutants regulation 

for composite wood products facilities (USEPA, 2002). 

As distributors may secure goods for customers outside of California, they may 

incur costs for keeping separate records for non-compliant HWPW, PB, and MDF 

destined for their non-California customers. These costs may be due to 

maintaining separate data management systems, storage facilities, and labels for 

California and non-California goods. 

2. Importers

Importers are individuals or business entities to whom HWPW, PB, MDF, or 

finished goods containing those materials are sold or supplied to from overseas 

sources, for the purposes of resale or distribution into commerce. In large part, 

importers (e.g., members of the International Wood Products Association) are 

familiar with the wide range of composite wood products that are presently 

available for sale or supply in California, and initiate agreements throughout the 

world for products of lower cost and/or made from rare tree species. As 

manufacturers, such as Masisa in Chile, supply E1-compliant products to 

Europe, and Chinese manufacturers supply F and F products to 

Japan, importers are well aware of the different emission and strength standards 

that exist across the world. Imported products are also being supplied to fulfill 

demand for green-products, as the availability of green-products is limited from 

U.S. manufacturers. As for distributors of domestic composite wood products, an 

increase in the availability of low HCHO emission PB, MDF, and HWPW, may 

require importers to track some additional stock keeping unit (SKU) numbers for 

Phase 1 and Phase 2 compliant materials. 

As for distributors of domestic goods, importers are familiar with the level of 

resources (manpower and cost) that need to be expended to participate in chainof-custody and labeling programs and recognize the beneficial aspects of their 

participation. It is projected that requiring importers to track their purchases and 

sales of CARB-compliant HWPW, PB, and MDF, would not constitute a 

significant increase in the efforts currently being done to comply with on-going 

chain-of-custody efforts, such as for the Forest Stewardship Council (Forest 

Stewardship Council, 1996). 

As importers may secure goods for customers outside of California, they may 

incur costs for keeping separate records for non-compliant HWPW, PB, and MDF 
Chapter VIII Page 211 

destined for their non-California customers. These costs may be due to 

maintaining separate data management systems, storage facilities, and labels for 

California and non-California goods. 

E. Fabricator Costs 

Fabricators are individuals or business entities that use HWPW, PB, or MDF to 

make other goods that are sold or supplied in California. Assuming that a major 

portion of fabricators purchase HWPW, PB, or MDF on an as-needed basis to fill 

their orders to customers, they would not maintain large surpluses of panels or 

components in their places of business. To comply with the proposed ATCM, it 

is estimated that fabricators may incur additional costs due to higher material 

costs, and depending on their participation in existing chain-of-custody and 

labeling programs, may incur additional costs to implement a rigorous recordkeeping system to track their purchases and sales of compliant and noncompliant goods. 

1. Case Studies

In the following subsections, three case studies were examined as a means to 

gauge the potential increase in cost to fabricators that elect to build products with 

HWPW, PB, and/or MDF that complies with the proposed Phase 2 standards 

(Table VI-1). As environment-friendly products are currently being sold as a 

separate product line (e.g., Neil Kelly Cabinets, Portland, OR), for sales to 

medium- or high-price point customers, increases in the cost of HWPW, PB, 

and/or MDF used to fabricate products in 2009-2012 will likely be passed on to 

the customer. 

a. Furniture

For furniture to be sold or supplied to California, any furniture maker that elects to 

build furniture with CARB-compliant HWPW, PB, and/or MDF, would only be in 

competition with other furniture makers that must incur the same composite wood 

costs as they do. Presently, aside from upgrading their record-keeping programs 

to be able to demonstrate the use of CARB-compliant composite wood products, 

it is not anticipated that the use of these materials would require any specialized 

equipment or tools for furniture makers than would be required for the use of 

non-compliant wood products. Should a furniture maker elect to make furniture 

for customers in California and out-of-state, and deciding to use both CARB- and 

non-compliant composite wood products, added costs associated with keeping 

separate records and work/storage areas for those products may be incurred. 

In discussions with the American Home Furnishings Alliance, familiarity with the 

USEPA’s chain-of-custody requirements for plywood and composite wood 

products facilities provides a template for complying with the chain-of-custody 

requirements for the proposed ATCM. 
Chapter VIII Page 212 

b. Cabinets

For cabinets to be sold or supplied to California, any cabinet maker that elects to 

build cabinets with CARB-compliant HWPW, PB, and/or MDF, would only be in 

competition with other cabinet makers that must incur the same composite woodrelated costs as they do. Presently, aside from upgrading their record-keeping 

programs to be able to demonstrate the use of CARB-compliant composite wood 

products, it is not anticipated that the use of these materials would require any 

specialized equipment or tools for cabinet makers than would be required for the 

use of non-compliant wood products. Should a cabinet maker elect to make 

cabinets for customers in California and out-of-state, requiring the use both 

CARB- and non-compliant composite wood products, they may incur added costs 

for keeping separate records and work/storage areas for those products. 

In discussions with the Kitchen Cabinet Manufacturers Association, for large 

cabinet makers that have captive HWPW, PB, or MDF manufacturing facilities, 

substantial investments may be needed to upgrade those facilities given that all 

the composite wood that is produced is used to build cabinets. This industry is 

not as familiar with chain-of-custody programs as the furniture industry, and as 

such, is likely to incur some costs in initiating a program and in its day-to-day 

operation. 

c. Windows and Doors

For windows and interior doors to be sold or supplied to California, window/door 

manufacturers that elects to build windows and interior doors with CARBcompliant HWPW, PB, and/or MDF, would only be in competition with other 

manufacturers that must incur the same composite wood-related costs as they 

do. Presently, aside from upgrading their record-keeping programs to be able to 

demonstrate the use of CARB-compliant composite wood products, it is not 

anticipated that the use of these materials would require any specialized 

equipment or tools for window and door manufacturers than would be required 

for the use of non-compliant wood products. Should a window/door 

manufacturer elect to make products for customers in California and out-of-state, 

requiring the use both CARB-compliant and non-compliant composite wood 

products, they may incur added costs associated with keeping separate records 

and work/storage areas for those products. 

In discussions with the Window and Door Manufacturers and the Door and 

Access System Manufacturers Associations, concern was expressed relative to 

potential costs associated with having to recertify the fire- and storm-ratings of 

their products with organizations such as Underwriters Laboratory. As 

certifications of this kind cost in excess of $1,000 a piece, manufacturers were 

not certain if the use of CARB-compliant HWPW, PB, or MDF would substantially 

alter their products such as to require recertification testing. In conversations 

with Underwriters Laboratory, staff learned that nearly all changes of this kind 
Chapter VIII Page 213 

may be subject to an engineering evaluation, and would not require product 

recertification. 

F. Retailer Costs 

Retailers are individuals or business entities that sell, supply or offer for sale 

HWPW, PB, or MDF, in either finished goods or in panel form to the public-atlarge (i.e., consumers). To comply with the proposed ATCM, beginning in 2009, 

retailers need to clear their inventories of non-compliant products consistent with 

the sell-through provisions in Table VI-6. A major effort may be needed to inform 

their suppliers, foreign and domestic, that they must verify that their products are 

compliant with the proposed ATCM. As such, retailers need to develop a recordkeeping system to track where they purchase the merchandise they sell to 

consumers, and maintain documentation that verifies that the products they sell 

comply with applicable Phase 1 or Phase 2 standards (i.e. chain-of-custody). 

Through contacts made at public workshops, efforts have already been made by 

a major retailer to secure composite wood products that comply with the 

European E1 standard. Presently, products meeting the E1 standard are subject 

to more stringent HCHO emission requirements than are required in the U.S., 

which may be more costly to sell than products meeting less stringent standards, 

such as the 1985 HUD standard for products used in mobile homes. With action 

of this kind already taking place, there may be a greater level of familiarity within 

the retail sector concerning low HCHO emitting composite wood products, and 

the efforts needed to assure their quality by the time the ATCM goes into effect. 

G. Consumer Costs 

In the following subsections, projected increases in the price of HWPW, PB, and 

MDF panels, and resultant increases in the cost of a small home, large home, 

and a typical home remodeling project, and a low-price point article of furniture 

are estimated. 

1. Incremental Increase in the Cost of a Standard Panel 

Previously, in Tables VIII-12, VIII-14, and VIII-16, estimates of the price 

increases for PB, MDF, and HWPW manufactured to comply with proposed 

Phase 2 standards were calculated, respectively. In the following analysis, it is 

assumed that the approximate increase in the production cost of PB, MDF, and 

HWPW compliant with the applicable Phase 2 Standard in 2010-2012 would be 

30%, 40%, and 15% higher than the wholesale cost of non-compliant products 

sold in markets outside of California (Table VIII-17). Based on the prices of 

standard-size panels sold today, in the post Phase 2 timeframe, the production 

cost of a standard PB, MDF, and HWPW panel is estimated to be approximately 

$3 to $4, $4 to $6, and $5 to $7 higher than a comparable panel made with UF 

resin, depending on the thickness of the panel. 
Chapter VIII Page 214 

Table VIII-17. Estimated Cost of Particleboard, Medium Density Fiberboard, and 

Hardwood Plywood Panels Following the Effective Date of the Phase 2 Standard 1

---------- Board Thickness ---------- 

Particleboard 3⁄8” 1⁄2” 5⁄8” 3⁄4” 

Pre-Phase 2 Effective Date $9.15 $9.57 $10.66 $11.90 

Post Phase 2 Effective Date $11.90 $12.44 $13.86 $15.47 

Estimated Increase $2.75 $2.87 $3.20 $3.57 

Medium Density Fiberboard 3⁄8” 1⁄2” 5⁄8” 3⁄4” 

Pre-Phase 2 Effective Date $9.89 $11.01 $12.86 $14.53 

Post Phase 2 Effective Date $13.85 $15.41 $18.00 $20.34 

Estimated Increase $3.96 $4.40 $5.14 $5.81 

Hardwood Plywood 1⁄2” Birch 3⁄4” Birch 3⁄4” Oak 3⁄4” Maple 

Pre-Phase 2 Effective Date $33.95 $39.99 $42.99 $38.00 

Post Phase 2 Effective Date $39.04 $45.99 $49.43 $43.70 

Estimated Increase $5.09 $6.00 $6.44 $5.70 

(1) Random Lengths (2006b). Pre-Phase 2 and Post Phase 2 dollar values are for a standard 4’ x 

8’ panel. 

2. Increase in Material Cost for New Home Construction

In this analysis of incremental new house construction, staff found that the 

increase in construction cost would be less than 0.1%. These costs are relative 

to statistics from the National Association of Realtors, which show the 2006 

average median home price for four southern California cities to be $574,000 

(National Association of Realtors, 2007). 

a. Two-bedroom House

Staff estimated the incremental cost of a one story, one bath, 800 ft2

 house 

(Appendix F). To develop the estimate, a building plan house was obtained 

(Dream House Source, Not Dated (a)), and commercially available software was 

used to calculate the amount of composite wood materials that would be used to 

build the kitchen and bathroom cabinets, where the major portion of the HWPW, 

PB, and MDF is used in a home (Planit Solutions, Inc., 2004). Based on the total 

amount of HWPW, PB and MDF estimated, the incremental “per panel” 

production cost was then applied. Based on this incremental cost analysis, staff 

found that the increased cost of construction for an 800 ft2

 house is about $200. 

Assuming that the incremental increase in construction cost is added to the price 
Chapter VIII Page 215 

of a median priced home of $574,000, the estimated increased cost is about 

0.03%. 

Alternatively, housing costs can be calculated a different way. If the proposed 

ATCM industry-wide cost increase for Phase 2 ($127 million) is assumed to be 

applied to new housing starts, then an overall cost per new house can be 

determined. According to real estate statistics, the two year average (2004 to 

2005) for California housing starts (single family homes and multi-family units) 

was about 200,000 per year (California Building Industry Association, 2006; Not 

Dated). If it is assumed that 50% of the HWPW, PB, and MDF for California is 

used for new home construction, then the overall increase would be $300 per 

new home (i.e., ($127 million x 0.5) ÷ 200,000 = $300 per housing start). 

b. Four-bedroom House 

To develop this estimate, staff performed the same analysis as the two-bedroom 

house, but based on the building plan for a four bedroom, three bath home 

(Dream House Source, Not Dated (b)). As Appendix F describes, the 

incremental construction cost of a 2,000 ft2

 house is about $390. Therefore, 

assuming this increase in construction cost is added to the price of a median 

priced home of $574,000, the estimated increased cost is about 0.07%. 

 

In the context of existing profit margins for large home builders, which range from 

8 to 16%, the increase in material cost of composite wood products poses an 

insignificant factor in the cost of new home construction. 

c. Remodeling Project

The average cost of a kitchen remodel ranges from $15,000 to $25,000, where 

the cost of the cabinets is a major portion of the cost. Depending on the size of 

the home being remodeled, the cost of the composite wood materials used to 

build the cabinets and countertops may range from $400 to $600 at present-day 

prices (Tables VIII-18 and VIII-19), while the purchase price of the cabinets 

would be ten- to 15-times higher. Assuming the mix of wood products identified 

previously would still be used, the increase in material cost is estimated to range 

from 26 to 27%. At this level of increase, the cost of composite wood materials 

used to build the cabinets in a kitchen remodeling project would rise by $104 to 

$160. This represents a 1% increase to the cost of a remodeling project. 

3. Increase in Material Costs for Low Price Point Case Goods

Particleboard is used to manufacture a wide variety of low price point case 

goods, such as pre-assembled or ready-to-assemble book cases. Assuming 

that the cost of Phase 2-compliant PB will be more expensive than currently 

available panels, an estimate of how much the cost of the PB in a pre-assembled 

book case would increase, in consideration of the previously developed cost 
Chapter VIII Page 216 

estimate for 2-compliant PB (Table 14). For purposes of this analysis, it was 

assumed that bookcases built with MDF or HWPW would be medium price point 

commodities and less affected by the projected increases in PB cost that could 

have a significant impact on the viability of low price point case goods. 

For a typical four-shelf bookcase (79” height x 29” width x 11” depth), the 

following amounts of PB are used: 

• one 4’ x 8’ panel of 3⁄4” PB for the shelves and side panels; 

• one 4’ x 8’ panel of 3⁄8” PB for the back; and 

• one 2’ x 8’ panel of 3⁄4” PB for the top and bottom rails, frames, etc. 

Assuming a present-day cost of a 3⁄4” panel at $11.90 and a 3⁄8” panel at $9.15 

(Table 14), the total cost of PB used to build the above bookcase would be 

$27.00 (i.e., [(11⁄2 x $11.90) + $9.15] = $27.00). To bracket the range of 

prospective cost increases, it is assumed that the cost of resin used to make 

Phase 2-compliant PB could range from 15 to 100% more expensive than UF 

resin. At 15%, the estimated increase in PB cost would be $1.22, bringing the 

total cost of PB to $28.22, a 5% increase over the present-day cost. At 100%, 

the estimated increase in PB cost would be $8.10, bringing the total cost of PB to 

$35.10, a 30% increase over the present-day cost. 

H. Impacts to Small Business 

As all HWPW, PB, MDF, and finished goods offered for sale or supply in 

California will be required to meet the proposed Phase 1 and Phase 2 standards 

in 2009 to 2012, there should be no specific detrimental impact on small 

business, and all entities in the distribution chain would be required to use or sell 

compliant products. 

I. References 

Akzo Nobel. 2005. Kenocatch 4315L. Product information, Casco Adhesives, 

Sundsvall, Sweden. 2 pp. 

American Plywood Association (APA). 2003. The Engineered Wood Association 

Market Outlook. Structural Panels and Engineered Wood 2003-2008. From: 

http://www.cintrafor.org/CONFERENCE_TAB/ifpm%202003/Presentations/Adair

Cintra%2003.pdf Accessed: 28 January, 2007. 

Answers.com. Not Dated. Hardwood Veneer and Plywood: Information From 

Answers.com. From: http://answers.com/topic/hardwood-veneer-and-plywood 

Accessed: 25 January 2006. 

Bomersheim W. Not Dated. A quick look at the best growth hardwood import 

markets based on current trends. 
Chapter VIII Page 217 

CARB. 2003. Analysis of Data Collected in the CARB 2003 Composite Wood 

Products Survey of Products Offered for Sale in 2002. Unpublished data. 

Cognard P. 2005. Woodworking and furniture adhesives. Part 5: Applications 

and end uses. Accessed: 20 September 2006. From: 

http://www.specialchem4adhesives.com/resources/articles/printarticle.aspx?id=1

235 

Columbia Forest Products. 2006. PurebondTM. Product Information, Columbia 

Forest Products, Portland, OR. 2 pp. 

Composite Panel Association (CPA). 2006. 2005 North American Shipments 

Report: Particleboard, Medium Density Fiberboard, Hardboard. CPA, 

Gaithersburg, MD. 18 pp. 

CPA. 2007. Welcome to the Composite Panel Association. From: 

http://www.pbmdf.com/AboutCPA/index.asp Accessed: 5 January 2007. 

CPA. ND. Buyers and Specifiers Guide to North American Particleboard, 

Medium Density Fiberboard, and Hardboard Products and Manufacturers: 2006. 

From: http://www.pbmdf.com/aboutCPA/memberdirectory.asp Accessed: 10 July 

2006. 

Dream House Source. Not Dated (a). Home Plan 9802. Accessed: 20 July 

2006. From: http://www.dreamhousesource.com/Plan.asp?PlanID=9802 

Dream House Source. Not Dated (b). Home Plan 18401. Accessed: 20 July 

2006. From: http://www.dreamhousesource.com/Plan.asp?PlanID=18401 

Encyclopedia of American Industries. 2007. SIC 2435: Hardwood veneer and 

plywood. Available: www.referenceforbusiness.com/industries/LumberWood/Hardwood-Veneer-Plywood.html Accessed: 30 January, 2007 

Forest Stewardship Coucil. 1996. Chain-of-custody. Fact sheet, 2 pp. 

Frihart CR. 2005. Chapter 9: Wood adhesion and adhesives, p. 215-278. In:

RM Rowell (ed). Handbook of Wood Chemistry and Wood Composites. CRC 

Press, Boca Raton. 

Global Trade Atlas. Wood Products Imports. Not Dated. From: 

http://www.fas.usda.gov/ffpd/wood_products_presentations/world_importers/worl

d’s_leading_wood_product_importers.pdf Accessed: 28 January 2007. 
Chapter VIII Page 218 

Global Wood Trade Network. 2005. Veneer, plywood and engineered wood 

product manufacturing in the U.S. Accessed: 28 January 2007. From: 

http://www.globalwood.org/market1/news20050501.htm 

Global Wood Trade Network. 2007. China wood products prices. Accessed: 28 

January 2007. From: http://www.globalwood.org/market1/aaw20070101d.htm 

Goldboard Development Corporation. 2000. Overview of Goldboard® Products. 

From: http://www.goldboard.com/products/products.html Accessed: 12 

December 2001. 

Hardwood Plywood and Veneer Association (HPVA). 2007. List of Email from 

Bill Altman to Angela Csondes. 

Home Depot. 2006. Product information table: Plywood. Accessed: 20 

September 2006. From: http://homedepot.bighammersoftware.com 

Howard, JL. 2001. United States Department of Agriculture (USDA). U.S. Timber 

Production, Trade, Consumption, and Price Statistics 1965-1999. 

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2001-2005. Research Note FPL-RN-0299, USDA, Forest Service, Forest 

Products Laboratory, Madison, WI. 11 pp. 

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Industry Canada. 2005b. Wood-based panel products: Technology roadmap. II. 

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Kamoun C, A Pizzi, and M Zanetti. 2003. Upgrading melamine-ureaformaldehyde polycondensation resins with buffering additives. I. The effect of 

hexamine sulfate and its limits. Journal of Applied Polymer Science, 90: 203-

214. 

Marutzky R. 1989. Chapter 10: Release of formaldehyde by wood products. In: 

Pizzi A (ed). 1989. Wood Adhesives: Chemistry and Technology, Volume 2: 

307-388. 

National Association of Home Builders (NAHB). Not Dated. Housing: 2004 

Facts, Figures & Trends. NAHB, Public Affairs, Washington, DC. 50 pp. 

NAHB. 2006. Median and average price per square foot of floor area in new 

one-family houses sold by location. Accessed: 7 February 2007. From: 

http://www.nahb.org/fileupload_details.aspx?contentID=560 
Chapter VIII Page 219 

Oakwood Veneer Company. 2006a. Company Price List: 4’ x 8’ A-B. From: 

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September 2006. 

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From: https://oakwoodveneer.com/shop/shop_3ply.html Downloaded: 20 

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Osman Z, A Pizzi, W Kantner, and MC Triboulot. 2005. PUF panel adhesives 

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plywood panels. From: http://www.sticktrade.com/members/5425.htm 

Accessed: 26 February 2007. 

Pizzi A. 1994. Advanced Wood Adhesives Technology. Marcel Dekker, Inc., 

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the relationship? Structural Building Components Magazine, March 2006: 20-23. 

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Forest Service, Forest Products Laboratory, Madison, WI. 12 pp. 

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economics. Panel World, March 1992: 22-24. 
Chapter VIII Page 220 

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Chapter IX Page 221 

IX. Environmental Impacts of the Proposed Airborne Toxic 

Control Measure 

The primary intent of the proposed ATCM is to protect public health by reducing 

emissions of and human exposure to HCHO released from composite wood 

products. The proposed ATCM also provides air quality benefits by reducing 

ozone formation, as HCHO is a compound that undergoes atmospheric 

transformations to form ozone. In consideration of the data analyses performed 

herein, staff has determined that no significant adverse environmental impacts 

should occur as a result of adopting this ATCM. This chapter describes the 

potential impacts that the proposed ATCM may have on the environment. 

A. Legal Requirements 

The California Environmental Quality Act (CEQA) and CARB policy require an 

analysis be performed to determine the potential adverse environmental impacts 

of proposed regulations. To meet this requirement, CARB must assess the 

extent and severity of reasonably foreseeable environmental impacts, and 

respond (in writing) to all significant environmental issues raised in the public 

review period and at the Board hearing. Presently, CARB’s regulatory program 

is certified by the Secretary of Resources (cf. Public Resources Code §21080.5), 

which allows CARB to include an environmental analysis in the Initial Statement 

of Reasons (ISOR) instead of preparing an environmental impact report or 

negative declaration. Written responses to significant environmental issues 

raised by the public will be included in the Final Statement of Reasons (FSOR) 

for the ATCM. 

Public Resources Code §21159 requires that the environmental analysis 

prepared by CARB include analyses of the following “reasonably foreseeable” 

items: 

• Impacts of the methods of compliance; 

• Feasible mitigation measures; and 

• Alternate means of compliance with the ATCM, (see subsection VII.G.). 

With respect to mitigation measures, CEQA requires state agencies to identify 

and adopt feasible mitigation measures that would minimize any significant 

adverse environmental impacts described in the environmental analysis. 

B. Analysis of Reasonably Foreseeable Environmental Impacts 

To manufacture HWPW, PB, and MDF that complies with the proposed Phase 1 

and Phase 2 standards, manufacturers may choose to use an alternative resin 

instead of UF, or modify their existing UF resin through the use of additives. A 

discussion of the potential health effects from the use of isocyanates, melamine, 
Chapter IX Page 222 

phenol and soy flour is provided below and in subsection VII.G. of this staff 

report. The principal compounds considered in the following evaluation are: 

• Phenol (from PF resins); 

• Melamine (as an additive to UF resins); 

• Polyvinyl acetate (as a no added HCHO adhesive for HWPW); 

• Methanol (as an additive/reagent used with UF resins); 

• Methylene Diisocyanate (as a no added HCHO adhesive for MDF); and 

• Soy flour (as a no added HCHO adhesive for HWPW). 

1. Air Quality 

In setting new HCHO emission standards for PB, HWPW, and MDF, reductions 

in statewide HCHO emissions would be expected to occur at all points along the 

distribution chain. Because HCHO is a VOC, the proposed ATCM would also be 

reducing an ozone precursor. For example, the use of soy flour-based resins 

would essentially reduce volatile organic compound emissions to near-zero. As 

some resin systems have lower energy requirements in their manufacturing 

process, reductions in carbon dioxide emissions that contribute to global warming 

would be expected. 

Of the projected alternative resin systems, reports indicate that exposure from air 

may occur for phenol, methanol, and methyl diisocyanate (MDI); however, none 

of these compounds have been classified as carcinogens by IARC (CARB, 

1997a, 1997b; Department of the Environment and Water Resources of the 

Australian Government, Not Dated; National Oceanic and Atmospheric 

Administration, 2003). Current typical UF resins can contain methanol, as a coreactant, however, we believe that Phase 2 emission standards will not result in 

increase in any methanol use. In fact, we anticipate that the future use of 

alternative resin systems, may decrease methanol use. Polyvinyl acetate (PVA) 

contains no hazardous materials under the current OSHA standard and is not 

listed as a carcinogen by IARC (Franklin International, 2006; Gamblin, 1997). In 

the workplace, potential respiratory effects from phenol and MDI have been the 

subject of controls for many years (Gilbert, 1987).

With regard to greenhouse gas emissions, use of an alternative resin system 

may provide a minor increase or decrease in energy-related carbon dioxide 

emissions. Overall, it is assumed that California’s demand for HWPW, PB, and 

MDF will continue to be met by manufacturers in the West, resulting in no net 

change in transport-related carbon dioxide emissions. Although, if the current 

trend continues, increasing amounts of products could be supplied from overseas 

manufacturers, whose market share has grown dramatically in the last ten years 

(Figures VIII-1 to VIII-3). The increase in overseas imports, and associated 

transport-related carbon dioxide emissions, may in part be due to the U.S. 

becoming a growing market for high-emitting products from overseas. As such, 

the establishment of more stringent HCHO emission standards in California may 
Chapter IX Page 223 

help to forestall the rising trend in transport-related carbon dioxide emissions, as 

those products would need to be sold elsewhere and may be sold closer to 

where they are manufactured. 

2. Potential Water Quality Impacts 

Use of any of the alternative resins is not expected to pose a significant threat to 

water quality. Phenol is reported to have a half-life of 2 to 20 days, and does not 

bioaccumulate in aquatic wildlife (Commonwealth of Australia, 2005). Melamine 

has a low toxicity to aquatic life, and is effectively degraded by waste-water 

treatment plants (DSM Melamine, 2002; Organization for Economic Cooperation 

and Development, Not Dated). Due to its miscibility in water, methanol 

principally dissolves and dilutes to very low concentrations in the event of surface 

water exposures (Malcolm Pirnie, 1999). The potential for environmental spills of 

MDI is low, and releases to water result in the formation of polyurea compounds, 

with no toxicological effects (Gilbert, 1987; Yakabe et al., 1999). 

3. Potential Hazardous Waste Impacts 

Potential hazardous waste impacts on soil quality from a spill of the alternative 

resin systems are not expected to be significant. Phenol can be transported to 

soil from air or water, and could possibly accumulate in landfills at low levels. 

Recently, Gusse et al. (2006) demonstrated that biodegradation of phenolic 

resins could be achieved using white rot fungi, which may provide opportunities 

for phenolic resin recycling and/or recovery of production constituents. 

Melamine, if released to soil could pose an accumulation problem, but due to its 

low toxicity, does not pose a significant environmental risk (Organization for 

Economic Cooperation and Development, Not Dated). Low concentrations of 

methanol are unlikely to persist, as it will undergo rapid biodegradation under a 

wide range of geochemical conditions (Malcolm Pirnie, 1999). Spills of MDI will 

result in the formation of soild polyurea compounds, whose ecological impacts 

are likely to be slight and reversible (Gilbert, 1987). 

4. Potential Bioaccumulation Impacts 

The toxicities of soy flour, PVA, and melamine are low, and as such, 

bioaccumulation does not pose a significant environmental risk to humans or 

wildlife. Phenol has a relatively short half-life and does not tend to 

bioaccumulate (Commonwealth of Austrailia, 2005). Bioaccumulation of MDI is 

unlikely due to its high reactivity with hydroxyl radicals in air, and low solubility in 

water (Gilbert, 1987; Yakabe et al., 1999). 
Chapter IX Page 224 

C. Reasonably Foreseeable Feasible Mitigation Measures 

Staff has concluded that no significant adverse environmental impacts would 

occur from implementing the proposed ATCM. As no adverse impacts are 

anticipated, no mitigation measures would be needed. 

 

D. Reasonably Foreseeable Alternative Means of Compliance 

The use of various types of alternative resin systems constitutes the alternative 

means of compliance with the proposed ATCM. The potential health effects 

resulting from the use of the alternative resin systems are discussed in Chapter 

VII of the ISOR. For example, while the use of MDI resin is not expected to be 

widespread, worker safety protocols have been developed in the U.S. for 

facilities that may choose to utilize those resins. Based on the data analyses 

performed and input from public meetings, the proposed HCHO emission limits 

for PB, HWPW, and MDF are needed to reduce emissions to ambient air and 

human exposures in homes, schools, and workplaces. The existence of a 

commercially viable “no added HCHO” technology provides justification for an 

incremental reduction by all manufacturers in the near-term and more stringent 

limits in 2011 to 2012. 

E. Community Health and Environmental Justice 

Environmental justice is a core consideration in CARB’s efforts to provide clean 

air for all California communities (CARB, 2001). The proposed ATCM, calling for 

more stringent HCHO emission limits in selected composite wood products, 

would not cause significant adverse impacts in any community. Rather, 

implementation of the proposed ATCM is aligned with the principle of pollution 

prevention, and would likely reduce exposures to HCHO in all communities, 

including low-income areas and ethnically diverse communities. 

F. References 

CARB. 1997a. Methanol. In: CARB. Toxic Air Contaminant List Summaries, p. 

631-634. Stationary Source Division, Sacramento, CA. 

CARB. 1997b. Phenol. In: CARB. Toxic Air Contaminant List Summaries, p. 

767-770. Stationary Source Division, Sacramento, CA. 

CARB. 2001. Policies and Actions for Environmental Justice. Planning & 

Technical Support Division, Sacramento, CA. 13 pp.

Commonwealth of Australia. 2005. Phenol. Substance fact sheet. From: 

http://www.npi.gov.au/database/substance-info/profiles/70.html Accessed: 26 

February 2007. 
Chapter IX Page 225 

Department of the Environment and Water Resources of the Australian 

Government. 2001. Not Dated. State of Knowledge Report: Air Toxics and 

Indoor Air Quality in Australia. Methylenebis(phenylisocyanate) MDI. From: 

http://www.environment.gov.au/atmosphere/airquality/publications/sok/profiles/m

ethylenebis.html. Accessed: 26 February, 2007. 

DSM Melamine. 2002. Safety Data Sheet: Melamine. Accessed: 26 February, 

2007. From: http://www.dsm.com/en_US/downloads/dmm/msdsenglish3.pdf 

Franklin International. 2006. Material Safety Data Sheet: Titebond II Premium 

Wood Glue. From: http://titebond.com/MsdsTB.asp?Frames='Y'&prod=5008 

Accessed: 26 February 2007. 

Gamblin R. 1997. Material Safety Data Sheet: Poly Vinyl Acetate Glue. From: 

http://www.gamblincolors.com/msds/pva.html Accessed: 26 February 2007. 

Gilbert DS. 1987. Fate of TDI and MDI in air, soil, and water. Polyurethanes 

World Congress 1987: 50 Years of Polyurethanes. From: http://md1.csa.com. 

Accessed: 26 February, 2007. 

Gusse AC, PB Miller, and TJ Volk. 2006. White-rot fungi demonstrate first 

biodegradation of phenolic resin. Environmental Science & Technology, 40: 

4196-4199. 

Malcolm Pirnie Incorporated. 1999. Evaluation of the Fate and Transport of 

Methanol in the Environment. Accessed: 26 February, 2007. From: http://wwwerd.llnl.gov/FuelsoftheFuture/pdf_files/evaluation.pdf. 

National Oceanic and Atmospheric Administration. 2003. Material Safety Data 

Sheet: Phenol Liquid. From: http://www.sefsc.noaa.gov/HTMLdocs/phenol.htm 

Accessed: 26 February 2007. 

Organization for Economic Cooperation and Development (OECD). Not Dated. 

SIDS Initial Screening Profile: Melamine. Accessed: 26 February, 2007. From: 

http://www.inchem.org/documents/sids/sids/108781.pdf. 

Yakabe Y, KM Henderson, WC Thompson, D Pemberton, B Tury, and RE Bailey. 

1999. Fate of methylenediphenyl Diisocyanate and toluene Diisocyanate in the 

aquatic environment. Environmental Science & Technology, 33: 2579-2583.