NAC/Interim 1: 07/2008



## INTERIM

ACUTE EXPOSURE GUIDELINE LEVELS (AEGLs)

FOR

FORMALDEHYDE

(CAS Reg. No. 50-00-0)FORMALDEHYDE NAC/Interim 1: 07/2008; Page 2 of 71

PREFACE 1

2 Under the authority of the Federal Adviso ry Committee Act (FACA) P. L. 92-463 of 3 1972, the National Advisory Committee for Acute Exposure Guideline Levels for Hazardous 4 Substances (NAC/AEGL Committee) has been es tablished to identify, review and interpret 5 relevant toxicologic and other scientific data and develop AEGLs for high priority, acutely toxic 6

chemicals. 7

8 AEGLs represent threshold exposure limits for the general public and are applicable to 9 emergency exposure periods ranging from 10 minutes to 8 hours. Three levels

CAEGL-1, 10

AEGL-2 and AEGL-3

Care developed for each of five exposure periods (10 and 30 minutes, 1 11 hour, 4 hours, and 8 hours) and are distinguished by va rying degrees of severity of toxic effects. 12

The three AEGLs are defined as follows: 13

14 AEGL-1 is the airborne concentration (expressed as parts per million or milligrams per 15 cubic meter [ppm or mg/m 3 ]) of a substance above which it is predicted that the general 16 population, including susceptible individuals, could experience notable discomfort, irritation, or 17 certain asymptomatic, non-sensory effects. Ho wever, the effects are not disabling and are 18 transient and reversible upon cessation of exposure. 19

20 AEGL-2 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above 21 which it is predicted that the general population, including susceptible individuals, could 22 experience irreversible or other serious, long-lasting adverse health effects or an impaired ability 23
to escape. 24

25 AEGL-3 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above 26 which it is predicted that the general population, including susceptible individuals, could 27 experience life-threatening health effects or death. 28

29 Airborne concentrations below the AEGL-1 represent exposure levels that could produce 30 mild and progressively increasing but transi ent and nondisabling odor, taste, and sensory 31 irritation or certain asymptomatic, non-sensory eff ects. With increasing airborne concentrations 32 above each AEGL, there is a progressive increase in the likelihood of occurrence and the 33 severity of effects described for each corresponding AEGL. Although the AEGL values 34 represent threshold levels for the general public, including susceptible subpopulations, such as 35 infants, children, the elderly, persons with asthma, and those with other illnesses, it is recognized 36 that individuals, subject to unique or idiosyncratic responses, could experience the effects 37 described at concentrations below the corresponding AEGL. 38FORMALDEHYDE NAC/Interim 1: 07/2008; Page 3 of 71

1

TABLE OF CONTENTS 2

PREFACE........................................................................................................................ .............................2 3

LIST OF TABLES................................................................................................................. .......................6 4

EXECUTIVE SUMMARY.............................................................................................................. .............7 5

1. INTRODUCTION................................................................................................................ ................9 6

2. HUMAN TOXI CITY DATA......................................................................................................... ....10 7

2.1. Acute Lethality ........................................................................................................... ...................10 8

2.2. Nonlethal Toxicity ........................................................................................................ .................10 9

2.2.1. Odor threshold.......................................................................................................... .................10 10 2.2.2. Indoor Air Exposures .................................................................................................... ............11 11 2.2.3. Occupational Exposures .................................................................................................. ..........11 12

2.2.4. Clinical Studies........................................................................................................ ..................13 13

2.3. Neurotoxicity ............................................................................................................. ....................26 14

2.4. Developmental/Reproductive Toxicity....................................................................................... ...27 15

2.5. Genotoxicity.............................................................................................................. .....................27 16

2.6. Carcinogenicity........................................................................................................... ...................27 17

2.7. Summary................................................................................................................... .....................28 18

3. ANIMAL TOXI CITY DATA........................................................................................................ ....29 19

3.1. Acute Lethality ........................................................................................................... ...................29 20

3.1.1. Rats.................................................................................................................... ........................30 21

3.1.2. Mice.................................................................................................................... .......................31 22

3.2. Nonlethal Toxicity ........................................................................................................ .................31 23

3.2.1. Nonhuman Primates ....................................................................................................... ...........32 24

3.2.2. Rats.................................................................................................................... ........................32 25

3.2.3. Mice.................................................................................................................... .......................34 26 3.2.4. Guinea Pigs............................................................................................................. ...................35 27

3.3. Neurotoxicity ............................................................................................................. ....................36 28

3.4. Developmental/Reproductive Toxicity....................................................................................... ...36 29

3.5. Genotoxicity.............................................................................................................. .....................36 30

3.6. Chronic Toxicity/Carcinogenicity .......................................................................................... .......37 31FORMALDEHYDE NAC/Interim 1: 07/2008; Page 4 of 71

3.7. Summary................................................................................................................... .....................41 1

4. SPECIAL CONS IDERATIONS ...................................................................................................... ..43 2

4.1. Metabolism and Disposition ................................................................................................ ..........43 3

4.2. Mechanism of Toxicity..................................................................................................... .............43 4

4.3. Structure-Activity Relationships.......................................................................................... ..........44 5

4.4. Other Relevant Information ................................................................................................ ...........44 6 4.4.1. Species Variability..................................................................................................... ................44 7 4.4.2. Susceptible Populations................................................................................................. ............45 8 4.4.3. Concentration-Exposur e Duration Relationship........................................................................46 9 4.4.4. Concurrent Exposure Issues .............................................................................................. ........47 10

5. DATA ANALYSIS FOR AEGL-1 .................................................................................................... 47 11

5.1. Summary of Human Data Relevant to AEGL-1 ............................................................................47 12

5.2. Summary of Animal Data Relevant to AEGL-1............................................................................47 13

5.3. Derivation of AEGL-1 ...................................................................................................... .............48 14

6. DATA ANALYSIS FOR AEGL-2 .................................................................................................... 48 15

6.1. Summary of Human Data Relevant to AEGL-2 ............................................................................48 16

6.2. Summary of Animal Data Relevant to AEGL-2............................................................................49 17

6.3. Derivation of AEGL-2 ...................................................................................................... .............50 18

7. DATA ANALYSIS FOR AEGL-3 .................................................................................................... 50 19

7.1. Summary of Human Data Relevant to AEGL-3 ............................................................................50 20

7.2. Summary of Animal Data Relevant to AEGL-3............................................................................50 21

7.3. Derivation of AEGL-3 ...................................................................................................... .............51 22

8. SUMMARY OF AEGLS ............................................................................................................ .......51 23

8.1. AEGL Values and Toxicity Endpoints ........................................................................................ ..51 24

8.2. Comparison with Other Standards and Guidelines ........................................................................51 25

8.3. Data Adequacy and Research Needs .......................................................................................... ...54 26

9. REFERENCES.................................................................................................................. .................54 27FORMALDEHYDE NAC/Interim 1: 07/2008; Page 5 of 71

APPENDIX A: LEVEL OF DI STINCT ODOR AWARENESS ..............................................................63 1

APPENDIX B: CARCINOGE NICITY ASSESSMENT...........................................................................64 2

APPENDIX C: DERIVATI ON OF AEGL VALUES ...............................................................................65 3

APPENDIX D: CATEGORY GRAPH OF TOXICITY DATA AND AEGL VALUES..........................68 4

APPENDIX E: DERIVATION SUMMARY FOR FORMALDEHYDE AEGLS....................................69 5
6FORMALDEHYDE NAC/Interim 1: 07/2008; Page 6 of 71

1

LIST OF TABLES 2

3
TABLE 1. Summary of AEGL Values for Formal dehyde ............................................................................... ..........8 4

TABLE 2. Chemical and Physical Pr operties ...................................................................................... ....................10 5

TABLE 3. Irritant Effects of Formal dehyde in Controlle d Human Studies .......................................................... ...13 6 TABLE 4. Summary of Acute Lethal Inha lation Data in Labor atory Anim als........................................................3 0 7 TABLE 5. Summary of Subchronic and Chronic/Carc inogenicity Studies in Laboratory An imals.........................39 8

TABLE 6. AEGL-1 Valu es for Fo rmalde hyde ........................................................................................ ................48 9

TABLE 7. AEGL-2 Valu es for Fo rmalde hyde ........................................................................................ ................50 10

TABLE 8. AEGL-3 Valu es for Fo rmalde hyde ........................................................................................ ................51 11
TABLE 9. Summary of AEGL Values ................................................................................................ ....................51 12

TABLE 10. Extant Standards a nd Guidelines fo r Formal dehyde ..................................................................... .........53 13

14FORMALDEHYDE NAC/Interim 1: 07/2008; Page 7 of 71

EXECUTIVE SUMMARY 1

2 Formaldehyde is a colorless flammable gas with a pungent, suffocating odor. It is 3 ubiquitous in the atmosphere as a constituent of smog, in homes that contain urea-formaldehyde 4 foam insulation or particle board construction, and at production sites. It is a naturally-occurring 5 constituent of many foods and is a normal metabolite in the human body. 6

7 The data base on formaldehyde is robust, with human and animal studies that address 8 various endpoints and cover acute through chroni c exposure durations. The primary effect 9 during short-term exposures is irritation of the ey e, nose, and throat. At low concentrations of 10 1 to 3 ppm, formaldehyde is well scrubbed in the nasal passages of both humans and rodents and 11 does not reach the lower respiratory tract. At higher concentrations, formaldehyde is an extreme 12 irritant. Chronic studies with moderate concentrations (14 ppm) result in carcinomas of the 13 anterior nasal passages of the rat. Formaldehyde is a weaker carcinogen in the mouse and is not 14 carcinogenic in the hamster. Because formaldehyde is so highly reactive and rapidly 15 metabolized/detoxified by the tissues of the nasal passages, inhalation is unlikely to result in 16 cancers at remote sites. Epidemiology studies have failed to show a clear relationship between 17 exposure and carcinogenicity. 18

19 The irritant properties of formaldehyde and its effects on pulmonary function parameters 20 have been reported in 22 clinical studies with over 500 healthy and sensitive subjects (potentially 21 sensitive subjects included both asthmatics and subjects who reported sensitivity to 22 formaldehyde). In most of the studies, eye irritation was the most sensitive endpoint. At 23 concentrations <1 ppm, there is no clear dose-response to the irritant properties of formaldehyde, 24 and responses do not differ greatly from those of control atmospheres. At 1 ppm, the eye 25 irritation response ranges from slight to moderate, with adaptation occurring with prolonged 26 exposure. At 3 ppm for several hours, the response in heavily exercising individuals and 27 moderately exercising individuals is similar (Green et al. 1987). Eye, nose, and throat irritation 28 ranged from mild to moderate, and there were small, transient decrements in pulmonary function 29 parameters in healthy subjects. In the absence of exercise, there are no decrements in pulmonary 30 function parameters in either healthy or asthmatic subjects inhaling 3 ppm for 3 hours 31 (Sheppard et al. 1984; Sauder et al. 1986; 1987). 32

33 The AEGL-1 was based on a NOAEL for eye irritation in a single study with subjects 34 whose eyes were sensitive to formaldehyde (Bender et al. 1983). In this study, groups of 5 to 28 35 healthy subjects were exposed eye-only for 6 minutes to 0, 0.35, 0.56, 0.7, 0.9, or 1.0 ppm. The 36 subjects had been selected for their response to formaldehyde at 1.3 or 2.2 ppm, i.e., subjects that 37 did not report eye irritation during previous expos ures to 1.3 or 2.2 ppm were excluded from the 38 study. At 0.35 to 0.9 ppm, the subjects = subjective eye irritation responses ranged from none to 39 slight, the same as their responses to clean air. The 0.9 ppm concentration was selected as the 40 basis for the AEGL-1. No intraspecies uncertainty factor was applied as no additional sensitive 41 populations were identified [there were no significant decrements in pulmonary function 42 parameters in exercising asthmatic subjects at 2 or 3 ppm, and asthmatic subjects reported less 43 than moderate eye irritation, the same as healthy subjects, at these concentrations (Green et al. 44 1987; Kulle et al. 1987; Sauder et al. 1987)]. Because several studies show there is adaptation to 45 irritation at this low concentration, the 0.9 ppm concentration was applied across all exposure 46 durations. This value is supported by the fact that animal studies show there is no damage to the 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 8 of 71

respiratory epithelium during single (Morgan et al . 1986b) or repeated exposures to 1 or 2 ppm 1 (Rusch et al. 1983; Maronpot et al.1986; Woutersen et al. 1987). 2

3 The AEGL-2 was based on the clinical study of Sim and Pattle (1957). Twelve healthy 4 male subjects inhaled 13.8 ppm for 30 minutes. Initially, the exposure caused considerable nose 5 and eye irritation. Mild lacrimation continued for some period of time. The eye irritation was 6 not considered severe, and adaptation occurred in about 10 minutes. Mild lacrimation at 13.8 7 ppm (rounded to 14 ppm) with adaptation was considered the threshold concentration for the 8 inability to escape. The lacrimation experienced by Barnes and Speicher (1942) at 20 ppm 9 during short exposures might impair the ability to escape. The 14 ppm concentration may also 10 be close to the threshold for an increase in airways resistance (Douglas 1974). No intraspecies 11 uncertainty factor was applied to the 14 ppm concentration because application of an uncertainty 12

factor of $ 3 would lower the value to close to a no-effect concentration in several studies with 13 exercising asthmatics. Because the endpoint is eye and nose irritation to which adaptation 14 occurs, the same value was used across all exposure durations. 15

16 The AEGL-3 values were based on the highest non-lethal value for the rat following a 4- 17 hour exposure to 350 ppm (Nagorny et al. 1979). The value was adjusted by interspecies and 18 intraspecies uncertainty factors of 3 each for a to tal of 10. These uncertainty factors, applied to 19 irritants, are protective of sensitive populations. Furthermore, application of larger uncertainty 20 factors, e.g., a total of 30, would reduce the value to the level of the AEGL-2. No data on time21 scaling were found. Therefore, the default value of n = 3 when scaling to shorter exposure 22 periods (NRC 2001) was applied. The 8-hour value was set equal to the 4-hour value because 23 formaldehyde is well scrubbed in the nasal passages. Furthermore, application of the default of n 24 = 1 when scaling to longer time periods would result in an 8-hour value of 18 ppm, similar to the 25 8-hour AEGL-2. The 8-hour value is supported by sublethal concentrations in additional animal 26 studies. For example, no deaths occurred in rats that inhaled 35 ppm for 18 hours 27 (Murphy et al. 1964). 28

29

The calculated values are listed in Table 1 below. 30

31

TABLE 1. Summary of AEGL Values for Formaldehyde

Classification 10-min 30-min 1-h 4-h 8-h Endpoint (Reference)

AEGL

B 1 a (Nondisabling) 0.90 ppm (1.1 mg/m 3 ) 0.90 ppm (1.1 mg/m 3 ) 0.90 ppm (1.1 mg/m 3 ) 0.90 ppm (1.1 mg/m 3 ) 0.90 ppm (1.1 mg/m 3 ) NOAEL for eye irritation - sensitive human subjects (Bender et al. 1983)

AEGL

B 2 (Disabling) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 ) Mild lacrimation with adaptation - humans (Sim and Pattle 1957)

AEGL

B 3 (Lethal) 100 ppm (123 mg/m 3 ) 70 ppm (86 mg/m 3 ) 56 ppm (69 mg/m 3 ) 35 ppm (43 mg/m 3 ) 35 ppm (43 mg/m 3 ) Highest non-lethal value - rat (Nagorny et all 1979)

a Most individuals will notice the distinct, pungent odor of fo rmaldehyde at the AEGL-1. The Level of Distinct Odor 32
Awareness is 3.6 ppm. 33

34FORMALDEHYDE NAC/Interim 1: 07/2008; Page 9 of 71

1. INTRODUCTION 1

2 Formaldehyde is a flammable colorless gas with a pungent, suffocating odor. Its high 3 chemical reactivity, good thermal stability, and ability to polymerize make it a useful material in 4 the synthesis of a wide variety of products. The most common form of the material is aqueous 5 solutions (formalin), with a formaldehyde content of 37-50%, by weight. Paraformaldehyde is a 6 solid polymer of formaldehyde which can be easily vaporized to its monomeric form (O = Neil et 7 al. 2001). Chemical and physical properties are listed in Table 2. 8

9 Total annual capacity for production in the United States in 1998 was 11.3 billion 10 pounds. The primary method of manufacture is from methanol with either silver or a metal oxide 11 as catalyst (ATSDR 1999). Most formaldehyde produced in the United States (23%) is used in 12 urea-formaldehyde resins. Other uses include phenolic resins (19%), acetylenic chemicals 13 (12%), polyacetal resins (11%), methylene diisocyanate (6%), pentaerythritol (5%), urea14 formaldehyde concentrates (4%), hexamethylenetetramine (4%), melamine resins (4%), and 15 miscellaneous (12%) (ATSDR 1999). The phenolic, urea, and melamine resins are used in the 16 manufacture of plywood, fiberboard, and partic le board. Worldwide production in 2000 was 21, 17 547 thousand tons (IARC 2006). 18

19 Formaldehyde is ubiquitous in the environment as it is found in a great number of 20 consumer products such as cosmetics, permanent press fabrics, particle board, plywood, floor 21 coverings, office furniture, and urea-formaldehyde foam insulation. Cigarette smoke may 22 contain up to 40 ppm formaldehyde (Turoski 1984). Outdoors, the major source of atmospheric 23 formaldehyde is from auto emissions and from the photooxidation of hydrocarbons in auto 24 emissions (NRC 1981). 25

26 Formaldehyde is found in a large number of common foods and drinks. It occurs as a 27 natural constituent of raw fruits including pears, apples, tomatoes, and white radish in amounts 28 varying from 3.7 to 60 ppm. It also occurs in raw vegetables such as cabbage, carrots, green 29 onions, and spinach in amounts varying from 3.3 to 26.3 ppm. Its maximum oral intake is 30 estimated to be 14.2 mg/person/day (Feron et al. 1991). 31

32 Formaldehyde is an essential metabolic intermediate in all cells. It is produced during 33 the normal metabolism of serine, glycine, methionine, and choline and also by the demethylation 34 of N-, S-, and O-methyl compounds. As such, it is a normal metabolite, and enters into the chain 35 of biochemical events in humans and other animals to give rise to essential cellular substances 36 (NRC 1981). 37

38FORMALDEHYDE NAC/Interim 1: 07/2008; Page 10 of 71

TABLE 2. Chemical and Physical Properties

Parameter Value Reference
Synonyms Methanal, oxomethane, oxymethylene, methylene oxide formic aldehyde, methyl aldehyde O = Neil et al. 2001

Chemical formula CH 2 O O = Neil et al. 2001 Molecular weight 30.03 O = Neil et al. 2001
CAS Reg. No. 50-00-0 ATSDR 1999 Physical state Gas O = Neil et al. 2001 Solubility in water Very soluble, up to 55%

980 L/L water at 20 E C O = Neil et al. 2001

Andersen and Molhave 1983 Vapor pressure @ 25 E C 3883 mm Hg ATSDR 1999 Vapor density (air =1) 1.067 O = Neil et al. 2001 Liquid density (water =1) 0.815 g/mL ATSDR 1999 Melting point

S 92 E C O = Neil et al. 2001 Boiling point

S 19.5 E C O = Neil et al. 2001 Flammability limits @ 25 E C 7-73% ATSDR 1999 Ignition temperature 300 E C O = Neil et al. 2001 Conversion factors 1 ppm = 1.23 mg/m 3
1 mg/m 3 = 0.813 ppm ATSDR 1999

1

2

2. HUMAN TOXICITY DATA 3 2.1. Acute Lethality 4

5 No reports of deaths from short-term inhalation of formaldehyde were located. 6

7 2.2. Nonlethal Toxicity 8

9 Formaldehyde is an eye, upper respiratory tract, and skin irritant. Dermal contact may 10 cause sensitization. Because it is extremely water soluble, it is extensively A scrubbed @ in the 11 anterior nasal passages. The irritant effects of formaldehyde from construction products in the 12 home, occupational exposures, and controlled clinical studies have been reported. 13

14

2.2.1. Odor threshold 15

16 Formaldehyde has a distinct, pungent odor. The odor threshold has been studied by 17 several groups. The odor of formaldehyde can be recognized by most individuals at 18 concentrations below 1 ppm. The concentration at which a group of observers can detect the 19 odor in 50% of the presentations is between 0.05 and 0.18 ppm. The individual odor detection 20

threshold covers A over two powers of ten, @ and the distribution is extremely positively skewed 21 (WHO 1989). Berglund et al. (1987) reported that the 50 th percentile detection threshold was 22 0.145 ppm, the 10-percentile threshold was 0.020 ppm and the 90-percentile threshold was 0.5 23 ppm. The Level of Distinct Odor Awareness (LOA) was derived using the data of Berglund et 24 al. (1987). Calculations are contained in A ppendix A. The LOA for formaldehyde is 3.6 ppm. 25

26 The odor threshold was measured for 64 subjects, ages 17-64 years, in a climate27 controlled chamber (Pettersson and Rehn 1977). The subjects placed their heads in a hood 28 during the exposures. The exposures were alternat ely to a formaldehyde-air mixture or clean air, 29FORMALDEHYDE NAC/Interim 1: 07/2008; Page 11 of 71

given in a random manner, and the subjects had to determine in which of the two exposures 1 formaldehyde was present. Concentration ranged from 0.01 to 1.0 ppm. The lowest detectable 2 odor was 0.04 ppm. There was a dose-response to odor detection above this level. At slightly 3 greater than 1.0 ppm all 64 subjects could correctly detect the odor. 4

5 In another study that addressed the odor threshold as well as effects on the central 6 nervous system, a panel of 12 persons, ages 19-64, judged 0.09 ppm as the threshold 7 concentration for odor perception (Melekhina 1964). Following adaptation to a climate 8 controlled chamber, the threshold for odor perception was 0.06 ppm. Additional odor threshold 9 values cited in U.S. EPA (1992) range from 0.06 to 0.3. Amoore and Hautala (1983) cite 0.83 10 ppm and Billings and Jonas (1981) cite 1.0 ppm as odor thresholds. The threshold for odor 11 recognition by a trained odor panel was 1.0 ppm (Leonardos et al. 1969). The odor was 12 characterized as hay/straw-like, pungent. 13

14 2.2.2. Indoor Air Exposures 15

16 As noted, formaldehyde is a commonly encountered environmental chemical. 17 Consumers may be exposed to formaldehyde from a number of sources, including cigarette 18 smoke, formaldehyde-containing resinous products, and cooking. Formaldehyde is present 19 indoors as an off-gassed product of construction materials such as plywood and urea20 formaldehyde foam insulation. An important source of indoor formaldehyde is cigarette smoke 21 (WHO 1989). The majority of complaints registered with the Consumer Product Safety 22 Commission involved eye and upper respiratory tract irritation attributed to off-gassing from 23 formaldehyde foam insulation, particle board, or plywood; concentrations ranged from 0.01 to 32 24 ppm (NRC 1980). Indoor air exposures can exceed 1.0 ppm (ATSDR 1999), but are generally 25 lower than in the work environment. A study of nearly 2000 residents of mobile and 26 conventional homes that reported symptoms related to formaldehyde was undertaken by Ritchie 27 and Lehnen (1987). Measured concentrations ranged from <0.1 ppm to ≥ 0.3 ppm. The study 28 reported a positive dose-response between formaldehyde concentrations and self-reported health 29 complaints. In all cases complaints were substantially more frequent with concentrations above 30 0.3 ppm. The percentage of respondents reporting eye irritation at <0.1, 0.1 to <0.3, and ≥ 0.3 31 ppm were similar between mobile and conventional homes (2 vs 1%, 32 vs 12%, and 93 vs 89%, 32 respectively). The contribution of smoking to ey e irritation was noted in both types of homes, 33 but exposure to other chemicals was not evaluated. The participants received a free medical test 34 and so were self-selected with a potential bias. 35

36 2.2.3. Occupational Exposures 37

38 Occupational sources and concentrations have been reviewed by several agencies. 39 Several such surveys are cited here as examples of past routine exposures. In some cases 40 symptoms were also reported, but many of the survey results are complicated by the presence of 41 other chemicals in the manufacturing process. Usually the frequency, exact concentration, and 42 duration of exposure are not provided. A few recent occupational studies are also cited. 43

44 NIOSH (1976) reviewed early reports on occupational exposures to formaldehyde. In these 45 reports, irritation of the upper respiratory tract was reported at formaldehyde concentrations 46 between 0.09 and 11 ppm. Sampling periods varied, but periods of 15 and 30 minutes were 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 12 of 71

reported in some studies. Examples of occ upations and workplace concentrations follow: 1 handling flame-proof fabrics, 1-11 ppm; dr ess shop, 0.13-0.45 ppm; resin manufacturing and 2 paper plant, 16-30 ppm; paper conditioning installation, 0.9-1.6 ppm; funeral home (use of 3 formaldehyde and paraformaldehyde in embalming process), average 0.25-1.39 ppm with range 4 up to 5.26 ppm; clothing store, 0.9-3.3 ppm; textile garment factory, 0.9-2.7 ppm (irritation noted 5 followed by adaptation), wood processing plant, 2.1-8.9 ppm, ranging up to 31 ppm (illnesses 6 noted); and two laminating plants using phenol-resorcinol glue (which emits formaldehyde), 7 0.04-10.9 ppm. Concentrations in the latter two plants depended on area of the plant and the 8 specific glue used. The authors reported that em ployees objected when airborne concentrations 9 exceeded 1 ppm, and the odor at concentrations of 4.2 to 10.9 ppm was considered unbearable. 10 Dermatitis was a common complaint in workers handling formaldehyde-impregnated materials. 11

12 OSHA (1996) estimated that in the late 1980s over 2 million workers were exposed to 13 formaldehyde. Most of these workers were in the garment industry. About 1.9 million workers 14 in the apparel, furniture, paper mill and plastic molding industries were exposed to between 0.1 15 and 0.5 ppm. Approximately 123,000 workers were exposed to between 0.5 and 0.75 ppm, and 16 about 84,000 were exposed to 0.75 to 1 ppm. A U.S. EPA (1982) survey of occupational 17 exposures found mean concentrations of 0.1 to 0.9 ppm, with ranges up to 2.2 ppm. Exposures 18 were highest during the direct manufacture of formaldehyde. IARC (2006) also summarized 19 workplace concentrations. Mean concentrations in formaldehyde and resin manufacturing 20 plants, plywood mills, particle-board mills, furniture factories, textile mills and garment 21 factories, foundries, mortuaries, building sites, etc., ranged from 0.1 to 38 ppm (range, <0.01 to 22 61 ppm). 23

24 Horvath et al. (1988) conducted a well-designed study with a formaldehyde exposed 25 group and an unexposed group. The exposed workers were employed in a particle board and 26 molded plastics plant; the duration of exposure was from <1 to 20 years. Formaldehyde 27 concentrations ranged from 0.17 to 2.93 ppm (mean 0.69 ppm). Formaldehyde concentrations 28 were determined by both passive and active sampling procedures. On the day of examination, 29 test subjects were monitored with formaldehyde monitors (3M, St. Paul, MN; lower limit of 30 sensitivity of 0.1 ppm). Area samples were taken with an sampling train that employed a liquid 31 medium impinger containing 1% sodium bisulfite. Both types of samples were analyzed 32 according to NIOSH 77-157A. Nuisance particles of softwood dust were present at similar 33 concentrations at the particle board plant and the two control plants. The control group was 34 employed in the food-processing industry. A symptom questionaire and spirometry were 35 administered to all participants before and after the workshift. 36

37 Spirometry results showed that exposed workers had some evidence of an acute decline 38 in some pulmonary function parameters. The authors considered the respiratory changes “small 39 and probably transient.” As baseline values were similar among controls and exposed workers, 40 the authors concluded that exposure to these low levels for up to ten years did not appear to 41 cause permanent respiratory impairment. Spirometry results showed that exposed workers had 42 some evidence of an acute decline in some pulmonary function parameters. These consisted of 43 statistically significant postshift decreases in forced expiratory volume in 1 second divided by 44 percent forced vital capacity (1%), peak expiratory flow rate during the middle half of the forced 45 vital capacity (5%), forced expiratory flow at 50% and 75% of the forced vital capacity (4% and 46 7%). The authors considered the respiratory changes “small and probably transient.” Controls 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 13 of 71

showed 1% declines in forced expiratory volume in 1 second and forced vital capacity (not 1 significant in the control group). As baseline values were similar among controls and exposed 2 workers, the authors concluded that exposure to the low levels of formaldehyde for up to ten 3 years did not appear to cause permanent respiratory impairment. Respiratory complaints were 4 higher in the exposed group than the control group for cough (35% vs 19%), chest pains (9% vs 5 2%), production of mucus (27% vs 10%) burning sensation of the nose (28% vs 2%), nasal 6 congestion (34% vs 14%), and dry or burning throat (22 vs 4%). The exposed group also 7 reported burning eyes with a greater frequency that the control group (40% vs 9%). Frequencies 8 between the control and exposed group were similar for shortness of breath and wheezing. 9

10 The responses of medical students to formaldehyde in a gross anatomy laboratory 11 compared with those of non-exposed students were reported in two studies. In the first study, 12 Akbar-Khanzadeh et al. (1994) found no statisti cally significant differences in pulmonary 13 function parameters (FVC, FEV 1 , FEV 3 and FEF 25-75% ) in 12 subjects exposed to an estimated 14 TWA of 1.24 ppm for 2- to 3-hour periods. In the second study (Akbar-Khanzadeh and Mlynek 15 1997), 50 medical students were exposed to a mean concentration of 1.88 ppm (range, 0.30-4.45 16 ppm) for 3 hours. These 157-minute samples were taken in the breathing zone of the students. 17 The control group consisted of 36 nonexposed physical therapy students. Eye and nose irritation 18 were reported by more than 70% of the exposed students. Respiratory function parameters for 19 both groups increased in a manner related to diurnal variation, but there was no relationship 20 between concentration of formaldehyde in the br eathing zone and changes in respiratory function 21 of exposed subjects. 22

23

2.2.4. Clinical Studies 24

25 Twenty-three clinical studies with human subjects were located (Table 3). Most of the 26 studies were conducted with controlled environmental exposure chambers supplied with filtered 27 air. Formaldehyde was generated from purifie d paraformaldehyde, although heated solutions of 28 formaldehyde were used in some studies. In the older studies, analytical measurements involved 29 the NIOSH-recommended chromotropic acid method, and more recent studies involved 30 formaldehyde specific air monitors. Pulmonary function parameters were measured with a 31 spirometer and included forced vital capacity (FVC or VC), forced expiratory volume in 1 32 second (FEV 1 ), forced expiratory flow during the middl e half of the functional residual capacity 33 (FEF 25-75 ), and PEF or PEFR (peak expiratory flow or flow rate). Airway resistance (Raw) and 34 functional residual capacity (FRC) were measured with a whole-body pressure plethysmographic 35 technique. Airway resistance was converted to specific airway conductance (SRaw or SGaw). 36 Exercise was incorporated into some of the protocols in order to increase minute ventilation 37 (V E ). 38

39 Entries in Table 3 are listed generally in order of increasing concentrations. Some of the 40 studies address the response of healthy and asthmatic subjects as well as subjects sensitized to 41 formaldehyde. Several studies address eye irritation only which has been identified as the most 42 sensitive irritant response to formaldehyde (Paustenbach et al. 1997). 43

44

TABLE 3. Irritant Effects of Formaldehyde in Controlled Human Studies

Concentration (ppm) Time Subjects/Effect (number of subjects) Reference
0, 0.35, 0.56, 0.7, 6 min Healthy subjects (groups of 7-28), excluded Bender et al. 1983FORMALDEHYDE NAC/Interim 1: 07/2008; Page 14 of 71

TABLE 3. Irritant Effects of Formaldehyde in Controlled Human Studies

Concentration (ppm) Time Subjects/Effect (number of subjects) Reference

0.9, 1.0 non-responders at 1.3 or 2.2 ppm; Eye irritation evaluated: average scores of none to slight at 0.35 to 0.9 ppm; slight to moderate at 1.0 ppm; slight adaptation with

time 0, 0.10, 0.69 90 min Asthmatic nonsmoking subjects (15): No significant change in pulmonary function parameters (FEV 1 and airway resistance) or in bronchial reactivity; no association of subjective ratings of asthmatic symptoms with increasing air

concentrations Harving et al. 1986;

1990

0, 0.41 2 h Healthy occupationally exposed (5) and contact dermatitis subjects (13): No effect on pulmonary parameters (VC,

FEV 1 ); immune response in subjects with contact dermatitis (increased chemiluminescense of neutrophils) Gorski et al 1992

0, 0.41 2 h Healthy (11) and patients with skin hypersensitivity to formaldehyde (9) (all nonsmokers): No differences in response between groups; transient increase in symptoms of sneezing, rhinorrhea, or eye irritation; nasal washings showed increases in eosinophils, albumin, total protein, but not neutrophil, basophil or

mononuclear cells Pazdrak et al. 1993

0, 0.41 2 h Healthy, non-occupationally exposed (10) and occupationally exposed asthmatic subjects (10): No differences in response between groups; transient increase in symptoms of sneezing, rhinorrhea, edema, or itchy eyes; increases in leucocytes and eosinophils in nasal washings; no allergic response; no clinical symptoms of bronchial irritation or effects on pulmonary function parameters (FEV 1 , PEF) Krakowiak et al. 1998

0, 0.40 1 hr 12 volunteers with intermittent asthma and allergy to pollen: No change in lung function (FEV 1 ); no enhanced response to allergens Ezratty et al. 2007

0, 0.17, 0.39, 0.9 5.5 h Form aldehyde exposed workers (32); controls (29): subjective symptoms (headache, tiredness) did not correlate with exposure; no clear effect of concentration on memory; some

concentration-related effects in a few tests (additional speed, response time) but limitations in experimental design and

control issues Bach et al. 1990

1.0 90 min Healthy (9) and formaldehyde-sensitive (9)subjects (previously complained about nonDay et al. 1984FORMALDEHYDE NAC/Interim 1: 07/2008; Page 15 of 71

TABLE 3. Irritant Effects of Formaldehyde in Controlled Human Studies

Concentration (ppm) Time Subjects/Effect (number of subjects) Reference
respiratory effects of urea formaldehyde foam insulation): No effects on pulmonary function parameters (FVC, FEV 1 , max and midexploratory flow rate); complaints of eye irritation, nasal congestion, tearing, and throat irritation; no severity index 0, 1.0 3 h Control asthmatic subjects (4); subjects with asthma attributed to urea formaldehyde foam (23): no differences between groups in immunologic parameters, either before or after exposure; minor immunologic changes in both groups postexposure Pross et al. 1987

0, 0.2, 0.4, 0.8, 1.6 (no concurrent control) 5 h Healthy subjects (16): No differences in nasal airway resistance or pulmonary function parameters; decrease in nasal mucus flow at all concentrations; no discomfort at 0.2 or 0.4 ppm for 2 hours (some slight discomfort reported in the 3 to 5 hours period [conjunctival irritation, dryness of nose and throat] but discomfort rated higher at 0.2 ppm than at 0.4 ppm and only 5 or fewer subjects reported any discomfort); average discomfort scored as slight during exposure to 1.6 ppm and first noted in the latter part of the first hour but decreased somewhat after three hours; no effect on performance on mathematical tests

or number transfer tasks Andersen and Molhave

1983

0, 0.15, 0.3, 0.5 ppm; 0.3 with 4 peaks to 0.6 ppm; 0.5 ppm with 4 peaks to 1.0 ppm;

some exposures combined with ethyl acetate as masking agent 4 h Healthy volunteers, 11 males and 10

females: All concentrations: no significant effects on nasal flow and resistance, pulmonary function, and decision reaction time; slight to moderately increased blinking frequency and conjunctival redness at 0.5 ppm with peaks to 1.0 ppm; subjective eye and olfactory symptoms reported at 0.3 ppm (no-effect level when “negative affectively” considered); subjective nasal irritation at 0.5 ppm with peaks to 1.0 ppm Lang et al. 2008

0, 2.0 (at rest) 0, 2.0 (exercise) 40 min Healthy (15) and asthmatic (15) nonsmoking subjects: No significant decrement in pulmonary function parameters (flow-volume parameters and airway resistance) or bronchial reactivity both at rest and with exercise; subjective symptoms ranged up to severe (but not incapacitating) for odor for some individuals, but median scores for nose, throat and eye irritation were

# moderate; no increase in symptomology Witek et al. 1986; 1987; Schachter et al. 1985; 1986FORMALDEHYDE NAC/Interim 1: 07/2008; Page 16 of 71

TABLE 3. Irritant Effects of Formaldehyde in Controlled Human Studies

Concentration (ppm) Time Subjects/Effect (number of subjects) Reference

with exercise 0, 0.1, 1.0, 3.0 20 min Asthmatic patients who suspected formaldehyde as the cause (13): No significant difference in pulmonary function parameters (FEV 1 , VC); no asthmatic response to formaldehyde challenge Frigas et al. 1984

0, 0.5, 1.0, 2.0, 3.0 at rest;

2.0 with exercise 3 h Healthy non-smoking subjects (19): (9 exposed to 3 ppm and 10 exposed to 0.05 ppm) No significant decrements in pulmonary function parameters (FVC, FEV 1 , FEF 25-75% , SGaw) or increases in bronchial reactivity (methacholine challenge) at any concentration; nasal flow resistanceincreased at 3.0 ppm; significant doseresponse relationship for odor sensation and eye irritation, but eye irritation scored mild (5/9) or mild to moderate 4/9) at 3 ppm; eye irritation began at 1 ppm Kulle et al. 1987;

Kulle 1993

0, 3.0 ppm With heavy exercise (healthy subjects);

moderate exercise (asthmatic subjects) 1 h Healthy (22) and asthmatic (16) nonsmoking subjects: No difference in symptoms between groups; eye, nose and throat irritation scored mild to mild-moderate (group means); small decreases in some pulmonary function parameters in healthy individuals engaging in heavy exercise Green et al. 1987

0, 3.0 With heavy exercise (15 minutes every half hour) 2 h Healthy non-smoking subjects (24): Increase in subjective symptoms of eye, nose and throat irritation, rated mild to moderate on average; small, but statistically significant increase in two (FEF 25-75% , SGaw) of several pulmonary function measurements at some time intervals (no

effect on FEV 1 , FVC, FEV 3 ), no increase in cough Green et al. 1989

0, 3.0 With

intermittent

exercise 3 h Healthy non-smoking subjects (9) non-biologically significant, transient change in some pulmonary function parameters (FEV 1 , FEF 25-75% ); increase in nose/ throat and eye irritation, rated mild to moderate by individuals; only one subject rated eye irritation as moderate Sauder et al. 1986

0, 3.0 3 h Asthmatic non-smoking subjects (9): no significant group change in pulmonary function parameters (FEV 1 , FVC, FEF 25-75% , SGaw, or FRC) or airway reactivity; significant increase in nose, throat (at 30 minutes), and eye irritation (at 60 minutes), rated as none to mild-moderate except for one subject who reported severe eye

irritation Sauder et al. 1987FORMALDEHYDE NAC/Interim 1: 07/2008; Page 17 of 71

TABLE 3. Irritant Effects of Formaldehyde in Controlled Human Studies

Concentration (ppm) Time Subjects/Effect (number of subjects) Reference
0, 1, 3 10 min Asthmatic non-smoking subjects (7): Similar responses in airway resistance following exposure to 0, 1, or 3 ppm with and without exercise (exercise increased all responses) Sheppard et al. 1984

0.03 to 3.2;

0, 1.0, 2.0, 2.9,

4.0 or 1.2, 2.1, 2.8,

and 4.0 37 min (n = 33); 1.5 min (n = 48) Healthy subjects (exposure groups of 33 and 48): Poorer air quality and greater nose irritation reported during the short exposures than during the 37-minute exposure, whereas the opposite was true for eye irritation; with increasing concentrations, both eye and

nose irritation increased from none to A a little; @ objectively-measured eye blinking not affected at 1.2 ppm, but was statistically significantly increased at 2.1 ppm Weber-Tschopp et al.

1977

0, 1, 2, 4, 5 5 min except for 2 ppm (12 min) Healthy students (groups of 7 to 75): Addressed eye irritation only (subjects exposed via goggles): 1 ppm considered threshold for detection; 5 ppm produced severe eye irritation Stephens et al. 1961

8, 13 Short exposures (<15 sec) Healthy/atopic subjects (1-6): Eye irritation for 5 of 6 subjects at 12 ppm but not at 8 ppm for 4 of 5; irritation of the throat at both concentrations; changes in airway resistance Douglas 1974

13.8 30 min Healthy male subjects (12): Nasal and eye irritation with mild lacrimation; adaptation to the eye irritation Sim and Pattle 1957

20 Several min Healthy subjects (2): Lacrimation (within 15-30 seconds); eye, nose, and throat irritation considered objectionable Barnes and Speicher

1942

FVC = 1

FEV 1 = 2

FEF 25-75% , = 3

FRC = 4

PEF = 5

SGaw = 6
7 In an early study that addressed the threshold for eye irritation, Shuck et al. (1966) 8 reported that a linear relationship between reported eye irritation and formaldehyde 9 concentration does not hold below 0.3 ppm. Most subjects experienced the same eye irritation at 10 0.05 and 0.5 ppm. The atmospheres in this study were generated by photooxidation of propylene 11 or ethylene in order to simulate photochemical air pollution. Although formaldehyde was 12 measured in the atmospheres, additional photochemical smog irritants were present. 13

14 In a similar study by the above group (Stephens et al. 1961), the eye irritation potential of 15 both photochemical smog and its individual constituents was examined. Healthy students in 16 groups of 7 to 75 were exposed to formaldehyde via eye goggles. Eye irritation (none, medium, 17FORMALDEHYDE NAC/Interim 1: 07/2008; Page 18 of 71

or severe) was reported every 30 seconds over 5- to 12-minute periods. Medium and severe 1 irritation were considered positive responses. In a static flow system, positive responses ranged 2 from 8% (6/75 individuals) during exposure to 1 ppm to 67% (18/27 individuals) at 5 ppm. In a 3 dynamic flow system, positive responses ranged from 24% (9/37 individuals) for 2 ppm to 100% 4 (7/7 individuals) for 4 ppm. One ppm was considered the threshold for detection and 5 ppm 5 produced severe eye irritation. 6

7 In a study to determine the threshold for eye irritation, Bender et al. (1983) exposed a 8 series of 7-member test panels to increasing concentrations of formaldehyde: 0, 0.35, 0.56, 0.7, 9 0.9, and 1.0 ppm. Several panels were used for most concentrations, i.e., groups of 5-28. The 10 panelists were selected for their ability to respond to formaldehyde at 1.3 and 2.2 ppm (i.e., 11 subjects that were unresponsive to these concentrations were not used). The exposures were 12 eye-only for 6 minutes. Response time in seconds was used as a measure of irritation, and 13 irritation was rated on a scale of 1-3, with 0 = none, 1 = slight, 2 = moderate, and 3 = severe. 14 Response time decreased with increasing exposure concentration, becoming statistically 15 significant, i.e., different from clean air, at 1.0 ppm. The severity index was similar for 16 concentrations of 0.35 ppm to 0.9 ppm (none to slight). The 1.0 ppm was rated slightly to 17 moderately irritating, both at first exposure and after 6 minutes of exposure. There was a slight 18 diminution of response at the end of the 6-minute exposure. 19

20 Harving et al. (1986; 1990) exposed 15 male and female non-smoking asthmatic subjects 21 (ages 15 to 36 years) to concentrations of formaldehyde typically found in the indoor air 22 environment. The study was conducted in a double-blind fashion with the order of exposure 23 randomized. The subjects were selected on the basis of their bronchial reactivity to histamine 24 (mean provocation challenge of 0.37 mg/mL for a 20% reduction in peak expiratory flow rate) 25 and all subjects except one required bronchodilator therapy regularly. Bronchodilator therapy 26 was discontinued 4 hours prior to the study. Subjects were exposed once a week for 90 minutes 27 to 0, 0.10, or 0.69 ppm. Pulmonary parameters consisting of FEV 1 , Raw, SRaw, as well as the 28 flow-volume curves showed no significant changes in the group as a whole or in any individuals. 29 Histamine challenge tests performed for up to 24 hours after the exposures showed no increase 30 in bronchial reactivity. There was no difference in subjective asthmatic symptoms (not 31 described) among the exposure days. 32

33 Gorski et al. (1992) exposed 5 healthy subjects and 13 patients with formaldehyde34 sensitive contact dermatitis to 0.41 ppm for 2 hours in order to measure pulmonary and 35 immunological responses. All patients had smoked for 10-15 years. The immunological 36 response was measured by of neutrophil chemiluminescence (due to the release of free radicals) 37 in the blood. Ventilatory parameters, which were also measured (VC, FEV 1 , and PEF), were not 38 affected by exposure in either group. Chemiluminescence of neutrophils was higher in the 39 sensitive group prior to exposure, increased to a greater degree than in the healthy subjects at 30 40 minutes postexposure, and remained elevated at 24 hours postexposure. Subjective symptoms 41

were not studied. 42

43 In a second study by the above group (Pazdrak et al. 1993), 11 patients with specific skin 44 sensitization to formaldehyde and 5 healthy subjects were evaluated for nasal response to 0.41 45 ppm as observed by changes in nasal lavage fluid. All subjects were nonsmokers. Nasal lavage 46 (saline washings) was performed prior to, immedi ately after the 2-hour exposure period, and at 4 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 19 of 71

and 18 hours after exposure. Albumen, total protein, numbers of eosinophils and basophils, and 1 the proportion of epithelial, neutrophil, eosinophil, basophil, and mononuclear cells were 2 counted or computed. Symptoms of the upper respiratory tract including sneezing, rhinorrhea, 3 mucosal edema, and itching, ranging on a scale 0-7, were summed. A positive clinical challenge 4 was defined as >3. The exposure to formaldehyde caused increases in the number and 5 proportion of eosinophils and elevated albumin and total protein levels in nasal lavage fluid. 6 These elevations were still present 16 hours postexposure. There were no differences in the 7 percent of neutrophil, basophil, or mononuclear cells. No differences in the nasal response 8 between healthy subjects and patients with skin sensitization were observed. Clinical symptoms 9 of itching, sneezing, and congestion were similar between the two groups (approximate score of 10 4 for both groups). Analytical measurements were not made on the day of testing. 11

12 In a third study by the above investigators, the airway response to 0.41 ppm 13 formaldehyde for 2 hours in 10 asthmatic subjects with suspected formaldehyde allergy was 14 compared to that of 10 healthy subjects (Krakowiak et al. 1998). The asthmatic subjects had 15 been exposed to gaseous formaldehyde or formaldehyde solutions in the workplace. The 16 primarily male subjects ranged in age from 19 to 52 years. Spirometry at rest and following 17 bronchial provocation with histamine were recorded before and after the exposure. The study 18 was conducted in a single-blind manner. Clinical symptoms of the upper and lower respiratory 19 tract and evaluation of morphological and biochemical changes in the nasal washings were 20 examined after placebo and formaldehyde exposures. Atopy of the workers was measured as 21 formaldehyde specific serum antibody (IgE). Responses to the challenge were evaluated by 22 saline washings (before and after exposure), nasal symptoms (sneezes, rhinorrhea, edema, and 23 itching; rated on a scale of 0-7), respiratory tr act symptoms, and pulmonary function testing. 24 Nasal symptoms were scored on a scale of 0-7, with >3 considered a positive clinical challenge. 25 The exposure A caused sneezing, itching and congestion in all subjects. @ Immediately after 26 inhalation, nasal symptoms were scored 4.6 and 4.3 by asthmatic and healthy subjects, 27 respectively, with no significant difference between the two groups. This effect was transient. 28 There were no clinical symptoms of bronchial irritation as measured by FEV 1 PEF, and 29 bronchial challenge with histamine. Statistically significant increases in eosinophils in the nasal 30 washings 30 minutes after the exposure were similar in the healthy and asthmatic subjects; 31 leucocytes were also increased in the nasal washings of healthy subjects. There was no increase 32 in basophilic cells or in the mediators tryptase and eosinophil cationic protein. No specific IgE 33 antibodies to formaldehyde were detected in the serum of workers with exposure to 34 formaldehyde. The authors concluded that inhala tion of formaldehyde did not induce a specific 35 allergic response in either asthmatic or healthy subjects and that the observed rhinitis was 36

transient. 37

38 Ezratty et al. (2007) found no change in lung function (measured as a change in FEV 1 , 39 FVC, or PEF) in volunteers exposed to 0.4 ppm formaldehyde for 1 hour. The 12 volunteers (7 40 men and 5 women) ranged in age form 18 to 44 years. All had been diagnosed with intermittent 41 asthma and allergy to pollen. Exposure to formaldehyde had no effect on lung function. Pre42 exposure to formaldehyde had no significant deleterious effect on air allergen responsiveness 43 (methacholine challenge following inhalation of a standardized pollen extract) or sputum 44 inflammatory markers including eosinophilic response. Subjective symptoms were similar 45 between the air only and formaldehyde exposures. No distinct odor was reported by the 46

volunteers. 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 20 of 71

1 Bach et al. (1990) compared the reaction performance of 32 subjects chronically exposed 2 to formaldehyde in the workplace (>5 years) with that of 29 control subjects. The subjects (all 3 male, ages 18-64) were exposed in groups of 4 for 5.5 hours, with the concentration reached 4 within the chamber during the first 30-minutes; exposure concentrations were 0, 0.12, 0.33, or 5 1.0 ppm (measured concentrations of 0, 0.17, 0.39, or 0.9 ppm). Furfurylmercaptan, a coffee 6 aroma constituent, was used to mask the odor of formaldehyde in the chamber. Exposures were 7 arranged in a 4x4 balanced design, involving 4 days of exposure in each of four weeks. This 8 computes to a total of 8 workers and 8 controls being exposed to each concentration. During the 9 exposures, general comfort was assessed with a standard questionnaire with questions involving 10 headache and physical and mental tiredness ( A heavy head @ ). An earlier publication (Bach et al. 11 1987), summarized subjective ratings of irritation in this study. Subjective ratings of irritation 12 did not correlate with a dose-response relationship. The performance tests consisted of digit 13 span, digit symbols, graphic continuous performance, and a computerized addition test. These 14 tests measure short-term memory, ability to concentrate, changes in psychomotor functions. 15 Heavy head and headache, the latter late in the exposure, were reported more often by the control 16 subjects than by the workers. On a linear scale of 60 mm, scores for these parameters for the 17 respective worker and control populations were 6.0 and 8.0 (heavy head; p<0.05) and 2.0 and 5.5 18 (headache; p<0.01). Significant differences were found among the exposures and between the 19 worker and control group, but the results were often confounded by the A inhomogeneity @ of the 20 dose-response. For example, the total time used for the graphic continuous performance test was 21 longest for the worker population at the intermediate dose, 0.33 ppm. Performance was also 22 poorest for the digit span test at 0.33 ppm. 23

24 Lang et al. (2008) conducted a double-blind study in which 21 healthy volunteers (11 25 males and 10 females; ages 19-39 years) were subjected to 10 different formaldehyde exposure 26 conditions: (1) 0 ppm, (2) 0.15 ppm, (3) 0.3 ppm, (4) 0.3 ppm with 4 peaks to 0.6 ppm, (5) 0.5 27 ppm, (6), 0.5 ppm with 4 peaks to 1.0 ppm, (7) 0 ppm, (8) 0.3 ppm and 12-16 ppm ethyl acetate 28 (used as a masking agent), (9) 0.5 ppm with 12-16 ppm ethyl acetate, and (10) 0.5 ppm with 4 29 peaks to 1.0 ppm plus ethyl acetate. Monitoring of the chamber atmospheres was carried out 30 with an Interscan formaldehyde monitor (Asynco ® ). Two air samples were also taken during 31 each exposure and analyzed using dinitrophenyl hydrazine followed by HPLC with UV detection. 32 Up to four subjects at a time were exposed in a 30m 3 chamber; all exposures were for 4 hours. 33 Groups were tested in a random fashion over a 2-week period. Exercise, three 15-minute 34 sessions on a bicycle at 80 watts, took place at 0, 120, and 195 minutes. Objective symptoms 35 (blinking frequency and conjunctival redness), and subjective symptoms (standard questionnaire; 36 scored on 6 levels) were reported after 195 minutes. Reaction time to visual and acoustic stimuli 37 was tested before and after exposure. There were no effects on nasal flow and resistance, 38 pulmonary function or decision reaction time unde r any condition. There were no significant 39 effects on nasal flow and resistance, pulmonary function, and decision reaction time. Slight to 40 moderately increased blinking frequency and conjunctival redness were measured at 0.5 ppm 41 with peaks to 1.0 ppm. Subjective eye and olfactory symptoms were reported at 0.3 ppm; 42 however, when personality traits were evaluated (evaluated in a personality questionnaire) the 43 concentration of 0.3 ppm was no longer an effect concentration. Subjective nasal irritation was 44 reported during the exposure to 0.5 ppm with peaks to 1.0 ppm. Increased symptom scores were 45 reversed 16 hours after exposure. The authors concluded that eye irritation was the most 46 sensitive measurement of formaldehyde exposure. 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 21 of 71

1 In a double-blind, exposure-randomized study, Witek et al. (1986; 1987; see also 2 Schacter et al. 1985; 1986) exposed 15 healthy male and female subjects, mean age 25, and 15 3 male and female subjects classified as mild asthmatics, mean age 22, to clean air or 2.0 ppm 4 formaldehyde for 40 minutes. On a separate day, all subjects exercised for 10 minutes at 450 5 kpm/min prior to the exposure to 2.0 ppm. Subjects refrained from taking medications for 24 6 hours prior to the sessions. Pulmonary function parameters including FVC, FEV 1 , peak 7 expiratory flow rate (PERF), the maximal flow at 50% of the vital capacity, and Raw were 8 measured. Baseline airway reactivity was assessed with progressive doses of methacholine. 9 Subjects completed a symptom survey upon entering the exposure chamber and at 30 minutes 10 into the exposure. Measurements were also taken at 24 hours after exposure. No significant 11 bronchoconstriction or airway resistance was noted during or 24 hours following exposure, 12 although methacholine challenge for some individuals showed non-significant lower thresholds 13 during the exposures to 2.0 ppm. Ratings for respiratory symptoms averaged mild to moderate 14 but ranged up to severe (non-incapacitating) for some individuals. This was especially true for 15 unusual odor. There was no difference in symptomology between rest and exercise sessions. 16

17 Nine subjects that had previously complained of nonrespiratory adverse effects from the 18 urea formaldehyde foam insulation (UFFI) in their homes and nine subjects that were either 19 unaffected by the insulation or had not been exposed to insulation inhaled 1.0 ppm of 20 formaldehyde for 90 minutes or the off-gas from UFFI (Day et al. 1984). The latter material 21 yielded a formaldehyde concentration of 1.2 ppm; the exposure was for 30 minutes. None of the 22 measured pulmonary parameters consisting of FVC, FEV 1 , or FEF 25-75% showed any clinically or 23 statistically significant response to exposure in either group. Incidences of subjective symptoms 24 were equally divided between the two groups of s ubjects. Fifteen of 18 subjects complained of 25 eye irritation during the exposure to 1.0 ppm formaldehyde (severity of symptoms was not 26 described). Fewer subjects complained of nasal congestion (7), tearing (6), and throat irritation 27 (5). Tolerance developed rapidly. 28

29 In a second study by this group (Pross et al. 1987), a broad range of immunologic 30 parameters was studied in subjects with a history of asthma attributed to UFFI. Twenty-three 31 asthmatic subjects came from homes insulated with urea-formaldehyde foam, and four asthmatic 32 control subjects came from conventionally insulated homes. All subjects were exposed to room 33 air for 30 minutes, formaldehyde gas at 1.0 ppm for 3 hours, or the UFFI off products for 3 hours 34 as described in Day et al. (1984) above. Data fr om the UFFI group were not different from data 35 of the subjects whose homes were insulated with conventional methods, either before or after the 36 exposures. Minimal but statistically significant increases in the percent of eosinophils and T8 37 positive lymphocytes were observed after the exposures to urea-foam off-products (including 38 mold) and formaldehyde. Natural killer lymphocyte response to α -interferon was decreased in 39 both groups of subjects after exposure to UFFI. Th e authors stated that the significance of these 40 changes is unclear. 41

42 A series of 5-hour exposures, during which 16 healthy male and female students, ages 43 20-33, inhaled 0.2, 0.4, 0.8, or 1.6 ppm, was conducted by Andersen and Molhave (1983). The 44 students entered the chamber in groups of f our, each group undergoing a different exposure on 45 each of four days. Five of the subjects were smokers. Control data were generated each day 46 during a 2-hour period in the chamber prior to the exposures. The following parameters were 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 22 of 71

measured: nasal mucociliary flow, nasal airflow resistance, FVC, FEV 1 , and FEF 25-75 . Subject 1 airway irritation was noted by each subject using a scale of 1-100. Three times a day, once 2 during the control session and twice during the exposures, the subjects performed two of three 3 mathematical tests, each of 15-minutes duration. These tests involved addition, multiplication, 4 and transfer of numbers to punchcards. The mucu s flow rate slowed during exposures to 0.2 and 5 0.4 ppm, with no further slowing at the higher exposures or after 3 hours. The decrease in mucus 6 flow was most pronounced in the anterior two thirds of the nose; the posterior nasal passage was 7 unaffected. No significant differences were f ound in nasal airway resistance or pulmonary 8 parameters. At 0.2 and 0.4 ppm, no discomfort was registered during the first two hours of 9 exposure. Discomfort increased and was registered earlier with higher concentrations. For 10 example, at the two higher concentrations, di scomfort was reported during the first hour of 11 exposure. Some subjects reported no discomfort at any time during any exposure. Although at 12 least one individual reported a discomfort rating of 50 (described as A discomfort @ ) during the 13 exposure to 1.6 ppm, the average rating was 18 which fell in the middle of the A slight 14

discomfort @ range. Performance on the mathematical tests was unaffected by the exposures. 15

16 Frigas et al. (1984) studied 13 patients with symptoms suggestive of formaldehyde17 induced asthma for response to a formaldehyde inhalation challenge. These patients had been 18 exposed either occupationally or in the home to formaldehyde at concentrations of 0.1 to 1.2 19 ppm for 4 months to 9 years. Reported symptoms during the home or work exposure involved 20 chest tightness, coughing, or wheezing. Five of the patients were being treated with 21 bronchodilators. Treatment was discontinued 24 hours prior to the challenge, and patients were 22 free of symptoms when tested. Patients were challenged with placebo (room air), 0.1, 1.0, or 3.0 23 ppm for 20 minutes via a face mask. Subjective symptoms were also noted. Following the 24 challenge and for up to 24 hours after, no patient had a decrease in FEV 1 greater than during the 25 room air challenge. Irritation of the eyes, nose, and throat and tightness of the chest were 26 reported as frequently with the placebo as with the formaldehyde challenges. The authors were 27 unable to substantiate that formaldehyde exposure in the home or workplace was the cause of the 28 asthmatic symptoms. 29

30 The following series of studies (Kulle et al. 1987; Kulle 1993; Green et al. 1987; Sauder 31 et al. 1986; 1987) were performed by the same gr oup of investigators. Kulle et al. (1987) 32 exposed 19 healthy nonsmoking male and female subjects, mean age 26.3 " 4.7 years, to each of 33 five randomly assigned exposures for three hours. Exposures were separated by one week. Ten 34 subjects were exposed to 0, 0.5, 1.0, or 2.0 ppm at rest or 2.0 ppm with exercise; nine subjects 35 were exposed to 0, 1.0, 2.0, or 3.0 ppm at rest or 2.0 ppm with exercise. The exercise consisted 36 of an 8-minute session on a bicycle ergometer every half hour. Each subject served as his or her 37 own control. Spirometric measurements including FVC, FEV 1 , FEF 25-75% were performed at 38 time = 0, 30, 60, 90, 120, 150, and 180 minutes and on the postexposure day. Airway resistance 39 and thoracic gas volume were measured prior to and at completion of each exposure. 40 Nonspecific airway reactivity was measured with a methacholine challenge at the completion of 41 each exposure. Nasal resistance was measured prior to and following each exposure. Symptoms 42 (nose or throat and eye irritation, chest discomfort, cough, and headache) were recorded via a 43 questionnaire at six intervals during the exposures. Symptoms were scored as 0 = none, 1 = mild 44 (not annoying), 2 = moderate (annoying), or 3 = se vere (debilitating). There were no significant 45 decrements in pulmonary function parameters or increases in bronchial reactivity at any 46 concentration; nasal flow resistance increased at 3.0 ppm. The dose-response relationship for 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 23 of 71

odor sensation and eye irritation were both si gnificant (p<0.0001), but respective scores were 1 only mild (1.0) or mild to moderate (1.4) at 3 ppm. The nose/throat irritation dose-response was 2 close to significant, but the mean subjective symptom score at 3.0 ppm was between none and 3 mild (0.22). At 2.0 ppm with exercise, nose/thro at irritation increased significantly (p<0.05), but 4 the symptom score was <1 (less than mild irritation). Exercise had no effect on eye irritation or 5 odor sensation. There was great variability in the odor threshold; four of nine subjects sensed 6 the odor of formaldehyde at 0.5 ppm. In a reexamination of the above study, Kulle (1993) 7 estimated the thresholds for odor and irritant responses. Estimated thresholds were <0.5 ppm for 8 odor sensation, 0.5-1.0 ppm for eye irritation and 1.0 ppm for nose/throat irritation. No 9 substantial differences were seen between the symptom responses of male and female subjects. 10

11 Green et al. (1987; see also Kulle et al. 1986) found small but significant decrements in 12 lung function in healthy normal subjects inhaling 3.0 ppm while engaged in heavy exercise. 13 Some individuals in the study exhibited decrements in FEV 1 of >10%. In this study, 22 healthy 14 male and female subjects, average age 27, and 16 male and female asthmatic subjects, average 15 age 27, were exposed to 3 ppm for 1 hour. All of the subjects were nonsmokers. Asthmatic 16 subjects discontinued medications within 12 hours of the study. Asthmatic subjects performed 17 intermittent moderate exercise (V E = 37 L/min), so as to minimize exercise-induced 18 bronchoconstriction, and healthy subjects engaged in intermittent heavy exercise (V E = 65 19 L/min). The study was performed in a double bli nd fashion in that both subjects and pulmonary 20 technicians were unaware of the exposure concentrations. Symptoms and pulmonary function 21 were assessed during exposure and SGaw was assessed after the exposure (see Kulle et al. 1987). 22 Both groups exhibited similar, significant increases in perceived odor, nose/throat irritation, and 23 eye irritation throughout the exposure. Mean scores for both groups for each of the three 24 parameters attained a score of approximately 1.8 (mild to mild/moderate) at 17 minutes which 25 decreased only slightly throughout the remaining exposure. There were small but significant 26 decrements in lung function in the healthy subjects near the end of the exposure. Although the 27

mean decrement in FEV 1 was 2%, 2 healthy individuals had decrements of >10% as did 2 28 asthmatic subjects. 29

30 In a follow-up study, Green et al. (1989) exposed 24 non-smoking healthy male and 31 female subjects, average age 24, to 3.0 ppm for 3 hours. For 15 minutes of each hour the 32 subjects performed heavy exercise on a bicycle that raised their minute ventilation to 60-70 33 L/min. Symptom questionnaires were completed and spirometric measurements were made as in 34 the study of Kulle et al. (1987). Symptoms ratings and scores ranged from none = 0 to severe = 35 5. All symptoms were significantly increased over the air exposures, but average scores were 36 <0.5 for headache and chest discomfort (none to mild) and between 1.0 and 1.5 for eye, nose, 37 and throat irritation (mild to mild-moderate) at all time points. There was no significant effect of 38 formaldehyde on FEV, FEV 2 or FEV 3 . There was a significant effect of formaldehyde exposure 39

on FEF 25-75% at 50 and 80 minutes and a decrease in peak flow at 120 minutes. Although 40 statistically significant, mean decrements were <6%. Formaldehyde exposure was not associated 41 with increased cough compared to clean air exposure. 42

43 Sauder et al. (1986) exposed nine healthy nonsmokers to 3 ppm for 3 hours. Each subject 44 served as his or her own control. Spirometric measurements (FVC, FEV 1 , and FEF 25-75 ) were 45 performed at 0, 20, 60, 90, 120, 150, and 180 minutes . A body plethysmograph technique was 46 used to determine FRC and Raw; SGaw was comput ed from Raw. A bicycle ergometer exercise 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 24 of 71

was completed two minutes prior to each spirometric measurement (except at 0 time). Airway 1 reactivity was measured with a methacholine challenge following the exposures to both clean air 2 and 3 ppm. Odor and symptoms of irritation (nos e or throat and eye irritation, chest discomfort, 3 tingling in feet or hands, cough, and heart palpitations) were recorded via a questionnaire at six 4 intervals during the exposures. Symptoms were scored as none (0), mild (1), moderate (2), or 5 severe (3). Statistically significant changes in FEV 1 of 2% and FEF 25-75% of 7% were not 6 biologically significant. No statistically signifi cant changes were observed in FVC, FRC, SGaw, 7 or airway reactivity. Odor and nose /throat irritation were scored as mild to moderate, 1.22 and 8 1.33, respectively. Eye irritation was scored as none to mild (0.78). Five of the subjects scored 9 the nose/throat irritation as moderate whereas only one subject scored the eye irritation as 10

moderate. 11

12 Using the same protocol as in the above study, Sauder et al. (1987) exposed nine 13 nonsmoking subjects with a characteristic clinical history of asthma and airway hyperreactivity 14 to 3 ppm of formaldehyde for 3 hours. The male and female subjects ranged in age from 26 to 15 40 years. Seven of the nine subjects were on regular medications prior to the study; all 16 medications were discontinued 12 hours prior to the study. Based on prestudy pulmonary 17 parameters, three subjects had mild airway obstruction and one subject had moderate airway 18 obstruction. All subjects had marked airway hyperreactivity to methacholine. Eight of the nine 19 subjects had a history of hayfever. During th e study, each subject served as his or her own 20

control and received clean air for 3 hours duri ng day 1. The following week, each subject was 21 exposed to 3 ppm formaldehyde for 3 hours (day 2). Pulmonary function parameters including 22 FVC, FEV 1 , FEF 25-75 , SGaw, and FRC were recorded several times during the exposures. 23 Airway reactivity was measured with a methacholine challenge following the exposures to both 24 clean air and 3 ppm. Symptoms (nose or throat and eye irritation, chest discomfort, tingling in 25 feet or hands, cough, and heart palpitations) were recorded via a questionnaire at six intervals 26 during the exposures. Symptoms were scored as mild, mild/moderate, moderate, 27 moderate/severe, or severe. Inhalation of 3 ppm resulted in no significant group change in 28 pulmonary function parameters or airway reactivit y. On an individual basis, none of the changes 29 were biologically significant. There was a significant increase in some nose or throat and eye 30 irritation during the 3-hour exposure to 3 ppm. But, the group mean value for nose or throat 31 irritation, statistically significant at p<0.05 at only the 30-minute interval, was rated as mild. For 32 the group, eye irritation was rated as mild/moderate beginning at 2 minutes into the exposure and 33 continuing throughout the exposure. However, one subject scored the eye irritation as severe. 34 This score was in response to a questionnaire (not self-reported) and the subject remained in the 35 room for the entire 3-hour exposure. This s ubject did not experience bronchoconstriction or 36 changes in pulmonary function during the entire exposure. It should be noted that in this study, 37 22% of the subjects reported eye irritation and 33% responded with nose/throat irritation during 38 the exposure to clean air. 39

40 Sheppard et al. (1984) exposed 7 nonsmoking male and female subjects, ages 18 to 37 to 41 0, 1, or 3 ppm for 10 minutes at rest or while exer cising on a bicycle ergometer at a work rate of 42 100 watts. The study was performed in a double-blind manner. Formaldehyde was delivered by 43 a mouthpiece. All subjects had a history of mild asthma as evidenced by recurrent episodes of 44 wheezing, chest tightness, and reversible airways obstruction. The subjects had marked airway 45 hyperresponsiveness to histamine. Six of the 7 subjects had responded with airways resistance 46 to <1 ppm sulfur dioxide in a previous study. All medications were discontinued prior to the 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 25 of 71

study. Inhalation of 1 or 3 ppm of formaldehyde at rest or during moderate exercise did not 1 significantly increase airway resistance compared to the control exposure. In two subjects, 2 exercise increased airway resistance in a similar manner following the control, 1, or 3 ppm 3

exposure. 4

5 Weber-Tschopp et al. (1977) exposed a group of 33 healthy male and female students to 6 concentrations that increased from 0.03 to 3.2 ppm over a period of 37 minutes. At discrete 7 concentrations (0.03, 0.5, 1.2, 1.7, 2.1, 2.5, 2.8, and 3.2 ppm), eye, nose and throat irritation were 8 rated on a scale of 1 to 4, with ratings of 1 = none, 2 = a little, 3 = moderate, and 4 = strong. 9 Compared with control scores of approximately 1.2, 1.2, and 1.1, respectively for eye, nose and 10 throat irritation (values read from graphs), respective scores for exposure to 3.2 ppm were 11 approximately 2.0, 2.0, and 1.1, respectively. Average severity scores for exposure to 1.2 ppm 12 were approximately 1.4, 1.3, and 1.1. In a second part of this study, 48 healthy students inhaled 13 0, 1, 2, 3, or 4 ppm, each for 1.5 minutes. Irritation as well as eye blinking were scored. 14 Average rates of eye blinking were not signi ficantly affected at 1.2 ppm, but significantly 15 increased at higher exposures (from about 22 blinks/minute to 35 blinks/minute at 2.1 ppm and 16 38 blinks/minute at 3.2 ppm). Compared with the 37 minute exposure, eye irritation scores were 17 lower during the 1.5 minute exposures, whereas nose irritation scores were higher. The lower 18 scores during the longer exposure indicate some adaptation to the irritancy. The authors 19 considered the threshold for both eye and nose irritation to be 1.2 ppm, the threshold for throat 20 irritation to be 2.1 ppm, and the threshold for eye blinking to be 1.7 ppm. 21

22 The above authors (Weber-Tschopp et al. 1977) also compared the irritation scores 23 during the formaldehyde exposures to the irritation scores of sidestream cigarette smoke from an 24 earlier study (Weber et al. 1976). The atmosphere for the earlier exposure was generated by 25 smoking cigarettes in a 30 m 3 controlled-air chamber. Mainstream smoke was directed out of 26 the laboratory. Following smoking of 10 cigarettes, the carbon monoxide, formaldehyde, and 27 acrolein levels in the room were 24, 0.46, and 0.11 ppm, respectively. On a scale of good (1), 28 acceptable (2), and bad (3), the quality of the air was considered bad (3); whereas, for the 29 formaldehyde exposure that ranged from 0.03 up to 3.2 ppm over 37 minutes, the highest score 30 was 2.2, and the 1.5 minute exposure to 4.0 ppm approached a score of 3. Auerbach et al. (1977) 31 notes that undiluted cigarette smoke may contain 32-114 ppm of formaldehyde. 32

33 In a study of eye irritation and reflex bronchoconstriction response to irritant gases, 34 Douglas (1974) exposed 1-6 healthy and atopic male and female subjects individually to 35 approximately 6, 8, 12, 18, 24, or 30 ppm (eye irritation) or 4, 8, 10, or 12 ppm (broncho– 36 constriction). Atmospheres were generated by bubbling air through formalin solutions. 37 Following collection of formaldehyde from the airstream in 3-methyl-2-benzothiazolone, 38 measurements were made with a colorimetric/spectrophotometric system. Separate eye and 39 inhalation exposures were conducted using goggles in the former case and a mouth tube in the 40 latter. Eye exposures lasted for 15 seconds. Time to onset of eye irritation was measured; no 41 symptom scores were recorded. During inhalation exposures, subjects inhaled 10 one-liter 42 breaths. A body plethysmograph was used for m easuring bronchoconstriction. A single subject 43 exposed to 6 ppm reported no eye irritation. Four of five subjects reported no eye irritation at 8 44 ppm, whereas, 5 of 6 subjects exposed to 12 ppm reported undefined irritation (one within 5 45 seconds). Neither of two subjects exposed to 18 ppm reported eye irritation. Single subjects 46 exposed to 24 or 30 ppm reported eye irritation within 10 seconds. 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 26 of 71

1 During mouth breathing (which bypasses the scrubbing capacity of the nose), the single 2 subject exposed to 4 ppm reported no subjective throat symptoms. Subjects inhaling 8 or 10 3 ppm reported mild sensations in the throat and subjects inhaling 12 ppm reported A irritancy @ in 4 the throat. There was a drop of 0 to 43% in airway resistance at 8 ppm and a drop in airway 5 resistance of 50-108% at 12 ppm. Neither ey e irritation nor bronchoconstriction appeared 6 related to atopy. 7

8

One of the earliest controlled studies aimed at assessing irritation from smog components 9 was performed by Sim and Pattle (1957). They exposed 12 healthy males, ages 18 to 45 to 10 13.8 ppm of formaldehyde in a chamber for 30 minutes. Initially, the exposure caused 11 considerable nose and eye irritation. Mild lacrimation continued for some period of time. The 12 eye irritation was not considered severe, and adaptation occurred in about 10 minutes. 13 Formaldehyde was dispersed into the chamber by bubbling air through a known volume of liquid 14 until all the liquid had evaporated. Chamber atmospheres were measured with a titration 15 technique. 16

17 During analytical determinations of chamber concentrations, Barnes and Speicher (1942) 18

entered the chamber A a number of times. @ Analytical measurements by two procedures, a 19 chemical method and the dropping mercury electr ode method, both indicated a concentration of 20 20 ppm. Upon entering the chamber, the authors noticed irritation of the eyes and upper 21 respiratory tract. Lacrimation started within 15 to 30 seconds, and irritation of the nose and 22 throat became quite pronounced. On some occasions, sneezing occurred within a minute or two. 23 The authors commented that they could continue the exposure A for some length of time but it 24 was distinctly uncomfortable... @ and objectionable. They suggested that formaldehyde in 25 workroom air should be at a value somewhat less than 20 ppm. 26

27 A panel of experts, the Industrial Health Foundation Panel, identified an occupational 28 exposure limit that would prevent irritation (Pau stenbach et al. 1997). Following a critique of 29 approximately 150 scientific articles, A the panel concluded that for most persons, eye irritation 30 clearly due to formaldehyde does not occur until at least 1.0 ppm. Information from controlled 31 studies involving volunteers indicated that moderate to severe eye, nose, and throat irritation 32 does not occur for most persons until airborne concentrations exceed 2.0-3.0 ppm. @ The panel 33 concluded that exposure to 0.3 ppm for several hours in controlled studies was no different than 34 exposure to room air. At 0.5 ppm, eye irritation is not observed in the majority of workers. 35 Consequently, the panel recommended an 8-hour TWA of 0.3 ppm with a ceiling concentration 36 of 1.0 ppm. The panel failed to identify a hypersensitive population or individuals that could be 37 sensitized. The panel also concluded that there was sufficient evidence to show that persons 38 with asthma respond no differently than healthy individuals following exposures up to 3.0 ppm. 39

40 2.3. Neurotoxicity 41

42 Two studies on neurotoxicity are described in Section 2.2.3 above. Andersen and 43 Molhave (1983) found no affect of 5-hour exposures to 0.2, 0.4, 0.8, or 1.6 ppm on performance 44

of mathematical tests. 45

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As noted in the Bach et al. (1990) study above, there was no concentration-response 1 relationship for changes in performance tests consisting of digit span, digit symbols, graphic 2 continuous performance, and addition during 5.5-hour exposures. These tests measure short3 term memory, ability to concentrate, and changes in psychomotor functions. However, the 4 investigators did attribute the poorer performance at the intermediate dose, 0.33 ppm (compared 5 with 0, 0.12, or 1.0 ppm), to either CNS effects or to distraction due to irritation caused by the 6

exposure. 7

8 2.4. Developmental/Reproductive Toxicity 9

10 Few studies addressed developmental or repr oductive effects in humans. No effect on 11 sperm number or morphology was found in a sma ll group of pathologists (Ward et al. 1984). 12 There was no evidence for increased rates of miscarriage among a group of 275 persons with 13 presumed residential exposure to formaldehyde (Garry et al. 1980). 14

15 2.5. Genotoxicity 16

17 The genotoxicity of formaldehyde has been reviewed by many groups including NRC 1980, 18 WHO (1989), Feron et al. (1991), ATSDR (1999), and IARC (2006). Results from occupational 19 studies, which usually involved exposures to low concentrations, are conflicting. Where 20 increased incidences of sister chromatid exchanges, chromosomal aberrations, or micronuclei 21 formation were recorded in exposed workers, differences were small when compared with those 22 of control workers. Formaldehyde easily haptenates human proteins (Maiback 1983). IARC 23 (2006) reviewed studies that showed increased DNA-protein cross-links in workers exposed to 24 formaldehyde. 25

26 2.6. Carcinogenicity 27

28 According to ATSDR (1999), there are over 40 epidemiology studies that examine the 29 potential for occupational exposure to formaldehyde to cause cancer in humans. Various 30 agencies and panels have reviewed the data and taken varying positions on this issue. The 31 reviews all suggest that formaldehyde induces cancer (nasal squamous cell carcinoma) in rats 32 and mice exposed to airborne levels that are associated with significant irritation resulting in 33 hyperplasia and tissue damage with repeated exposure. In humans, the overall evidence for 34 cancer is inconsistent and associations are relatively weak when significant. 35

36 Formaldehyde is carcinogenic to the Fischer 344 rat at dose levels that are within the 37 same order of magnitude as those to which humans are exposed. However, epidemiology studies 38 have failed to show any convincing evidence correlating formaldehyde exposure and nasal 39 cancer in exposed populations (Federal Panel on Formaldehyde 1982; Starr et al. 1983; Blair et 40 al. 1986; Ad Hoc Panel on Health Aspects of Formaldehyde 1988). Carcinogenicity risk has 41 been evaluated in occupational groups with known exposure to formaldehyde; these include 42 pathologists, anatomists, morticians, and chemical workers. Cancers at remote sites have 43 occasionally been correlated with exposure, but because formaldehyde is so highly reactive and 44 rapidly metabolized/detoxified, inhalation is unlik ely to affect a distant site. The Industrial 45 Health Foundation panel of experts concluded that cancer risk of formaldehyde is negligible at 46 airborne concentrations that do not produce chronic irritation (Paustenbach et al. 1997). 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 28 of 71

1 An independent international panel of scientists, the Ad Hoc Panel on Health Aspect of 2 Formaldehyde (1988) reviewed and evaluated more than 30 epidemiology studies. The panel 3

concluded that A (1) for no malignancy in man is there convincing evidence of a relationship with 4 formaldehyde exposure, and (2) furthermore, if a relationship does exist, the excess risk, in 5 absolute terms, must be small. @ 6

7 The U.S. EPA (2003) in their Weight-of-Evidence characterization classifies 8 formaldehyde as B1, probable human carcinogen. This classification is based on limited 9

evidence in humans and sufficient evidence in animals. A Human data include nine studies that 10 show statistically significant associations between site-specific respiratory neoplasms and 11 exposure to formaldehyde or formaldehyde-contai ning products. An increased incidence of 12 nasal squamous cell carcinomas was observed in long-term inhalation studies in rats and in mice. 13 The classification is supported by in vitro genotoxicity data and formaldehyde = s structural 14 relationships to other carcinogenic aldehydes such as acetaldehyde. @ The discussion provided in 15 the IRIS report points out the inadequacies and non-site specificity of many of the epidemiology 16 studies. Although several studies were well-conduc ted, all suffered from one or more of the 17 following problems: lack of control for smoking, l ack of trend with increasing concentration or 18 cumulative exposure, cancers at sites other than the nasopharynx, lack of atmospheric 19 measurements, small sample size, and exposure to other agents. 20

21 In 2006, IARC reevaluated their previous assessment of cancer based on epidemiologic 22 studies and concluded that there was “sufficient epidemiological evidence that formaldehyde 23 causes nasopharyngeal cancer in humans.” They upgraded their evaluation from Group 2A, 24 “probably carcinogenic to humans” to Group 1. IA RC also concluded that “there is strong but 25 not sufficient evidence for a causal association between leukemia and occupational exposure to 26 formaldehyde.” 27

28 The Consumer Product Safety Commission has acted to ban formaldehyde in products as 29 a cancer risk (Fed. Reg. 47:14366). This ban was set aside by a reviewing court in 1983. 30

31 In the carcinogenicity study of Kerns et al. (1983; see Section 3.6), the target dose of 32 formaldehyde in the nasal mucosa of rats was not linearly proportional to the airborne 33 concentration, so that a linear extrapolation of the target doses at concentrations above 5.6 ppm 34 would overestimate the target doses at low concentrations (Starr 1990). Therefore, a quantitative 35 risk assessment using airborne formaldehyde concentrations would overestimate the tumor risk 36 at low exposure concentrations. This group (Kerns et al. 1983; Heck et al. 1990; Starr 1990) also 37 found that at the same concentrations, doses in the monkey were about 5-10 times lower than 38 those in the rat. This indicates that tumor risk for primates would be overestimated if the 39 quantitative risk assessment were done using the dosimetry data in the rat. Animal studies are 40 summarized in Section 3.6. A carcinogenicity assessment using the rat data of Section 3.6 is in 41 Appendix B. 42

43 2.7. Summary 44

45 The discomfort of sensory irritation is difficu lt to measure with certainty. Studies with 46 controlled human exposures indicate that short-term exposure to 1 to 3 ppm induces eye, nose, 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 29 of 71

and throat irritation that is generally described as slight to mild/moderate by most subjects 1 (Weber-Tschopp et al. 1977; Andersen and Molh ave 1983; Bender et al. 1983; Day et al. 1984; 2 Witek et al. 1986; Kulle et al. 1987; ATSDR 1999). Sensory irritation below 1 ppm is difficult 3 to distinguish from the control situation (Bende r et al. 1983; 2002). At the upper end of the 1-3 4 ppm range, a greater number of subjects experience mild irritation, i.e., at 3 ppm most subjects 5 rated eye, nose, or throat irritation mild. The multi-dose clinical studies (Weber-Tschopp et al. 6 1977; Andersen and Molhave 1983; Bender et al. 1983) show that minimal to no discomfort is 7 observed at levels up to 1 ppm; at 1 ppm and above some subjects show definite signs of 8 discomfort. Elevated eosinophil counts and protein in nasal lavage fluid consistent with mild 9 irritation were observed following 4 hours of e xposure to 0.41 ppm (Gorski et al. 1992; Pazdrak 10 et al. 1993; Krakowiak et al. 1998; ATSDR 1999) . There were no changes in pulmonary 11 parameters at concentrations between 0.41 and 3 ppm in healthy subjects, asthmatics, or subjects 12 with dermal sensitivity to formaldehyde (Andersen and Molhave 1983; Day et al. 1984; Frigas et 13 al. 1984; Sheppard et al. 1984; Harving et al. 1986; 1990; Witek et al. 1986; 1987; Pross et al. 14 1987; Sauder et al. 1987). Furthermore, there we re no biologically significant differences in 15 pulmonary parameters or symptoms greater than moderate irritation in exercising healthy 16 subjects (Witek et al. 1986; Green et al. 1987; Kulle et al. 1987), asthmatics at rest (Frigas et al. 17 1984; Sheppard et al. 1984), or exercising asthma tics (Sheppard et al. 1984; Witek et al. 1986; 18 Green et al. 1987) exposed to 2 or 3 ppm for up to 3 hours. In all studies, symptoms were related 19 to eye and upper respiratory tract irritation. There was no evidence of these low concentrations 20 having an effect on the lower respiratory tract. 21

22 The studies of Gorski et al. (1992); Pazdra k et al. (1993); and Krakowiak et al. (1998) 23 were not summarized with the above studies because (1) the authors found irritation at levels not 24 found irritating in approximately 20 other well-conducted clinical studies (that included 25 analytical measurements), and (2) the authors did not make chamber measurements on the days 26 the study was conducted. 27

28 Concentrations of 5 to 13.8 ppm were considered extremely irritating to the eyes of some 29 subjects (Stephens et al. 1961), but not others (Douglas 1974). Unfortunately, some of the 30 procedures and methods of exposure in the Douglas (1974) study make it of limited relevance for 31

AEGL consideration. Mild lacrimation occu rred at 13.8 ppm, but adaptation took place during 32 the 30-minute exposure (Sim and Pattle 1957). Barnes and Speicher (1942) considered short 33 exposures to 20 ppm objectionable. Only one study addressed airway A conductance @ (Douglas 34 1974). Air was inhaled through a mouth tube in this study, thus bypassing the scrubbing 35 capacity of the nasal passages. 36

37

3. ANIMAL TOXICITY DATA 38 3.1. Acute Lethality 39

40 Salem and Cullumbine (1960) exposed groups of 50 mice, 20 guinea pigs, and 5 rabbits 41 to 15.3 ppm formaldehyde vapor or 16.1 ppm formaldehyde aerosol for up to 10 hours or until 42 the animals died. Exposure took place in 1 m 3 glass flow-through chamber. Most deaths 43 occurred on subsequent days (not specified). Total mortalities for mice (deaths during exposures 44 plus deaths on subsequent days) for the vapor and aerosol were 34% (17/50) and 96% (48/50), 45 respectively. Total mortalities for guinea pigs for the vapor and aerosol were 40% (8/20) and 46 5% (1/20), respectively. Total mortalities for rabbits for the vapor and aerosol were 60% (3/5) 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 30 of 71

and 20% (1/5), respectively. At autopsy, all species displayed expanded, edematous, and 1 hemorrhagic lungs and fluid in the pleural cavity. These lethal values appear low in comparison 2 to the human experience and additional animal studies discussed below. Studies utilizing lethal 3

concentrations are summarized in Table 4. 4

5

TABLE 4. Summary of Acute Lethal Inha lation Data in Laboratory Animals

Species Concentration (ppm) Exposure Time Effect a Reference

Rat 820 30 min LC 50 Skog 1950

Rat 350

478 4 h

4 h No deaths

LC 50 Nagorny et al. 1979

Rat 250 4 H 33-66% Mortality Carpenter et al. 1949

Mouse 1000

2162 10 min

10 min No deaths

LC 50 Alarie 1981

Mouse 900

140 2 h

2 h × 4 d 100% Mortality

No substantial

distress Horton et al. 1963

Mouse 320

320 100 min

55 min Lt 50 5% Mortality Bitron and Aharonson 1978

Mouse 98

410 2 h

2 h No deaths

LC 50 Nagorny et al. 1979

6

3.1.1. Rats 7

8 Skog (1950) exposed groups of 8 rats to c oncentrations ranging from approximately 490- 9 1400 ppm for 30 minutes. Rats were observed for 3 weeks postexposure. Extreme respiratory 10 difficulty was observed immediately after exposure. This sign lasted for several days. The first 11 deaths occurred 6 hours postexposure. At autopsy, microscopic changes in the lungs included 12 hemorrhages and intra-alveolar and perivascular edema. Hyperemia, perivascular edema, and 13 necroses were found in the livers and perivascular edema was observed in the kidneys. The late 14 death of one rat, 15 days postexposure, was attributed to purulent bronchitis and diffuse 15 bronchopneumonia. The LC 50 was 810 ppm. In referring to a series of experiments with 16 aldehydes, the authors stated that the lowest doses generally produced 0% mortality, and the 17 highest dose generally produced 100% mortality. 18

19 Nagorny et al. (1979) exposed 21 groups of 6-12 male rats to various concentrations for 4 20 hours. Concentrations of 228 to 350 ppm were not lethal. Some deaths may have occurred in 21 groups exposed to 317 to 732 ppm (data not clear), and all rats died at >732 ppm with the 22 exception of the group exposed to 764 ppm. The 4-hour LC 50 was 478 ppm. Clinical signs 23 preceding death included excitement, increased respiration, open mouth, and bloody discharge 24 from the nose, followed by a prone position. Deaths occurred one or more days after exposure. 25 Some of the deaths were attributed to the combination of toxicity and pneumonia. 26

27 Carpenter reported that 2 to 4 of 6 rats died following a 4-hour exposure to 250 ppm. 28 The postexposure observation period was 14 days. No further details were reported in this 29 screening study. 30

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Kamata et al. (1996) exposed groups of 6 male Fischer rats to 0, 128, or 295 ppm for 6 1 hours in order to study effects on pulmonary surfactant. Dyspnea and closed eyes were observed 2 immediately after the start of exposure, and lacrimation, bloody nasal discharge, and salivation 3 were observed shortly afterwards. No mortalities occurred during the treatment, but one rat in 4 the high-concentration group died just after completion of treatment. Autopsy showed the 5 following dose-related findings: edema surrounding the trachea, hydrothorax, congestion of the 6 lungs and nasal cavities and retention of mucus in the lungs. Lung washes showed that 7 surfactant production was depressed. A number of hematological and clinical chemistry changes 8

were also observed. Animals were sacrificed imme diately after the exposures; therefore, the true 9 mortality incidence could not be ascertained. 10

11

3.1.2. Mice 12

13 As part of a study on respiratory depression by irritant chemicals, Alarie (1981) also 14

determined 10-minute LC 50 values. The 10-minute LC 50 for formaldehyde in Swiss-Webster 15 mice was 2162 ppm (95% confidence interval, 1687-2770 ppm). Mortality was recorded during 16 the following 3-hour period. From the concentration mortality graph provided in the report, the 17 10-minute concentration resulting in no deaths was estimated at 1000 ppm. The California 18 Environmental Protection Agency (1999) estimated MLE 05 and BC 05 of 1440 and 778 ppm, 19 respectively. Because deaths may occur later than 3 hours postexposure, these values should be 20

considered estimates. 21

22 A single 2-hour exposure to 900 ppm resulted in deaths from massive pulmonary 23 hemorrhage and edema in C3H mice. When mice were subjected to 163 ppm for three 1-hour 24 periods each week, substantial deaths occurred after the 6 th exposure. Concentrations of 41 and 25 81 ppm were well tolerated for up to 35 weeks. Mice inhaling 114 ppm for 2 hours daily for 4 26 days did not show signs of substantial distress (Horton et al. 1963). 27

28 Nagorny et al. (1979) exposed 14 groups of 6- 8 male and female mice to formaldehyde 29 for 2 hours. Concentrations of 64 to 98 ppm were not lethal. Concentrations of 109 to 745 ppm 30 caused 12.5-83.3% lethality. At 746 to 820 ppm all mice died. The 2-hour LC 50 was 410 ppm. 31

The authors also calculated a 2-hour LC 16 of 126 ppm and a 2-hour LC 84 of 695 ppm. 32

33 Bitron and Aharonson (1978) exposed groups of 28-112 mice to 320 ppm for varying 34 periods of time and then calculated the Lt 50 , the time at which 50% of the mice died. The mice 35 were restrained in tight-fitting cylindrical chambers. The postexposure observation period was 36 45 days. The Lt 50 was 100 minutes. Exposure durations of 55, 90, 150, and 320 minutes 37 resulted in mortalities of approximately 5, 44, 81, and 100%, respectively (data read from a 38 graph). 39

40 3.2. Nonlethal Toxicity 41

42 Few studies involving acute exposures were lo cated. Those studies that did employ acute 43 exposures were usually directed at histopathological changes in the nasal tissues, and animals 44 were sacrificed immediately after exposures. A few repeat-exposure studies are included in the 45

discussions below. 46

47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 32 of 71

3.2.1. Nonhuman Primates 1

2 Groups of three Rhesus monkeys inhaled 0 or 6 ppm for 6 hours/day, for one week, or 3 6 ppm, 6 hours/day, 5 days/week, for 6 weeks in order to study effects on the respiratory 4 epithelium (Monticello et al. 1989). The formaldehyde-exposed animals showed signs of ocular 5 irritation - mild lacrimation and conjunctival hyperemia - throughout each exposure period. 6 Open mouth breathing was observed during the fi rst 15 minutes of each exposure. After one 7 week of exposure, bilateral changes in the re spiratory epithelium included loss of goblet cells 8 and cilia, minimal to mild epithelial hyperplasia with or without early stages of squamous 9 metaplasia, and an associated neutrophilic inflammatory response. After six weeks of exposure, 10 there was minimal progression of lesions, although the affected area was more extensive. After 11 one week of exposure, lesions showed a progression of severity with the anterior most sections 12 being the most severely affected; the larnyx/trachea was little affected. After six weeks, lesions 13 were more similar in the anterior and posterior areas of the nasal cavity. The maxillary sinuses 14 showed no response to exposure, and there were no treatment-related lesions present in the 15 lungs. Tritiated thymidine labeling indices of the nasal passages, larynx, trachea, and carina 16 showed highest labeling indices in the transitional epithelium; the elevation was less than two17 fold greater than that of the controls. 18

19

3.2.2. Rats 20

21 In an early study, Murphy et al. (1964) examined the biochemical effects in 8 adult male 22 Sprague-Dawley rats following exposure to a A sublethal concentration @ of 35 ppm for 18 hours. 23 Dyspnea, eye and nasal irritation, and other signs of generalized debility were observed in the 24 rats during the exposures. No further details of the clinical signs were given, and 25 histopathological results were not reported. The level of serum alkaline phosphatase was 26 unaffected by exposure, whereas, the liver alkaline phosphatase was elevated five-fold. 27

28 Tobe et al. (1985) exposed groups of 12 male Wistar rats to 0, 10, 20, or 30 ppm for 6 29 hours in order to observe behavioral as well as biochemical and hematological responses. Signs 30 in the group exposed to 10 ppm were similar to those of the control group. In the group inhaling 31 20 ppm, rats sniffed the air about 1 minute after the start of exposure; this was followed by face32 washing movements. Movements in the 30-ppm group were similar to those in the 20-ppm 33 group. Yellowing of hair around the genital areas was observed in both the 20 and 30-ppm 34 groups. Irritation of the nasal mucosa membrane and trachea (undefined) were observed in these 35 two groups. Biochemical changes included a decrease in leukocytes and plasma alkaline 36 phosphatase and an increase in lung alkaline phosphatase activity. The 10- and 30-ppm groups 37 had a decrease in the mean corpuscular volume and mean corpuscular hemoglobin. The 30-ppm 38 group has a decrease in white blood cells. 39

40 Boja et al. (1985) described the behavior and neurotoxicity of adult male Sprague41 Dawley rats exposed to 0, 5, 10, or 20 ppm formaldehyde for 3 hours on 2 consecutive days. 42 Rats were sacrificed after the second exposure and brains were analyzed for neurotransmitters. 43 Data were presented for only the 5 ppm exposure. On day 1, motor activity decreased within 15 44 minutes of exposure with controls showing 80% activity at 15 minutes compared with 45% in 45 the exposed group. Exposure to 5 ppm increased 5-hydroxyindoleacetic acid, 3,4- 46FORMALDEHYDE NAC/Interim 1: 07/2008; Page 33 of 71

dihydroxyphenylacetic acid, and dopamine in the hypotha lmus, but did not affect norepinephrine 1 or 5-hydroxytryptamine. 2

3 Chang et al. (1981) conducted an RD 50 study (concentration that lowers the respiratory 4 rate by 50%) with F-344 rats. The RD 50 value was 31.7 ppm. The RD 50 in male Wistar rats was 5 10.0 ppm (C.L., 4.7-13.7 ppm) (Cassee et al. 1996). A maximum decrease in breathing 6 frequency was observed within three minutes of exposure followed by marked desensitization 7 during the remaining exposure (total exposure 30 minutes). The RD 50 in male Crl:Cd (Sprague8 Dawley) rats was 13.8 ppm (Gardner et al. 1985). Concentrations of ≥ 5.5 ppm produced 9 considerable depressions in respiratory rate within the first minute of exposure, reaching a 10 maximum at about 3 minutes. Incomplete recovery took place during the remainder of the 15- 11 minute exposure. 12

13 Chang et al. (1983) exposed groups of male Fischer 344 rats to 0, 6, or 15 ppm for 6 14 hours in order to study nasal cavity deposition, cell proliferation, and histopathology. Both 15 exposures resulted in approximately a 15% depression in respiratory rate and minute volume. 16 The nasal respiratory epithelium of control rats had a very slow rate of cell turnover. Eighteen 17 hours after a single 6-hour exposure to 15 ppm, a 13-fold increase in cell proliferation was 18 observed. The proliferative response was most pronounced in the basal cell layer. Treatment for 19 5 days almost doubled the labeling index. Ea rly degeneration and sloughing of respiratory 20 epithelial cells were observed immediately follo wing the single 6-hour exposure. Necrobiotic 21 cells were observed in the most anterior areas of nasal cavity. When rats were sacrificed 18 22 hours after the exposure, hyperplasia, characterized by a thickened epithelium, scattered 23 degenerate cells, neutrophilic infiltrates, and isolated areas of epithelial sloughing were 24 observed. The olfactory epithelium appeared normal. Lesions observed following a 5-day 25 exposure were much more extensive and more severe. Lesions following the exposure to 6 ppm 26

were not described. 27

28 Morgan et al. (1986a) evaluated the effect of exposure on the nasal mucociliary apparatus 29 of groups of F-344 rats exposed to 0.5, 2, 6, or 15 ppm. for 6 hours. Additional groups of rats 30 were exposed to the same concentrations for up to 3 weeks. The relationship between inhibition 31 of the mucociliary clearance mechanism and histopathologic changes in the underlying 32 epithelium was also evaluated. No signs of irritation were observed in rats exposed to 0 or 0.5 33 ppm. Rats exposed to 2, 6, or 15 ppm exhibited concentration-related evidence of eye and nose 34 irritation including ocular and nasal discharge. These signs were minimal at 2 ppm. After a 35 single 6-hour exposure to 15 ppm, direct impairment of nasal mucociliary function and cessation 36 of ciliary activity were observed in the anterior region of the nose. Lesions in this area were 37 characterized by separation of epithelial cells and intravascular margination and local tissue 38 infiltration by neutrophils and monocytes. The investigators characterized the lesions as 39

A minimal effects, @ but indicated that the lesions were followed by severe degenerative changes. 40 In what appears to be the same group of animals, Swenberg et al. (1983) characterized the 41 lesions as acute degeneration of the respiratory epithelium with edema and congestion... evident 42 at the end of one day of exposure. Less severe changes were found in rats exposed to 6 ppm for 43 6 hours, and no epithelial lesions were detected in rats exposed to 2 or 0.5 ppm for 6 hours. 44 Repeated exposures resulted in more extensive changes in the anterior nasal passages. The 45 investigators considered inhibition of mucociliary function a more sensitive indicator of toxicity 46 than epithelial lesions. 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 34 of 71

1 In a second study (Morgan et al. 1986b), rats were exposed to 0, 2, or 15 ppm for 10, 20, 2 45, or 90 minutes or 6 hours with recovery groups examined 1 hour after the 90-minute and 6- 3 hour exposures. There was no evidence of impaired mucociliary function in rats exposed to 2 4 ppm for 90 minutes or 6 hours. A 90-minute or 6-hour exposure to 15 ppm followed by a 1-hour 5 recovery period resulted in extensive recovery of both ciliary activity and mucus flow. Recovery 6 was almost complete in the group exposed to 15 ppm for 90 minutes, whereas recovery was 7

A considerable but incomplete @ in the group exposed for 6 hours. 8

9 Groups of 48 male F-344 rats inhaled 0 (filtered air), 0.7, 2, or 6 ppm for 6 hours/day, 5 10 days/week for up to three weeks (Andersen et al. 2008). Atmospheres were generated by 11 thermal depolymerization of paraformaldehyde into 8 m 3 steel and glass chambers. Atmospheres 12 were monitored by infrared analysis (measured concentrations of 1, 0.6, 1.8, 5.0, and 14 ppm). 13 Sacrifices (n = 8 for each group) took place after 6 hours of exposure, after 18 hours of exposure, 14 at the end of six days of exposure, 18 hours after the sixth exposure, and at the end of 15 days of 15 exposure. Minimal inflammatory infiltrates were frequently noted in controls and all treated 16 groups, with consistent increases evident only in the 6 ppm group. Neither cell proliferation nor 17 histopathology was observed at 0.6 ppm at any time point. Immediately following exposure on 18 day 1, minimal inflammatory cell infiltrate of the maxilloturbinate was present in 6 of 8 rats that 19 inhaled 1.8 ppm and in all rats that inhaled 5.0 ppm. At day 1 recovery, epithelial hyperplasia 20 was observed in 0, 1, 3, and 8 rats in the control through 5.0 ppm groups, respectively. 21 Following 15 days of exposure, rats in the 1.8 ppm and 5.0 ppm groups exhibited epithelial 22 hyperplasia (2 of 8 and 7 of 8, respectively), but all rats failed to exhibit squamous metaplasia. 23 Squamous metaplasia had been observed in 7 of 8 rats in the 5.0 ppm group at the end of the first 24 week of exposure. Cell proliferation, evaluated only at days 5 and 15 was observed only in the 25 5.0 ppm group. 26

27 In the above study (Andersen et al. 2008), an additional group of 8 rats inhaled 15 ppm; 28 sacrifice took place following the 6-hour exposure. Gene expression in rat nasal epithelium was 29 evaluated and compared with that of the groups above. Both temporal and concentration30 dependent transitions in genomic signatures were observed between 0.6 and 5.0 ppm. These 31 concentration affected primarily genes associated with extracellular componenets and plasma 32 membrane. The number of genes altered at 15 ppm (evaluated after only a single exposure) was 33 18-fold greater than those altered at 5.0 ppm. 34

35 Dubreuil et al. (1976) observed slight irritation in rats continuously exposed to 1.6 ppm 36 for up to two months. Minimal adverse effects occurred at 4.6 ppm, and clear signs of nasal 37 irritation were observed at 8.1 ppm. 38

39

3.2.3. Mice 40

41 Kane and Alarie (1977) evaluated sensory irritation in male Swiss-Webster mice. 42 Percent decreases in respiratory rate were measured in groups of four mice inhaling 0.52 to 10 43 ppm formaldehyde for 10 minutes. From the data, a 50% decrease in respiratory rate, the RD 50 , 44 was calculated at 3.1 ppm. Chang et al. (1981) conducted a similar study with B6C3F 1 mice. 45

The RD 50 values in mice and rats were 4.9 and 31.7 ppm, respectively. The authors of the latter 46 study point out that the ability of mice to depress their respiratory rate in response to irritants 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 35 of 71

results in minimization of the inhaled dose and may contribute to differences in respiratory tract 1 toxicity between mice and rats. 2

3 A series of immune function and host resistance parameters ere examined in female B6C3F1 4 mice following inhalation exposure to 15 ppm of formaldehyde for 6 hours/day, 5 days/week for 5 3 weeks (Dean et al. 1984). There were no deat hs, and no significant differences in body weight 6 between the control and exposed group were observed. Lymphoid organ weight, bone marrow 7 cellularity, and hematology parameters were unchanged in formaldehyde-exposed mice. The 8 percentage of T and B lymphocytes and their proliferative responses to mitogens were not 9 significantly altered. Antibody plaque-forming cell response following antigen challenge was 10 unchanged. Macrophage function was normal although some evidence of enhanced hydrogen 11 peroxide production associated with elevated b actericidal activity was observed in resident 12 macrophages. Resistance to challenge with the bacteria Listeria monocytogenes was 13 significantly enhanced, while resistance to tumor challenge remained unchanged. 14

15 3.2.4. Guinea Pigs 16

17 The airway reactivity of guinea pigs to formaldehyde was assessed in several studies. 18 Amdur (1960) measured pulmonary mechanics in groups of 4 to 18 guinea pigs exposed to 0.05, 19 0.31, 0.58, 1.22, 3.6, 11.0, or 49 ppm for 1 hour. Preexposure values served as control values. 20 An increase in resistance and a decrease in compliance, suggestive of bronchoconstriction, 21 became statistically significant at 0.31 ppm. Decreases in respiratory rate and minute volume 22 became statistically significant at 11 ppm. Delivery of formaldehyde directly to the trachea via a 23 cannula increased the response to formaldehyde. In both cases, the resistance change was 24 reversible in an hour after the exposure ended. 25

26 Inhalation of 6 or 10 ppm, 6 or 8 hours/day, for 5 consecutive days failed to elicit 27 pulmonary hypersensitivity or produce antibodies in guinea pigs, although two of four animals 28 that had inhaled 10 ppm for 8 hours over 5 days developed skin sensitivity (Lee et al. 1984). 29 Pulmonary sensitivity, both immediate and delayed, was assessed by measurement of bronchial 30 reactivity in response to a formaldehyde challenge. Dermal sensitivity was assessed with a 31 topical challenge, and antibodies were assessed with formaldehyde-specific antigens. 32 Respiratory rates of animals inhaling 10 ppm for 6 hours were measured over the course of the 33 first day. Respiratory rates first decreased by 45% within the first hours of exposure and 34 remained depressed during he following 5 hours of exposure. The pattern of respiration changed 35 over the course of the exposure, with the first hour resembling that of animals exposed to a 36 sensory irritant and the second hour characteristic of animals with tracheal cannulation, i.e., 37 indicating the formaldehyde had reached the lower respiratory tract. Antibodies to formaldehyde 38 were observed only in guinea pigs administered the material by injection. 39

40 In a another study, Swiecichowski et al. (1993) investigated the changes in pulmonary 41 resistance and airway reactivity to intravenous acetylcholine in guinea pigs exposed to selected 42 concentrations of formaldehyde. Groups of 5 to 7 male Hartley guinea pigs were exposed to 0, 43 0.86, 3.4, 9.4, or 31.1 ppm for 2 hours or to 0, 0.11, 0.31, 0.59, or 1.05 ppm for 8 hours. 44 Baseline reactivities were measured prior to exposure and up to 24 hours postexposure. Tracheal 45 histology was also examined immediately after exposure and for up to 96 hours after exposure to 46 3.4 ppm for 8 hours. Specific pulmonary resistance to infused acetylcholine increased by 31% 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 36 of 71

after exposure to 9.4 ppm for 2 hours, but not at the lower exposures. A similar increase was 1 observed following an 8-hour exposure to 1.0 ppm. Microscopic examination of the trachea 2 revealed no changes in the number of ciliated cells of the epithelium or in inflammatory cell 3 infiltration into the lamina propria of the epithelium. 4

5 3.3. Neurotoxicity 6

7 No information on neurotoxicity in animals was located. 8

9 3.4. Developmental/Reproductive Toxicity 10

11 Inhalation, oral gavage, dietary, and drinking water studies have been used to study the 12 effects of formaldehyde on reproduction and development. Study results published prior to 1982 13 were reviewed by the Federal Panel on Formalde hyde (1982). Many of the studies suffered from 14 an unreported or inadequate number of animals in treated dose groups. Details in the studies 15 were often conflicting. Dietary studies with dogs and rats, gavage studies with mice, and 16 drinking water studies with rats, the latter with hexamethylenetetramine (which is metabolized to 17 formaldehyde in vivo ), were also conducted. Although formaldehyde was not teratogenic in 18 these studies, the panel concluded that additional, well-conducted studies should be performed. 19 In a multi-generation study with rats administered 1% hexamethylenetetramine in the drinking 20 water (Della Porta et al. 1970), there was no eff ect of treatment on survival or body weight of 21 any generation. 22

23 Saillenfait et al. (1989) exposed Sprague-Dawley rats to 0, 5, 10, 20, or 40 ppm for 6 24 hours/day from day 6 to 20 of gestation. On da y 21 of gestation the fetuses were examined. 25 There were no effects on embryo or fetal lethality and no teratogenic effects. The concentration 26 of 40 ppm was maternally toxic as reflected by a significant reduction in dam body weight. 27 Concentrations of 20 and 40 ppm were fetot oxic as reflected by reduced fetal weights, 28 characterized as slight at 20 ppm and 20% at 40 ppm. 29

30 Morgan (1990) exposed 25 mated female Sprague-Dawley rats whole-body to 1.9, 4.9, or 31 9.5 ppm formaldehyde for 6 hours/day from day 6 th rough day 15 of gestation. Both an air and a 32 room control group were included in the study. Dams were weighed and sacrificed, and 33 examined for reproductive indices; fetuses were weighed and examined for malformations. A 34 significant decrease in maternal food consumption and weight gain was observed in the 10 ppm 35 group. Pregnancy rate, number of corpora lutea, implantation sites, live fetuses, dead fetuses and 36 resorptions, and fetal weight, sex ratio, and preimplantation and postimplantation losses were 37 unaffected by treatment. Incidences of litters and fetuses with major malformations, minor 38 external visceral anomalies, and minor skel etal anomalies were unaffected by treatment. 39 Incidences of reduced ossification of the pubic and ischial bones in the 5 and 10 ppm groups 40 were significantly increased when compared to the air control group but not when compared to 41 the room control group. This effect appeared to be related to the larger litter sizes in the higher 42

exposure groups. 43

44 3.5. Genotoxicity 45

46FORMALDEHYDE NAC/Interim 1: 07/2008; Page 37 of 71

The genotoxicity of formaldehyde has been reviewed by many groups including NRC 1 1980, WHO (1989), Feron et al. (1991), ATSDR ( 1999), and IARC (2006). According to IARC 2 (2006), formaldehyde A demonstrates positive effects in a large number of in vitro tests for 3 genotoxicity, including bacterial mutation, DNA strand breaks, chromosomal aberrations, and 4 sister chromatid exchange. Studies in humans showed inconsistent results with regard to 5 cytogenetic changes (micronuclei, chromosomal aberrations, and sister chromatid exchange).” 6 Formaldehyde induced DNA-protein cross-links in vitro in human bronchial epithelial cells, 7 fibroblasts, and lymphocytes. Studies in formaldehyde-exposed workers revealed increased 8 DNA-protein cross-links, consistent with results of inhalation studies with rats and monkeys. 9

10 In a dominant lethal test with mice, intraperitoneal injections of males with 16, 20, 32, or 11 40 mg/kg did not affect spermatogenesis or fertility, i.e., no dominant lethal mutations (Epstein 12 et al. 1972). According to WHO (1989) formaldehyde is mutagenic in different test systems, 13 especially at high concentrations. However, evidence that formaldehyde may induce mutations 14 in vivo is lacking.?? 15

16 Formaldehyde readily reacts with a variety of cellular nucleophiles including DNA. 17 Reaction products with DNA include adducts and DNA-protein cross-links in vitro (WHO 18 1989). In inhalation studies of rats exposed to formaldehyde, formaldehyde induces the 19 formation of DNA -protein cross-links in the nasal respiratory mucosa in vivo (Casanova20 Schmitz and Heck 1983; Casanova-Schmitz et al. 1984). The concentration-response curve is 21 sublinear below 6 ppm, but linear above. DNA-protei n cross-links were not found at other sites. 22

23 3.6. Chronic Toxicity/Carcinogenicity 24

25 Studies of intermediate duration as well as chronic toxicity/carcinogenicity studies are 26

summarized in Table 5. Subchronic studies show that precursor carcinogenic effects - 27 pathologic lesions of the nasal mucosa occur if concentrations are sufficiently high. Generally 28

no nasal lesions occurred in 13-week studies at concentrations of 1-4 ppm for 6-8 hours/day. 29

Concentrations $ 10 ppm for at least 13 weeks caused lower respiratory tract damage as 30 evidenced by nasal, laryngeal and tracheal lesi ons (Rusch et al. 1983; Maronpot et al. 1986; 31 Woutersen et al. 1987; Feron et al. 1988; Wilmer et al. 1989). Respiratory tract lesions were 32 always greater in rats than in mice and were generally absent in hamsters. Only the chronic 33 studies are discussed in the following text. 34

35 Several studies addressed carcinogenicity in rodents at low levels of exposure. In the 36 earliest such study (Swenberg et al. 1980; Kerns et al. 1983) groups of 120 male and 120 female 37 Fischer 344 rats and groups of 120 male and 120 female B6C3F 1 mice inhaled measured 38 concentrations of 0, 2.0, 5.6, or 14.3 ppm for 6 hours/day, 5 days/week for 24 months. Some 39 animals were sacrificed at 6, 12, and 18 months. Rats exposed to all concentrations had a 40 concentration-dependent yellow discoloration of th e fur. Clinical signs were limited to the 14.3 41 ppm group and included dyspnea and emaciation. At the end of 24 months, body weights of 42 male and female rats in the 5.6 and 14.3 ppm groups were decreased (p<0.05); body weight 43 recovery took place during a 3-month postexpos ure non-treatment period. Concentration44 dependent observations of rhinitis, epithelial dysplasia, and squamous metaplasia occurred in all 45 exposure groups of rats. Squamous cell carcinomas were observed in the nasal cavities of 51 of 46 117 male rats (44%) and 52 of 115 female rats (45%) exposed to 14.3 ppm and in one male (of 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 38 of 71

119) and one female (of 116) rat exposed to 5.6 ppm (both approximately 1%). At 24 months, 1 the adjusted incidence rates of squamous cell carcinomas in male and female rats in the 14.3 ppm 2 exposure group were 67 and 87%. The nasal lesions were described as A squamous metaplasia 3 with zones of squamous epithelial hyperplasia and increased keratin production that appeared to 4 precede areas of squamous papillary hyperplasia with foci of cellular atypia. @ Carcinomas 5 invaded the nasal turbinates. In many animals in this exposure group, the excessive 6 accumulation of keratin and inflammatory exudate within the nasal cavity caused severe dyspnea 7 and death. Polyploid adenomas of the nasal mucosa were seen in rats at all doses in a significant 8 dose-related trend. At study termination, squamous cell carcinomas were found in 2 of 106 male 9 mice exposed to 14.3 ppm (2%) and in none of the female mice (0/109) exposed to 14.3 ppm. 10 Mouse survival was not affected by exposure. 11TABLE 5. Summary of Subchronic and Chronic/Carcinogenicity Studies in Laboratory AnimalsSpeciesConcentration(ppm)ExposureDuration Effect ReferenceMonkey (malecynomolgus)0, 0.19, 0.98, 2.95 22 h/d,7 d/w,26 wkNo effect at 0.19 or 0.98 ppm; hoarseness, congestion andsquamous cell metaplasia in the nasal turbinates at 2.95 ppmRusch et al. 1983Rat (male SpragueDawley)0, 15 6 h/d,5 d/wk,lifetimeControls: epithelial or squamous hyperplasia of the nasal mucosa, 0/99 tumors;15 ppm: squamous hyperplasia and metaplasia; nasal cavity tumors: 38/100squamous cell carcinomas, 1/100 fibrosarcoma, 1/100 mixed carcinomaSellakumar et al. 1985;Albert et al. 1982Rat (male andfemale Wistar)0, 1, 9.7, 20 6 h/d5 d/wk,13 wks1 ppm: minimal focal hyperplasia in the nose9.7 ppm: moderate squamous metaplasia, nasal respiratory epithelium19.8 ppm: growth retardation, squamousmetaplasia, squamous cell carcinomas(4/44 vs 0/45 controls), carcinomain situ, adenomasWoutersen et al. 1987;Feron et al. 1988;Rat (male Wistar) 1, 22,48 h/d, 5 d/wk,13 wks8 x 30-min/d,30-min break,13 wksContinuous, 8 hours: 1, 2 ppm: no histopathology of the noseInterrupted, 4 hours: 2 ppm: rhinitis (considered incidental);4 ppm: squamous metaplasia and hyperplasia, nasal turbinates, increased cellturnoverWilmer et al. 1989Rat (male andfemale Fischer 344)0, 0.19, 0.98, 2.95 22 h/d,7 d/w,26 wksNo effect at 0.19 or 0.98 ppm; squamousmetaplasia in the nasal turbinates,decreased body weight, and decreased liver weight at 2.95 ppmRusch et al. 1983Rat (male Wistar) 0, 0.1, 1, 10 12 months No adverse effects at 0.1 and 1ppm; growth retardation, reduced urineproduction, and rhinitis accompanied bysquamous metaplasia of the nasalrespiratory epithelium at 10 ppmAppleman et al. 1988Rat (male Fischer344)0, 0.3, 2.0, 3.3, 15 6 h/d,5 d/wk,24-28 monthsDose-related incidences of rhinitis and nasal hyperplasia15 ppm: 88% mortality; squamous cell carcinomas, 14/27 vs 0/27 controlssurviving past 12 monthsTobe et al. 1985Rat (male Fischer344)0, 0.3, 2.1, 14.9 6 h/d,5 d/wk,28 monthsInflammatory cell infiltration, erosion, or edema observed in all groupsincluding controls; concentration dependent nasal epithelial cell hyperplasiawith squamous cell metaplasia at all concentrations; 15ppm: squamous cellcarcinomas, papillomas in 8/32 by 24 monthsKamata et al. 1997Rat (male Fischer344)0, 0.7, 2, 6, 10, 15ppm6 h/d,5 d/wk,24 months0.7, 2 ppm: no squamous cell carcinomas6, 10, 15 ppm: tumor incidences of 1, 22, and 47%, respectivelyMonticello et al. 1996Rat (male andfemale Fischer 344)0, 2, 5.6, 14.3 6 h/d,5 d/wk,24 monthsRat: 2 ppm: no clinical signs, no carcinomas5.6 ppm: rhinitis, increased mortality (males), nasal squamous metaplasia,squamous carcinomas (2/153 vs 0/156 controls)14.3 ppm: dyspnea, emaciation, increased mortality, nasal squamouscarcinomas (94/140 vs 0/156 controls)Swenberg et al. 1980;Kerns et al. 1983Rat (male Wistar) 0, 0.1, 1, 10 6 h/d,5 d/wk,28 monthsNo effect on nasal respiratory epithelium at 0.1 or 1 ppm; degenerativeinflammatory, and hyperplastic changes at 10 ppm; nasal squamous cellcarcinomas in 0/26, 1/26, 1/28, and 1/26 rats, respectivelyWoutersen et al. 1989Mouse (male andfemale B6C3F1)0, 2, 4, 10, 20, 40 6 h/d,5 d/wk13 wks2, 4 ppm: no histopathology of the nasal epithelium;10 ppm: nasal lesions;20 ppm: nasal, laryngeal, and tracheal lesions;40 ppm: ataxia, body weight depression,inflammation and metaplasia of theMaronpot et al. 1986FORMALDEHYDE NAC/Interim 1: 07/2008; Page 40 of 71TABLE 5. Summary of Subchronic and Chronic/Carcinogenicity Studies in Laboratory Animalsnasal cavity, larynx, trachea, and lungs, 80% mortalityMouse (male andfemale B6C3F1)0, 2, 5.6, 14.3 6 h/d,5 d/wk,24 months2 ppm: no noteworthy lesions5.6, 14.3 ppm: squamouscell carcinomas, 2/116 malesKerns et al. 1983Hamster (male andfemale goldenSyrian)0, 0.19, 0.98, 2.95ppm22 h/d,7 d/w,26 wkNo effect at any concentration (no increase in squamous metaplasia in thenasal cavity of treated hamsters)Rusch et al. 1983Hamster(male Syriangolden)0, 10 5 h/d,5 times/wk,lifetimeNo increase in rhinitis; hyperplastic and metaplasticareas in nasal epitheliumin 5% of hamsters exposed to 10 ppm;no tumors in treated or control groupDalbey 1982Studies are arranged by species followed by length of study.FORMALDEHYDE NAC/Interim 1: 07/2008; Page 41 of 71

Sellakumar et al. (1985; see also Albert et al. 1982) exposed groups of 100 male Sprague1 Dawley rats to 15 ppm for a lifetime. Two additional groups were included in the experiment: a 2 group exposed to air only and a group exposed to 15 ppm formaldehyde and 10 ppm hydrogen 3 chloride (HCl). HCl was administered to see if tumor response was enhanced by an additional 4 irritant effect or by the combination of the tw o chemicals to form bis-(chloromethyl)ether, a 5 known carcinogen. Squamous cell carcinomas of the anterior nasal cavity were induced in 6 38/100 rats that received formaldehyde alone. C oncurrent administration of HCl had no effect 7 on the incidences of nasal cancers. In addition to rhinitis, hyperplasia and squamous metaplasia 8 of the nasal mucosa, larynx and trachea were observed in all formaldehyde exposed group. 9 Exposure to HCl alone resulted in only hyperplasia. 10

11 Tobe et al. (1985) conducted a 28-month study with male F-344 rats. Groups of 32 rats 12 were exposed 6 hours/day, 5 days/week to 0, 0.3, 2.0, 3.3, or 15 ppm in aqueous methanol. 13 Another group was exposed to the methanol only. Exposure to 15 ppm ended at 24 months at 14 which point the mortality was 88%. Squamous cell carcinomas were observed in 14/27 rats in 15 the 15 ppm group surviving past 12 months (cont rols, 0/27). No polyploid adenomas were 16 observed. Incidences of rhinitis and hyperplasia were dose-related. 17

18 Using male Wistar rats, Woutersen et al. (1989) observed nasal squamous cell 19 carcinomas in only 1/26, 1/28, and 1/26 exposed to 0.1, 1.0, or 10 ppm, respectively, for 6 20 hours/day, 5 days/week for 28 months. There were no carcinomas in 26 control rats. Physical 21 damage to the nasal mucosa (electrocoagulation) increased the response in a group subsequently 22 exposed to 10 ppm group (15/58 compared with 1/54 in controls treated with 23 electrocoagulation). 24

25 Male F-344 rats inhaled 0.3, 2, or 15 ppm for 6 hours/day, 5 days/week for 28 months 26 (Kamata et al. 1997). Clinical signs of irrita tion were observed in the 15 ppm group. No nasal 27 tumors were observed in the groups that inhaled 0.3 or 2 ppm. By 14 months, nasal tumors were 28 macroscopically evident in the in the 15-ppm group, and this group had early deaths. By 24 29 months, 8/32 rats had squamous cell papillomas and carcinomas. 30

31 Dalbey (1982) exposed male Syrian golden hamsters to 10 ppm formaldehyde 5 32 hours/day, 5 times/week, throughout their lifetimes. Beginning with the 20 th week, survival time 33 was reduced in the exposed group compared with unexposed controls. No tumors were observed 34 in the respiratory tract of either the control or exposed group. Only a minimal increase in 35 hyperplastic and metaplastic areas was observed in the nasal epithelium of 5% of the exposed 36

group. 37

38 As noted in Section 2.6, the U.S. EPA (2003) in their Weight-of-Evidence 39 characterization classifies formaldehyde as B 1, probable human carcinogen. This classification 40 is based on limited evidence in humans and sufficient evidence in animals. IARC (2006) 41 concluded there is sufficient evidence in humans for the carcinogenicity of formaldehyde. 42

43 3.7. Summary 44

45

Lethal concentrations were available for the rat and mouse. LC 50 values for the rat 46 ranged from 820 ppm for 30 minutes (Skog 1950) to 250-482 ppm for 4 hours (Carpenter et al. 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 42 of 71

1949; Nagorny et al. 1979). For the mouse, the value was similar to the rat when the duration 1 was shorter (Nagorny et al. 1979), whereas the Lt 50 (similar to the LC 50 ) was 320 ppm for 100 2 minutes (Bitron and Aharonson1978). Mice survived a 4-day repeat exposure to 140 ppm with 3 little signs of distress (Horton et al. 1963). 4

5

Few studies at sublethal concentrations we re of acute duration. Murphy et al. (1964) 6 reported that 35 ppm for 18 hours was a sublethal concentration for the rat. Rats exposed to 15, 7 20 or 30 ppm for 6 hours showed eye and nose irritation, inhibition of the mucociliary clearance 8 mechanism, and damage of the nasal mucosa which extended to the trachea at the higher 9 exposures (Chang et al. 1983; Tobe et al. 1985; Mo rgan et al. 1986a). There was no evidence of 10 damage to the anterior respiratory epithelium after exposures to 2 ppm for up to 6 hours 11 (Morgan et al. 1986b). Repeated exposures to 1 or 2 ppm for 6 hours/day also produced no 12 histopathology in rats (Woutersen et al. 1987). It should be noted that rats are obligate nose 13 breathers. Horton et al. (1963) observed no subs tantial distress in mice during a 4-day repeat 14 exposure to 140 ppm (of 2 hours duration). The RD 50 in mice is 3.1 ppm (Kane and Alarie 15 (1977). 16

17 Guinea pigs are the only species to react with bronchoconstriction during exposure to low 18

concentrations. A concentration of 0.3 ppm produced bronchoconstriction (Amdur 1960). 19

20 Formaldehyde has been evaluated for potential teratogenicity in several test systems. 21 Inhalation studies with rats, although lacking in detail, indicate no teratogenic response. 22 Inhalation exposure of pregnant rats to 20 or 40 ppm on days 6-20 of gestation reduced fetal 23 body weight but failed to cause malformations (Saillenfait 1989). No teratogenic responses were 24 observed in dogs or mice treated orally. The reviewed studies do not show any evidence of the 25 embryo being unusually sensitive to formaldehyde, and there is no information that indicates 26 formaldehyde is teratogenic to rodents when administered by a number of routes. 27

28 A 13-week repeat exposure to 2 or 4 ppm did not result in pathologic changes in the nasal 29 epithelium of mice (Maronpot et al. 1986). However, repeat exposures to 10, 20, or 30 ppm 30 produced squamous metaplasia and inflammation. The 40 ppm exposure was lethal to most mice 31 during the 13-week exposure. Subchronic exposures were carcinogenic to the rat (Woutersen et 32 al. 1987). 33

34 Chronic studies have been carried out with rats, mice, and hamsters. In these studies, 35 formaldehyde-induced effects were restricted to non-neoplastic and neoplastic lesions in the 36 anterior regions of the nasal epithelium. Non-neoplastic lesions in rats such as metaplasia were 37 found at concentrations as low as 2 ppm (Kamata et al. 1997). Neoplastic lesions - squamous 38 cell carcinomas, squamous cell papillomas, or polyploid adenomas - were observed in rats 39 exposed to 5.6 ppm and in mice exposed to 14.3 ppm (Kerns et al. 1983). Neoplastic lesions 40 were not found in hamsters exposed to 10 ppm (Dalbey 1982). 41

42 Studies with several species of animals confirm that the upper respiratory tract is a 43 critical target for inhaled formaldehyde. These studies describe exposure-response relationships 44 for upper respiratory tract irritation and epithelial damage. Inhaled formaldehyde damages 45 epithelial tissue in specific regions of the upper respiratory tract in rats, mice, and monkeys. 46 Lesions consist of hyperplasia and squamous cell metaplasia. Lung damage occurs at higher 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 43 of 71

concentrations than those affecting only the upper respiratory tract. Mice and hamsters are less 1 susceptible to formaldehyde-induced upper respiratory tract epithelial damage than rats. Rats 2 and monkeys may be equally susceptible to epithelial damage, but display damage in different 3 regions of the respiratory tract. 4

5

4. SPECIAL CONSIDERATIONS 6 4.1. Metabolism and Disposition 7

8 Inhaled formaldehyde, being highly water soluble, is rapidly and almost completely 9 absorbed from the respiratory tract. Studies with mongrel dogs exposed to 122-235 ppm of 10 vapor showed that the retention of vapor is n early 100%, with most of the absorption in the 11 upper respiratory tract (Egle 1972; ATSDR 1999). Gastric absorption is also high, but dermal 12 absorption is quite low. Although all tissues are capable of metabolizing formaldehyde, rapid 13 local metabolism in the tissues of the respiratory tract results in little or no formaldehyde 14 reaching the blood. Given the high absorption and metabolism in the tissues of the respiratory 15 tract, storage or distribution to other tissues in unlikely. 16

17 Heck et al. (1985) measured the blood level of formaldehyde in six volunteers 18 immediately following inhalation of 1.9 ppm for 40 minutes and compared the results to pre19 exposure values. Although individual differences in blood concentrations were noted both pre20 and post-exposure, differences in the mean values were not statistically significant following 21 exposure (control value, 2.61 F g/g; postexposure, 2.77 F g/g). Similar results were found by 22 Heck et al. (1985) following exposure of eight male F-344 rats to 0 or 14.4 ppm for 2 hours and 23 sacrificed immediately after. Blood levels in the control and exposed groups were 2.24 and 2.25 24

F g/g, respectively. After intravenous injection of monkeys, formaldehyde is rapidly eliminated 25 from the blood with a half-life of about 1.5 minutes (McMartin et al. 1982). 26

27 In the cell, the initial reaction of formaldehyde is with glutathione to form a hemiacetal. 28 The hemiacetal is then metabolized to formate, primarily by formaldehyde dehydrogenase, 29 although other aldehyde dehydrogenases are capable of metabolizing formaldehyde (ATSDR 30 1999). This enzyme is present in all animal tissues. The actual endproduct of the dehydrogenase 31 reaction is S-formylglutathione which slowly hydr olyzes to formate. Formate can undergo three 32 reactions: oxidation to carbon dioxide and water, elimination in the urine as a sodium salt, or 33 entrance into the metabolic one-carbon cycle. Formaldehyde may also enter the one-carbon pool 34 directly. Formaldehyde also reacts with protein and single-strand DNA. 35

36 4.2. Mechanism of Toxicity 37

38 Formaldehyde is a primary irritant that is extensively scrubbed in the anterior nasal 39 passages. The mechanism of action of primary irritants involves activation of sensory nerve 40 fibers which relay to the trigeminal nerve to reflexively induce bronchoconstriction through the 41 vagus nerve. This mechanism of action has been observed in guinea pigs (Amdur 1960), but has 42 not been observed at the low concentrations used in clinical studies with healthy subjects and 43

asthmatics. 44

45 Formaldehyde is a highly cytotoxic respiratory tract irritant. The exact mechanism of 46 formaldehyde = s irritant, corrosive, and cytotoxic effects is unknown. Aldehydes as a group are 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 44 of 71

highly reactive chemicals. The highly electronegative oxygen atom and less electronegative 1 carbon atoms convey a substantial dipole moment. The electrophilic carbonyl atom reacts easily 2 with nucleophilic sites on cell membranes and in body tissue fluids. Formaldehyde also 3 combines readily with free, unprotonated ami no groups of amino acids to yield hydroxymethyl 4 amino acid derivatives and a proton (H+). This action may be responsible for its germicidal 5 properties. Higher concentrations will precipitate protein (ATSDR 1999). 6

7 The precursor of tumor formation for respiratory irritants is persistent tissue damage 8 followed by sustained cell proliferation. Induction of nasal squamous carcinomas in rats by 9 formaldehyde requires long-term exposure to concentrations of 10-20 ppm that result in 10 epithelial degeneration and cell death accompanied by rhinitis, followed by regenerative 11 hyperplasia and metaplasia, changes associated with increased cell proliferation 12 (Feron et al. 2001). Studies of nasal epithelial lesions and cell proliferation in formaldehyde13 exposed rats demonstrated a good correlation of cellular injury with cell proliferation and 14 neoplasia. At concentrations of 10 and 15 ppm there is a 4- to 10-fold increase in cell 15 proliferation in rat nasal tissue (Monticello et al. 1996). Formaldehyde is weakly genotoxic, 16 inducing DNA cross-links in the nasal respiratory epithelium of rats and monkeys (Casanova and 17 Heck 1991). At 10 ppm, the major pathway for detoxification in the rat is saturated. And above 18 10 ppm there is a 7-fold greater level of fo rmation of DNA-protein cross-links per ppm of 19 exposure than what occurs at lower concentr ations. Areas of DNA-protein cross links are 20 correlated with regional sites of formaldehyde-induced epithelial damage in the nose of rats. 21 Inhibition of mucociliary function, epithelial degeneration, inflammation, squamous metaplasia, 22 and increased cell proliferation in the nasal tissue all correlate with the site-specific uptake and 23 cancer pattern observed in experimental studies (Paustenbach et al. 1997). 24

25 4.3. Structure-Activity Relationships 26

27 In their study of the irritancy of six aldehydes, Sim and Pattle (1957) reported that 28 acrolein and crotonaldehyde were highly irritant, and acetaldehyde, propionaldehyde, 29 butyraldehyde, and isobutryaldehyde were almost nonirritant. The irritancy of formaldehyde 30 was intermediate between that of the highly irritant and nonirritant groups. Pattle and 31 Cullumbine (1956) reported formaldehyde toxicity to be between the unsaturated aldehydes and 32 acetaldehyde. U.S. EPA (2003) notes that when inhaled, acetaldehyde causes cancers in the nose 33

and trachea of hamsters and nasal cancers in rats. 34

35 Kane and Alarie (1977) compared the irritancy of formaldehyde and acrolein. The 36 respective RD 50 values were 3.1 and 1.7 ppm, demonstrating that formaldehyde is approximately 37 half as irritating as acrolein. 38

39

4.4. Other Relevant Information 40

41 Dermal exposure to formaldehyde produces allergic contact dermatitis. This is a delayed 42 hypersensitivity reaction in which only minute quantities of a material are necessary to elicit an 43 overt reaction. Allergic contact dermatitis is preceded by sensitization to the allergen. 44 Subsequent exposures elicit clinical effects (Cohen and Rice 2001). 45

46 4.4.1. Species Variability 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 45 of 71

1 The carcinogenic response to formaldehyde is species specific. Formaldehyde was 2 carcinogenic to F-344 rats and Wistar rats, but not hamsters. Wistar rats were much less 3 responsive than F-344 or Sprague-Dawley rats. Mice were much less susceptible than F-344 4 rats. Both the rat and monkey reacted to subchronic exposure with squamous metaplasia (Rusch 5 et al. 1983). There are differences in the deposition of formaldehyde in the nasal regions of the 6 rat and monkey, due to anatomical differences which influence air-flow patterns. In addition, 7 monkeys develop much lower amounts of DNA-protein crosslinks than rats after exposure to 8 formaldehyde (Casanova et al. 1991). For mice, differences in the carcinogenic response appear 9 due to differences in dose. Mice respond to formaldehyde with decreased minute volume and 10 therefore have less formaldehyde available for deposition in the nasal epithelium than rats 11 (Chang et al. 1983). 12

13 Nasal airflow patterns appear to play a dominant role in determining olfactory lesions 14 (Morgan and Monticello 1990). To estimate local formaldehyde dose in rat and monkey nasal 15 passages and in the human respiratory tract, researchers at the CIIT developed and applied three16 dimensional nasal airflow models and computa tional fluid dynamics modeling (Bush et al. 1998; 17 Frederick et al. 1998; Kimball et al. 2001; Cono lly et al. 2003; 2004). Additional key elements 18 of their approach were (1) association of the flux of formaldehyde into the nasal mucosa with 19 formation of DNA-protein cross-links and with ce ll death and cell proliferation, and (2) use of a 20 two-stage clonal growth model to link DNA-protein cross-links and cell proliferation with tumor 21 formation. Based on this computer modeling maximum likelihood estimates of cancer risk are 22

de minimis at relevant human exposures. 23

24 4.4.2. Susceptible Populations 25

26 Several studies indicate that there is wide variation in subjective response to irritation. 27 Response of subjects exposed to 1.6 ppm ranged from no discomfort to discomfort (Andersen 28 and Molhave 1977). Subjects were excluded from the study of Bender et al. (1983) if they did 29 not respond to 1.3 or 2.2 ppm. Green et al. (1987) reported that during exposure of 38 exercising 30 healthy and asthmatic subjects to 3 ppm, scores for odor, nose/throat irritation, and eye irritation 31 ranged from none to severe. Slightly less than a third of the subjects scored odor and eye and 32 nose/throat irritation as moderate or above and approximately 18% of the subjects reported no 33 odor perception. Up to 3 ppm, exercising asthmatics were not more susceptible to the irritant 34 effects of formaldehyde than exercising healthy subjects. 35

36 A small proportion of the population may develop formaldehyde asthma as a result of 37 occupational exposure. Of a total of 230 patients who had been exposed to formaldehyde and 38 suffered from asthma-like respiratory symptoms, 12 were considered a result of specific 39 sensitization to asthma (Nordman et al. 1985). Exposures ranged from 1 month to 19 years. 40 Diagnosis was made on the basis of bronchial reactivity to formaldehyde at a challenge 41 concentration of 2 ppm. In another study, 13 patients who had been chronically exposed to 42 formaldehyde in the home or workplace and had asthmatic-like symptoms at the site of exposure, 43 were tested with a challenge dose of formaldehyde or room air (Reed and Frigas 1984). One to 44 several concentrations were administered: 0.1, 1.0, and 3 ppm. Reactivity was measured as a 45

decline in FEV 1 of greater than 20%; a dose-response to formaldehyde and a lack of response to 46 room air were also considered in the positive response. These patients did not response to the 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 46 of 71

formaldehyde bronchial challenges. Furthermore, it has been difficult to demonstrate antibodies 1 to formaldehyde in individuals affected by asthma (Hendrick et al. 1982). 2

3 4.4.3. Concentration-Exposure Duration Relationship 4

5 The slight to moderate irritation that accompanies low concentrations of formaldehyde is 6 concentration rather than concentration x time dependent. Based on a review of several studies 7 including the subchronic study of Rusch et al. (1983), the Industrial Health Foundation expert 8 panel concluded that irritant effects of formalde hyde are concentration rather than concentration 9 x time dependent. They noted that nasal irritation did not occur below 0.98 ppm for three animal 10 species, even after 22 hours of exposure, and that no lower respiratory tract effects were 11 observed at 2.95 ppm, i.e., squamous metaplasia was confined to the nasal epithelium. 12

13 A number of studies indicate that adaptation takes place during continuous exposure. For 14 example, Weber-Tschopp et al. (1977) demonstrated that continuous exposure was subjectively 15 less irritating than discontinuous exposures to identical concentrations. Longer-term animal 16 studies also show a concentration effect. For example, in a 26-week inhalation study with rats, 17 monkeys and hamsters (Rusch et al. 1983), no nasal irritation or lower respiratory effects 18 occurred at or below 0.98 ppm, whereas, nasal lesions (squamous metaplasia) was observed in 19 rats and monkeys at 2.95 ppm. 20

21 Exposure duration has little effect on pulmonary function changes. In the clinical study 22 of Sauder et al. (1986), the maximal pulmonary response in healthy subjects inhaling 3 ppm for 3 23 hours (a 2% decrease in FEV 1 and a 7% decrease in FEF 25-75% ) occurred during the first 30 24 minutes of exposure and was no longer detectable between 60 and 180 minutes. 25

26 However, for a carcinogenic effect, exposure mu st be of sufficient duration. A 13-week 27 exposure at 10 ppm produced non-neoplastic changes in the nasal mucosa of rats (Woutersen et 28 al. 1987; Feron et al. 1988), whereas a 13-week exposure at 20 ppm caused squamous cell 29 carcinoma, carcinoma in situ, and polyploid adenom as in rats (Feron et al. 1988). A 4- or 8- 30 week exposure at 20 ppm failed to produce nasal cancers in rats (Feron et al. 1988). 31

32 Conolly et al. (2002) presented a dose-response analysis for formaldehyde-induced 33 respiratory tract cytotoxicity. Regenerative cellular proliferation data (secondary to cytotoxicity) 34 from F-344 rats inhaling 0, 0.7, 2.0, 6.0, 10, or 15 ppm 6 hours/day, 5 days/week for up to 2 35 years (Monticello et al. 1996) was extrapolated to humans (human flux model) to predict the 36 extent and intensity of the cytotoxic response throughout the human respiratory tract. The dose37 response to regenerative cellular proliferation was J-shaped, with the rates of regenerative 38 cellular proliferation at 0.7 and 2.0 ppm not statis tically different from control. Both the J39 shaped and hockey-stick-shaped curves were fitted to the raw data to predict human dose 40 response for regenerative cellular proliferation. A computational fluid dynamics model of air 41 flow and gas transport in the human nasal airways was linked to a typical path model of the 42 human lung to provide site-specific flux. Three working levels (respiratory rates) were 43 considered. Using the most vigorous working leve l, the lowest concentrations of formaldehyde 44 predicted to exert any cytotoxic effects in humans were 1.0 and 0.6 ppm for the J-shaped and 45 hockey-stick-shaped curves, respectively. 46

47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 47 of 71

For the endpoint of lethality, a time-scaled concentration-response probably occurs. 1 However, the diverse lethality data, including the LC 50 values of Skog (1950), Carpenter et al. 2 1949), Bitron and Aharonson (1978), and Nagorny et al. (1979) do not show a good relationship. 3

4 4.4.4. Concurrent Exposure Issues 5

6 Particulate matter may enhance the irritant effects of chemicals. Green et al. (1989) 7 tested the acute response of healthy nonsmoking subjects inhaling both 3.0 ppm formaldehyde 8 and 0.5 mg/m 3 respirable activated carbon aerosol (see Section 2.2.2 for results of exposure to 9 3.0 ppm formaldehyde alone). Synergistic increases in cough, but not in other irritant respiratory 10 tract symptoms were observed. Small (<5%) synergistic decreases in FVC and FEV 3 were also 11

seen. The authors could draw no conclusions concerning the clinical significance of these 12

effects. 13

14

5. DATA ANALYSIS FOR AEGL-1 15 5.1. Summary of Human Data Relevant to AEGL-1 16

17 A number of controlled exposure studies have been conducted. These 22 clinical 18 exposure studies with controlled atmospheres and involving over 500 subjects provide the most 19 scientific evidence for dose-response effects. The most sensitive endpoint in these studies is eye 20 and upper respiratory tract irritation. These studies show that irritation ranges from none to mild 21 to moderate at concentrations up to 1 ppm. Below 1 ppm many studies show no dose-response 22 relationship. Above 1 ppm, definite symptoms of discomfort are reported. However, even at 3 23 ppm, the majority of subjects reported only mild-moderate eye and upper respiratory tract 24 irritation (Green et al. 1987; 1989; Kulle et al. 1987; Sauder et al. 1986; 1987; Weber-Tschopp et 25 al. 1977). Of the 180 subjects tested in these latter studies, only one reported severe eye 26 irritation at 3 ppm (Sauder et al. 1987). Occupational studies report symptoms at lower levels 27 than in clinical studies, but the occupational studies have concomitant exposures to other 28 chemicals and particulates which increases irritancy. 29

30 Individuals may differ greatly in their response to the irritancy of formaldehyde. Several 31 of the studies were designed to include presumably sensitive individuals such as asthmatics. At 32 concentrations up to 3 ppm, asthmatics engaged in moderate exercise suffered no decrements in 33 several pulmonary function parameters (Sheppard et al. 1984; Green et al. 1987). This and 34

additional studies with asthmatics indicate that at # 3 ppm, formaldehyde is scrubbed in the upper 35 respiratory passages. In evaluating eye irritation, Bender et al. (1983) excluded nonsusceptible 36 individuals, i.e., individuals that did not repor t eye irritation at 1.3 or 2.2 ppm were excluded 37 from the study. The sensitive subjects in the Bender et al. (1983) reported the same irritant 38 response (none to slight) during exposures to clean air and to formaldehyde concentrations 39

# 0.9 ppm. 40

41 5.2. Summary of Animal Data Relevant to AEGL-1 42

43 Several animal studies addressed low concentrations and damage to the respiratory 44 epithelium. A concentration of 2 ppm for 6 hours did not damage the anterior respiratory 45 epithelium in obligate nose-breathing rats (Morgan et al. 1986b). A 13-week repeat exposure to 46 2 or 4 ppm did not result in pathologic changes in the nasal epithelium of mice (Maronpot et al. 47FORMALDEHYDE NAC/Interim 1: 07/2008; Page 48 of 71

1986). Repeated exposures to 1 or 2 ppm for 6 hours/day filed to induce lesions in rats 1 (Woutersen et al. 1987). Concentrations of 2 or 4 ppm did not damage the respiratory epithelium 2 in mice exposed for 13 weeks (Maronpot et al. 1986) or rats exposed to 3 ppm for 22 hours/day, 3 7 days/week, for 26 weeks (Rusch et al. 1983). Rodents have higher respiratory rates than 4 humans, which increases the dose delivered to the target tissues. 5

6

5.3. Derivation of AEGL-1 7

8 Rather than a weight-of-evidence approach, the AEGL-1 was based on a NOAEL for eye 9 irritation in a single study with sensitive subjects (Bender et al. 1983). In this study, groups of 5 10 to 28 healthy subjects were exposed eye-only for 6 minutes to 0, 0.35, 0.56, 0.7, 0.9, or 1.0 ppm. 11 The subjects had been selected for their response to formaldehyde at 1.3 or 2.2 ppm, i.e., 12 subjects that did not report eye irritation duri ng previous exposures to 1.3 or 2.2 ppm were 13 excluded from the study. At 0.35 to 0.9 ppm, the subjects = subjective eye irritation responses 14 ranged from none to slight, the same as their responses to clean air. The 0.9 ppm concentration 15 was selected as the basis for the AEGL-1. No intraspecies uncertainty factor was applied as no 16 additional sensitive populations were identified [there were no significant decrements in 17 pulmonary function parameters in exercising asthmatic subjects at 2 or 3 ppm, and asthmatic 18 subjects reported <moderate eye irritation, the same as healthy subjects, at these concentrations 19 (Green et al. 1987; Kulle et al. 1987; Sauder et al . 1987)]. Because several studies show there is 20 adaptation to irritation at this low concentration, the 0.9 ppm concentration was applied across 21 all exposure durations (Table 6). 22

23 The 0.90 ppm value is supported by the fact that animal studies show there is no damage 24 to the respiratory epithelium during single (Morgan et al. 1986b) or repeated exposures to 1 or 2 25 ppm (Rusch et al. 1983; Maronpot et al.1986; W outersen et al. 1987). Derivations of AEGL 26 values are in Appendix C and a category graph of human and animal toxicity data in relation to 27 AEGL values is in Appendix D. 28

29

TABLE 6. AEGL-1 Values for Formaldehyde

10-min 30-min 1-h 4-h 8-h

0.90 ppm (1.1 mg/m 3 ) 0.90 ppm (1.1 mg/m 3 ) 0.90 ppm (1.1 mg/m 3 ) 0.90 ppm (1.1 mg/m 3 ) 0.90 ppm (1.1 mg/m 3 )

30

31

6. DATA ANALYSIS FOR AEGL-2 32 6.1. Summary of Human Data Relevant to AEGL-2 33

34 Only a few studies with controlled exposures addressed effects defined by the AEGL-2. 35 Stephens et al. (1961) reported that 5 ppm deliv ered via goggles produced severe eye irritation , 36 whereas, Douglas (1974) reported eye irritation fo r 1 of 5 subjects at 8 ppm and for 5 of 6 37 subjects at 13 ppm during short exposures. Delivery to the eye was also via goggles. During 38 100% mouth breathing, airway resistance was increas ed at both concentrations. The decrement 39 was less than 50% at 8 ppm and 50-108% at 13 ppm. Lacrimation was mild and adaptation 40 occurred during a 30-minute exposure to 13.8 ppm (Sim and Pattle 1957). Two healthy 41 investigators considered the lacrimation and eye, nose, and throat irritation during several short 42 exposures to 20 ppm objectionable (Barnes and Speicher 1942). Average concentrations in 43FORMALDEHYDE NAC/Interim 1: 07/2008; Page 49 of 71

occupational situations have ranged up to 38 ppm (IARC 2006). Exposure durations and 1 concomitant exposures to other chemicals or particles were unknown. 2

3 6.2. Summary of Animal Data Relevant to AEGL-2 4

5

Few animal acute studies addressed effects that meet the definition of the AEGL-2. 6 Several studies reported on exposures of rats to concentrations as high as 15 ppm for 6 hours 7 (Chang et al. 1983; Morgan et al. 1986a; 1986b). These exposures inhibited mucociliary 8 clearance and resulted in histopathologic lesions of the respiratory epithelium, but little effect on 9 the olfactory epithelium. When exposure was discontinued, extensive recovery took place. 10

11FORMALDEHYDE NAC/Interim 1: 07/2008; Page 50 of 71

6.3. Derivation of AEGL-2 1

2 The AEGL-2 was based on the clinical study of Sim and Pattle (1957). Twelve healthy 3 male subjects inhaled 13.8 ppm for 30 minutes. Initially, the exposure caused considerable nose 4 and eye irritation. Mild lacrimation continued for some period of time. The eye irritation was 5 not considered severe, and adaptation occurred in about 10 minutes. Mild lacrimation at 13.8 6 ppm (rounded to 14 ppm) with adaptation was considered the threshold concentration for the 7 inability to escape. The lacrimation experienced by Barnes and Speicher (1942) at 20 ppm 8 during short exposures might impair the ability to escape. The 14 ppm concentration may also 9 be close to the threshold for an increase in airways resistance (Douglas 1974). No intraspecies 10 uncertainty factor was applied to the 14 ppm concentration because application of an uncertainty 11

factor of $ 3 would lower the value to close to a no-effect concentration in several studies with 12 exercising asthmatics. Because the endpoint is eye and nose irritation to which adaptation 13 occurs, the same value was used across all exposure durations (Table 7). 14

15

TABLE 7. AEGL-2 Values for Formaldehyde

10-min 30-min 1-h 4-h 8-h

14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 )

16

17

7. DATA ANALYSIS FOR AEGL-3 18 7.1. Summary of Human Data Relevant to AEGL-3 19

20 No human data relevant to development of AEGL-3 values were located. 21

22 7.2. Summary of Animal Data Relevant to AEGL-3 23

24

Lethal concentrations were available for the rat and mouse. LC 50 values for the rat 25 ranged from 820 ppm for 30 minutes (Skog 1950) to 250-482 ppm for 4 hours (Carpenter et al. 26 1949; Nagorny et al. 1979). For the mouse, the Lt 50 (similar to the LC 50 ) was 320 ppm for 100 27 minutes (Bitron and Aharonson 1978). These assorted studies did not show a good 28 concentration-response relationship. 29

30

Few studies at sublethal concentrations were of acute duration. Mice survived a 2-hour, 31 4-day repeat exposure to 140 ppm with little signs of distress (Horton et al. 1963). Murphy et al. 32 (1964) reported that 35 ppm for 18 hours was a sublethal concentration for the rat. Rats exposed 33 to 15, 20 or 30 ppm for 6 hours showed eye and nose irritation, inhibition of the mucociliary 34 clearance mechanism, and damage of the nasal mucosa which extended to the trachea at the 35 higher exposures (Chang et al. 1983; Tobe et al . 1985; Morgan et al. 1986a). Pregnant rats 36 inhaling 20 or 40 ppm on days 6-20 of gestation suffered no mortalities, but delivered fetuses of 37 reduced body weight (Saillenfait 1989). Mice did not survive a 13-week, 5 hour/day, exposure 38 to 40 ppm (Maronpot et al. 1986). In chronic studies, mice survived 5 hour/day exposures to 14 39 ppm (Swenberg et al. 1983). 40

41FORMALDEHYDE NAC/Interim 1: 07/2008; Page 51 of 71

7.3. Derivation of AEGL-3 1

2 The AEGL-3 values were based on the highest non-lethal value for the rat (350 ppm) 3 during a 4-hour exposure (Nagorny et al. 1979). The value was adjusted by interspecies and 4 intraspecies uncertainty factors of 3 each for a to tal of 10. These uncertainty factors, applied to 5 irritants, are protective of sensitive populations. Furthermore, application of larger uncertainty 6 factors, e.g., a total of 30, would reduce the value to the level of the AEGL-2. No data on time7 scaling were found. Therefore, the default value of n = 3 when scaling to shorter exposure 8 periods (NRC 2001) was applied (Table 8). 9

10 The 8-hour value was set equal to the 4-hour value because formaldehyde is well 11 scrubbed in the nasal passages. Furthermore, application of the default of n = 1 when scaling to 12 longer time periods would result in an 8-hour value of 18 ppm, similar to the 8-hour AEGL-2. 13 The 8-hour value is supported by sublethal concentrations in additional animal studies. Rats 14 were exposed to the sublethal concentration of 35 ppm for 18 hours in the study of Murphy et al. 15 (1964), and no deaths were attributable to eff ects of formaldehyde on the lungs during chronic 16 exposures of mice to 15 ppm (Swenberg et al. 1983). 17

18

TABLE 8. AEGL-3 Values for Formaldehyde

10-min 30-min 1-h 4-h 8-h

100 ppm (123 mg/m 3 ) 70 ppm (86 mg/m 3 ) 56 ppm (69 mg/m 3 ) 35 ppm (43 mg/m 3 ) 35 ppm (43 mg/m 3 )

19

20

8. SUMMARY OF AEGLS 21 8.1. AEGL Values and Toxicity Endpoints 22

23 AEGL values are summarized in Table 9. Derivation summary tables are in Appendix E. 24

25

TABLE 9. Summary of AEGL Values

Exposure Duration
Classification 10-min 30-min 1-h 4-h 8-h

AEGL-1 (Nondisabling) 0.90 ppm (1.1mg/m 3 ) 0.90 ppm (1.1mg/m 3 ) 0.90 ppm (11.mg/m 3 ) 0.90 ppm (1.1mg/m 3 ) 0.90 ppm (1.1mg/m 3 )

AEGL-2 (Disabling) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 ) 14 ppm (17 mg/m 3 )

AEGL-3 (Lethal) 100 ppm (123 mg/m 3 ) 70 ppm (86 mg/m 3 ) 56 ppm (69 mg/m 3 ) 35 ppm (43 mg/m 3 ) 35 ppm (43 mg/m 3 )

26

27 8.2. Comparison with Other Standards and Guidelines 28

29 Standards and guidance levels for workplace and community exposures are listed in 30 Table 10. Emergency Response Planning Guidelines (ERPGs) are similar to AEGLs, but are set 31 for only 1-hour exposures. The ERPG-1 of 1 ppm is based on human exposure data including 32 the studies of Weber-Tschopp et al. (1977), Kulle et al. (1987), and Sauder et al. (1987). At the 33 exposure of 1 ppm, it is felt that nearly all individuals would experience no greater health effects 34 than odor or mild sensory irritation. The ERPG-2 of 10 ppm is based on the studies of Kulle et 35FORMALDEHYDE NAC/Interim 1: 07/2008; Page 52 of 71

al. 1987 and Sim and Pattle (1957). Concentrations greater than this might impair the ability to 1 escape. The ERPG-3 of 25 ppm is based on acute exposure data in animals (Carpenter et al. 2 1946, Skog 1950) and human data cited in Patty = s Industrial Hygiene and Toxicology (Morandi 3 and Maberti. 2001). 4

5 The NIOSH IDLH of 20 ppm is based on a report that exposure to 10 to 20 ppm produces 6 almost immediate eye irritation and a sharp burning sensation of the nose and throat which may 7 be associated with sneezing, difficulty in taking a deep breath, and coughing; recovery is prompt 8 from these transient effects (personal observations reported in Morandi and Maberti 2001 ). 9 NIOSH standards carry carcinogen notations. NIOSH (1976) notes that their recommended 10 standard is not designed to protect an i ndividual already sensitized to formaldehyde. 11

12 The NRC (1994) SMAC of 0.4 ppm is based on the prevention of mucosal irritation. In 13 setting this value, the NRC considered complaints of workers and residents in mobile homes. It 14 should be noted that exposure to 0.4 ppm was not i rritating in most of the clinical studies and 15 that the exposures in mobile homes and factories were to a mixture of chemicals. 16

17 The NRC (2007) 1-hour EEGL of 2 ppm was based on a range of 1-3 ppm in multiple 18 controlled human studies which allowed for up to moderate irritation with reversible symptoms. 19

20 Noisel et al. (2007; IRSST 2006) addressed the impact of lowering the occupational 21 standard for exposure to formaldehyde in Quebec, Canada. They assessed the exposure-response 22 relationship from a pooled analysis of published controlled human studies on the incidence of the 23 most sensitive effects related to acute formaldehyde exposure (irritation of the eyes, nose, and 24 throat). The exposure-irritating effect relati onship compiled from concentration ranges and by 25 degree of severity was best described by quadr atic regression. The authors concluded that 26 workers exposed to formaldehyde concentrations <0.75 ppm should not experience moderate or 27 severe irritating effects to the eyes, nose, or throat that may be attributed to formaldehyde. 28

29FORMALDEHYDE NAC/Interim 1: 07/2008; Page 53 of 71

TABLE 10. Extant Standards and Guidelines for Formaldehyde

Exposure Duration Guideline 10 min 30 min 1 h 4 h 8 h

AEGL-1 0.90 ppm 0.90 ppm 0.90 ppm 0.90 ppm 0.90 ppm AEGL-2 14 ppm 14 ppm 14 ppm 14 ppm 14 ppm AEGL-3 100 ppm 70 ppm 56 ppm 35 ppm 35 ppm ERPG-1 (AIHA) a 1 ppm ERPG-2 (AIHA) 10 ppm ERPG-3 (AIHA) 25 ppm

SMAC (NRC) b 0.4 ppm

EEGL (NRC) c 2 ppm

PEL-TWA

PEL-STEL (OSHA) d 0.75 ppm 2 ppm (15 minute) IDLH (NIOSH) e 20 ppm*

REL-TWA

REL-STEL (NIOSH) f 0.016 ppm* 0.1 ppm (15 minute) TLV-Ceiling (ACGIH) g 0.3 ppm*

MAK

Peak Limit (Germany) h 0.3 ppm* 1 ppm

MAC

Peak Limit (The Netherlands) i 1 ppm 2 ppm

*potential occupational carcinogen 1
2

a ERPG (Emergency Response Planning Guide lines, American Industrial Hygiene Association (AIHA 2004) 3

The ERPG-1 is the maximum airborne concentration belo w which it is believed nearly all individuals could be 4 exposed for up to one hour without experiencing other than mild, transient adverse health effects or without 5 perceiving a clearly defined objectionable odor. 6

The ERPG-2 is the maximum airborne concentration belo w which it is believed nearly all individuals could be 7 exposed for up to one hour without experiencing or devel oping irreversible or other serious health effects or 8 symptoms that could impair an individual = s ability to take protection action. 9

The ERPG-3 is the maximum airborne concentration belo w which it is believed nearly all individuals could be 10 exposed for up to one hour without experiencing or developing life-threatening health effects. 11
12

b SMAC (Spacecraft Maximum Allowable Concentration ) (NRC 1994) 13 SMACs provide guidance on chemical exposures during normal operations of spacecraft as well as emergency 14

situations. The one-hour SMAC is a concentration of airborne substance that will not compromise the 15 performance of specific tasks by astronauts during emerge ncy conditions or cause serious or permanent toxic 16 effects. Such exposure may cause reversible effects such as skin or eye irritation, but they are not expected to 17 impair judgment or interfere with proper responses to emergencies. 18 19

c EEGL (Emergency and Continuous Exposu re Levels for Chemicals in Submarines) (NRC 2007) 20 EEGLs provide guidance on chemical exposures during normal operations of submarines. The one-hour EEGL 21 is a concentration that would allow up to moderate irr itation in some individuals, but would not interfere with 22 critical duties. These exposures are for healthy adults. 23
24FORMALDEHYDE NAC/Interim 1: 07/2008; Page 54 of 71

d OSHA PEL-TWA (Occupational Safety and Health Ad ministration, Permissible Exposure Limits - Time 1
Weighted Average) (NIOSH 1997) is defined analogous to the ACGIH-TLV-TWA, but is for exposures of no 2 more than 10 hours/day, 40 hours/week. The OSHA P EL-STEL (Permissible Exposure Limits - Short Term 3 Exposure Limit) is defined analogous to the ACGIH-TLV-STEL. 4
5

e IDLH (Immediately Dangerous to Life and Health, Nati onal Institute of Occupational Safety and Health) 6 (NIOSH 1997) represents the maximum concentration from which one could escape within 30 minutes without 7 any escape-impairing symptoms, or any irreversible health effects. 8 9

f NIOSH REL-TWA (National Institute of Occupational Safety and Health, Recommended Exposure Limits - 10
Time Weighted Average) (NIOSH 1997) is defined analogous to the ACGIH-TLV-TWA. The NIOSH REL11 STEL (Recommended Exposure Limits - Short Term Exposur e Limit) is defined analogous to the ACGIH TLV12

STEL. 13
14

g ACGIH TLV-TWA (American Conference of Governmental Industrial Hygienists, Threshold Limit Value - 15
Time Weighted Average) (ACGIH 2004) is the time-weighted average concentration for a normal 8-hour 16 workday and a 40-hour workweek, to which nearly all workers may be repeatedly exposed, day after day, 17

without adverse effect. 18 19

h MAK (Maximale Arbeitsplatzkonzentrat ion [Maximum Workplace Concentration]) List of MAK and BAT 20 Values 2007 (Deutsche Forschungsgemeinschaft [German Re search Association] 2007) is defined analogous to 21 the ACGIH-TLV-TWA. In the case of formaldehyde a momentary value of 1 ppm should not be exceeded. 22 The MAK Spitzenbegrenzung (Peak Limit [give category ]) constitutes the maximum average concentration to 23 which workers can be exposed for a period up to 30 minutes with no more than 2 exposure periods per work 24 shift; total exposure may not exceed 8-hour MAK. 25 26

i MAC (Maximaal Aanvaarde Concentratie [Maximal Accepted Concentration]) (SDU Uitgevers [under the 27 auspices of the Ministry of Social Affairs and Em ployment], The Hague, The Netherlands 2000) is defined 28 analogous to the ACGIH-TLV-TWA. The peak limit is defined analogous to the ACGIH ceiling. 29

30 8.3. Data Adequacy and Research Needs 31

32 Formaldehyde has a robust data set of controlled human exposures. Data from 22 well33 conducted clinical studies involving over 500 subj ects form a reliable basis for setting AEGL-1 34 and AEGL-2 values. The data base for lethality involves relatively old animal studies that lack 35 details of methodology as well as clear results. However, the data, with support from repeat36 exposure studies with animals, can be used to set non-lethal values for humans. 37

38

9. REFERENCES 39

40
ACGIH (American Conference of Government and Industrial Hygienists). 2004. Documentation of the Threshold 41 Limit Values and Biological Exposure Indices : Formaldehyde. Cincinnati, OH: ACGIH. 42 43 Ad Hoc Panel on Health Aspects of Formaldehyde. 1988. Epidemiology of chronic occupational exposure to 44 formaldehyde. Toxicol. Ind. Health 4:77-90. 45 46 AIHA (American Industrial Hygiene Association). 2004. Emergency Response Planning Guidelines: 47 Formaldehyde. Akron, OH: AIHA. 48 49 Akbar-Khanzadeh, F. and J.S. Mlynek. 1997. Changes in respiratory function after one and three hours of exposure 50 to formaldehyde in non-smoking subjects. Occup. Environ. Med. 54:296-300. 51 52 Akbar-Khanzadeh, F., M.U. Vaquerano, Akbar-Khanzadeh, M., and M.S. Bisesi. 1994. Formaldehyde exposure, 53 acute pulmonary response, and exposure control options in a gross anatomy laboratory. Am. J. Ind. med. 54

26:61-75. 55FORMALDEHYDE NAC/Interim 1: 07/2008; Page 55 of 71

1 Alarie, Y. 1981. Toxicological evalua tion of airborne chemical irritants a nd allergens using respiratory reflex 2 reactions. In: Leong, B.K.J., ed., Proceedings of the Inhalation Toxicology and Technology Symposium, 3 Kalamazoo, MI. Ann Arbor, Michigan: Ann Arbor Science. 4
5
Albert, R.E., A.R. Sellakumar, S. Laskin, M. Kuschner, N. Nelson, and C.A. Snyder. 1982. Gaseous formaldehyde 6 and hydrogen chloride induction of nasal cancer in rats. J. Natl. Cancer inst. 68:597-603. 7 8 Amdur, M.O. 1960. The response of guinea pigs to inha lation of formaldehyde and formic acid alone and with a 9

sodium chloride aerosol. Int. J. Air Pollut. 3:201-220. 10
11
Amoore, J.E. and E. Hautala. 1983. Odor as an aid to chemical safety; odor thresholds compared with threshold 12

limit values and volatilities for 214 industrial chemicals in air and water dilution. J. Appl. Toxicol. 3:272- 13

290. 14 15
Andersen, I. and L. Molhave. 1983. Controlled human st udies with formaldehyde. pp. 154-165 in Gibson, J.E. , ed, 16 Formaldehyde Toxicity. Washington, DC : Hemisphere Publishing Corporation. 17 18
Andersen, M.E., H.J. Clewell, III, E. Bermudez, G.A. Willson, and R.S. Thomas. 2008. Genomic signatures and 19 dose dependent transitions in nasal epithelial responses to inhaled formaldehyde in the rat. Toxicol. Sci. 20
May, 2008. 21
22 Appleman, L.M., R.A. Woutersen, A. Zwart, H.E. Falke, and V.J. Feron. 1988. One-year inhalation toxicity study 23 of formaldehyde in male rats with a damaged or undamaged nasal mucosa. J. Appl. Toxicol. 8:85-90. 24 25 ATSDR (Agency for Toxic Substances and Disease Regist ry). 1999. Toxicological Profile for Formaldehyde. 26 Washington, DC: U.S. Public Health Service. 27 28
Auerbach, C., M. Moutschen-Dahmen, and J. Moutschen. 1977. Genetic and cytogenetic effects of formaldehyde 29 and related compounds. Mutat. Res. 39:317-362. 30 31
Bach, B., O.F. Pedersen, and L. Molhave. 1987. Human reaction to formaldehyde. Proj. 1981-48/1985/08. 32
Aarhus, Denmark: Institute of Environmental and Occ upational Medicine. (Danish, English abstract). 33

Cited in Bach et al. 1990. 34 35
Bach, B., O.F. Pedersen, and L. Molhave. 1990. Huma n performance during experimental formaldehyde exposure. 36

Environ. Intl. 16:105-113. 37 38 Barnes, E.C. and H.W. Speicher. 1942. The determination of formaldehyde in air. J. Ind. Hyg. Toxicol. 24:10-17. 39 40 Bender, J.R., L.S. Mullin, G.J. Grapel, and W.E. Wilson. 1983. Eye irritation response of humans to formaldehyde. 41 Am. Ind. Hyg. Assoc. J. 44:463-465. 42 43 Bender, J. 2002. The use of noncancer endpoints as a basis for establishing a reference concentration for 44 formaldehyde. Regul. Toxicol. Pharmacol. 35:23-31. 45 46 Berglund, B., U. Berglund, L. Hogman, J. Johansson, and T. Lindvall. 1987. The psychophysics of formaldehyde 47 odor. Pp. 655-660 in Seifert, B., et al. eds., Indoor Air 87. Berlin: Institute for Water, Soil and Air 48 Hygiene, BGA. (Cited in WHO 1989). 49 50 Billings, C.E. and L.C. Jonas. 1981. Odor threshold in ai r as compared to threshold limit values. Am. Ind. Hyg. 51

Assoc. J. 42:479. 52 53
Bitron, M.D. and E.F. Aharonson. 1978. Delayed mortality of mice following inhalation of acute doses of CH 2 O, 54

SO 2 , CL 2 , and Br 2 . Amer. Ind. Hyg. Assoc. J. 39:129-138. 55 56FORMALDEHYDE NAC/Interim 1: 07/2008; Page 56 of 71

Blair, A. P. Steuart, M. O’Berg, W. Gaffey, J. Walwrath , J. Ward, R. Bales, S. Kaplan, and D. Cubit. 1986. 1 Mortality among industrial workers exposed to fo rmaldehyde. J. Natl. Cancer Inst. 76:1071-1084. 2 3 Boja, J.W., J.A. Nielsen, E. Foldvary, and E.B. Truitt, Jr. 1985. Acute low-level formaldehyde behavioural and 4 neurochemical toxicity in the rat. Prog. Neuro-Psychhopharmacol Biol. Psychiat. 9:671-674. 5 6
Bush, M.L., C.B. Frederick, J.S. Kimball, and J.S. U ltman. 1998. A CFD-PBPK hybrid model for simulating gas 7 and vapor uptake in the rat nose. Toxicol. Appl. Pharmacol. 150:133-145. 8 9 California Environmental Protection Agency. 1999. Ac ute Toxicity Summary: Formaldehyde. Online database: 10 http://www.oehha.ca.gov/air/

. 11
12 Carpenter, C.P., H.F. Smyth and U.C. Pozzani. 1949. The assay of acute vapor toxicity and the grading and 13 interpretation of results on 96 chemical co mpounds. J. Ind. Hyg. Toxicol. 31:343-346. 14 15
Casanova-Schmitz, M. and d = A.H. Heck. 1983. Effects of formal dehyde exposure on the extractability of DNA 16 from proteins in the rat nasal mucosa. Toxicol. Appl. Pharmacol. 70:121-132. 17 18
Casanova-Schmitz, M., T.B. Starr, and H.d = A. Heck. 1984. Differentiation between metabolic incorporation and 19 covalent binding in the labeling of macromolecules in the rat nasal mucosa and bone marrow by inhaled 20 ( 14 C) and ( 3 H) formaldehyde. Toxicol. Appl. Pharmacol. 76:26-44. 21
22
Casanova, M. and d = A.H. Heck. 1991. The impact of DNA-prot ein cross linking studies on quantitative risk 23 assessment of formaldehyde. CIIT Activities Bull. 11:1-6. 24 25 Casanova, M., K.T. Morgan, W.H. Steinhagen, J.I. Everitt, J.A. Popp, and H. D’A. Heck. 1991. Covalent binding 26 of inhaled formaldehyde to DNA in the respiratory tract of rhesus monkeys: pharmacokinetics, rat-to 27 monkey interspecies scaling, and extrapolati on to man. Fund. Appl. Toxicol. 17:409-428. 28 29
Cassee, F.R., J.H.E. Arts, J.P. Groten, and V.J. Feron. 1996. Sensory irritation to mixtures of formaldehyde, 30 acrolein, and acetaldehyde in ra ts. Arch. Toxicol. 70:329-337. 31 32 Chang, J.C.F., W.H. Steinhagen, and C.S. Barrow. 1981. Effect of single or repeated formaldehyde exposure on 33

minute volume of B6C3F 1 mice and F-344 rats. Toxicol. Appl. Pharmacol. 61:451-459. 34 35 Chang, J.C.F., E.A. Gross, J.A. Swenberg, and C.S. Barrow. 1983. Nasal cavity deposition, histopathology, and 36 cell proliferation after single or repeated formaldehyde exposures in B6C3F1 ice and F-344 rats. Toxicol. 37 Appl. Pharmacol. 68:161-176. 38 39 Cohen, D.E., and R.H. Rice. Chapter 19: Toxi c Responses of the Skin. In Casarett & Doull = s Toxicology: The 40

Basic Science of Poisons. New York @ McGraw-Hill. 41
42 Conolly, R.B., J.S. Kimball, D.B. Janszen, and F.J. Miller. 2002. Dose response for formaldehyde-induced 43 cytotoxicity in the human respiratory tr act. Regul. Toxicol. Pharmacol. 35:32-43. 44 45 Conolly, R.B., J.S. Kimball, D. Janszen, P.M. Schlosser, D. Kalisak, J. Preston, and F.J. Miller. 2003. Biologically 46 motivated computational modeling of formaldehyde carci nogenicity in the F344 rat. Toxicol. Sci. 75:432- 47

447. 48 49 Conolly, R.B., J.S. Kimball, D. Janszen, P.M. Schlosser, D. Kalisak, J. Preston, and F.J. Miller. 2004. Human 50 respiratory tract cancer risks of inhaled formaldehyde : dose-response predictions derived from biologically51 motivated computational modeling of a combined rode nt and human data set. Toxicol. Sci. 82:279-296. 52 53 Dalbey, W. 1982. Formaldehyde and tumors in hamster respiratory tract. Toxicology 24:9-14. 54
55 Day, J.H., R.E.M. Lees, R.H. Clark, and P.L. Pattee. 1984. Respiratory response to formaldehyde and off-gas of 56 urea formaldehyde foam insulation. Can. Med. Assoc. J. 131:1061-1065. 57FORMALDEHYDE NAC/Interim 1: 07/2008; Page 57 of 71

1
Dean, J.H., L.D. Lauer, R.V. House, M.J. Nurray, W.S. Stillman, R.D. Irons, W.H. Steinhagen, M.C. Phelps, and 2

D.O. Adams. 1984. Studies of immune functi on and host resistance in B6C3F1 mice exposed to 3 formaldehyde. Toxicol. Appl. Pharmacol. 72:519-529. 4
5
Della Porta, G., F.R. Cabral, and G. Parmiani. 1970. Tran splacental toxicity and carcinogenesis studies in rats with 6 hexamethylenetetramine. Tumori 56:325-334. 7 8 Douglas, R.B. 1974. Human reflex bronchoconstriction as an adjunct to conjunctival sensitivity in defining the 9 threshold limit values of irritant gases and vapours. Thesis, TUC Centenary Institute of Occupational 10 Health, London School of Hygiene and Tropical Medicine. 11
12 Dubreuil, A., G. Bouley, J. Godin, C. Boudine, and F. Gira rd. 1976. Inhalation, en contince, de faibles doser de 13 formaldehyde: etude experimentale chez le rat. Eur. J. Toxicol. 9:245-250. 14 15 Egle, J.L. 1972. Retention of inhaled formaldehyde, pr opionaldehyde, and acrolein in the dog. Arch. Environ. 16

Health 25:119-124. 17 18 Epstein, S.S., E. Arnold, J. QAndrea, W. Bass, and Y. Bishop. 1972. Detection of chemical mutagens by the 19 dominant lethal assay in the mouse. Toxicol. Appl. Pharmacol. 23:288-325. 20
21 Ezratty. V., M. Bonay, C. Neukirk, G. Orset-Guillossou, M. Dehoux, S. Koscielny, P.A. Cabanes, J. Lambrozo, and 22 M. Aubier. 2007. Effect of formaldehyde on asthmatic response to inhaled allergen challenge. Environ. 23 Health Persp. 115:210-214. 24 25 Federal Panel on Formaldehyde. 1982. Report of the Fede ral Panel on formaldehyde. Environ. Health Persp. 26

43:139-168. 27 28 Feron, V.J., J.P. Bruynitjes, R.A. Woutersen, H.R. Immel, and L.M. Appleman. 1988. Nasal tumours in rats after 29 short-term exposure to a cytotoxic concentra tion of formaldehyde. Cancer Lett. 39:101-111. 30 31 Feron, V.J., H.T. Til, F. de Vrije r, R.A. Woutersen, F.R. Cassee, a nd P.J. van Bladeren. 1991. Aldehydes: 32 occurrence, carcinogenic potential, mechanisms of ac tion and risk assessment. Mutat. Res. 259:363-385. 33 34
Feron, V.J., J.H.E. Arts, C.F. Kuper, J. Slootweg, and R.A. Woutersen. 2001. Health risks associated with inhaled 35

nasal toxicants. Crit. Rev. Toxicol. 31:313-347. 36 37
Frederick, C.B., M.L. Bush, L.G. Lomax, K.A. Black, L. Fi nch, J.S. Kimball, K.T. Morgan, R.P. Subramaniam, J.B. 38 Morris, and J.S. Ultman. 1998. Use of a hybrid co mputational fluid dynamics and physiologically based 39 inhalation model for interspecies dosimetry extrapola tion of acidic vapors in the upper airways. Toxicol. 40 Appl. Pharmacol. 152:211-231. 41
42 Frigas, E., W.V. Filley, and C.E. Reed. 1984. Br onchial challenge with formaldehyde gas: lack of 43 bronchoconstriction in 13 patients suspected of havi ng formaldehyde-induced asthma. Mayo Clin. Proceed. 44

59:295-299. 45 46 Gardner, R.J., B.A. Burgess, and G.L. Kennedy, Jr. 1985. Sensory irritation potential of selected nasal tumorigens 47

in the rat. Fd. Chem. Toxicol. 23:87-92. 48 49 Garry, V.F., L. Oatman, R. Pleur, et al. 1980. Formalde hyde in the home: some environmental disease perspectives. 50

Minn. Med. 63:107-111. 51 52 German Research Association (Deutsche Forschungsgemein schaft). 2007. List of MAK and BAT Values 2007. 53 Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area: Report 54 No. 43. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. 55 56FORMALDEHYDE NAC/Interim 1: 07/2008; Page 58 of 71

Gorski, P., M. Tarkowski, A. Krakowiak, and M. Kl ec-Swierczyriska. 1992. Neutrophil chemiluminescence 1 following exposure to formaldehyde in healthy subjects and in patients with contact dermatitis. Aller. 2 Immunopath. 20:20-23. 3
4
Green, D.J., L.R. Sauder, T.J. Kulle, and R. Bascom. 1987. Acute response to 3.0 ppm formaldehyde in exercising 5 healthy nonsmokers and asthmatics. Am. Rev. Respir. Dis. 135:1261-1266. 6
7 Green, D.J., R. Bascom, E.M. Healey, J.R. Hebel, L.R. Sa uder, and T.J. Kulle. 1989. Acute pulmonary response in 8 healthy, nonsmoking adults to inhalation of formalde hyde and carbon. J. Toxicol. Environ. Health 28:261- 9

275. 10
11 Harving, H., J. Korsgaard, R. Dahl, O.F. Pedersen, and L. Molhave. 1986. Low concentrations of formaldehyde in 12 bronchial asthma: a study of exposure under c ontrolled conditions. Brit. Med. J. 293:310. 13
14 Harving, H., J. Korsgaard, O.F. Pedersen, L. Molhave, and R. Dahl. 1990. Pulmonary function and bronchial 15 reactivity in asthmatics during low-leve l formaldehyde exposure. Lung 168:15-21. 16 17
Heck, H.d = A., M. Casanova-Schmitz, P.B. Dodd, E.N. Schachter, T. Witek, and T. Tosun. 1985. Formaldehyde 18 (CH 2 O) concentration in the blood of humans and Fischer-344 rats exposed to CH 2 O under controlled 19 conditions. Amer. Ind. Hyg. Assoc. J. 46:1-3. 20
21
Heck, H. d @ A., M. Casanova, and T.B. Starr. 1990. Formal dehyde toxicity - new understanding. Crit. Rev. 22

Toxicol. 20:397-426. 23
24
Hendrick, D.J., R.J. Rando, D.J. Lane, and M.J. Morris. 1982. Formaldehyde asthma: challenge exposure levels 25 and fate after five years. J. Occup. Med. 24:893-897. 26 27 Horton, A.W., T. Tye, and K.L. Stemmer. 1963. Experi mental carcinogenesis of the lung. Inhalation of gaseous 28 formaldehyde or an aerosol of coal tar by C3H mice. J. Natl. Cancer Inst. 30:31-40. 29 30
Horvath, E.P., H. Anderson, W.E. Pierce, et al. 1988. Effects of formaldehyde on the mucous membranes and 31 lungs: a study of an industrial population. J. Amer. Med. Assoc. 259:701-707. 32 33 IARC (International Agency for Research on Cancer). 2006. IARC Monographs on the Evaluation of Carcinogenic 34 Risks to Humans. Formaldehyde, 2-Butoxyethanol a nd 1-tert-Butoxypropane-2-ol. Volume 88. Lyon, 35 France: World Health Organization, pp. 39-325. 36 37 IRSST (Institut de recherché Robert Sauve en santé et en securite du travail). 2006. Impact of Lowering the 38 Permissible Exposure Value for Formaldehyde: Health Impact of an Occupational Exposure to 39 Formaldehyde (Appendix). Available online: www.irsst.qc.ca

. 40
41 Kamata, E., M. Nakadate, Y. Ogawa, T. Kaneko, Y. Kur okawa, and M. Yukawa. 1996. Acute inhalation toxicity 42 study of formaldehyde in rats: effect of vapor on th e pulmonary surfactant. Pharmacometrics 51:33-37. 43
44 Kamata, E., M. Nakadate, O. Uchida, Y. Ogawa, S. Suzuki , T. Kaneko, M. Saito, and Y. Kurokawa. 1997. Results 45 of a 28-month chronic inhalation toxicity study of formal dehyde in male Fisher-344 rats. J. Toxicol. Sci. 46

22:239-254. 47 48 Kane, L.E. and Y. Alarie. 1977. Sensory irritation for formaldehyde and acrolein during single and repeated 49 exposures in mice. Amer. Ind. Hyg. Assoc. J. 38:509-522. 50 51
Kerns, W.D., K.L. Pavkov, D.J. Donofrio, E.J. Gralla, a nd J.A. Swenberg. 1983. Carcinogenicity of formaldehyde 52 in rats and mice after long-term inhala tion exposure. Cancer Res. 43:4382-4392. 53 54 Kimball, J.S., P.M. Schlosser, R.B. Conolly, and F.J. M iller. 2002. Dosimetry modeling of inhaled formaldehyde. 55

CIIT Activities 22:1-12. 56
57FORMALDEHYDE NAC/Interim 1: 07/2008; Page 59 of 71

Krakowiak, A., P. Gorski, K. Pazdrak, and U. Ruta. 1998. Airway response to formaldehyde inhalation in asthmatic 1 subjects with suspected respiratory formaldehyde sensitization. Amer. J. Ind. Med. 33:274-281. 2 3 Kulle, T.J. 1993. Acute odor and irritation response in healthy nonsmokers with formaldehyde exposure. Inhal. 4

Toxicol. 5:323-332. 5 6
Kulle, T.J., D.J. Green, and L.R. Sauder. 1986. Acute pulmonary effects of 3.0 ppm formaldehyde in exercising 7 healthy nonsmokers and asthmatics. Amer. Rev. Respir. Dis. 133:A355. 8 9
Kulle, T.J., L.R. Sauder, J.R. Hebel, and D.J. Green. 1987. Formaldehyde dose-response in healthy nonsmokers. J. 10

Air Pollut. Control Assoc. 37:919-924. 11
12 Lang, I., T. Bruckner, and G. Triebig. 2008. Formalde hyde and chemosensory irritation in humans: A controlled 13 human exposure study. Regul. Toxicol. Pharmacol. 50:23-36. 14 15
Lee, H.K., Y. Alarie, and M.H. Karol. 1984. Induction of formaldehyde sensitivity in guinea pigs. Toxicol. Appl. 16

Pharmacol. 75:147-155. 17 18
Leonardos, G., D. Kendall, and N. Barnard. 1969. Odor th reshold determinations of 53 odorant chemicals. J. Air 19

Pollut. Control Assoc. 19:91-95. 20
21 Maiback, H. 1983. Formaldehyde: effects on animal and human skin. Pp. 166-174 in Gibson, J. ed., Formaldehyde 22 Toxicity. Washington, DC: Hemisphere Publishing Corporation. 23
24 Maronpot, R.R., R.A. Miller, W.J. Clarke, R.B. Westerbe rg, J.R. Decker, and O.R. Moss. 1986. Toxicity of 25 formaldehyde vapor in B6C3F1 mice exposed for 13 weeks. Toxicology 41:253-266. 26 27
McMartin, K.E., G. Martin-Amat, P.E. N oker, and T.R. Tephly. 1979. Lack of a role for formaldehyde in methanol 28 poisoning in the monkey. Biochem. Pharmacol. 18:645-649. 29 30 Melekhina, V.P. 1964. Hygienic evaluation of formaldehyde as an atmospheric air pollutant. Pp. 9-17 in Levine, 31 B.S. (translation): USSR Literature on Air Pollution and Related Occupational Diseases - A Survey. NTIS 32 TT64-11573. Springfield, VA: National Technical Information Service. (Cited in NIOSH 1976). 33 34 Monticello, T.M., K.T. Morgan, J.I. Everitt, and J.A. P opp. 1989. Effects of formaldehyde gas on the respiratory 35 tract of rhesus monkeys. Amer. J. Pathol. 134:515-527. 36 37 Monticello, T.M., J.A. Swenberg, E.A. Gross, J.R. Leiniger , J.S. Kimball, S. Seilkop, T. B. Starr, J.E. Gibson, and 38 K.T. Morgan. 1996. Correlation of regional a nd nonlinear formaldehyde-induced nasal cancer with 39 proliferating populations of ce lls. Cancer Res. 56:1012-1022. 40
41
Morandi, M.T. and S. Maberti. 2001. Ch apter 73: Aldehydes and Acetals. In Patty = s Toxicology, Vol. 5, 5 th ed., pp. 42 963-1087. New York: John Wiley & Sons, Inc. 43
44 Morgan, K.T. and T.M. Monticello. 1990. Airflow, gas de position, and lesion distribution in the nasal passages. 45 Environ. Health Persp. 85:209-218. 46 47 Morgan, K.T., D.L. Patterson and E.A. Gross. 1986a. Respons es of the nasal mucociliary apparatus of F-344 rats to 48 formaldehyde gas. Toxicol. Appl. Pharmacol. 82:1-13. 49 50 Morgan, K.T., E.A. Gross and D.L. Patterson. 1986b. Distribution, progression , and recovery of acute 51 formaldehyde-induced inhibition of nasal mucociliary f unction in F-344 rats. Toxicol. Appl. Pharmacol. 52

86:448-456. 53 54 Murphy, S.D., H.V. Davis and V.L. Zaratzian. 1964. Bioc hemical effects in rats from irritating air contaminants. 55 Toxicol. Appl. Pharmacol. 6:520-528. 56
57FORMALDEHYDE NAC/Interim 1: 07/2008; Page 60 of 71

Nagorny, P.A., Zh.A. Sudakova and S.M. Schablenko. 1979. On the general toxic and allergic action of 1 formaldehyde. Gig. Tr. Prof. Zabol. 1:27-30. 2 3

NIOSH. 1976. Criteria for a Recommended Standard: O ccupational Exposure to Formaldehyde. Cincinnati, OH: 4 Department of Health , Education and Welfare, Nati onal Institute for Occupational Safety and Health. 5

DHEW Publication No. 77-126. 6
7

NIOSH. 1997. NIOSH Pocket Guide to Chemical Hazards. U.S. Department of Health and Human Services. June, 8

1997. 9 10
Noisel, N., M. Bouchard,and G. Carrier. 2007. Evaluati on of the health impact of lowering the formaldehyde 11 occupational exposure limit for Quebec workers. Regul. Toxicol. Pharmacol. 48:118-127. 12 13 Nordman, H., H. Keshinen, and M. Tuppurainen. 1985. Form aldehyde asthma - rare or overlooked? J. Aller. Clin. 14

Immunol. 75:91-99. 15 16 NRC (National Research Council). 1980. Formaldehyde - An Assessment of Its Health Effects. Washington, DC: 17 National Academy Press. 18 19 NRC (National Research Council). 1981. Formaldehyde and Other Aldehydes. Washington, DC: National 20 Academy Press. 21
22 NRC (National Research Council). 1994. Spacecraft Maximu m Allowable Concentrations for Selected Airborne 23 Contaminants, Volume 1. Washington, DC: National Academy Press. 24 25 NRC (National Research Council). 2001. Standing Op erating Procedures for Developing Acute Exposure 26 Guideline Levels for Hazardous Chemicals. Washington, DC: National Academy Press. 27 28 NRC (National Research Council). 2007. Emergency a nd Continuous Exposure Guideline Levels for Selected 29 Submarine Contaminants. Washington, DC: National Academy Press. 30 31

O = Neil, M.J., A. Smith, and P.E. Heckelman. 2001. The Merck Index. Whitehouse Station, NJ: Merck & Co., Inc. 32 33 OSHA (Occupational Safety and Health Administration). 1996. Occupational Exposure to Formaldehyde. OSHA 34 Fact Sheet No. 97-27. Washington, DC: U.S. Department of Labor. 35 36
Paustenbach, D., Y. Alarie, T. Kulle, N. Schacter, R. Smith , J. Swenberg, H. Witchi, and S.B. Horowitz. 1997. A 37 recommended occupational exposure limit for formaldehyde based on irritation. J. Toxicol. Environ. 38

Health 50:217-263. 39 40
Pazdrak, K., P. Gorski, A. Krasowiak and U. Ruta. 1993. Changes in nasal lavage fluid due to formaldehyde 41 inhalation. Int. Arch. Occup. Environ. Health 64:515-519. 42 43
Pettersson, S. and T. Rehn. 1977. Hyg. Miljo 10:35-37. 44 45 Pross, H.F., J.H. Day, R.H. Clark, and R.E.M. Lee. 1987. Immunological studies of subjects with asthma exposed 46 to formaldehyde and urea-formaldehyde foam insulati on (UFFI) off products. J. Allergy Clin. Immunol. 47

79:797-810. 48 49 Reed, C.E. and E. Frigas. 1984. Does formaldehyde cause allergic respiratory disease? pp. 379-386 in Gammage, 50

R.B. et al. eds. Indoor Air and Human Hea lth. Chelsea, MI: Lewis Publishers, Inc. 51 52
Ritchie, I.M. and R.G. Lehnen. 1987. Formaldehyde-related health complaints of residents living in mobile and 53

conventional homes. Am. J. Public Health 77:323-328. 54
55 Rusch, G.M., J.J. Clary, W.E. Rinehart, and H.F. Bolte. 1983. A 26-week inhalation toxicity study with 56 formaldehyde in the monkey, rat, and hamste r. Toxicol. Appl. Pharmacol. 68:329-343. 57FORMALDEHYDE NAC/Interim 1: 07/2008; Page 61 of 71

1
Saillenfait, A.M., P. Bonnet, and J. deCeaurriz. 1989. The effects of maternally inhaled formaldehyde on 2 embryonal and foetal development in rats. Food Chem. Toxicol. 27:545-548. 3
4
Salem, H. and H. Cullumbine. 1960. Inhalation toxicitie s of some aldehydes. Toxicol. Appl. Pharmacol. 2:183- 5

187. 6
7
Sauder, L.R., C.D. Chatham, D.J. Green, and T.J. Ku lle. 1986. Acute pulmonary response to formaldehyde 8 exposure in healthy nonsmokers. J. Occup. Med. 28:420-424. 9 10
Sauder, L.R., D.J. Green, M.D. Chatham, and T.J. Kulle. 1987. Acute pulmonary response of asthmatics to 3.0 ppm 11 formaldehyde. Toxicol. Ind. Health 3:569-577. 12 13
Schachter, E.N., T.J. Witek, T. Tosun, G.J. Beck and B. P. Leaderer. 1985. Respirator y effects of exposure to 2.0 14 ppm of formaldehyde in asthmatic subjects. Am. Rev. Respir. Dis. 131:A170. 15 16
Schachter, E.N., T.J. Witek, T. Tosun, B.P. Leaderer, and G.J. Beck. 1986. A study of respiratory effects from 17 exposure to 2.0 ppm formaldehyde in healthy subjects. Arch. Environ. Health 41:229-239. 18 19 SDU Uitgevers. 2000. Nationale MAC List: 2000. Th e Hague, The Netherlands: Under the Auspices of the 20 Ministry of Social Affairs and Employment. 21
22 Sellakumar, A.R., C.A. Snyder, J.J. Solomon, and R.E. Albert. 1985. Carcinogenicity of formaldehyde and 23 hydrogen chloride in rats. Toxicol. Appl. Pharmacol. 81:401-406. 24 25 Sheppard, D., W..L. Eschenbacher and J. Epstein. 1984. Lack of bronchomotor response to up to 3 ppm 26 formaldehyde in subjects with asthma. Environ. Res. 35:133-139. 27 28 Shuck, E.A., E.R. Stephens, and J.T. Middleton. 1966. Eye irritation response at low concentrations of irritants. 29

Arch. Environ. Health 13:570-575. 30 31 Sim, V.M. and R.E. Pattle. 1957. Effect of possible sm og irritants on human subjects. J. Amer. Med. Assoc. 32

165:1908-1913. 33 34 Skog, E. 1950. A toxicological investigation of lo wer aliphatic aldehydes. I. Toxicity of formaldehyde, 35 acetaldehyde, propionaldehyde, and butyraldehyde, as we ll as of acrolein and crotonaldehyde. Acta 36

Pharmacol. Toxicol. 6:299-318. 37 38
Starr, T.B., J.E. Gibson, C.S. Barrow, C.J. Boreiko, H.d = A. Heck, R.J. Levine, K.T. Morgan, and J.A. Swenberg. 39 1983. Estimating human cancer risk from formaldehyde: cr itical issues. Pp. 299-333 in Turoski, V. (ed.), 40 Formaldehyde: Analytical Chemistry and Toxicology, Advances in Chemistry Series 210. Washington, 41 DC: American Chemical Society. 42 43 Starr, T.B. 1990. Workshop on indoor air quality. Quan titative cancer risk estimation for formaldehyde. Risk 44

Anal. 10:85-91. 45 46 Stephens, E.R., E.R. Darley, O.C. Taylor, and W.E. Scott. 1961. Photochemical reaction products in air pollution. 47

Int. J. Air Water Pollut. 4:79-100. 48 49 Swenberg, J.A., W.D. Kerns, R.J. Mitchell, R.E. Gra lla, and K.C. Pavkov. 1980. Induction of squamous cell 50 carcinomas of the rat nasal cavity by inhalation e xposure to formaldehyde vapor. Cancer Res. 40:3398- 51

3402. 52 53 Swenberg, J.A., E.A. Gross, J. Martin, and J.A. Popp. 1983. Mechanisms of formaldehyde toxicity. Chapter 12 in 54 Gibson, J. ed., Formaldehyde Toxicity. Washi ngton, DC: Hemisphere Publishing Corporation. 55 56FORMALDEHYDE NAC/Interim 1: 07/2008; Page 62 of 71

Swiecichowski, A.L., K.J. Long, M.L. Miller, and G.D. Leikauf. 1993. Formaldehyde-induced airway 1 hyperreactivity in vivo and ex vivo in gui nea pigs. Environ. Res. 61:185-199. 2 3
Tobe, M., K. T. Kaneko, Y. Uchida, et al. 1985. Studi es of the inhalation toxicity of formaldehyde. U.S. 4 Environmental Protection Agency translation, TR-85-0236. Washington, DC: U.S. EPA. 5 6 Turoski, V. (ed.). 1984. Formaldehyde: Analytical Chemis try and Toxicology, Advances in Chemistry Series 210. 7 Washington, DC: American Chemical Society. 8 9 U.S. EPA (U.S. Environmental Protection Agency). 1982. Exposure Assessment for Formaldehyde. Washington, 10

DC. 11
12 U.S. EPA (U.S. Environmental protection Agency). 1992. Reference Guide to Odor Thresholds for Hazardous Air 13

Pollutants Listed in the Clean Air Act Amendments of 1990. EPA/600/R-92/047. 14 15 U.S. EPA (U.S. Environmental Protection Agency). 2003. Integrated Risk Information System, online data base: 16 www.epa.gov/iris/subst/0419.htm. 17 18 van Doorn, R., M. Ruijten, and T. van Harreveld. 2002. Guidance for the application of odor in chemical 19 emergency response. (In press). 20
21
Ward, J.B.J., J.A. Hokanson, E.R. Smith, et al. 1984. Sperm count, morphology and fluorescent body frequency in 22 autopsy service workers exposed to formaldehyde. Mutat. Res. 130:417-424. 23
24 Weber, A., C. Jermini, and E. Grandjean. 1976. Irritati ng effects on man of air pollution due to cigarette smoke. 25

Amer. J. Publ. Health 66:672-676. 26 27 Weber-Tschopp, A., T. Fischer, and E. Grandjean. 1977. Irritating effects of formaldehyde on men. Int. Arch. 28 Occup. Environ. Health 39:207-218. 29 30 WHO (World Health Organization). 1989. Environmen tal Health Criteria 89: Formaldehyde. Geneva: World 31 Health Organization. 32 33 Wilmer, J.W.G.M., R.A. Woutersen, L.M. Appleman, W.R. Leeman, and V.J. Feron. 1989. Subchronic (13-week) 34 inhalation toxicity study of formaldehyde in male rats: 8 hour intermittent versus 8-hour continuous 35 exposures. Toxicol. Lett. 47:287-293. 36 37
Witek, T.J., E.N. Schacter, T. Tosun, B.P. Leaderer , and G.J. Beck. 1986. Controlled human studies on the 38 pulmonary effects of indoor air pollution: experiences w ith sulfur dioxide and formaldehyde. Environ. Intl. 39

12:129-135. 40
41
Witek, T.J., E.N. Schacter, T. Tosun, G.J. Beck, and B. P. Leaderer. 1987. An eval uation of respiratory effects 42 following exposure to 2.0 ppm formaldehyde in asthmatics: lung function, symptoms, and airway reactivity. 43

Arch. Environ. Health 42:230-237. 44 45 Woutersen, R.A., L.M. Appleman, J.W.G.M. Wilmer, H.E. Falke, and V.J. Feron. 1987. Subchronic (13-week) 46 inhalation toxicity study of formaldehyde in rats. J. Appl. Toxicol. 7:43-49. 47 48
Woutersen, R.A., van Garderen-Hoetmer, A. Bruijntjes, J.P., et al. 1989. Nasal tumors in rats after severe injury to 49 the nasal mucosa and prolonged exposure to 10 ppm formaldehyde. J. Appl. Toxicol. 9:39-46. 50FORMALDEHYDE NAC/Interim 1: 07/2008; Page 63 of 71

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### APPENDIX A: Level of Di stinct Odor Awareness 2

3 The LOA derivation follows the guidance given by van Doorn et al. (2002). 4

5 The odor detection threshold (OT 50 ) for formaldehyde reported by Berglund et al. (1987) is 6 0.145 ppm. 7

8 The concentration C leading to an odor intensity (I) of distinct odor detection (I=3) is derived 9 using the Fechner function: 10

11

I = k

w x log 8 /OT 50 ) + 0.5 12

13 For the Fechner coefficient, the default of k

w = 2.33 was used due to the lack of chemical14 specific data: 15

16 3 = 2.33 x log C /0.145) + 0.5 which can be rearranged to 17 log C /0.145) = (3 - 0.5) / 2.33 = 1.266 and results in 18 C = (10 1.266 ) x 0.145 = 2.675 ppm 19

20 The resulting concentration is multiplied by an empirical field correction factor of 1.33. 21

22 LOA = C x 1.33 = 2.675 ppm x 1.33 = 3.6 ppm 23

24 The LOA for formaldehyde is 3.6 ppm. 25

26

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### APPENDIX B: Carcinogenicity Assessment 2

3 The U.S. EPA (2003) in its Integrated Risk Information System (IRIS) has calculated dose 4 levels for cancer risk levels of 1 in 10,000, 1 in 100,000, and 1 in 1,000,000 individuals. The 5 calculations are based on the study of Kerns et al. (1983) with Fischer 344 rats (see Section 3.6 6 for discussion of this study). The concentration over a lifetime of 70 years that would result in a 7 risk level of 1 in 10,000, a virtually safe dose, is 8 F g/m 3 (6.5 ppb). 8

9 To convert a 70-year exposure to a 24-hour exposure, multiply by the number of days in 70 10 years (25,600): 11

12 24-hour exposure = dose x 25,600 13

= 8 F g/m 3 x 25,600 14 = 205 mg/m 3 15

16 To account for uncertainty regarding the variability in the stage of the cancer at which 17 formaldehyde or its metabolites may act, a multistage factor of 6 is applied(Crump and Howe 18

1984: 19

20 205 mg/m 3 /6 = 34.17 mg/m 3 (28 ppm) 21

22 Therefore, based upon the potential carcinogenicity on formaldehyde, an acceptable 24-hour 23 exposure would be 34 mg/m 3 . If the exposure is limited to a fraction of a 24-hour period, the 24 values are adjusted accordingly: 25

26 24-hour exposure = 34 mg/m 3 (28 ppm) 27 8-hour exposure = 103 mg/m 3 (83 ppm) 28 4-hour exposure = 205 mg/m 3 (167 ppm) 29 1-hour exposure = 820 mg/m 3 (667 ppm) 30 30-min exposure = 1640 mg/m 3 (1333 ppm) 31 10-min exposure = 4920 mg/m 3 (6052 ppm) 32

33

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### APPENDIX C: Derivation of AEGL Values 2

3

Derivation of AEGL-1 4

5 Key Study: Bender et al. 1981 6

7 Toxicity endpoint: 0.9 ppm: NOAEL for eye irritation in sensitive subjects 8

9 Time scaling: not applied; there is adaptation to the slight irritation defined by the 10

AEGL-1 11

12 Uncertainty factors: 1 - the subjects had been selected for their eye sensitivity to slightly 13 higher concentrations of formaldehyde 14

15 Modifying factor: none applied 16

17 Calculations: none; 0.90 ppm used across all exposure durations 18

19 10-minute AEGL-1: 0.90 ppm 20 30-minute AEGL-1: 0.90 ppm 21 1-hour AEGL-1: 0.90 ppm 22 4-hour AEGL-1: 0.90 ppm 23 8-hour AEGL-1: 0.90 ppm 24

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Derivation of AEGL-2 2

3 Key Study: Sim and Pattle 1957 4

5 Toxicity endpoints: 14 ppm for 30 minutes 6

7 Time scaling none applied; there was adaptation to the eye and mild nose irritation 8

9 Uncertainty factors: none applied; applicati on of an uncertainty factor would lower the 10 value to a no-effect level in exercising asthmatics 11

12 Modifying factor: none applied 13

14 Calculations: none; 14 ppm used across all exposure durations 15

16 10-minute AEGL-2: 14 ppm 17 30-minute AEGL-2: 14 ppm 18 1-hour AEGL-2: 14 ppm 19 4-hour AEGL-2: 14 ppm 20 8-hour AEGL-2: 14 ppm 21FORMALDEHYDE NAC/Interim 1: 07/2008; Page 67 of 71

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Derivation of AEGL-3 2

3 Key Study: Nagorny et al. 1979 4

5 Toxicity endpoint: 350 ppm for 4 hours: highest non-lethal value in the rat 6

7 Time scaling default value of 3 when extrapolating to shorter exposure durations 8 (NRC 2001) 9

10 Uncertainty factors: interspecies and intraspeci es of 3 each for a total of 10; these factors 11 have been protective of sensitive subjects exposed to irritants 12

13 Modifying factor: none applied 14

15

Calculations: C 3 x t = k 16 (350 ppm/10) 3 x 240 minutes = 10290000 ppm 3 $ minutes 17

18 10-minute AEGL-3: 100 ppm 19 30-minute AEGL-3: 70 ppm 20 1-hour AEGL-3: 56 ppm 21 4-hour AEGL-3: 35 ppm 22 8-hour AEGL-3: 35 ppm 23

24 The 8-hour AEGL-3 was set equal to the 4-hour value because formaldehyde is well-scrubbed in 25 the nasal passages. 26

27

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### APPENDIX D: Category Graph of Toxicity Data and AEGL Values 2

3

4

0.1 1.0 10.0 100.0 1000.0 10000.0ppm

0 60 120 180 240 300 360 420 480

Minutes Human - No Effect

Human - Discomfort

Human - Disabling

Animal - No Effect

Animal - Discomfort

Animal - Disabling

Animal - Some Lethality

Animal - Lethal

AEGL AEGL-3

AEGL-1 AEGL-2

5 6

7

8

9FORMALDEHYDE NAC/Interim 1: 07/2008; Page 69 of 71



### APPENDIX E: Derivation Summa ry for Formaldehyde AEGLs

ACUTE EXPOSURE GUIDELINE LEVELS FOR FORMALDEHYDE (CAS Reg. No. 50-00-0)

DERIVATION SUMMARY

AEGL-1 VALUES

10-min 30-min 1-h 4-h 8-h
0.90 ppm 0.90 ppm 0.90 ppm 0.90 ppm 0.90 ppm
Key Reference: Bender, J.R., L.S. Mullin, G.J. Grapel , and W.E. Wilson. 1983. Eye irritation response of humans to formaldehyde. Am. Ind. Hyg. Assoc. J. 44:463-465. Test Species/Strain/Number: Humans, sensitive subjects/gr oups of 5-28; subjects whose eyes were not sensitive to 1.3 or 2.2 ppm were excluded from the study Exposure Route/Concentrations/Durations: Eye exposur e/ 0, 0.35, 0.56, 0.7, 0.9, 1.0 for 6 minutes

Effects: 0.35-0.90 ppm: responses same as those to clean air 1.0 ppm: slight irritation, adaptation with time Endpoint/Concentration/Rationale: NOAEL for irritation/0.90 ppm Uncertainty Factors/Rationale:

Total uncertainty factor: 1

Interspecies: not applicable Intraspecies: 1 - subjects whose eyes we re sensitive to formaldehyde were used Modifying Factor: not applied Animal to Human Dosimetric Adjustment: not applied Time Scaling: not applied; there was no irritation; in othe r cases, there is adaptation to the slight irritation that

defines the AEGL-1 Data Adequacy: There over 22 clinical studies involving 500 subjects that show that concentrations <1 ppm are generally non-irritating.FORMALDEHYDE NAC/Interim 1: 07/2008; Page 70 of 71

AEGL-2 VALUES

10-min 30-min 1-h 4-h 8-h
14 ppm 14 ppm 14 ppm 14 ppm 14 ppm
Key Reference: Sim, V.M. and R.E. Pattle. 1957. E ffect of possible smog irritants on human subjects. J.

Amer. Med. Assoc. 165:1908-1913. Test Species/Strain/Number: Humans/male/12 Exposure Route/Concentrations/Durations: Inhalation/14 ppm/30 minutes Effects: Initial nose and eye irritation with mild lacrimation; adaptation in 10 minutes Endpoint/Concentration/Rationale: mild irritation at 14 ppm for 30 minutes meets the definition of the AEGL-2 Uncertainty Factors/Rationale:

Total uncertainty factor: 1

Interspecies: not relevant Intraspecies: 1 - application of an uncertainty factor would lower the value to a no-effect level in exercising

asthmatics Modifying Factor: not applied Animal to Human Dosimetric Adjustment: not relevant Time Scaling: not applied; there was adaptation to the irritation in 10 minutes Data Adequacy: The abundance of clinical studies at lower concentrations and involving over 500 subjects support the 14 ppm concentration as a reasonable value.FORMALDEHYDE NAC/Interim 1: 07/2008; Page 71 of 71

AEGL-3 VALUES

10-min 30-min 1-h 4-h 8-h
100 ppm 70 ppm 56 ppm 35 ppm 35 ppm
Key Reference: Nagorny, P.A., Zh.A. Sudakova and S. M. Schablenko. 1979. On the general toxic and allergic action of formaldehyde. Gig. Tr. Prof. Zabol. 1:27-30. Test Species/Strain/Number: rat/not given/groups of 6-12 Exposure Route/Concentrations/Dura tions: Inhalation/not given/4 hours Effects: 228-350 ppm, no deaths; # 732 ppm, some lethality; >732 ppm, 100% lethal Endpoint/Concentration/Rationale: highest non-lethal va lue, 350 ppm for 4 hours, meets definition of AEGL-3 Uncertainty Factors/Rationale:

Total uncertainty factor: 10

Interspecies: 3 - rodents with higher respir atory rates than humans have greater uptake Intraspecies: 3 - applied to irritants; protective of the sensitive population Modifying Factor: none applied Animal to Human Dosimetric Adjustment: not applied Time Scaling: default values of 3 and 1 when ex trapolating to shorter and longer exposure durations, respectively Data Adequacy: The lethality studies are old and lack details of methodology and results. Longer-duration and repeat-exposure studies (Horton et al. 1963; Murphy et al. 1964; Tobe et al. 1985) support the 4 and 8-hour

values.