## Industrial Hygiene

Exposure Control William P. Robert BASF Corporation2 

# Overview

• Possible Anticipated Exposures

• Considerations for Controlling Exposure



### • Isocyanate Neutralization and Decontamination

• Dermal Protection Considerations

• Respiratory Protection Considerations

• Conclusion3 

# Possible Anticipated Exposures

• Respiratory Exposure (TDI / MDI)

– Process conditions such as heating or atomization (e.g., spraying)

– Poor ventilation

– Sawing / sanding / grinding parts



### – Thermal degradation4 

# Possible Anticipated Exposures

• Possible Dermal Exposure

– Handling liquid isocyanate

– Open pouring (e.g., molding)

– Incomplete cure (e.g., off ratio molding)

– Cleaning equipment



### – Exposure to contaminated surfaces5 

# Possible Anticipated Exposures

• Possible Ingestion

– Swallowing isocyanates

• Eating or drinking in work station
• Smoking or using other tobacco products near isocyanates6 

## Considerations for Controlling 

# Exposure

• Engineering

– Providing adequate ventilation when working in an enclosed area (e.g., spray booth).

– Having hand wash stations or showers available in work area.

– Decontaminating surfaces that have come into contact with isocyanates .7 

## Considerations for Controlling 

# Exposure

• Personal Protective Equipment

– Chemical worker‟s goggles

– MDI or TDI - resistant long - sleeve coveralls or full body suits

– MDI or TDI - resistant fitted boots

– Head protection, such as a close - fitting hood

– Air respirator or air - purifying respirator (consult your MSDS for guidance)8 

## Considerations for Controlling 

# Exposure

• Administration

– Controlling unauthorized or unprotected employee access to exposure areas.

– Training workers and staff on how to handle isocyanates.

– Conducting medical examinations of workers who will be handling isocyanates.

– Making material data safety sheets (MSDS) and other training materials available to persons working with isocyanates.9 

## Isocyanate Neutralization and 

# Decontamination - Surfaces

• Surface Contamination Assessment
• Methods for detection of isocyanates may include:

– Colorimetric swipes

– Turn red on contact with isocyanate

– Good for housekeeping check, employee training10 

## Isocyanate Neutralization and 

# Decontamination - Surfaces

• Neutralization means treating MDI or TDI with solid or liquid neutralizer to destroy the isocyanate groups and minimize exposure.

• Decontamination means removing all detectable traces of diisocyanate from a given surface or area.11 

## Isocyanate Neutralization and 

# Decontamination - Surfaces

• Isocyanates react to form inert solids with :

– Alcohols

– Amines

– Water (slow reaction )



### • Therefore, the basis for decontamination solutions usually include alcohol or amine in 

### water solutions with surfactants

– Water

– main reactant

– Amine/ Ammonia

– catalyst

– Surfactant

– surface tension breaker (greater contact between the water and the isocyanate )12 

# Dermal Exposure Considerations

• Available data includes:

– API Technical Bulletin 178

– PMDI User Guidelines for Protective Clothing Selection



### – API Technical Bulletin 179 - TDI User Guidelines for Protective Clothing Selection

– Polyurethanes Expo 1999 Proceedings

– paper by Robert and Hayward13 

# Respiratory Protection Considerations

• Air purifying respirators (APRs)

• Supplied air respirators (SARs)14 

# Respiratory Protection - APR

• Three types of Air Purifying Respirators 

## :

– Full - face

– Half - face

– Powered APR



### • Select cartridge type based on chemical and physical form of hazards present15 

# Respiratory Protection - APR

• Select APR cartridge based on chemical and physical form of diisocyanates present:

• Consider organic vapor & particulate (OV/P100) APR Cartridge for MDI;Use Organic Vapor Cartridge for TDI

### Industrial Hygiene

Monitoring for Diisocyanates William P. Robert BASF Corporation17 

# Overview

• Why monitor for diisocyanates ?
• Exposure evaluation


## • Types of monitoring
• Summary of Product Stewardship 

## monitoring in various industries
• Conclusion18 

# Why monitor for diisocyanates ?

• Why establish a monitoring program for diisocyanates ?

– To assess and reduce the potential for workplace and community exposure

– Monitor airborne releases (e.g., spills, stack, 

### etc.) from the site to identify and reduce exposures to the community or environment

– Compliance with regulatory requirements19 

# Why monitor for diisocyanates ?

• Workplace monitoring can be effective when conducted periodically, and, when there is the following:

– Reported health effect

– New process or product

– Change to existing equipment/process

– Suspected leak

– Spill or release20 

# Why monitor for diisocyanates ?

• Further, it may also be appropriate to monitor the community and the environment. Some additional monitoring may include:



### – Stack emissions testing

– Airborne release during and after spills (e.g., 

### transportation incidents)21 

# Exposure Evaluation

• The potential for exposure can depend on:

– Physical form and properties of the material

– Handling procedures

– Ventilation and type of environment (e.g., confined space)

– Personal protective equipment

– Conditions of temperature and pressure

– Contact with other materials22 

# Exposure Evaluation

• Routes of exposure

– Inhalation

– Dermal

– Eye

– Ingestion


## • Nature of exposure

– Vapor (gas)

– Aerosol (mist)23 

# Types of Monitoring

• Industrial Hygiene

– Personal
• Time - weighted average (TWA), long - term
• Short term exposure limit (STEL)
• Ceiling limit (C)

– Area
• Point source
• Leaks, spills and accidents 

### • Other

– Emissions (Stack) Sampling*

– Fugitive emissions* *Not discussed in this presentation.24 

# Types of Monitoring Exposure Limits* MDI TDI Ave Concentration (ppb) Long Term (TWA) 5 5 Short Term (STEL) 20 Max Concentration (ppb) Ceiling 20 20 * As determined by OSHA , ACGIH25 

## Measurements of Airborne MDI 

# Concentration in the U.S. Workplace This article summarizes data collected in 1984 through 1999.

• 606 surveys were conducted for 251 companies at 317 facilities

– 3583 personal (breathing zone) samples and 4551 area samples

• Extremely low airborne MDI concentrations were measured

• 74.6% of personal samples were non - detectable

• Modifications of OSHA Method 47

• The LOQs ranged from 0.1
– 0.5 μg /sample

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.26 

# Air Sampling Data

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.27 

# Air Sampling Data

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.28 

# Discussion Based on MDI concentrations measured:
• very low vapor pressure
• whether the material is heated or sprayed
• how the diisocyanate is reacted
• whether manufacturing processes are open or closed systems
• whether impinger or filter paper sampling methods are used

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.29 

# Conclusions

• Majority of personal samples show MDI concentrations ranging from below the LOQ to < TLV, however there can be higher concentrations. They include the following:

• Where MDI mixtures are spray applied or in situations where MDI is heated concentrations may be higher.

• When MDI is sprayed or used at elevated temperatures, consider additional control measures.

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.30 

# Industrial Hygiene Sampling Methods

• Air Sampling Techniques Most Commonly Used for Diisocyanates include:

– Direct Methods
• Paper tape
• Colorimetric (e.g., passive/active badge)



### – Indirect Methods
• Chemically - treated filters
• Impinger solutions31 

## Direct Sampling Methods Paper Tape 

# Technology

• Summary

– Typically, the type of sampling method used to collect “real time” measurements of airborne isocyanates may use chemically treated paper tape. This technology is based on a comparison of light reflectance to the color/stain on the tape, which could be subject to interference.32 

## Direct Sampling Methods Colorimetric 

# Technology

• Summary

– Things to consider when using badge technology:
• Can be a valuable tool for the industrial hygienist:

– Worker acceptance is high

– Badge programs can operate efficiently with the oversight of an IH/Safety Professional

– screening tool

– visually evident characteristic color change33 

# Indirect Sampling Methods

• Benefits:

– Provides a representative sampling of the environment

– Enables efficient collection and accurate reporting

– Lower LOQ and greater sensitivity than direct reading instrument

– Analysis available for:
• Monomers and oligomers 

### • Considerations:

– Will need air sampling equipment (i.e., pump, calibrator, etc.) and training as to the use of this equipment

– Sample media (filter/ impinger solution) requires preparation/handling prior to and after sampling34 

# Indirect Sampling Methods

• Non - Spray applications

– When monomeric isocyanates are involved (i.e., MDI and TDI) consider glass fiber filters coated with a reagent (i.e., PP or MP ).

• When sampling for MDI, desorb filters in the field.

– An impinger also can be used with a solution containing PP or MP (depending upon preference ).
• Spray applications

– Where reactive aerosols (PMDI or polyisocyanates ) are generated, consider impingers (containing a PP or MP solution ).

• If aerosols are less than 3 μ m, consider backing - up the impinger with a filter.35 

# Exposure Monitoring Sampler Types:

– Coated Filter

– Impinger

Impinger + filter36 

# Conclusion

• Consider periodic monitoring of airborne diisocyanates in the workplace.

• Various instruments are available to assist in the assessment of the workplace.

• CPI is another resource; technical bulletins are available on the website for “easy access” at www.polyurethane.org .

# APPENDIX

## Industrial Hygiene



## Exposure Control39 

# Isocyanate Decontamination - Skin

• Animal testing concluded

– Polypropylene glycol, corn oil and polyglycol - based cleaner were generally more effective than soap and water

– Cleaning soon after exposure was important

– Cleaning did not completely remove skin contamination

– Engineering controls, good work practices and PPE should be first defense against skin contamination40 

# Respiratory Protection - APR

• To meet the OSHA criteria for APR use, respirators have a NIOSH certified End of 

## Service Life Indicator (ESLI) or employers must follow a cartridge change schedule.

• APR cartridge change schedules are typically based on objective information or data.41 

# Respiratory Protection - APR

• OSHA Respirator Rule:

– User cannot rely on odor as a signal to change respirator 

### cartridge for any chemical.42 

# Respiratory Protection - APR

• Objective Information or Data for Cartridge Change Schedules

– Respirator manufacturers (e.g., see product pamphlet or website)

– OSHA Technical Links „ Isocyanates ‟ website (Spence et al.; no breakthrough for OV/P100 after 24 hrs at 500 ppb MDI aerosol)

– Technical Journals ( Dharmarajan et al.[Am. Ind.Hyg . Assoc. J. (47):393 - 398 (1986)]; no breakthrough after 40 hrs at 2000 ppb TDI43 

# Respiratory Protection - SARs

• Sources of breathing air include:

– Self contained breathing apparatus (SCBA)

– Air - lines


## • Per OSHA, supply air should be equal to atmospheric air 

## :

– 19.5 % to 23.5% oxygen

– Maximum 1000 ppm CO 2

– Maximum 10 ppm CO44 

## Respiratory Protection Written 

# Respirator Program

• Voluntarily or company policy required by OSHA if employees wear respirators - 

## Applies to all respirators.

## Industrial Hygiene



## Monitoring for Diisocyanates46 

# Discussion

• OSB and many of the Binder applications involve spraying. Some CASE and Rigid Foam applications may also be spray applied.

• During the manufacturing of OSB, engineered lumber, MDF, particleboard, etc., the PMDI on/in the substrate can be viable for hours, since there are no catalysts or polyol components to accelerate the reaction. The curing of PMDI on/in the various substrates takes place in the press under high temperature and pressure.

• On the other hand, spray applications in CASE, Rigid Foam, and some Binders usually involve a two - component system where the PMDI/MDI and catalyst containing polyols are combined via separate pressurized hoses into a mix head in the desired ratio. Once the two components are sprayed onto a surface, the reaction is completed within a minute or less. Some applications are made with rollers or brushes.
Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.47 

# Binders/ OSB

• 97.5% of the personal and 88.2% of the area samples were below the TLV. End - use applications are in construction (mainly in OSB), machinery and foundry.

• For OSB, 97.2% of the personal and 93.4% of the area samples were below the TLV. *ACGIH MDI TLV is 0.051 mg/m3

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.48 

## CASE (Coatings, Adhesives, 

# Sealants, and Elastomers)

• Of the 417 personal entries, 126 were spray applications, 124 were brush/roller coating applications, and 79 were pour applications.

• Of the 26 sampling results that were above the TLV, 17 were spray applications; of the 13 that were the PEL, 9 were spray applications. Personnel conducting spray applications are normally equipped with additional PPE, including respiratory protection. *ACGIH MDI TLV is 0.051 mg/m3 * OSHA MDI PEL is 0.2 mg/m3

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.49 

# Rigid Foam

• Personal and area sampling results below the TLV were 96.3% and 84.6% respectively.

• Spray - applied rigid foams are used as 

### insulation on roofs of commercial buildings and as wall insulation for residential homes.

• Many pour - in - place applications are used as insulation.

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.50 

# Rigid Foam

• The area (42/113) and personal (17/53) sample results for laminate boardstock that were above the TLV, 37.2%, and 32.1% were non - spray applications .

• In boardstock production, the chemical components are brought together in a mix head and open poured onto a continuous facing that is being transported by a conveyor. As the foam begins to rise, a second facing is brought into contact with the rising foam. The assembly moves through a heated conveyor press that controls the board thickness and accelerates the curing of the foam. The cured, sandwiched foam bonds to the facings and exits the press where it is cut to length, stacked, and made ready for shipment. Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.51 

# Flexible Foam

• Personal (99.1%) and area (95.5%) sampling results were below the TLV. End - use applications are in transportation, bedding, furniture, packaging, textiles, and others.

• Subcategories under this product type include mainly foam - in - place or pour - in - place applications.

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.52 

# RIM (Reaction Injection Molding)

• Personal (99.5%) and area (97.0%) sampling results were below the TLV.

• These processes refer to the injection of MDI/ polyol mixture into a closed mold. The main applications (subcategories) are in the automotive and associated transportation, machinery, and foundry industries.

• End products include automobile hoods, bumpers, body panels, chassis parts, spare wheel covers, tractor roofs, tractor seats, and others.

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.53 

# Other Foam

• Personal (97.3%) and area (93.9%) sampling results were below the TLV.

• Subcategories include filling sealant cans and mostly carpet backing ( rebond )/pour - in - place applications.

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.54 

# Other

• Personal (98.1%) and area (92.7%) sampling results were below the TLV.

• Subcategories under this product type include extrusion (TPU), injection molding, bulk unloading from railcars/trucks, R&D lab testing, packaging, tote charging, and others.

Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.55 

# Sampling When monitoring for airborne MDI/PMDI, the analytical results can vary depending on the sampling method used.
• Use of impingers is suggested when air sampling for two component, spray - applied systems that are fast reacting. The captured airborne particulates dissolve in the impinger , thereby facilitating the reaction between diisocyanates and the derivatizing agent in the liquid medium.
• If a filter paper method is used, the airborne MDI/ polyol particulates impact on the filter media and the unreacted diisocyanate groups, which react rapidly with the polyol , may be physically hindered from reacting with the derivatizing agent on the filter. Consequently, the viable MDI in the sample could be underestimated.
• Therefore , consider field desorption of the filters to prevent the underestimation of MDI in the samples collected.
Source: Booth, K. , Cummings, B. , Karoly , W. J. , Mullins, S. , Robert, W. P. , Spence, M. , Lichtenberg, F. W. , et al. (2009). Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace. Journal of Occupational and Environmental Hygiene , 6 (4), 228
- 238.56 

## Indirect Sampling Methods

• Most frequently used methods:

– OSHA 42 (37mm PP - coated filter) - TDI

– OSHA 47 (37mm PP - coated filter)

– MDI*

– NIOSH 5521 ( Impinger with MP in toluene)

– TDI/MDI • Less frequently used methods:

– NIOSH 5525 (MAP)
• Total NCOs (complex analysis) for monomer and oligomer species

– ISO - CHEK® (2 - stage (untreated/MAMA) filter) PP = 1 - (2 - pyridyl) piperazine MP = 1 - (2 - methoxyphenyl) piperazine MAP = 1 - (9 - anthracenylmethyl) piperazine MAMA = 9 - (N - methylaminomethyl ) anthracene Note: Airborne MDI is best collected using a 13mm filter which then is field desorbed