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Toluene Diisocyanate (TDI) 

And Related Compounds 

Action Plan 

I. Overview 

This Action Plan addresses the use of toluene diisocyanate (TDI) and related compounds 

in products that may result in consumer and general population exposures, particularly in or 

around buildings, including homes and schools. Diisocyanates are well known dermal and 

inhalation sensitizers in the workplace and have been documented to cause asthma, lung damage, 

and in severe cases, fatal reactions. This Action Plan focuses on the potential health effects that 

may result from exposures to the consumer or self-employed worker while using products 

containing diisocyanates (e.g., spray applied sealants and coatings) or incidental exposures to the 

general population while such products are used in or around buildings, including homes or 

schools. In conducting this review of TDI compounds, EPA considered a number of potential 

actions, including regulatory actions under TSCA sections 4, 5, 6, and 8; cooperative actions 

with other federal agencies; and voluntary actions. 

II. Introduction 

 As part of EPA's efforts to enhance the existing chemicals program under the Toxic 

Substances Control Act (TSCA)1

, the Agency identified an initial list of widely recognized 

chemicals, including TDI, for action plan development based on their presence in human blood; 

persistent, bioaccumulative, and toxic (PBT)2

 characteristics; use in consumer products; 

production volume; and other similar factors. This Action Plan is based on EPA’s initial review 

of readily available use, exposure, and hazard information3 on TDI. EPA considered which of the 

various authorities provided under TSCA and other statutes might be appropriate to address 

potential concerns with TDI in developing the Action Plan. The Action Plan is intended to 

describe the courses of action the Agency plans to pursue in the near term to address its concerns 

and does not constitute a final Agency determination or other final Agency action. Regulatory 

proceedings indicated by the Action Plan will include appropriate opportunities for public and 

stakeholder input, including through notice and comment rulemaking processes. In a concurrent 

action, a separate Action Plan is under development for Methylene Diphenyl Diisocyanate 

(MDI), a substance chemically related to TDI with similar hazard and exposure concerns. 

III. Scope of Review 

Diisocyanates (also commonly known as isocyanates) are highly reactive and versatile 

chemicals with widespread commercial and consumer use. Over 90% of the diisocyanates’ 

 

1

 15 U.S.C §2601 et seq. 

2

 Information on PBT chemicals can be found on the EPA web site at http://www.epa.gov/pbt/. 3

 Information sources customarily employed include Inventory Update Report (IUR) submissions; Toxic Release 

Inventory (TRI) reporting; data submitted to the HPV Challenge Program; existing hazard and risk assessments 

performed by domestic and international authorities including but not limited to U.S. Federal government agencies, 

the Organization for Economic Cooperation and Development, the Stockholm Convention on Persistent Organic 

Pollutants, Health and Environment Canada, the European Union; and others. Action plans will reference specific 

sources used. 
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market is dominated by two diisocyanates and their related polyisocyanates: MDI and TDI 

(Allport et al., 2003). They have unique properties and functional versatility, and contain free 

isocyanate functional groups (-N=C=O). When isocyanates are combined with other compounds 

that contain free hydroxyl functional groups (i.e. –OH) they react and begin to form polyurethane 

polymers. This chemical reaction is completed when all of the initially free –N=C=O groups are 

bound within the polymer network. This process is commonly referred to as “curing.” Products 

that contain free –N=C=O groups are intended to react and undergo “curing” in the process of 

use. An example would be an adhesive, which is sold to be initially applied in an uncured form 

and as it cures (hardens), bonds two pieces of wood together. Other polyurethane products, such 

as mattresses, pillows, and bowling balls, are considered completely cured products before they 

are sold. 

Because of their reactivity and the diversity of uses, TDI and its related polyisocyanates 

are generally supplied by their manufacturers as raw materials to formulators who take 

advantage of the diisocyanates’ chemistry to combine them with other chemicals to create 

different polyurethanes with a wide diversity of applications. This diversity of applications also 

means that exposures to diisocyanates can occur in a broad range of production facilities from 

small workshops to automated production lines. Diisocyanates are potent dermal and lung 

sensitizers and a major cause of work-related asthma worldwide (NIOSH, 2006). Diisocyanates 

are also commonly available in unreacted forms as part of product mixtures widely used in 

construction, automotive, and other similar applications that require an end-use reaction as part 

of the functional performance of these products. Such applications occurring beyond the 

confines of a controlled production facility could result in exposures unless there is careful 

observance of best practices and controls to prevent exposures, including the use of protective 

equipment, containment, ventilation, proper clean-up practices, and medical surveillance of 

anyone who may be exposed. 

In the past, consumer exposures have not been a focus of concern with respect to 

diisocyanates, because it has been assumed that consumers were generally exposed to products 

containing cured polyurethanes, which have been generally considered to be inert and non-toxic 

(Krone & Klinger, 2005). However, an increase in the consumer availability of or exposure to 

polyurethane products intended to further react and undergo “curing” has occurred in the 

marketplace. For example, consumer products, such as adhesives sealants may contain TDI 

compounds that are not completely reacted when applied and can provide potential exposures 

both to the consumer as the direct user or as a bystander to such product use by others (Krone, 

2004; Bello et al., 2007). In addition, certain workers (e.g., self-employed) are not subject to the 

applicable OSHA exposure limits, and are not legally required to receive health and safety 

training and chemical hazard information, or wear personal protective equipment (PPE) and 

therefore could potentially be overexposed to uncured polyurethane products. 

Given the difference in potential health hazards presented by exposure to uncured vs. 

cured polyurethane products, the growing exposure to these products by or around consumers as 

well as other unprotected building occupants, and the lack of guidance or regulations to protect 

them, this action plan will focus on consumer and non-OSHA covered (e.g., self-employed) 

worker uses of and exposures to polyurethane products containing uncured TDI and its related 

polyisocyanates. Potential exposures of concern include direct use as well as incidental or 

bystander exposures. 
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IV. Uses and Substitutes Summary 

MDI and TDI are the largest volume aromatic diisocyanates, are high production volume 

chemicals, and are predominantly used in the production of polyurethanes. In 2008, the U.S. 

demand for TDI was 425.2 million pounds (ACC, 2009). There are many types of polyurethane 

products in the marketplace, with foams representing the largest sector of the polyurethane 

industry. Non-foam polyurethane use sectors of TDI include coatings, adhesives, binders, and 

sealants. However, these products comprise a small amount of the total production volume. 

Polyurethane foams take two forms: flexible and rigid. Flexible foam is primarily used for 

cushioning, while rigid foam is used mainly for insulation. TDI chemicals are primarily used in 

the production of flexible foams. The majority of polyurethane products undergo curing prior to 

reaching the consumer. However, other polyurethane products such as coatings, sealants and 

adhesives may be sold and used, most often in a mixture of formulated product, in an uncured 

form. Consequently, the general population may unknowingly be exposed to diisocyanates in a 

variety of ways, such as use of consumer and biomedical products that contain diisocyanates, as 

well as environmental release that may occur when diisocyanates are used in auto refinishing, 

construction and other commercial activities. Thus there could be increased potential for 

cumulative exposures, with heightened concern for individuals who are already chemically 

sensitized (Bello, et al, 2007). 

Because of its hazards, industry claims that uncured TDI is used in products intended for 

industrial use only (DOW, 2009). Generally, MDI and aliphatic diisocyanates have been 

replacing TDI in coating and adhesive products (Ott et al., 2003). The 2006 Inventory Update 

Reporting (IUR) database indicates that TDI chemicals are used in the following 

consumer/commercial categories: adhesives and sealants; paints and coatings; transportation 

products; rubber and plastic products; wood and wood furniture; and electrical and electronic 

products (EPA, 2010). The Household Products Database currently lists one uncured TDI 

product, a concrete sealant for floors (NIH, 2010 ). That product and the deck coating used in an 

exposure study (Jarand et al., 2002) are still available for purchase and it is not clear that the 

products are limited to professional use only. Based on online research, it appears that floor 

coatings and sealants are the primary types of products containing uncured TDI which might be 

available to consumers. 

Additionally, the synthetic recreational surfacing industry uses a variety of polyurethane 

components in formulating its products for both indoor and outdoor surfaces (Advanced Polymer 

Technology Corporation, 2010). Polyurethane coatings are available for professional use to seal 

concrete, waterproof walls and refinish floors. So-called “for professional use” products may 

also be available for purchase and use by consumers or could be used in the presence of 

consumers. Polyurethane sealants have a variety of uses in the automotive sector, the largest 

being glass installation of windshields and side windows. Consumer use of adhesives and 

sealants is a potential growth sector as noted by an industry overview of this sector in late 2009. 

This growth reflects increasing numbers of DIY energy-conscious homeowners doing more of 

their own home renovation and repair work in order to save money, as well as from craftsmen 

and consumers generally continuing to use adhesives (Pinaoforte, November 1, 2009). 
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Replacement of diisocyanates in an environmentally and economically friendly manner 

presents a significant green-chemistry challenge. However, a new class of non-isocyanate 

polyurethanes that offers potentially safer alternatives to conventional polyurethanes has been 

reported by two research groups (Figovsky & Shapovalov, 2006; Javni et al., 2008). Other 

reported technologies include an isocyanates-free expanding foam product (Soudal, 2010) and a 

faster curing “isocyanates-free” flexible food packaging adhesive that reportedly prevents 

potential migration of isocyanates into non-dry food. Of note, a soy-based adhesive intended to 

replace formaldehyde-urea adhesives received a Presidential Green Chemistry Award but more 

research is needed to determine if soy-based adhesives would be an adequate substitute for 

polyurethane adhesives. While research and development of appropriate alternatives is 

underway with a goal of direct product substitutions, it is important to focus on the safe use of 

existing polyurethane products through hazard communication and educating product users. 

V. Hazard Identification Summary 

Environmental Hazard. Because of their low ecotoxicity profiles, the hazards associated 

with exposures to TDI chemicals have centered on human health effects not ecological effects. 

Experimental ecotoxicological data for TDI and its degradation products indicate moderate to 

low toxicity to aquatic organisms (Curtis et al., 1978; MITI, 1992; Tadokora et al., 1997; 

Pedersen et al., 1998). Other toxicity data suggest low likelihood of effects to terrestrial biota 

such as plants, earthworms (Van der Hoeven et al., 1992a; Van der Hoeven et al., 1992b), and 

birds exposed to 2,4-TDI and 2,6-TDI (IUCLID, 2000). 

Toxicity in Humans. Most of the data on human health hazards resulting from 

diisocyanate exposures are based on occupational populations. These data indicate that exposure 

to diisocyanates can cause contact dermatitis, skin and respiratory tract irritation, immune 

sensitization, and asthma (NIOSH, 2006). Both inhalation and dermal exposures to 

diisocyanates are thought to contribute to the development of isocyanate asthma (Bello et al., 

2007). It is well documented that isocyanate exposure is the leading cause of work-related 

asthma, and prevalence in the exposed workforce is estimated at 1-20% (Ott et al., 2003; Bello et 

al., 2004). Once a worker is sensitized to diisocyanates, subsequent exposures can trigger severe 

asthma attacks. Most workers who develop diisocyanate asthma have experienced long periods 

of exposure (months). However, the minimum exposure to isocyanates that can elicit 

sensitization responses or asthma is not known. In addition, immune response and subsequent 

disease in humans can be quite variable (Redlich et al., 2006). Fatalities linked to diisocyanate 

exposures in sensitized persons have been reported (NIOSH, 1996; ACC, 2005). 

There are very few reports of non-occupational exposures to TDI available; however, 

there are case reports suggesting that paraoccupational asthma may have resulted from incidental 

exposure to TDI (De Zotti et al., 2000). In addition, antibodies to TDI have been detected in 

some residents living near a facility that manufactured polyurethane foam, indicating that 

exposures may be occurring from environmental releases from the plant and sensitizing some 

individuals (Orloff et al., 1998; Darcey, 2002). 

 Toxicity in Laboratory Animals. TDI has low acute toxicity via the oral and dermal 

routes, but is considered toxic via the inhalation route in animals (Collins, 2002; ECB, 2005). 
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TDI is uniformly distributed throughout the body, following inhalation exposure (Collins, 2002; 

Gledhill et al., 2005). TDI causes skin, eye, and lung irritation, progressive impairment of lung 

function with long-term inhalation exposure and is a respiratory sensitizer via both the dermal 

and inhalation routes of exposure in animals (Collins, 2002). Cross-sensitization has been 

observed between MDI, TDI, hexamethylene diisocyanate(HDI) and dicyclohexylmethane 

diisocyanate (HMDI) in mice, and between MDI, TDI and HDI in humans (O'Brien et al., 1979). 

TDI is positive in gene mutation assays in vitro and negative in an in vivo mouse micronucleus 

assay (Collins, 2002). Animal data indicate that TDI may be carcinogenic; however, a consistent 

association has not been reported in epidemiologic studies (IARC, 1987b; IARC, 1987a; ECB, 

2005). 

VI. Fate Characterization Summary 

 Hydrolysis is the dominant process in determining the overall environmental fate, 

transport, and bioaccumulation potential of diisocyanates. Commercially, diisocyanates react at 

room temperature with other chemicals (i.e. polyols) to form various polymers. Data shows that 

water from humidity in air can hydrolyze TDI thus forming the amine, toluene diamine (TDA), 

which also has hazards associated with it. Although their rapid hydrolysis in surface water will 

reduce persistence and bioaccumulation in the environment (Yakabe et al., 1999), under 

conditions of low humidity, diisocyanates may be stable long enough to be transported some 

distances and inhaled. Data from the Toxics Release Inventory shows releases to all media 

(EPA, 2008b). Despite their apparent rapid reaction time, there is uncertainty regarding 

diisocyanate vapors and TDA in ambient air as a function of humidity (Dyson & Hermann, 

1971). Air releases are of particular concern, because the hydrolysis products formed are 

irritants and there is a potential for inhalation exposure. 

VII. Exposure Characterization Summary 

Occupational Exposure. Approximately 280,000 U.S. workers were estimated to be 

potentially exposed to diisocyanates in 1996 (NIOSH, 1996) but given industry growth and new 

applications (Bello et al., 2007), this estimate is expected to be higher today. OSHA regulates 

workplace exposures to TDI through its permissible exposure limits (PELs). To reduce worker 

exposures when exposure levels exceed its PELs, OSHA requires use of PPE when engineering 

controls (e.g., ventilation) or administrative controls are infeasible or fail to reduce levels 

adequately. 

There is a potential for workplace exposure to TDI in all industrial, commercial, or 

manufacturing settings where TDI is present (DOW, 2009). Because of the high volatility of 

TDI, exposure can occur in all phases of its manufacture and use (NTP, 2005). Short-term 

airborne concentrations that exceed OSHA’s ceiling PEL for TDI continue to be reported in 

polyurethane foam production facilities (Ott et al., 2003), especially during upset conditions, 

within the foam line tunnel, or in close contact with fresh cut buns (Cummings & Booth, 2002). 

Overexposures to TDI were documented for floor finishing in both personal and area samples in 

one NIOSH evaluation (NIOSH, 2004). In another NIOSH evaluation of flexible polyurethane 

foam workers, although airborne exposures to TDI were below recommended exposure limits, 

respiratory (TDI-induced bronchitis and asthma), mucous membrane, and skin problems were 
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noted for workers and these symptoms were associated with indicators of TDI exposure (NIOSH, 

1998). Some sensitized workers susceptible to developing occupational asthma could react to 

isocyanate monomers at concentrations that are below 1% of the 8-hour threshold limit value 

(TLV) of 5 ppb for TDI/MDI (Gagne et al., 2005). For TDI, NIOSH recommends exposure 

reduction to the lowest feasible minimum (NIOSH, 2005) and ACGIH is looking at reducing its 

2011 TLVs for 2,4- and 2,6-toluene diisocyanate from current limits through a Notice of 

Intended Change (NIC). See Appendix 2 for numerical values. 

 Self-employed workers and small firms may not have access to or be aware of the hazard 

information and appropriate precautions to take when using uncured polyurethane products 

(Krone, 2004). Investigators observed workers applying a TDI-containing moisture cure 

urethane (MCU) floor finish without using any respiratory protection in one investigation of 

airborne exposures during residential application of the MCU product (ATSDR, 2005).

EPA is aware that there is uncertainty about curing time of various products under 

different situations and that additional data are needed to address certain concerns, such as reentry time, which are important for improving communication to prevent exposure. 

Additionally, while OSHA and NIOSH have developed methods to estimate air concentrations 

within workplaces, current methods underestimate air concentrations and may warrant the use of 

a compensation factor and/or development of improved analytical methods. Methods for 

detection of dermal exposure are in the early stages of development. There are several data gaps 

associated with dermal exposure, sensitization, and the availability of uncured isocyanate groups 

(Streicher et al., 1998; Bello et al., 2007). In the U.S., only isocyanate monomers (e.g., TDI and 

MDI) are regulated, although similar polyisocyanates that are widely used in commercial and 

consumer products contain the same reactive isocyanates. EPA is concerned that there does not 

appear to be sufficient recognition that potential exposures of consumers and non-OSHA 

regulated workers to MDI, TDI and their related polyisocyanates may need to be addressed with 

similar recommendations for use of engineering controls, PPE, and hazard communication as 

those required for OSHA-regulated occupational settings. 

Consumer/General Population Exposure. Potential exposure concerns for workers also 

may apply to consumers, bystanders, building occupants (including children), hobbyists and DIY 

applicators. Little information is available to document consumer use of products containing 

uncured TDI. It appears that over the years, MDI has been substituted for TDI in some 

consumer products (ACC, 2009). Although industry claims that uncured TDI products are for 

industrial use only, many such products are available on the Internet and it is not clear if there is 

any control over who purchases them. Unlike workers who are protected by workplace 

regulations and, in most cases, have access to hazard information and training for working with 

diisocyanates, it is likely that most consumers are unaware of the potential hazards of consumer 

products containing uncured TDI. Consequently, incorrect use because of insufficient and 

inadequate hazard communication may lead to increased consumer exposure. Even if consumers 

are aware of the hazards, they may not take appropriate precautions. 

While there is not much information available about direct consumer use, numerous 

bystander exposures to TDI products have been found in the literature, including: emissions of 

TDI from concrete patio sealants (Kelly et al., 1999; Jarand et al., 2002); and detection of TDI in 
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building air samples following use of urethanes containing TDI to coat wood floors (NYCDOHMH, 2010). In addition, two cases of paraoccupational TDI asthma were documented 

through specific inhalation challenges after the individuals were exposed to uncured TDI (De 

Zotti et al., 2000). 

Children may have greater potential for exposure to some types of polyurethane products, 

either as users of the products or as bystanders. Since children spend a large amount of time 

indoors, the use of household chemicals in the indoor environment has been identified as a 

principal source of exposure. Air tight conditions in new homes may also increase the potential 

for exposure to children. One 2005 mail survey of California home users found that many never 

use their windows for ventilation and ventilation rates in some new homes are lower than 

recommended levels (Offerman, February, 2010). Children exposed to the same airborne 

concentrations of TDI as adults may receive a larger dose because they breathe more per pound 

body weight and per unit respiratory surface area. Additionally, children may be more highly 

exposed to environmental toxicants through dermal routes than adults. For instance, children 

may crawl, roll or sit on surfaces treated with chemicals (i.e., carpets and floors) and play with 

objects such as toys where residues may settle. Children have a higher surface area relative to 

body weight, which would result in a greater dose relative to body weight for a child than for an 

adult with an equal amount of skin exposure (EPA, 2008a). Children may have a greater 

potential for exposure if they use uncured TDI products, because they may not have fully 

developed judgment for following labeling instructions and safety precautions and may not cease 

activity even when they are experiencing symptoms of exposure. Children with asthma are an 

especially vulnerable population for exposure, because they are more susceptible to 

inflammatory narrowing of the airways, which results in a proportionally greater obstruction for 

breathing (Trasande & Thurston, 2005). 

In contrast to the large amount of exposure data available for professional workers who 

work with diisocyanates, there is limited exposure data available characterizing the use and 

exposure scenarios of consumer and commercial products containing uncured TDI. Additional 

data characterizing the concentration of TDI in the air is needed. It is unknown to what extent 

factors such as application techniques, product composition, and method of measurement 

influence the availability of uncured TDI. In addition, comparing concentrations to existing 

workplace exposure limits is not appropriate because the worker PEL is not sufficiently 

protective for the consumer (Redlich, et al, 2006). 

IX. Risk Management Considerations 

Similar types of uncured products are available for purchase by either professionals or 

consumers. Numerous authors have noted the versatility of polyurethane as well as its increasing 

uses. EPA is concerned that the potential exists for similar exposures in non-OSHA-regulated 

situations. Both primary users and bystanders should be made aware of the potential risks and 

appropriate precautions to take when uncured TDI is being used. It is unclear how many 

products containing uncured TDI are available for consumer purchase. However, even if 

uncured TDI products are being used by professionals, they could be used in locations, such as 

surfacing running tracks and gymnasium floors, where unintended exposure of bystanders, 

especially children, could be a concern. It is important to determine whether there are uncured 
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TDI products being used in ways that could present potential exposure concerns. In addition, 

some personal and health care products could contain uncured diisocyanates but are beyond the 

scope of this action plan. However, exposures from use of such products could contribute to 

cumulative diisocyanate exposures (Sommer et al., 2000; Donnelly et al., 2003). The factors 

described above suggest that a heightened concern for potential risks of diisocyanate exposure to 

children should be addressed during actions taken to manage these chemicals. 

Current and Ongoing Regulatory and Related Activities

 TDI and its related polyisocyanates are the subjects of a variety of regulatory and related 

activities, some of which are summarized below. Additional details, including numerical values, 

are provided in Appendix 2. 

EPA Regulatory Activities. TDI is regulated under the Clean Air Act as a hazardous air 

pollutant and under RCRA and CERCLA as a hazardous waste. Diisocyanates as a category and 

TDI individually are subject to Toxics Release Inventory reporting. Under TSCA, EPA has 

previously used its authority under TSCA sections 8(a) and 8(d) to request information from 

industry (see 40 CFR parts 712 and 716). EPA has also received submissions regarding 

diisocyanates under TSCA section 8(c) and TSCA section 8(e). Diisocyanates are a TSCA New 

Chemicals Program Chemical Category and any new chemical substance falling in that category 

may be further regulated after a TSCA section 5 premanufacture notice has been submitted 

(EPA, 2002). 

Spray Polyurethane Foam (SPF) Federal Partnership Promoting Stewardship & 

Research. In 2009, EPA convened a multi-agency partnership with OSHA, NIOSH, and the 

Consumer Product Safety Commission (CPSC) to evaluate and address potential exposures to 

isocyanates and other chemicals during installation of spray polyurethane foam (SPF) insulation 

and air sealants in homes and schools. Commercial and DIY applicators, as well as building 

occupants are often unaware of inhalation and dermal hazards. Applicators and others at the 

work site may not wear adequate PPE. Building occupants, who remain on the premises during 

the operations or re-enter the site before the product is fully cured may be at risk. The federal 

agencies are working with the polyurethanes industry to ensure accessible hazard 

communication, applicator training, and best workplace practices to prevent exposure to 

isocyanates and other SPF chemicals. In addition, the federal group has identified critical 

research needs to assess and measure exposures to total reactive isocyanate groups (TRIG) 

during use and curing of SPF products. EPA will continue to work with its federal partners, the 

polyurethanes industry, and others to ensure improved labeling and product safety information 

for polyurethane products containing unreacted isocyanates, especially products targeted to 

consumers. EPA is also considering a green chemistry challenge to encourage the development 

of safer alternative chemicals. 

Canada. On May 12, 2010, Canada added TDI to its List of Toxic Substances following 

an assessment which determined that TDI is carcinogenic and affects the respiratory system. 

Environment Canada published a proposed P2 Pollution Prevention Planning Notice for the 

polyurethane and other foam sector. A proposed action to investigate non-foam consumer 
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products containing TDIs under the Hazard Products Act is in development (Environment 

Canada, 2010). 

IARC. The International Agency for Research on Cancer (IARC) has classified TDI as 

possibly carcinogenic to humans (IARC, 1987b). 

X. Next Steps 

 In conducting this review, EPA considered a number of potential actions, including 

regulatory actions under TSCA sections 4, 5, 6, and 8; cooperative actions with other federal 

agencies; and voluntary actions as described above. Based on EPA’s screening level review of 

TDI and its related polyisocyanates (Appendix 1), EPA intends to: 

1. Initiate rulemaking under TSCA section 5(a)(2) for a Significant New Use Rule 

(SNUR) designating the new use as use of uncured TDI and its related polyisocyanates in a 

consumer product. 

If it is determined that there are existing consumer uses of uncured TDI products, 

work with industry to develop a voluntary phase-out and follow it with a proposed 

SNUR. Propose a TSCA section 4 test rule to require exposure monitoring studies on 

TDI and its related polyisocyanates in consumer products if the voluntary phase-out is 

not complete in one year from the date of a phase-out agreement with industry. 

2. Issue a data call-in under TSCA section 8(c) to determine if there are allegations of 

significant adverse effects and initiate a TSCA section 8(d) rule for relevant unpublished health 

and safety studies. 

3. Initiate a TSCA section 4 test rule to require general population exposure monitoring 

studies in representative locations where commercial products with uncured TDI would be used. 

4. Consider initiating rulemaking under TSCA section 6 to regulate commercial uses of 

uncured TDI products in locations where the general population could be exposed. 

5. Identify additional diisocyanates and polyisocyanates that may be present in an 

uncured form in consumer products that should be evaluated for regulatory and/or voluntary 

action. 

XI. References 

ACC (2005). American Chemistry Council. TSCA 8(e) Notice of Substantial Risk 8EHQ-0905-

16225 Fatalities linked to diisocyanates. EPA. 

ACC (2009). American Chemistry Council. 2008 End Use Market Survey on the Polyurethanes 

Industry in the US, Canada, and Mexico. (A. IAL Consultants, Ed.). 

Advanced Polymer Technology Corporation (2010). Advanced Polymer Technology 

Corporation July 6, 2010. http://www.advpolytech.com/index.htm.

Allport, D., Gilbert, D., and Outterside, S. (2003). MDI and TDI: Safety, Health and the 

Environment. John Wiley & Sons, Ltd, West Sussex, England. 
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ATSDR (2005). Agency for Toxic Disease Registry. Airborne Exposures to Moisture Cure 

Urethane (MCU) in Multi-Family Residential Buildings. In New York Health 

Consultation: Exposure Investigation Report U.S. Department of Health and Human 

Services Public Health Service Agency for Toxic Substances and Disease Registry 

Division of Health Assessment and Consultation. 

Bello, D., Herrick, C. A., Smith, T. J., Woskie, S. R., Streicher, R. P., Cullen, M. R., Liu, Y., and 

Redlich, C. A. (2007). Skin Exposure to Isocyanates: Reasons for Concern. Environ 

Health Perspect 115. 

Bello, D., Woskie, S. R., Streicher, R. P., Liu, Y., Stowe, M. H., Eisen, E. A., Ellenbecker, M. J., 

Sparer, J., Youngs, F., Cullen, M. R., and Redlich, C. A. (2004). Polyisocyanates in 

occupational environments: a critical review of exposure limits and metrics. Am J Ind 

Med 46, 480-491. 

California EPA (2010). Office of Environmental Health Hazard Assessment (OEHHA). Air 

Toxics Hot Spots Program – Proposed Revised Reference Exposure Levels For Toluene 

Diisocyanate And Methylene Diphenyl Diisocyanate [04/23/10]. 

<http://www.oehha.ca.gov/air/chronic_rels/RELS042310.html>.

Collins, M. A. (2002). Toxicology of Toluene Diisocyanate. Applied Occupational and 

Environmental Hygiene 17, 846-855. 

Cummings, B. J., and Booth, K. S. (2002). Industrial hygiene sampling for airborne TDI in six 

flexible slabstock foam manufacturing facilities in the United States: a comparison of the 

short-term and long-term sampling data. Appl Occup Environ Hyg 17, 863-871. 

Curtis, M. W., Copeland, T. L., and Ward, C. H. (1978). Aquatic toxicity of substances proposed 

for spill prevention regulation National Conference Control of Hazardous Material Spills 

pp. 99-103. 

Darcey, D. (2002). Clinical findings for residents near a polyurethane foam manufacturing plant 

Archives of Environmental Health 57, 239-246. 

De Zotti, R., Muran, A., and Zambon, F. (2000). Two cases of paraoccupational asthma due to 

toluene diisocyanate (TDI). Occupational and Environmental Medicine 57, 837-839. 

Donnelly, R., Buick, J., and Macmahon, J. (2003). Occupational asthma after exposure to plaster 

casts containing methylene diphenyl diisocyanate. Occupational Medicine 53, 432-434. 

DOW (2009). Product Safety Assessment DOW Modified Toluene Diisocyanate (TDI) Products 

July 16, 2010. 

http://www.dow.com/PublishedLiterature/dh_034d/0901b8038034d515.pdf?filepath=pro

ductsafety/pdfs/noreg/233-00617.pdf&fromPage=GetDoc.

Dyson, W., and Hermann, E. (1971). Reduction of Atmospheric Toluene Diisocyanate American 

Industrial Hygiene Association Journal 741-744. 

ECB (2005). European Chemicals Bureau. European Union Risk Assessment Report MDI. 

http://ecb.jrc.ec.europa.eu/documents/ExistingChemicals/RISK_ASSESSMENT/REPORT/mdireport304.pdf.

Environment Canada (2010). Risk Management Action Milestones July 21, 2010. 

http://www.chemicalsubstanceschimiques.gc.ca/challenge-defi/summarysommaire/batch-lot-1/action-tab-eng.php.

EPA (1995). 2,4-/2,6-Toluene diisocyanate mixture (TDI) (CASRN 26471-62-5) 2010. 

http://www.epa.gov/ncea/iris/subst/0503.htm.

EPA (2002). TSCA New Chemicals Program (NCP) Chemical Categories July 16, 2010. 

http://www.epa.gov/oppt/newchems/pubs/cat02.pdf.
*** Interagency Review DRAFT Deliberative – Do Not Cite, Quote or Release During the Review *** 

DRAFT of 11/10/2010 

Page 11 of 14 

EPA (2008a). Child-Specific Exposure Factors Handbook (Final Report) 2008. (E. P. Agency, 

Ed.), Washington D.C. 

EPA (2008b). Toxic Release Inventory, TRI Explorer, Search of 2008 Data for Releases of 

Diisocyanates. 

EPA (2010). 2006 IUR Public Database Version 2.0 Modified 5/7/2010. 

http://www.epa.gov/iur/tools/data/2006-db.html.

Figovsky, O., and Shapovalov, L. (2006). Cyclocarbonate based polymers including Nonisocyanate polyurethane adhesives and coatings. In Encyclopedia of Surface and Colloid 

Science, pp. 1633-1652. Taylor & Francis. 

Gagne, S., Lesage, J., Ostiguy, C., Cloutier, Y., and Van Tra, H. (2005). Quantitative 

determination of hexamethylene diisocyanate (HDI), 2,4-toluene diisocyanate (2,4-TDI) 

and 2,6-toluene diisocyanate (2,6-TDI) monomers at ppt levels in air by alkaline adduct 

coordination ionspray tandem mass spectrometry. Journal of Environmental Monitoring

7, 145-150. 

Gledhill, A., Wake, A., Hext, P., Leibold, E., and Shiotsuka, R. (2005). Absorption, distribution, 

metabolism and excretion of an inhalation dose of 14 C 4,4 ' -methylenediphenyl 

diisocyanate in the male rat. Xenobiotica 35, 273-292. 

IARC (1987a). International Agency for Research on Cancer. 4,4'-Methylenediphenyl 

diisocyanate and polymeric 4,4'-Methylenediphenyl diisocyanate May 3, 2010. 

<http://monographs.iarc.fr/ENG/monographs/vol71/mono71-47.pdf>. 

IARC (1987b). International Agency for Research on Cancer. Toluene Diisocyanates May 3, 

2010. <http://monographs.iarc.fr/ENG/monographs/vol71/mono71-37.pdf>. 

IUCLID (2000). CAS RN 26471-62-5 m-tolyidene diisocyanate. European Commission 

Jan, R. L., Chen, S. H., Chang, H. Y., Yeh, H. J., Shieh, C. C., and Wang, J. Y. (2008). Asthmalike syndrome in school children after accidental exposure to xylene and methylene 

diphenyl diisocyanate. J Microbiol Immunol Infect 41, 337-341. 

Jarand, C. W., Akapo, S. O., Swenson, L. J., and Kelman, B. J. (2002). Diisocyanate emission 

from a paint product: a preliminary analysis. Appl Occup Environ Hyg 17, 491-494. 

Javni, I., Hong, D. P., and Petrovic, Z. S. (2008). Soy-based polyurethanes by nonisocyanates 

route Journal of Applied Polymer Science 108, 3867-3875. 

Kelly, T. J., Myers, J. D., and Holdren, M. W. (1999). Testing of household products and 

materials for emission of toluene diisocyanate. Indoor Air 9, 117-124. 

Krone, C., and Klinger, T. (2005). Isocyanates, polyurethane and childhood asthma. Pediatric 

Allergy and Immunology 16, 378-379. 

Krone, C. A. (2004). Diisocyanates and Nonoccupational Disease: A Review. Archives of 

Environmental Health 59, 306-316. 

MITI (1992). Ministry of International Trade & Industry. Biodegradation and bioaccumulation: 

data of existing chemicals based on the CSCL. Chemical Industry Ecology-Toxicology & 

Information Center., Tokyo, Japan. 

NIH (2010 ). National Institute of Heath. Household Products Database. June 9, 2010. 

<http://householdproducts.nlm.nih.gov/cgi-bin/household/brands?tbl=chem&id=1949>. 

NIOSH (1996). National Institute for Occupational Safety and Health. Preventing asthma and 

death from diisocyanate exposure: NIOSH Alert. (DHHS, Ed.). 

NIOSH (1998). National Institute for Occupational Safety and Health. HETA 98-0011-2801, 

Woodbridge Corporation, Brodhead, Wisconsin. 

http://www.cdc.gov/niosh/hhe/reports/pdfs/1998-0011-2801.pdf. 
*** Interagency Review DRAFT Deliberative – Do Not Cite, Quote or Release During the Review *** 

DRAFT of 11/10/2010 

Page 12 of 14 

NIOSH (2004). National Institute for Occupational Safety and Health. A Summary of Health 

Hazard Evaluations: Issues Related to Occupational Exposure to Isocyanates 1989-2002. 

(D. o. H. a. H. Services, Ed.), pp. 1-42, Cincinnati, OH. 

NIOSH (2005). National Institute of Occupational Safety and Health. NOISH Pocket Guide to 

Chemical Hazards July 16, 2010. http://www.cdc.gov/NIOSH/npg/npgdcas.html.

NIOSH (2006). National Institute for Occupational Safety and Health. Preventing Asthma and 

Death from MDI Exposure During Spray-on Truck Bed Liner and Related Applications: 

NIOSH Alert. <http://www.cdc.gov/niosh/docs/2006-149/default.html>.

NTP (2005). National Toxicology Program. Report on Carcinogens, Eleventh Edition; U.S. 

Department of Health and Human Services, Public Health Service. Substance Profile, 

Toluene Diisocyanates. http://ntp.niesh.nih.gov/ntp/roc/eleventh/profiles/s177tdi.pdf. 

NYC-DOHMH (2010). New York City Department of Health and Mental Hygiene. Moisture 

Cure Urethanes (MCU)s July 16, 2010. http://www.nyc.gov/html/doh/html/epi/mcufact.shtml.

O'Brien, I. M., Harries, M. G., Burge, P. S., and Pepys, J. (1979). Toluene di-isocyanate-induced 

asthma I. Reactions to TDI, MDI, HDI and histamine. Clinical & Experimental Allergy 9, 

1-6. 

Offerman, B. (February, 2010). Unintended Consequences: Formaldehyde Exposures in Green 

Homes, February 2010 In The Synergist pp. 31-33. American Industrial Hygiene 

Association. 

Orloff, K. G., Batts-Osborne, D., Kilgus, T., Metcalf, S., and Cooper, M. (1998). Antibodies to 

toluene diisocyanate in an environmentally exposed population. Environ Health Perspect

106, 665-666. 

Ott, M. G., Diller, W. F., and Jolly, A. T. (2003). Respiratory effects of toluene diisocyanate in 

the workplace: a discussion of exposure-response relationships. Crit Rev Toxicol 33, 1-

59. 

Pedersen, F., Bjornestad, E., Vulpius, T., and Rasmussen, H. (1998). Immobilisation Test of 

Aniline Compounds with the Crustacean Daphnia magna Proj.No.303587, Report to the 

Danish EPA, Copenhagen, Denmark. 

Pinaoforte, K. (November 1, 2009). Adhesives and sealants market update. In Coatings World. 

Redlich, C. A., Bello, D., and Wisnewski, A. (2006). Isocyanate exposures and health effects. In 

Environmental and Occupational Medicine (W. Rom, and S. Markowitz, Eds.), pp. 502-

516. Lippincott Willimas & Wilkins Philadelphia, PA. 

Sommer, B. G., Sherson, D. L., Kjoller, H., Hansen, I., Clausen, G., and Jepsen, J. R. (2000). 

Asthma caused by methylene-diphenyl-diisocyanate cast in a nurse. Ugeskr Laeger 162, 

505-506. 

Soudal, N. (2010). New from Soudal: Isocyanate Free Foam. 

http://www.infrasite.net/products/productnews_article.php?ID_productnews=304&langu

age=en.

Streicher, R. P., Reh, C., and Key-Schwartz, R. (1998). Determination of airborne isocyanate 

exposure. NIOSH Manual of Analytical Methods. (NIOSH, Ed.), pp. 115-140. 

Tadokora, H., Nozaka, T., Hirata, R., and Tounai, T. (1997). Ecotoxicities of TDI and TDA to 

fish, algae and aquatic invertebrates. . In Chemicals Inspection and Reserach Instititute, 

Japan British Library Document Supply Centre, Boston Spa, Wetherby, West Yorks. . 

Trasande, L., and Thurston, G. (2005). The role of air pollution in asthma and other pediatric 

morbidities. J Allergy Clin Immunol 115, 689 - 699. 
*** Interagency Review DRAFT Deliberative – Do Not Cite, Quote or Release During the Review *** 

DRAFT of 11/10/2010 

Page 13 of 14 

Van der Hoeven, N., Roza, P., and Henzen, L. (1992a). Determination of the effect of TDI, 

TDA, MDI, and MIDA on the emergence and growth of the plant species Avena sativa

and Lactuca sativa according to OECD Guideline No. 208. . British Library Document 

Supply Centre, Boston Spa, Wetherby, West Yorks. 

Van der Hoeven, N., Roza, P., and Henzen, L. (1992b). Determination of the LC50 (14 days) of 

TDi, TDA, MDI, and MDA to the earthworm Eisenia fetida according to OECD 

guideline no. 207. British Library Document Supply Centre, Boston Spa, Wetherby, 

West Yorks. . 

Yakabe, Y., Henderson, K. M., Thompson, W. C., Pemberton, D., Tury, B., and Bailey, R. E. 

(1999). Fate of Methylenediphenyl Diisocyanate and Toluene Diisocyanate in the 

Aquatic Environment. Environmental Science & Technology 33, 2579-2583. 

Appendix 1 

Tier 1: TDI monomers and related isomers and polymers

No CASRN CA Index Name Acronym Common Name 

1 91-08-7 Benzene, 1,3-diisocyanato-2-methyl- 2,6-TDI 2,6-Toluene 

diisocyanate 

2 584-84-9 Benzene, 2,4-diisocyanato-1-methyl- 2,4-TDI 2,4-Toluene 

diisocyanate 

3 26471-62-5 Benzene, 1,3-diisocyanatomethyl- TDI 80/20 Toluene diisocyanate 

4 9017-01-0 Benzene, 1,3-diisocyanatomethyl-, 

homopolymer 

Polymeric

TDI 

Poly(toluene 

diisocyanate) 

Tier 2: TDI dimers, trimers and polymers

No CASRN CA Index Name Acronym Common Name 

5 26747-90-0 1,3-Diazetidine-2,4-dione, 1,3-

bis(3-isocyanatomethylphenyl)- 

2,4-TDI 

dimer 

Tolylene diisocyanate 

dimer 

6 26603-40-7 

1,3,5-Triazine-2,4,6(1H,3H,5H)-

trione, 1,3,5-tris(3-

isocyanatomethylphenyl)- 

TDI 

trimer 

Tolylene diisocyanate 

trimer 

Appendix 2 – Regulatory and Exposure Limits for TDI 

EPA. The EPA’s Integrated Risk Information System (IRIS) program has developed a 

reference concentration (RfC) for TDI of 7 x 10-5 mg/m3

 using chronic decline in lung function 

(FEV1) in an occupationally exposed population as the critical effect (EPA, 1995). 

OSHA. Diisocyanate hazards are addressed by OSHA in specific standards for the 

general industry, shipyard employment, and the construction industry, including PELs for 

workplace exposure. 

OSHA’s PEL for the TDI monomer 0.140 mg/m3

 (0.02 ppm) as a ceiling limit (29 CFR 

1910.1000). OSHA also requires the use of PPE to reduce worker exposure to hazards when 
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Page 14 of 14 

engineering and administrative controls are not feasible or effective in reducing exposure below 

its PELs. 

NIOSH. In 1996 and 2006, NIOSH issued Alerts to prevent asthma and death from 

diisocyanate exposure to workers in certain situations (NIOSH, 1996; NIOSH, 2006). 

NIOSH also considers TDI to be an occupational carcinogen and recommends exposure 

reduction to the lowest feasible minimum (NIOSH, 2005). 

ACGIH. American Conference of Governmental Industrial Hygienists. Threshold Limit 

Values (TLVs) for TDI address respiratory sensitivity but not dermal sensitivity. It has been 

suggested that there is now sufficient information to recommend the addition of a “skin notation” 

to the TLVs for TDI to bring attention to the potential for absorption of diisocyanates through the 

skin. 

ACGIH has assigned TDI a TLV of 0.036 mg/m3

 (0.005 ppm) as a TWA for a normal 8-

hour workday and a 40-hour workweek and a 15-minute Short Term Exposure Limit (STEL) of 

0.14 mg/m3 (0.02 ppm) (ACGIH, 2009). 

As noted in its 2010 Notices of Intended Changes (NIC) for the 2011 TLVs, ACGIH is 

also considering reducing the TLV for 2,4 and 2,6 Toluene Diisocyanate (TDI) (CAS 584-84-9; 

91-08-7) from 0.005 ppm to 0.001 ppm. 

California, OEHHA. In April 2010, California’s Office of Environmental Health 

Hazard Assessment (OEHHA) released “for comment” draft documents describing proposed 

Reference Exposure Levels (RELs) for TDI which have been revised to include consideration of 

possible differential effects on the health of infants, children and other sensitive subpopulations 

(California EPA, 2010) 

 

Canada. On May 12, 2010, Canada added TDI to its List of Toxic Substances following 

an assessment which determined that TDI is carcinogenic and affects the respiratory system. 

Environment Canada published a proposed P2 Pollution Prevention Planning Notice for the 

polyurethane and other foam sector. A proposed action to investigate non-foam consumer 

products containing TDIs under the Hazard Products Act is in development. 

In 2005, Canada (Ontario Province) updated and lowered its air quality standard for TDI 

(http://www.ene.gov.on.ca/envision/env_reg/er/documents/2005/airstandards/PA02E0010.pdf). 

IARC. The International Agency for Research on Cancer (IARC) has classified TDI as 

possibly carcinogenic to humans (IARC, 1987b).