U.S. Environmental Protection Agency April 2011 

Toluene Diisocyanate (TDI) 

And Related Compounds 

Action Plan 

[RIN 2070-ZA14] 

I. Overview 

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

(See Appendix 1) 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 uncured (unreacted) 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. 

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

 Sources initially consulted for basic background information for all the action plan chemicals, including TDI, 

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. Details about the specific sources used for this Action Plan can be found in the 

reference list in Section XI. of this document. 

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U.S. Environmental Protection Agency April 2011 

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’ 

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. Completely cured products are fully reacted and therefore are considered to be inert 

and non-toxic (Krone & Klinger, 2005). This Action Plan focuses on concerns for unreacted, 

uncured products. 

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

(see Appendix 1) 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 (see additional discussion in section on Consumer/General Population Exposure). 

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. 

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U.S. Environmental Protection Agency April 2011 

EPA is concerned about the presence of uncured TDI in products used by or around 

consumers, as well as other unprotected building occupants, and the lack of guidance or 

regulations to protect them. Therefore, this Action Plan focuses on potential health effects that 

may result from exposures to the consumer or self-employed worker when such a person uses 

products containing uncured TDI, or incidental exposures to the general population when such 

products are used in or around buildings, including homes or schools. 

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. Researchers looking at workplace exposures to diisocyanates have noted an increase in the 

number of isocyanate-containing products used by consumers. These researchers also noted that 

community exposures to isocyanates could potentially result from industrial exposures as well as 

the use of consumer products containing isocyanates (Redlich, et al, 2006). 

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 (see for example, 

Dow, 2011). 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 

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U.S. Environmental Protection Agency April 2011 

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 (Pianoforte, 2009). The spray foam industry, 

recognizing the growing use of these products by DIYers, recently developed a website on the 

use of spray foam with guidance directed specifically to DIYers, in addition to homeowners and 

professionals (ACC, 2010). 

Replacement of diisocyanates in an environmentally and economically friendly manner 

presents a significant 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 (EPA, 2009), 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 and Ecological Hazards. 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. Higher incidences of asthma are typically associated with processes that 

generate higher exposures, such as spray application or heated processes that generate airborne 

vapors and mists that can expose workers via respiratory and dermal routes. For example, the 

UK Health and Safety Executive reported that vehicle refinishers who spray coatings containing 

isocyanates have an 80 times higher risk of getting asthma compared with the UK working 

population. (HSE 2009) [http://www.hse.gov.uk/mvr/priorities/isocyanates.htm/]. Fewer cases 

of diisocyanate asthma have been reported in work settings with lower isocyanate airborne 

exposures, and most workers who develop diisocyanate asthma have experienced long periods of 

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exposure (months or longer). 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). The EPA IRIS 

program has developed a reference concentration based on occupational exposure data (see 

Appendix 2) 

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. In acute, subacute, and chronic animal exposure 

studies, the respiratory tract was the target organ, with nasal irritation evident at concentrations 

above 0.1 ppm and effects becoming more severe with increasing concentration. (Collins, 2002; 

ECB, 2005). 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). Crosssensitization 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 (Collins, 2002). Data from recent 

studies of animals show that cancer is associated with exposure to commercial-grade TDI (an 

80:20 mixture of 2,4- and 2,6-TDI). The responses of both rats and mice treated with TDI meet 

the OSHA criteria for classifying a substance as a potential occupational carcinogen (29 CFR 

1990.112). NIOSH therefore recommends that occupational exposure to TDI and its isomers be 

minimized (NIOSH 1989). 

The carcinogenic effects of TDI (Loeser 1983; NTP 1986) were also investigated by the 

International Agency for Research on Cancer (IARC) and the World Health Organization 

(WHO) (IARC 1986; WHO 1987). IARC concluded that data were sufficient to show that TDI 

causes cancer in animals. WHO concluded that TDI should be treated as a potential human 

carcinogen. In addition, NIEHS has listed TDI in its 11th Report on Carcinogens as reasonably 

anticipated to be carcinogenic to humans. 

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), 

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U.S. Environmental Protection Agency April 2011 

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) (see Appendix 2). 

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 

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. 

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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. Consumers, bystanders, building occupants 

(including children), hobbyists and DIY applicators may be exposed to uncured TDI in some 

products. 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 an industry product safety assessment states that 

uncured TDI products are intended for industrial use only (Dow, 2009), many such products are 

available on the Internet from formulators and distributors further down the supply chain 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 

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 exposed to the same levels of TDI vapor as adults may receive a larger dose 

because they have greater lung surface area:body weight ratios and increased minute 

volumes:weight ratios. TDI vapor is heavier than air and may layer close to the floor. Children 

who 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 may receive higher doses of inhaled toxicants than 

adults present in the same room (ATSDR, 2002). Because of their relatively larger surface 

area:body weight ratio, children are more vulnerable to toxicants absorbed through the skin. 

Children may have a greater potential for exposure if they use or are bystanders to the use of 

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. Additionally, chronic exposure may be more serious for 

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U.S. Environmental Protection Agency April 2011 

children because of their potential longer latency period, as they have more opportunity for both 

exposure to and expressions of harmful effects from exposure to substances such as TDI 

(ATSDR, 2001; ATSDR, 2002, EPA, 2008a). Children with asthma are an especially vulnerable 

population for exposure; they are more susceptible to inflammatory narrowing of the airways, 

which results in a proportionally greater obstruction of their smaller respiratory system (NIH, 

2011; 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 

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 

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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 

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

(SNUR), designating the use of uncured TDI and its related polyisocyanates in a consumer 

product as a new use. As indicated in Section IV, Uses and Substitutes Summary, some 

members of the industry have stated that uncured TDI is not used in consumer products. 

(B) If, however, public comments on the proposed SNUR indicate that there are ongoing 

uses of uncured TDI in consumer products, since on-going uses are by definition not new, EPA 

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intends to consider working with industry to develop a voluntary phase-out of such uses within 

one year, to be followed by a SNUR. 

(C) If voluntary phase-out is not agreed upon, or is not completed as agreed upon, EPA 

intends to consider initiating rulemaking under TSCA section 4 to require exposure monitoring 

studies on TDI and its related polyisocyanates in consumer products. 

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 one-time reporting of 

relevant unpublished health and safety studies. 

3. Consider initiating a TSCA section 4 test rule to require 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. Consider identifying additional diisocyanates and their related 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.). Note: this is a 

proprietary document. 

ACC (2010). American Chemistry Council. Spray Polyurethane Foam Health and Safety. 

March 3, 2011. http://spraypolyurethane.org/. 

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

Environment. John Wiley & Sons, Ltd, West Sussex, England. 

ATSDR (2001). Agency for Toxic Disease Registry. Medical Management Guidelines for 

Toluene Diisocyanate. In Managing Hazardous Materials Incidents, Vol. III Medical 

Management Guidelines for Acute Chemical Exposures. Atlanta, GA: USDHHS, PHS. 

ATSDR (2002). Case Studies in Environmental Medicine: Pediatric Environmental Health. 

ATSDR Publication No. ATSDR-HE-CS-2002-0002. 

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. 

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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 and trimers 

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 

14 
 

 

 

U.S. Environmental Protection Agency April 2011 

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 

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 

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U.S. Environmental Protection Agency April 2011 

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). 

16