CAREX Canada

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CAS No. 26471-62-5

Photo: Wikimedia Commons^[1]

IARC Monograph Vol. 71, 1999 (Group 2B)

General Information

Toluene diisocyanates (TDI) are colourless to pale yellow liquids, solids, or crystals with a distinctive pungent odour.^[2] Toluene diisocyanates are highly reactive compounds widely used in the manufacturing of polyurethane foams and coatings.^[3] TDI are typically available as a mixture of 80% 2,4-TDI isomer and 20% 2,6-TDI isomer.^[2]

TDI may also be referred to as 2,4- or 2,6-diisocyanato-1-methyl-benzene.^[4] There are numerous other synonyms and product names; see HSDB for more information.^[3]

Toluene diisocyanates have been classified by IARC as Group 2B, possibly carcinogenic to humans.^[5] Administration of TDI in animal experiments caused benign liver, mammary-gland and pancreas tumours in rats and mice.^[2] Exposure also caused both benign and malignant tumours of blood vessels and subcutaneous tissues in rats and mice.^[2] Epidemiological studies which specifically investigated TDI exposure and human cancer were unavailable; other studies which included TDI as an exposure have not found strong and consistent associations between TDI exposure and cancer in humans.^[2,5]

The toxicity of TDI has been recognized for many years. Exposure to high levels of TDI causes severe irritation of the skin, eyes, and nose, as well as nervous system effects.^[6] It is a potent skin and respiratory sensitizer and a well-known cause of occupational asthma.^[5,7,8] TDI can also cause hypersensitivity pneumonitis and chronic bronchitis.^[5]

Toluene diisocyanates have been ranked by CAREX Canada as Group A (immediate high priority) for occupational settings and as Group B (possible high priority) for environmental settings. Prioritization was based on the carcinogenicity and other toxic properties of the substance, the prevalence of exposure in Canada, and the feasibility of assessing exposure.

Regulations and Guidelines

Occupational Exposure Limits (OEL)

Canadian Jurisdictions	OEL (ppm)
Canada Labour Code	0.005 [sen] 0.02 [stel]
BC	0.005 [sen] 0.01 [c]
AB, ON	0.005 0.02 [c]
MB, NL, PE, NB, NS, SK	0.005 [sen] 0.02 [stel]
QC	0.005 [sen, em] 0.02 [stel]
NT, NU, YT	0.02 [c]
Other Jurisdiction	OEL (ppm)
ACGIH 2011 TLV	0.005 [sen] 0.02 [stel]

ppm = parts per million

c = ceiling (not to be exceeded at any time)

em = exposure must be reduced to the minimum

sen = potential for sensitization

stel = short term exposure limit (15 min. maximum)

Canadian Environmental Guidelines

Jurisdiction	Limit	Year
Cosmetic Ingredients Hotlist	Not Permitted	2011^[15]

TDI were not included in other Canadian government environmental guidelines reviewed.^[9,10,16]

Canadian Agencies/Organizations

Agency	Designation/Position	Year
Health Canada	DSL – high priority substance with greatest potential for exposure (for mixed isomers) and intermediate potential for exmposure (for 2,4-TDI and 2,6-TDI individually)	2006^[11]
Challenge to Industry	Batch 1	2007^[12]
CEPA	Recommended to be added to the toxic substances list	2008^[3]

Main Uses

Toluene diisocyanates are used for the preparation of polyurethane foams, elastomers and coatings.^[5] Polyurethane foam (PUF) is used in furniture, bedding, refrigerators, laminate flooring and roofing, truck and trailer insulation, and in cargo containers;^[2] polyurethane elastomers are used in coated fabrics and clay-pipe seals;^[5] and polyurethane coatings are used in floor finishes, wood finishes and sealers, and coatings for aircraft, tank trucks, truck trailers and truck fleets.^[5]

TDI are also used as a cross-linking agent for nylon-6 and as a hardener in polyurethane adhesives.^[5]

Canadian Production and Trade

TDI are not produced in Canada, but they are used extensively.^[17] Over 10,000 tonnes of TDI, including TDI in mixtures and consumer products if in amounts > 100 kg, were imported into Canada in 2006.^[3]

Production and Trade

Activity	Quantity	Year
Canadian Production	None	2006^[3]
Domestic Demand	27,500 t	2001 (forecasted)^[17]
Export: Mainly to Malaysia, Chile	332 t of ‘isocyanates’	2010^[18]
Import: Mainly from US	24,615 t of 'isocyanates'	2010^[18]

t = tonne

Occupational Exposures

Inhalation and dermal contact are the most important routes of occupational exposure.^[2] Exposure can occur during all phases of TDI’s manufacture and use.^[2]

The main occupations exposed include adhesive workers, insulators, diisocyanate resin workers, lacquer workers, organic chemical synthesizers, paint and urethane foam sprayers, polyurethane makers, rubber workers, ship builders, textile processors and wire coating workers.^[2] The highest exposures occur to workers who spray foam insulation, and this task generally takes place in confined spaces.^[2]

Potential for exposure exists from processes involving heating (welding, soldering or hot-wire cutting) polyurethane products.

Environmental Exposures

The most important route of environmental exposure is inhalation; dermal exposure via some consumer products is also possible.^[3] In Canada, most industrial releases of TDI are into the air. Long range atmospheric transport is unlikely due to the short half-life of TDI in the environment (~2 days).^[3]

Most Canadian releases of TDI to the environment occur in Ontario.^[19]

In Canada, potential sources of TDI exposure to the general population include industrial releases during urethane foam manufacture and processing, where the estimated annual average concentration of TDI in Canada in close proximity to a foam manufacturing facility is 1.06 μg/m³; industrial releases from the manufacture, use or disposal, of other TDI-based products; and the use of consumer products such as polyurethane foams, varnishes, adhesives, and sealants.

Searches of environmental and consumer product databases yielded the following results on current potential for exposure to toluene diisocyanates in Canada:

NPRI and US Household Products Database

NPRI 2009^[20]
Search term: ‘toluene-2,4-diisocyanate'
Category	Quantity	Industry
Released into Environment	0.001 t	Foam and kitchen cabinet manufacture (6 companies)
Disposed of	0.749 t
Sent to off-site recycling	None
Search term: ‘toluene-2,6-diisocyanate'
Category	Quantity	Industry
Released into Environment	None	Foam and kitchen cabinet manufacture (5 companies)
Disposed of	0.050 t
Sent to off-site recycling	None
Search term: ‘toluenediisocyanate (mixed isomers)'
Category	Quantity	Industry
Released into Environment	1.2 t	Foam and kitchen cabinet manufacture (23 companies)
Disposed of	0.524 t
Sent to off-site recycling	None