State of the Science Report for Dichloroethene

Identity, Uses and Sources of Exposure

Submissions made under Section 71 of CEPA 1999 indicate that 58.4 tonnes of 1,1-dichloroethene (DCE) were manufactured in, and imported into, Canada in 2000 (Environment Canada, 2001). DCE is used primarily as a chemical intermediate, being an ingredient in the manufacture of polyvinylidene chloride (PVDC) polymers and copolymers. Consumer products in which PVDC is used include plastic films in the food industry, carpets, awnings and photographic film. PVDC polymers and copolymers are also used as flame retardants in paper and paperboard coatings (IPCS, 1990). It is expected that exposure to DCE in PVDC products is minimal, as DCE is present in these products only at low residual levels; for example, monomer residual levels have been reported to be <5 mg/kg in both carpet latex and food packaging (U.S. EPA, 2002b).

Because of its volatility (boiling point 31.6°C), DCE can readily enter the atmosphere as emissions during its production and use (ATSDR, 1994). Other sources of DCE emissions are the environmental degradation of tetrachloroethene, trichloroethene, 1,1,1-trichloroethane (ATSDR, 1994; U.S. EPA, 1995) and polyvinyl chloride (OME, 2001). However, 1,1,1-trichloroethane production will be phased out by 2005 under the Montreal Protocol (Environment Canada, 2003b).

Information reported under Section 71 of CEPA 1999 indicated that DCE is formed as a by-product in the manufacture of hydrogen chloride (Environment Canada, 2003a). There were also releases at companies where DCE was used as a solvent (12.7 tonnes released on site) or was being processed for disposal. Based on the use pattern for this substance in Canada, fugitive emissions from industrial processes would pose the greatest source of potential exposure to DCE in the environment.