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Screening Assessment of Six Substances on the Domestic Substances List

Summary of Information Used as Basis for this Screening Assessment

An industrial survey conducted under section 71 of CEPA 1999 revealed no non-pesticidal uses of these substances in Canada above reporting thresholds in 2000 (Environment Canada 2001). Entry characterizations consisted of additionally searching for information on releases and sources of the substances in relevant databases and on the internet, and reviewing findings for both Canada and elsewhere. Searches for these substances were conducted up to September 2007, and no information was found on non-pesticidal uses or releases of these substances in Canada (ATSDR 2002; CCOHS 2003; Cornell University 1985; Health Canada 2007b; Howard 1991; HSDB 2007 ; IARC 1991; IPCS 1987, 1990, 1995, 1996; Merck 2001; NIH 1997; PAN 2002, 2007; US EPA date unknown a,b). Therefore, the likelihood of exposure to these substances in Canada resulting from non-pesticidal uses is low.

Since no uses or releases other than those covered by the PCPA have been identified in Canada for the above six substances, no additional efforts were made under CEPA 1999 to collect or analyze information relevant to the persistence, bioaccumulation, and inherent toxicity to human and non-human organisms of these substances beyond what was done for categorization. Therefore, the decisions on the hazard properties for these substances remain unchanged in this assessment (Environment Canada 2003, 2006). All six substances, with the exception of chlorophacinone meet the criteria for persistence (half lives in soil and water ≥ 182 days and half life in sediment ≥ 365 days) as set out in the Persistence and Bioaccumulation Regulations (Canada 2000). Only trifluralin and chlorophacinone meet the criteria for bioaccumulation (BAF, BCF > 5000 or log kow> 5) as set out in the Persistence and Bioaccumulation Regulations (Canada 2000). All six substances are considered to be inherently toxic to aquatic organisms (LC50 or EC50 <1 mg/L). Four substances (trifluralin, atrazine, chlorothalonil and pentachlorophenol) are considered to be inherently toxic to humans (Health Canada 2006). It should be noted that all of these hazard properties may be re-examined and revised during re-evaluations of these substances under the PCPA.