The scoring scheme for mutagenicity/genotoxicity used for the assessments produced by Health Canada differs from that used by the Ontario Ministry of the Environment, in that it was designed to match the criteria used by Health Canada for new substances evaluations and priority substances evaluations done by the department under the Canadian Environmental Protection Act (CEPA).
The criteria used by Health Canada are based more upon the type of positive test data available, rather than mechanism of action.
The CEPA Priority Substances screen for genotoxicity/mutagencity is as follows:
|Indicator(1)||All genotoxicity||Positive results(2)|
|Mutation(1)||data negative||Positive results(2)|
|Somatic cell mutation(1)||Positive results(2)|
|Germ cell mutation(1)||Positive results|
|In vitro Tests:|
1 - For "in vitro" positive results, the score is increased by two levels (i.e. 4) if there are no negative tests in a category (row) beside this row. For "in vivo" positive results, the score is increased by one level (i.e. 2) if there are no negative tests in a category (row) below this row.
2 - Indicator tests include sister chromatid exchanges, recombinations, DNA adducts, sperm morphology and DNA damage. Mutation includes gene mutations, chromosomal aberrations and micronuclei.
[Ref.: Koniecki, et al. (1997), "Screening Candidate Substances for the Second Priority Substances List under the Canadian Environmental Protection Act", Environ. Carcino. & Ecotox. Revs., C15(1), 41-59]