The first Priority Substances List (PSL1) was published in 1989 and included 44 substances or groups of substances. Environmental assessments and human health assessments were completed under the Priority Substances Assessment Program by early 1994. Assessment Reports for each of these PSL1 substances were completed and published following a critical review of relevant identified data. Conclusions of whether the substances were considered toxic under the Canadian Environmental Protection Act were published.

In some cases, there were substances for which a conclusion could not be reached. Follow-up to the orignal assessment report has been undertaken following a review of new information.

For substances on which the final decisions have been made, please click the following links below to obtain the related assessment information.

• 1,1,1-Trichloroethane
• 1,1,2,2-Tetrachloroethane
• 1,2-Dichlorobenzene
• 1,2-Dichloroethane
• 1,4-Dichlorobenzene
• 3,3'-Dichlorobenzidine
• 3,5-Dimethylaniline
• Benzene
• Benzidine
• Bis (2-chloroethyl) ether
• Bis (2-ethylhexyl) phthalate
• Bis (chloromethyl) ether
• Chlorinated wastewater effluents
• Chlorobenzene
• Chloromethyl methyl ether
• Creosote-contaminated sites
• Dibutyl phthalate
• Dichloromethane
• Di-n-octyl phthalate
• Effluents from pulp mills using bleaching
• Hexachlorobenzene
• Hexavalent chromium compounds
• Inorganic arsenic compounds
• Inorganic cadmium compounds
• Inorganic fluorides
• Methyl methacrylate
• Methyl tertiary-butyl ether
• Organotin compounds
• Oxidic, sulphidic and soluble, inorganic nickel compounds
• Pentachlorobenzene
• Polychlorinated dibenzodioxins
• Polychlorinated dibenzofurans
• Polycyclic aromatic hydrocarbons
• Refractory ceramic fibre
• Styrene
• Tetrachlorobenzenes
• Tetrachloroethylene
• Trichlorobenzenes
• Trichloroethylene
• Toluene
• Xylenes

Following considerations of comments received, the Draft Follow-Up Reports listed below will be revised as appropriate and published with final conclusions as to whether or not the substances are considered to be "toxic" as defined in CEPA 1999.

• Aniline
• Chlorinated paraffins
• Used crankcase oils