Asbestos:
Toronto Star article, The Belated Demise of Canada’s Asbestos Industry
Health Canada Asbestos information
Mold:
Health Canada Mould information
Environment Canada’s “Indoor Air Quality” includes mould.
Lead:
EPA (Environmental Protection Agency) America
Animal Feces:
Health Canada information on rats and mice in the home.
Workplace/Occupational Health and Safety:
Infrastructure Health and Safety Association (formerly CSAO) provides a wide range of safety training for the Ontario construction industry.
NIOSH, (National Institute of Occupational Health and Safety) is a branch of the CDC (Centers for Disease Control) involved in preventing workplace illness and accidents.
General:
CDC (Centers for Disease Control & Prevention) website is an excellent resource with a good search engine.