There is ever mounting evidence that among the many thousands of chemical in commerce there are substances that are harmful to human and ecosystem health. DDT and its metabolites, PCBs and tributyltin are well recognized examples of such chemicals while polybrominated diphenylethers[1-3] and perfluorinated sulphonic acids[4-6] and carboxylic acids[7-9] are chemicals of emerging concern. Such chemicals can pose lasting problems especially if they are persistent and bioaccumulative which causes them to remain in the environment for long times, distribute globally and pose risks to humans and wildlife. The risks of existing and new chemicals are recognized in a number of international and national regulatory initiatives which aim to prevent and ameliorate risks. They include the UNEP Protocol on Long Range Transboundary Air Pollutants (2004), the 1999 Canadian Environmental Protection Act (CEPA), the REACh program in the EU and the TSCA regulations in the US. These regulations aim to prevent the impacts of chemical substances by categorizing all chemicals in commerce for persistence, bioaccumulation and toxicity and to conduct full scale risk assessments for the substances of greatest concern. In Canada, the regulations apply to approximately 23,000 existing substances and 16,000 new chemicals. Globally, approximately 100,000 chemicals are involved, while new chemicals are being added at a rate of 1000-1500/year. The majority of these chemicals are organic substances and approximately 5,000 of these chemicals are high volume production chemicals. The many benefits derived from commercial chemicals comes with the responsibility of environmental stewardship. The enormous variety in commercial substances and human and wildlife receptors and environments that these chemicals interact makes this an important scientific challenge.

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