Using a new approach to measure chemical contaminants in polar bears, scientists from Canada and the United States found a large variety of new chlorinated and fluorinated substances, including many new polychlorinated biphenyl metabolites. Worryingly, these previously unrecognized contaminants have not declined in the past decades, and many long-chain fluorinated alkyl sulfonic acids have been increasing over time, says the study published in the journal Angewandte Chemie.