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This website provides resources on Persistent Organic Pollutants (POPs) such as pesticides, dioxins, PCBs, and wastes. Valuable examples of community monitoring of health and environmental impacts of toxic chemicals are also furnished.

Further, there is an entire section devoted to chemical safety in its proper socio-political context or in relation to issues such as globalization and people's empowerment.


POPs in Ice

by Louisa Dalton

Ice can be more dangerous than water when it comes to the toxicity of environmental contaminants. Reactions in ice can result in more toxic photoproducts.

Chemists at Masaryk University in the Czech Republic compared the fate of 2-chlorophenol and 4-chlorophenol—widespread contaminants from the paper and pesticide industries—when exposed to ultraviolet light both in ice and in water [Environ. Sci. Technol., published online April 15, http://dx.doi.org/10.1021/es035076k]. The water reaction proceeded far faster; within 30 minutes, all chlorophenols (CPs) had converted to dihydroxybenzenes, which are themselves not stable in sunlight.

In ice, on the other hand, the CPs lasted for up to 10 hours and the major products were more stable dimers: 5-chlorobiphenyl-2,4'-diol, for example. In addition, the ice products, after prolonged irradiation, were more toxic to marine bacteria and rat liver cells than both the water photoproducts and the parent contaminants.

“Arctic ecosystems are a sink of anthropogenic pollutants,” says Jana Klánová, a coauthor and chemist at Masaryk. Pollutants evaporate in warm climates, travel, and condense at the cold poles, where the photochemistry can be different and more damaging. The Masaryk group believes that ice may catalyze unique reactions because of the distribution and motion of organic pollutants in frozen water. They are now testing photoproducts of other pollutants in ice: polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and DDT.

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