Properties that result in a chemical being classified as a POP along with long-range transport (LRT), while understood in a generic way often vary among jurisdictions. Under the Stockholm Convention, POPs are identified by a combination of bulk (intensive) properties, including persistence and biomagnification and inherent  toxicity or toxic potency. Potential for toxic effects or risk is extensive because it depends on exposure. Instead of classifying chemicals as PBT based solely on a few simple, numeric criteria, it is suggested that an overall weight of evidence approach (WoE), which can also consider unique properties of the substance, be applied. Here properties of chlorpyrifos (CPY) and its active metabolite, chlorpyrifos oxon (CPYO) are assessed relative to classification as persistent, bioaccumulative, and toxic substances. While toxic under the simple classification system used in EC 1107/2009, based on its intensive properties and results of monitoring and simulation modeling, we conclude that there is no justification for classifying CPY or its metabolite CPYO as a POP or PBT.

Assessing pesticides for properties related to POPs and PBT: Chlorpyrifos as an example

248th National Meeting (2014)

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