Environmental Persistence of Organic Pollutants: Guidance for Development and Review of POP Risk Profiles

Abstract

Environmental persistence is an important property that can enhance the potential of a chemical substance to exert adverse effects and be transported to remote environments. The persistence of organic compounds is governed by the rates at which they are removed by biological and chemical processes, such as biodegradation, hydrolysis, atmospheric oxidation, and photolysis. The persistence workgroup in a recent Society of Environmental Toxicology and Chemistry (SETAC) Pellston workshop (Pensacola, FL, USA, January 2008) focused on evaluating persistence of organic compounds in environmental media (air, water, soil, sediment) in terms of their single-medium degradation half-lives. The primary aim was to provide guidance to authors and reviewers of chemical dossiers for persistent organic pollutants (POPs) and persistent, bioaccumulative, and toxic substances (PBTs) proposed for action. A second objective was to provide a summary of the current state of the science with respect to POP fate assessment. Assessing the persistence of chemical substances in the environment is not straightforward. A common misconception is that, like many chemical properties, environmental persistence is an inherent property of the substance and can be readily measured. In fact, rates of degradation of a substance in the environment are determined by a combination of substance-specific properties and environmental conditions. This article addresses how persistence can be evaluated based on an assortment of supporting information. Special attention is given to several critical issues, including transformation products, nonextractable residues, and treatment of uncertainty and conflicting data as part of a weight-of-evidence assessment.

Interaction of matrix metalloproteinases with pulmonary pollutants: Table 1–

“…POPs are organic chemicals that are persistent and widely distributed in the environment, have bioaccumulative properties and are toxic to humans and wildlife [46]. They include pesticides, as well as dioxins, furans and polychlorinated biphenyls.…”

Proposal for a harmonised PBT identification across different regulatory frameworks

“…Persistence is not characterised consistently in the different frameworks, but, as suggested by Boethling et al [15] and in [9], it is the degradation half-life (DegT 50 ) which should be compared to the trigger values in the various compartments, as a mere transfer (dissipation) from one compartment to the other does not affect the persistence of a substance. DegT 50 values are commonly estimated from the parent substance in extractable residues in degradation simulation studies performed according to e.g.…”

Assessment of PBTs in the European Union: a critical assessment of the proposed evaluation scheme with reference to plant protection products

“…If all data are of equal quality, several options are available. If the worst-case values are less than the cut-off values, then the (PPP) can be removed from further consideration as P, B, or T. If there is a range of values that cannot be explained by regional or other environmental factors, the median or geometric mean value could be used [34]. For example, the median was used by Beyer and Matthies [35], and Matthies et al [36] derive soil degradation half-lives for 45 currently used pesticides when more than one simulation test results were available.…”