Thursday, July 29, 2010

More on Pesticide Impurities

A supplement to the FLASH UPDATE of earlier today, provided by Dr. Wayne Dwernychuk-The Hatfield Group, Retired

Paul … more on what George Claxton posted on pesticide impurities.


Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans (PCDD/Fs) Impurities in Pesticides: A Neglected Source of Contemporary Relevance

Eva Holt, Roland Weber, Gavin Stevenson and Caroline Gaus

The University of Queensland, National Research Centre for Environmental Toxicology (EnTox), 39 Kessels Road Coopers Plains, QLD 4108, Australia, POPs Environmental Consulting, 73035 Gppingen, Germany, and The National Measurement Institute, Dioxin Analysis Unit, Pymble, NSW 2072, Australia

Environ. Sci. Technol., 2010, 44 (14), pp 5409-5415

DOI: 10.1021/es903915k

Publication Date (Web): June 18, 2010

Copyright© 2010 American Chemical Society

* Address correspondence to either author. e-mail:;

The University of Queensland.

POPs Environmental Consulting.

The National Measurement Institute.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) may be formed during the manufacture of chlorinated pesticides, and can remain in the products as impurities. However, the contemporary release of PCDD/Fs to the environment from pesticide use is poorly understood. For this study, 27 pesticide formulations were analyzed for PCDD/Fs (n = 23 registered for use in Australia). PCDD/F impurities were present in all samples, ranging from 0.020 to 2100 ng ΣPCDD/F g−1 active ingredient (AI). Among current use pesticides, pentachloronitrobenzene (PCNB) contained the highest impurity levels (up to 2000 ng ΣPCDD/F g−1 AI and 5.6 ng TEQ g−1 AI). The quantity of pesticide used in Australia and associated release of PCDD/Fs was estimated for PCNB and phenoxy herbicides (2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenoxybutyric acid (2,4-DB)) using a probabilistic approach. Input parameters to model pesticide use contributed the highest proportions to the variability of the estimated PCDD/F release, and were considered to have the highest uncertainty. Preliminary estimates of PCDD/F release suggest that contaminated pesticides represent an important ongoing PCDD/F source to the Australian environment (10th−90th percentiles for PCNB = 14−42 and 2,4-D/2,4-DB = 0.35−1.6 g TEQ annum−1). These results may have global relevance given that many of the pesticides analyzed were imported into Australia, and are used in high volumes in other countries.

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