Formation of dioxins during exposure of pesticide formulations to sunlight

Holt, Eva, Weber, Roland, Stevenson, Gavin and Gaus, Caroline (2012) Formation of dioxins during exposure of pesticide formulations to sunlight. Chemosphere, 88 3: 364-370. doi:10.1016/j.chemosphere.2012.03.058

Author Holt, Eva
Weber, Roland
Stevenson, Gavin
Gaus, Caroline
Title Formation of dioxins during exposure of pesticide formulations to sunlight
Journal name Chemosphere   Check publisher's open access policy
ISSN 0045-6535
Publication date 2012-07
Sub-type Article (original research)
DOI 10.1016/j.chemosphere.2012.03.058
Volume 88
Issue 3
Start page 364
End page 370
Total pages 7
Place of publication Kiddlington, Oxford, United Kingdom
Publisher Permagon
Collection year 2013
Language eng
Formatted abstract
Chlorinated pesticides can contain impurities of dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and their precursors, as a result of various manufacturing processes and conditions. As precursor formation of PCDD/Fs can also be mediated by ultraviolet light (UV), this study investigated whether PCDD/Fs are formed when currently used pesticides are exposed to natural sunlight. Formulations containing pentachloronitrobenzene (PCNB; n=2) and 2,4-dichlorophenoxyacetic acid (2,4-D; n=1) were exposed to sunlight in quartz tubes, and the concentration of 93 PCDD/F congeners were monitored over time. Considerable formation of PCDD/Fs was observed in both PCNB formulations (by up to 5600%, to a maximum concentration of 57000μg∑PCDD/Fkg -1) as well as the 2,4-D formulation (by 3000%, to 140μg∑PCDD/Fkg -1). TEQ also increased by up to 980%, to a maximum concentration of 28μgkg -1 in PCNB, but did not change in the 2,4-D formulation. Assuming similar yields as observed in the present study as a worst case scenario the use of PCNB in Australia may result in the formation of 155gTEQ annum -1, contributed primarily by OCDD formation. This warrants detailed evaluations on the contemporary release of PCDD/Fs to the environment after the use of pesticides. Changes in congener profiles (including the ratio of PCDDs to PCDFs (DF ratio)) suggest that pesticide sources of PCDD/Fs after sunlight exposure may not be recognized based on matching source fingerprints established from manufacturing impurities. These changes also provide preliminary insights into the possible formation routes and types of precursors involved.
Keyword Pcdd/f
Congener profile
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online: 17 April 2012.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
National Research Centre for Environmental Toxicology Publications
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