ASSESSING PESTICIDES AS A SOURCE OF DIOXINS TO THE AUSTRALIAN ENVIRONMENT Holt, Eva 1 , Vetter, Walter 2 , Symons, Robert 3 , Stevenson, Gavin 3 , Weber, Roland 4 , Gaus, Caroline 1 1 The University of Queensland (National Research Centre for Environmental Toxicology (EnTox)), 39 Kessels Road Coopers Plains 4108, Australia 2 Institut für Lebensmittelchemie (Institute for Food Chemistry) (170), University of Hohenheim, Garbenstrasse 70599 Stuttgart, Germany 3 Dioxin Analysis Unit, National Measurement Institute, 1 Suakin Street, Pymble, Australia 4 POPs Environmental Consulting, Ulmenstrasse 3, 73035 Goeppingen, Germany Abstract Chlorinated pesticide production, use and disposal, has contributed significantly to polychlorinated dibenzo-p- dioxins and dibenzofuran (PCDD/F) contamination in the environment. Global pesticide application has been and continues to be extensive, including those which are known to contain or potentially contain PCDD/Fs. The aim of this study was to investigate the significance of pesticides as historical and current sources of PCDD/Fs to the Australian environment by determining their levels in a range of different formulations. PCDD/Fs were detected in all pesticide formulations analysed in this study at concentrations ranging from 0.0081 to 1,000 ng PCDD/F g -1 formulation (0.037 to 2,100 ng PCDD/F g -1 active ingredient), with the highest levels detected in current use pesticides containing pentachloronitrobenzene (PCNB). For most pesticides, data on volume of use are not available in Australia. However, using estimates based on market value and use volume trend data, label information and respective application area in Australia, pesticides have the potential to contribute significantly to the current PCDD/F emissions in Australia. Introduction It is well recognised that pesticide production, use and disposal have contributed significantly to polychlorinated dibenzo-p-dioxins and dibenzofuran (PCDD/F) emissions in the past. However, beyond the two pesticides notorious for PCDD/F contamination - 2,4,5-trichlorophenoxy acetic acid (2,4,5-T) and pentachlorophenol (PCP) - there is a general lack of historical and current data on PCDD/F impurities. Accordingly, PCDD/F emissions from pesticide production and in particular pesticide use are difficult to quantify and generally not included into source inventories. This information gap leads to the inability to assess the significance of pesticides as (both primary and secondary) dioxin sources to the environment and whether these should be addressed. The USEPA lists >70 pesticides that have the potential to contain halogenated PCDD/Fs (1), many of which are still used globally (2) and some of which are applied in high volumes (3). This study was carried out to screen a limited range of historical and current use pesticides from Australia in order to evaluate the potential for, and levels of PCDD/F impurities. Results were combined with pesticide use estimates and compared to the Australian emission inventory (4) to evaluate the significance of pesticides as a current source. Materials and Methods Twenty one pesticide formulations were selected for PCDD/F analysis. These included mainly agrochemical formulations (n=16) but also some household formulations (n=5). Samples included redundant pesticide formulations (banned, restricted or largely phased out) and pesticide formulations currently used in Australia. Active ingredients included a number of phenoxy herbicides (MCPA; 2,4-D; 2,4-DB; 2,4,5-T), fungicides (chlorothalonil; quintozene), insecticides (lindane; heptachlor; chlordane) and other herbicides (chlorthal; fluroxypyr; triclopyr/picloram). For pesticides in liquid form, PCDD/Fs were extracted by liquid/liquid partitioning into dimethyl sulphoxide (DMSO). DMSO was collected and diluted with 500mL MilliQ water. The samples were then re-extracted into n-hexane. Solid pesticide samples, PCDD/Fs were extracted by accelerated soxhlet extraction with toluene. Crude extracts for all samples underwent the same cleanup process. All extracts first underwent an acid pre-clean using pure concentrated sulphuric acid. Samples were then purified using Powerprep TM automated system (Fluid Management Systems, Waltman, MA, USA) (5). In brief, sample extracts Vol. 71, 2009 / Organohalogen Compounds page 000292