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This project aims to develop cost-effective biomarkers of mixed pesticide exposure. The pesticides have been selected on the basis of their occurrence as residues in food.
Study Duration : April 2006 to December 2007
Contractor : Health and Safety Laboratory
This project addressed a research requirement to develop cost-effective biomarkers or other robust indicators of population exposure and body burdens of mixtures of pesticides and relevant veterinary residues. The Health and Safety Laboratory (HSL) has previously developed biomarker assays for the Agency (project T10003) to assess exposure to mixtures of pesticides including organophosphate and carbamate anticholinesterases as well as benzimidazole and dithiocarbamate fungicides. This study aimed to build on this work to develop further biomarkers using similar methodology with the aim to be able to offer a full suite of pesticide biomarkers in a practical and cost-effective way. This study addressed those chemicals specified by the Agency in the research call, i.e. paraquat/diquat, triazole fungicides, conazoles and pyrethroids, but focused on those most commonly found as residues in food.
In order to complement their previous Agency project, HSL proposed to focus primarily on liquid chromatography – mass spectrometry (LC-MS) techniques with common or compatible extraction procedures, that can preferably be automated.
A solid phase extraction (SPE) liquid chromatography-mass spectrometry (LC-MS) method was developed for paraquat and diquat based on existing literature methods. The extraction method was also suitable for chlormequat, although a different LC-MS method needed to be used. Methods were linear over the range 0 to 80 µg/l as a minimum, with detection limits varying from 0.25 µg/l (chlormequat) to 10 µg/l (paraquat) and reproducibility ranging from 5% to 15%. Due to the chemical nature of these metabolites, they were not investigated for common extraction procedures.
An LC-MS method was developed for specific metabolites of permethrin/cypermethrin and deltamethrin and for a generic metabolite for synthetic pyrethroids. Methods were linear over the range 0 to 100 µg/l with detection limits between 1 and 2.1 µg/l and reproducibility 18 – 22%.
LC-MS or liquid chromatography-tandem mass spectrometry (LC-MS-MS) methods were developed for putative metabolites of penconazole, imazalil and iprodione. Methods were linear over the range 0 to 80 nM as a minimum, with detection limits varying from 4 nM (imazalil metabolite) to 10 nM (iprodione metabolite) and reproducibility ranging from 8% to 15%.
A sample extraction strategy was developed, allowing extraction of six classes of pesticides, herbicides and fungicides from a 10 ml urine sample. This work complements that done previously under project T10003. The sample extraction procedure is common to all; however, analytes fall into acid, basic and neutral groups. Alkalinating the urine with 0.5M sodium hydroxide is suitable for extracting metabolites of pirimicarb, benzimidazole fungicides and imazalil. Acidifying the urine with 0.2% phosphoric acid is suitable for extracting metabolites of synthetic pyrethroids, iprodione and penconazole. Ethylenethiourea (ETU) prefers neutral extraction and elution with dichloromethane. Assuming 2 ml of urine for each extraction and allowing for duplicate aliquots, a minimum sample volume of 15 ml would allow analysis for all of the above metabolites. For screening purposes, 10 ml would be sufficient (accepting lower sensitivity for ETU).
select this link to view the (External) Final Report for project T10013
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