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Cost effective biomarkers of exposure to mixtures of pesticides - method development

Project Code: T10003

01/07/2006

Health and Safety Lab (HSL)
Jones, K ; Mason, H; Sams, C; Patel, K

This project was proposed to directly address the Food Standards Agency (FSA) research requirement (RRD11/T10/A) to develop cost-effective biomarkers or other robust indicators of population exposure and body burdens of pesticides and relevant veterinary residues.

Objectives

The objectives were to develop biological monitoring assays for the following compounds, using common approaches where possible:

Organophosphate pesticides.
Anticholinergic carbamates (pirimicarb and carbaryl).
Benzimidazole fungicides (carbendazim, benomyl and thiabendazole).
Synthetic pyrethroids
Dithiocarbamates

Main Findings

A number of approaches were investigated for the dialkylphosphate metabolites but, due to the highly polar nature and small size of the analytes, it was not possible to develop a method that was entirely suitable for monitoring low-level exposure to all analytes.
Immunoassay screening assays were developed for chlorpyrifos, pirimicarb, pirimiphos and synthetic pyrethroids.
A combined assay was developed for pirimicarb and the benzimidazole fungicides using ChemElut extraction and LC-MS analysis. Carbaryl could not be included.
HSL’s existing method for synthetic pyrethroids was extended to include metabolites of deltamethrin, bifenthrin and cyhalothrin.
A method was developed for ethylenethiourea, a generic metabolite of dithiocarbamates. It was possible to analyse ETU using the method developed for pirimicarb although there was a loss of sensitivity.

Recommendations

Further work on developing a common assay for organophosphates would be worthwhile.
Further development of a chlorpyrifos immunoassay method using an alternative hapten to achieve greater sensitivity.
Other assays are ready to be used in large-scale population studies. Such studies could utilise samples taken as part of the FSA’s Total Diet Surveys, which would also provide contextual dietary information to aid interpretation.
A follow-on project (T10013) looking at herbicides and fungicides will build on the findings of this project and will attempt to use similar sample extraction and analysis methods where appropriate.

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