Analysis of Urinary Biomarkers for Early-Life Exposure to Organophosphate Pesticides and Pyrethroids

摘要

Organophosphate pesticides (OPs) and pyrethroids (PYRs) are widely used for pest control. Exposure to these chemicals has been linked to various negative health outcomes, particularly for young children. Urinary metabolites are commonly used biomarkers of exposure for non-persistent chemicals such as OPs and PYRs. A method is established for quantitatively measuring these biomarkers in human urine samples. Non-specific OP metabolites dialkylphosphates (DAPs; 6 compounds) are analysed using a lyophilisation method coupled with a subsequent derivatisation procedure using pentafluorobenzyl bromide. Samples are analysed using a gas chromatography coupled to triple quadrupole mass spectrometer. Other chemicals (13 compounds) are analysed via solid phase extraction using hydrophilic-lipophilic balance cartridges after hydrolysed by glucuronidase. Target compounds are analysed using liquid chromatography coupled to tandem mass spectrometry. Synthetic urine is prepared and used as blank samples. Method detection limit (MDL) is calculated as average of the levels in blank samples plus three times the standard deviation and ranges from 0.0083 to 0.83 μg L-1 in urine depending on compounds. Quality control (QC) samples are prepared by fortifying the synthetic urine with target compounds. Accuracy of the method is evaluated as the ratio of calculated levels against expected levels and ranges from 0.68 -1.4. Method precision is expressed as the relative standard deviation of calculated levels from replicated QC samples (n=15) and is generally lower than 20%. The method is then applied to the analysis of 20 pooled urine samples from general Australian population, which are stratified into 5 age strata (0-1,1-2, 2-3, 3-4, and 4-5 years) and two gender strata (2xmales and 2xfemales). The highest mean concentration is measured for 3,5,6-trichloro-2-pyridinol (TCPy, 12 pg L-1 urine). Significant trend of concentrations by age (P<0.05) is observed for various OP and PYR metabolites.