Use of biomarkers to indicate exposure of children to organophosphate pesticides: implications for a longitudinal study of children's environmental health.

Abstract

Because of their history of widespread use in the United States and unknown long-term health effects, organophosphate pesticides (OPs) are being considered as a chemical class of interest in planning for the National Children's Study, a longitudinal study of children's environmental health. The availability and appropriate use of biomarkers to determine absorbed doses of environmental chemicals such as OPs are critical issues. Biomarkers of OP exposure are typically measured in blood and urine; however, postpartum meconium has been shown to be a promising matrix for assessing cumulative in utero exposure to the fetus, and studies are currently in progress to determine the utility of using saliva and amniotic fluid as matrices. In this article, we discuss the advantages and disadvantages of the currently available OP exposure monitoring methods (cholinesterase inhibition in blood, pesticides in blood, metabolites in urine and alternative matrices); study design issues for a large, long-term study of children's environmental health; and current research and future research needs. Because OPs are rapidly metabolized and excreted, the utility of one-time spot measurements of OP biomarkers is questionable unless background exposure levels are relatively stable over time or a specific time frame of interest for the study is identified and samples are collected accordingly. Biomarkers of OP exposure can be a valuable tool in epidemiology of children's environmental health, as long as they are applied and interpreted appropriately.

Organophosphorus Pesticide Exposure of School Children in Agricultural Villages in Indonesia

“…The exposure level in this study was not high compared with children's exposure level in several developed countries such as US, Italy, and Canada [9,10,20]. With similar levels of detection sensitivity, the United States CDC's nationwide survey in 2001 showed that more than 90% of the subjects were positive for at least one of the OP metabolites examined [17].The median levels of dimethyl-and diethyl-DAPs in this study, i.e., 5.8 and 3.1 nmol/L, were approximately 10 times lower than those reported inthe US [10], i.e., 90 and 60 nmol/L, respectively. Possible reasons for this result are considered as follows.…”

“…The mean recoveries within series and between days were 94.2 and 109.7% for DMP, 100.6 and 105.7% for DMTP, 93.9 and 94.7% for DEP, and 85.7 and 82.9% for DETP, respectively. The limit of detection (LOD) and quantitative limit were 1.0 and 2.0 μg/L for DMP and 0.5 and 1.0 μg/L for DMTP, DEP, and DETP, respectively, indicating similar or greater sensitivity to those in recent studies on urinary DMP levels [9,10,17]. Values below LOD were assigned a value of LOD/2.…”

“…According to our interview results regarding the pesticide use in village C and its neighboring village, 13.7% of the pesticides used were OP pesticides (profenofos (13.5%) and glyphosate (0.2%)) [23]. According to Wessels et al [17], metabolites of profenofos are not DAP compounds, which possibly explains the low DAP concentration in urine samples. The AChE activity in the blood samples of children from village B was significantly lower than those of the children from the other two villages.…”

Measurement of dialkyl phosphate metabolites of organophosphorus pesticides in human urine using lyophilization with gas chromatography-tandem mass spectrometry and isotope dilution quantification

“…To properly evaluate risks associated with these exposures and to document exposure trends over time, viable techniques for evaluating exposure are required. One technique that has been widely accepted and used in the scientific community is the measurement of biomarkers of exposure (Needham et al, 1995;Anwar, 1997;Azaroff, 1999;Wessels et al, 2003). However, to produce meaningful data, we must have analytical methods that are accurate, precise, and are adequately sensitive to detect biomarker concentrations resulting form incidental human exposures.…”

Expressing urine from a gel disposable diaper for biomonitoring using phthalates as an example

“…organophosphate pesticides) that have a common mechanism of toxicity (USEPA, 2006b). Organophosphate pesticides are powerful inhibitors of carboxylic hydrolases, including acetylcholinesterase, and several studies in different countries have shown higher exposure to organophosphate pesticides in children than in adults (Wessels et al, 2003). Children of pesticide applicators, younger children within the zero-to six-year age range, children living closer to pesticide-treated orchards, children living in urban areas, and those living where pesticides are used inside or outside the home have all been shown to have higher levels of a urinary biomarker for organophosphate pesticides, suggesting higher exposures to either the pesticides or their breakdown products (Wessels et al, 2003).…”