Concentrations of dialkyl phosphate metabolites of organophosphorus pesticides in the U.S. population.

Abstract

We report population-based concentrations, stratified by age, sex, and racial/ethnic groups, of dialkyl phosphate (DAP) metabolites of multiple organophosphorus pesticides. We measured dimethylphosphate (DMP), dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), diethylphosphate (DEP), diethylthiophosphate (DETP), and diethyldithiophosphate (DEDTP) concentrations in 1,949 urine samples collected in U.S. residents 6-59 years of age during 1999 and 2000 as a part of the ongoing National Health and Nutrition Examination Survey (NHANES). We detected each DAP metabolite in more than 50% of the samples, with DEP being detected most frequently (71%) at a limit of detection of 0.2 microg/L. The geometric means for the metabolites detected in more than 60% of the samples were 1.85 microg/L for DMTP and 1.04 microg/L for DEP. The 95th percentiles for each metabolite were DMP, 13 microg/L; DMTP, 46 microg/L; DMDTP, 19 micro g/L; DEP, 13 microg/L; DETP, 2.2 microg/L; and DEDTP, 0.87 microg/L. We determined the molar sums of the dimethyl-containing and diethyl-containing metabolites; their geometric mean concentrations were 49.4 and 10.5 nmol/L, respectively, and their 95th percentiles were 583 and 108 nmol/L, respectively. These data are also presented as creatinine-adjusted concentrations. Multivariate analyses showed concentrations of DAPs in children 6-11 years of age that were consistently significantly higher than in adults and often higher than in adolescents. Although the concentrations between sexes and among racial/ethnic groups varied, no significant differences were observed. These data will be important in evaluating the impact of organophosphorus pesticide exposure in the U.S. population and the effectiveness of regulatory actions.

Pesticide Exposure and Stunting as Independent Predictors of Neurobehavioral Deficits in Ecuadorian School Children

“…An increased reaction time is in accordance with observations in children and adults exposed to organophosphates, 41,42 and it could, therefore, likely reflect an effect of current pesticide exposures. On the other hand, concentrations of organophosphate metabolites in the urine were similar to levels reported for US children aged 6 -11 years, 43 and the 90th percentile for composite metabolite excretions at 574 g/g of creatinine was not exceeded by any of the Ecuadorian children. However, these results may not be directly comparable, because the metabolites may originate from different parent organophosphates.…”

Biomarkers of Organophosphate Pesticides and Attention-Deficit/ Hyperactivity Disorder in Children: A Case-Control Study

“…Young children whose age range from six to eleven years having greatest urinary levels of dialkyl-phosphate metabolites (biomarkers of organophosphate exposure), contrast to another group of different age [5]. Body of young children containing minor levels of metabolizing enzymes (paraoxonase or chlorpyrifosoxonase) that disrupt OP pesticides than adults [6,7], indicating that children may be higher susceptible to risk of exposure.…”

Organophosphorous Pesticides - Mechanisms of Their Toxicity

“…On the basis of structural characteristics they are divided into at least 13 types, including phosphates, phosphonates, phosphinates, phosphorothioates (S=), phosphonothioates (S=), phosphorothioates (S substituted), phosphonothioates (S substituted), phosphorodithioates, phosphorotrithioates, phosphoramidothioates (Gupta, 2006). OPs are the most widely used pesticides worldwide and their metabolites are widespread across different populations (Aprea, 2000;Barr, 2004;Curl, 2003). The adverse short-term effects of exposure to these chemicals have been studied mostly in the nervous system, which is their primary target (Gupta at al., 2001), but there is a growing concern about their possible toxic effects in non-target tissues and (long-term) chronic effects that have not been studied in such detail.…”