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Pesticide exposure and creatinine variation among young children
M K O'Rourke1, P S Lizardi, S P Rogan
1EOH, College of Public Health, The University of Arizona, Tucson 85721-0468, USA.
Insights
Young children in farmed communities show significant organophosphate pesticide exposure. Urinary biomarker screening revealed that many children exceeded safe daily intake levels, highlighting risks for this vulnerable population.
Area of Science:
- Environmental Health
- Toxicology
- Pediatrics
Background:
- Young children are more susceptible to pesticide exposure due to physiological and behavioral factors.
- Organophosphate (OP) pesticides are widely used in agriculture, posing potential risks to communities near farming areas.
Purpose of the Study:
- To evaluate pesticide exposure in young children (≤6 years) living in a US-Mexico border community using a urinary organophosphate biomarker screen.
- To assess the internal dose of pesticide metabolites and compare estimated daily intake with reference doses (RfDs).
Main Methods:
- A urinary biomarker screen (gas chromatography with flame photometric detection, GC/FPD) was used to detect diethylphosphates (DEPs) and dimethylphosphates (DMPs).
- 154 children were screened, and biomarker concentrations were adjusted for urine dilution using creatinine (Cr) levels.
- Absorbed daily dose (ADD) estimates were calculated for children with the highest metabolite concentrations.
Main Results:
- 33% of children had detectable OP metabolites, with DMP and DMTP being the most frequent.
- Creatinine concentrations varied significantly by season, impacting internal dose measurements.
- For children with the highest metabolite levels, estimated ADDs frequently exceeded the RfD, even at the 95th percentile.
Conclusions:
- The urinary OP screen effectively identified children with elevated internal pesticide doses.
- Creatinine variability is a critical factor in calculating internal doses and requires careful consideration in young children.
- Findings indicate a significant risk of exceeding safe pesticide intake levels among young children in this agricultural border community.
Abstract:
Pesticide exposure may differentially impact young children; they live closer to the ground and take in greater amounts of food relative to body mass than older children or adults. We are using an organophosphate (OP) urinary biomarker screen (gas chromatography with flame photometric detection, GC/FPD) to evaluate pesticide exposure among 154 children < or = 6 years of age living in a heavily farmed border (US-Mexico) community. The screen detects diethylphosphates (DEPs) and dimethylphosphates (DMPs) above a reference range of 1000 non-occupationally exposed individuals (DL=25 microg/g creatinine, Cr). At least one metabolite was detected for 33% of the subjects; many samples contained multiple biomarkers. DEP was detected in 5% of the subjects. DMP and DMTP were frequently measured (25% and 26%, respectively). Biomarker concentrations are adjusted by the body's metabolism of Cr as an indicator of urine dilution. Cr concentrations were examined separately to evaluate their effect on internal dose measures. Cr concentrations were significantly different by season (K-W=0.83, P=0.022). Significant differences exist between the autumn:spring (P=0.038) Cr concentrations and between summer:autumn (P=0.041) Cr concentrations based on Mann-Whitney U=1070.5, z=-2.041, (P=0.041). Our analysis of NHANES III data did not reflect seasonal Cr differences for 6 year olds. No younger children were included. Absorbed daily dose (ADD) estimates were calculated for children with the highest concentrations of metabolite. Calculations are theoretical values assuming that the entirety of a given metabolite was metabolized from a single pesticide. Several class appropriate pesticides were evaluated. For the children with the highest levels, almost all estimated ADDs exceeded the RfD. Although the actual metabolite concentrations dropped appreciably, ADD were still exceeded RfDs at the 95th percentile. The urinary OP screen was effective in identifying subjects with atypical internal doses. Daily Cr yield is a critical component in ADD calculations. Cr variability produces differences in internal dose measurement and estimates of ADD independent of exposure. Cr variability among young children needs to be examined, and caution should be applied when evaluating Cr adjusted internal doses for children.