Format

Send to

Choose Destination
Environ Health Perspect. 2013 Jan;121(1):118-24. doi: 10.1289/ehp.1104808. Epub 2012 Oct 9.

Variability of organophosphorous pesticide metabolite levels in spot and 24-hr urine samples collected from young children during 1 week.

Author information

1
Center for Environmental Research and Children’s Health, School of Public Health, University of California, Berkeley, Berkeley, California 94704, USA. abradman@berkeley.edu

Abstract

BACKGROUND:

Dialkyl phosphate (DAP) metabolites in spot urine samples are frequently used to characterize children's exposures to organophosphorous (OP) pesticides. However, variable exposure and short biological half-lives of OP pesticides could result in highly variable measurements, leading to exposure misclassification.

OBJECTIVE:

We examined within- and between-child variability in DAP metabolites in urine samples collected during 1 week.

METHODS:

We collected spot urine samples over 7 consecutive days from 25 children (3-6 years of age). On two of the days, we collected 24-hr voids. We assessed the reproducibility of urinary DAP metabolite concentrations and evaluated the sensitivity and specificity of spot urine samples as predictors of high (top 20%) or elevated (top 40%) weekly average DAP metabolite concentrations.

RESULTS:

Within-child variance exceeded between-child variance by a factor of two to eight, depending on metabolite grouping. Although total DAP concentrations in single spot urine samples were moderately to strongly associated with concentrations in same-day 24-hr samples (r ≈ 0.6-0.8, p < 0.01), concentrations in spot samples collected > 1 day apart and in 24-hr samples collected 3 days apart were weakly correlated (r ≈ -0.21 to 0.38). Single spot samples predicted high (top 20%) and elevated (top 40%) full-week average total DAP excretion with only moderate sensitivity (≈ 0.52 and ≈ 0.67, respectively) but relatively high specificity (≈ 0.88 and ≈ 0.78, respectively).

CONCLUSIONS:

The high variability we observed in children's DAP metabolite concentrations suggests that single-day urine samples provide only a brief snapshot of exposure. Sensitivity analyses suggest that classification of cumulative OP exposure based on spot samples is prone to type 2 classification errors.

PMID:
23052012
PMCID:
PMC3553429
DOI:
10.1289/ehp.1104808
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Atypon Icon for PubMed Central
Loading ...
Support Center