Pesticide Residues in Man - Pesticides: Evaluation of Environmental Pollution - page 478

in other environmental studies, the urinary excretion of OP metabolites exceeds dietary
intake several folds; this has been estimated from the data in various duplicate dietary
studies.
Barr et al. (2005) reported population-based concentrations (stratified by age, sex, and
composite race/ethnicity variables) of selective metabolites of chlorpyrifos (3,5,6-tri-
chloro-2-pyridinol; TCPY), chlorpyrifos-methyl (TCPY), malathion (malathion dicar-
boxylic acid, MDA), diazinon (2-isopropyl-4-methyl-6-hydroxypyrimidine, IMPY),
methyl parathion (para-nitrophenol, PNP), and parathion (PNP). They measured the
concentrations of TCPY, MDA, IMPY, and PNP in 1997 urine samples from participants,
aged 6-59 years, of the National Health and Nutrition Examination Survey (1999-2000).
The authors detected TCPY in more than 96% of the samples tested. Other OP pesticide
metabolites were detected less frequently: MDA, 52%; IMPY, 29%; and PNP, 22%. The
geometric means for TCPY were 1.77 mg/L and 1.58 mg/g creatinine. The 95th percen-
tile for TCPY was 9.9 mg/L (8.42 mg/g creatinine). The 95th percentile for MDA was
1.6 mg/L (1.8 mg/g creatinine). The 95th percentiles for IMPY and PNP were 3.7 mg/L
(3.4 mg/g creatinine) and 5.0 mg/L (4.2 mg/g creatinine), respectively (Figure 15.4).
Multivariate analyses showed that children aged 6-11 years had significantly higher
concentrations of TCPY than adults and adolescents. Similarly, adolescents had signifi-
cantly higher TCPY concentrations than adults. Although the concentrations between
sexes and among composite racial or ethnic groups varied, no significant differences
were observed.

25

TCPY MDA

IMPY PNP

20

15

10

5

0

Demographic category

FIGURE 15.4
The 95th percentile concentration (95th PC) of selected metabolites of organophosphorus pesticides in urine
samples collected from the US population. Metabolite abbreviation corresponding to the parental pesticide : TCPY,
Chlorpyrifos; MDA, Malathion; IMPY, Diazinon; PNP, Parathion. (Adapted from Barr, D. B., Allen, R., Olsson,
A. O., et al. 2005. Concentrations of selective metabolites of organophosphorus pesticides in the United States
population. Environ. Res. 99: 314-326.)