Simultaneous quantification of pyrethroid metabolites in urine of non-toilet-trained children in Japan

Abstract

Background: Pyrethroid (PYR) insecticides are widely used for controlling various pests. There are two types that differ in terms of usage: agricultural-purpose PYR (agriculture-PYR) and hygiene purpose PYR (hygiene-PYRs). Few studies exist on the exposure to these chemicals in small children. In this study, we conducted biomonitoring of urinary pyrethroid metabolites in 1.5-year-old children throughout the year.

Methods: Study subjects were 1075 children participating in an Aichi regional sub-cohort of the Japan Environment and Children's Study as of 18-month health check-up. The concentrations of four specific hygiene-PYR metabolites including 2,3,5,6-tetrafluoro-1,4-benzenedimethanol (HOCH₂-FB-Al), and five common metabolites of hygiene- and agriculture-PYRs including 3-phenoxybenzoic acid (3PBA) and cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (DCCA), were measured in urine samples extracted from soiled diapers using a triple quadrupole gas chromatograph-mass spectrometer.

Results: The highest detection frequencies were for 3PBA, followed by DCCA, 1R-trans-chrysanthemum dicarboxylic acid, and HOCH₂-FB-Al. Among the six metabolites, urinary concentrations were seasonally varied. However, this variation was not observed in the most studied PYR metabolite, 3PBA. Spearman's correlation analysis demonstrated a significant positive correlation between FB-Al and DCCA (r = 0.56) and HOCH₂-FB-Al and 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol (r = 0.60).

Conclusions: This biomonitoring survey found widespread and seasonally specific exposure to multiple hygiene- and agriculture-PYRs in 1.5-year-old Japanese children.

Keywords: Human biomonitoring; Pyrethroid; Small children; Urine samples.

Fig. 1

Boxplot of urinary concentration of pyrethroid (PYR) metabolites (µg/g Cre) throughout a year. The dotted line connects the median values of each month. The limits of detection (LOD) values divided by the square root of 2 were assigned to urine samples with undetectable PYR metabolites. The value in parentheses below the x-axis indicates the number of subjects in each month.

Fig. 2

Scatter plots and coefficients of correlations between each log-transformed concentration of biomarkers (µg/g Cre). The value indicates coefficients of correlations for all sample analysis (upper) and without under LOD samples (in parentheses). Asterisks indicate a p value less than 0.01.