Ten-year temporal trends (2006-2015) and seasonal-differences in urinary metabolite concentrations of novel, hygiene-used pyrethroids in Japanese children.

BACKGROUND AND AIM

Metofluthrin, profluthrin, tefluthrin, and transfluthrin are pyrethroid (PYR) insecticides increasingly used to control mosquitoes, flies, and moths in households and public places (hygiene-PYRs). Currently, there is limited data available concerning exposure to these novel hygiene-PYRs. The goal of this study was to monitor exposure to these hygiene-PYRs by analysing their urinary metabolites and to investigate the temporal and seasonal trends in the concentrations of these metabolites.

METHODS

First morning urine samples were obtained from 50 Japanese children (four-six years old) in October of 2006, 2011, and 2015 (total = 150 children) in order to investigate temporal trends. Additionally, first-morning urine samples were collected from 44 three-year-old children in August-September of 2012 (summer) and in February of 2013 (winter) to investigate seasonal differences. The urinary concentrations of 2,3,5,6-tetrafluorobenzyl alcohol (FB-Al; a specific metabolite of transfluthrin), 4-methyl-2,3,5,6-tetrafluorobenzyl alcohol (CH-FB-Al; a common metabolite of tefluthrin and profluthrin), 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol (CHOCH-FB-Al; a specific metabolite of metofluthrin), and 2,3,5,6-tetrafluoro-1,4-benzenedimethanol (HOCH-FB-Al; a common metabolite of metofluthrin, tefluthrin, and profluthrin) were measured using GC-MS/MS.

RESULTS

For the investigated years, rapid increases in the detection rates of the hygiene-PYR metabolites were observed. In 2015, FB-Al was identified in 64% of the samples, CH-FB-Al in 46%, CHOCH-FB-Al in 50%, and HOCH-FB-Al in 83%. Significant increasing trends were found for the concentrations of all hygiene-PYR metabolites from 2006 to 2015 (Jonckheere-Terpstra test, p < 0.001). The concentrations of FB-Al and CHOCH-FB-Al were higher in summer than in winter (Mann Whitney-U test, p < 0.05).

CONCLUSIONS

These findings suggest that, in Japanese children, exposure to hygiene-PYRs has increased over the past decade, and that children are exposed to higher levels of hygiene-PYRs in summer than in winter.