Estimation of dietary intake and sources of organohalogenated contaminants among infants: 24-h duplicate diet survey in Fukuoka, Japan

The widespread occurrence of persistent organic pollutants (POPs) in the environment is a matter of concern. In this study, selected organohalogenated contaminants, including dichlorodiphenyltrichloroethane and its metabolites (DDTs) polychlorinated biphenyls (PCBs), chlordanes (CHLs), hexachlorobenzene (HCB), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), tetrabromobisphenol A (TBBPA), 2,4,6-tribromophenol (TBP), were measured in complete meal sets (24-h duplicate-diet) of Japanese infants to investigate the levels, profiles, and possible sources of contamination. In total, 46 whole-day meals of infants (7-24-months old) were collected during 2017 from Fukuoka, Japan. To the best of our knowledge, this is the first report based on the duplicate-diet method for infants. The median intakes among the POP groups were highest for Sigma DDTs (18 ng/day, maximum 251 ng/day), followed by Sigma PCBs (17 ng/day, maximum 198 ng/day), Sigma CHLs (14 ng/day, maximum 105 ng/day), HCB (11 ng/day, maximum 64 ng/day), TBP (3.5 ng/day, maximum 109 ng/day), Sigma HBCDs (1.9 ng/day, maximum 70 ng/day), TBBPA (0.72 ng/day, maximum 34 ng/day), and Sigma PBDEs (0.11 ng/day, maximum 4.5 ng/day). Among the PCBs, PCB-138 and PCB-153 were the most abundant congeners (27% and 23%, respectively). p,p'-DDE, the major DDT metabolite, accounted for 96% of total DDTs. Among PBDEs, BDE47 was the only detected congener (present in 4% of the samples). The dietary intake of the targeted compounds was lower than the intake via breast milk, suggesting that the exposure from baby food was limited. In the principal component analysis, chlorinated and brominated compounds were separated on principal component 1, while TBP and alpha-HBCD were separated on principal component 2, likely suggesting a differing emission time trend or source. PCB-153, PCB-138, trans-chlordane, cis-chlordane, and trans-nonachlor were correlated with seafood consumption (Spearman's rho = 0.45 to 0.57, p < 0.05), while TBP was correlated with seaweed consumption (Spearman's rho = 0.46, p < 0.05). Also, four species of commercial edible seaweed in Japan were analyzed to confirm the findings of the duplicate-diet study. The relatively high concentration of TBP (5.5 +/- 6.6 ng/g wet weight) was observed in the seaweed samples, indicating that seaweed is a potential exposure source of TBP.

Automated summary

The study measured the levels of selected organohalogenated contaminants in complete meal sets of Japanese infants and found that DDTs and PCBs were the highest among the POP groups. The intake of these pollutants mainly came from food, with seafood and seaweed consumption showing correlations with certain contaminants. Seaweed was identified as a potential exposure source of TBP, based on analysis of seaweed samples and dietary intake data.