DDTs in mothers' milk, placenta and hair, and health risk assessment for infants at two coastal and inland cities in China

• DDT concentrations in mothers' milk, placenta and hair were investigated.
• Body burdens of DDTs in women living in coastal cities were higher than inland city.
• High DDT levels in women living in coastal cities were due to high seafood intakes.

This study is a one of the very few investigating the dichloro-diphenyl-trichloroethanes (DDTs) (summation of o,p′-DDE, p,p′-DDE, o,p′-DDD, p,p′-DDD, o,p′-DDT, and p,p′-DDT) in multiple human matrices in mothers' milk, placenta and hair collected from residents from two coastal cities: Guiyu (GY) and Taizhou (TZ) and one inland city: Lin'an (LA). TZ (milk: 360 ± 319 ng/g lipid wt.) showed significantly higher concentrations of DDTs than those from LA (milk: 190 ± 131 ng/g lipid wt.), whereas, concentrations of DDTs in GY (milk: 305 ± 109 ng/g lipid wt.) were in between TZ and LA. In addition, levels of DDTs in the human tissues from TZ (placenta: 122 ± 109 ng/g lipid wt.; hair: 79.9 ± 215 ng/g dry wt.) were significantly higher than those from Lin'an (placenta: 49.2 ± 30.2 ng/g lipid wt.; hair: 10.8 ± 7.09 ng/g dry wt.). The above concentrations of DDTs in milk exceeded the Codex Maximum Residue Limits/Extraneous Maximum Residue Limits for milk (20 ng/g lipid wt. whole milk), indicating that the human milk samples were grossly polluted. The present study revealed that human specimens collected from the coastal city (TZ) were more contaminated with inland one (LA), based on the levels of DDTs contained in samples which may be due to the higher dietary exposure to DDTs via consumption of contaminated seafood. The estimated daily intakes of DDTs by GY, TZ and LA infants were 1.69 ± 1.86, 1.48 ± 0.79, and 0.95 ± 0.73 μg/kg body wt./day, respectively which did not exceed 10 μg/kg body wt./day, the provisional tolerable daily intake proposed by the Food and Agriculture Organization/World Health Organization.