Human Exposure to Short- and Medium-Chain Chlorinated Paraffins via Mothers’ Milk in Chinese Urban Population

TLDR

Chlorinated paraffins are high‑production synthetic chemicals found ubiquitously in the environment, yet little is known about their contamination in mothers’ milk. The study aimed to map CP geographical distribution and congener profiles to assess levels and identify human exposure sources. The authors collected 1,370 milk samples from 12–16 provinces and analyzed 28 pooled samples for 48 SCCP and MCCP congeners using GC×GC‑ECNI‑HRTOFMS. Median SCCP concentrations were 681 and 733 ng/g lipid in 2007 and 2011, with MCCPs at 60.4 and 64.3 ng/g lipid; CP levels varied over two orders of magnitude across provinces, increased over time, and the high concentrations in Chinese mothers’ milk raise concerns about potential toxic effects for mothers and infants.

Abstract

Chlorinated paraffins (CPs) are high production volume synthetic chemicals, found ubiquitously in various environmental matrices. However, little information is available on CP contamination in mothers' milk. In this study, 1370 urban mothers' milk samples were collected from 12 Chinese provinces in 2007 and 16 provinces in 2011. CP geographical distribution and congener group profiles were studied to assess the CP levels and figure out the source of exposure in humans. Twenty-eight pooled samples were analyzed for 48 short-chain CP (SCCP) and medium-chain CP (MCCP) congener groups using the GC × GC-ECNI-HRTOFMS method. The median concentrations of SCCPs were 681 and 733 ng/g lipid in 2007 and 2011, respectively; median concentrations of MCCPs were 60.4 and 64.3 ng/g lipid in 2007 and 2011, respectively. Variations of more than 2 orders of magnitude in CP exposure levels were found between different provinces. The levels of CPs increased from 2007 to 2011, which indicates that CP production and use may be an important exposure source. This is the first global comprehensive and large-scale investigation of CPs in mothers' milk, and it lays foundations for improving our understanding of the metabolism of CPs in humans. The high CP concentrations found in Chinese mothers' milk should raise concern about potential toxic effects in both mothers and breastfeeding infants.