Short-, Medium-, and Long-Chain Chlorinated Paraffins in Indoor Dust from South China and the Midwestern United States

In the present study, liquid chromatography–quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) was employed to analyze chlorinated paraffin (CP) homolog distributions and concentrations in household dust from South China and the Midwestern United States. The median levels of short-, medium-, and long-chain CPs (∑SCCPs, ∑MCCPs, ∑LCCPs) in South China were quantified as 23.1, 36.2, and 32.8 μg/g, respectively. Comparatively, the corresponding values in the Midwestern U.S. samples were 9.4, 39.5, and 15.4 μg/g, respectively. Notably, ∑LCCP concentrations in South China significantly exceeded those in the U.S. (p < 0.05), while no difference was found for ∑SCCPs and ∑MCCPs. Additionally, very short-chain CPs (C≤9) were detected in 13% of samples across both regions. The distribution of CP homologues in the dust samples from the two regions was similar, with C13, C14, and C18 groups as the predominant carbon homologue and Cl7-8, Cl7-9, and Cl9-10 as the predominant chlorine homologue of SCCPs, MCCPs, and LCCPs, respectively. Risk assessment indicated dust ingestion-derived CP intakes for adults and toddlers were 2–5 orders of magnitude below reference doses. However, given other exposure pathways and the combined effects of CP monomers, the potential health risks from exposure via dust should not be underestimated.