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. (<i>p</i> < 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 Cl_7-8, Cl_7-9, and Cl_9-10 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.