Methyl Siloxanes in Environmental Matrices around a Siloxane Production Facility, and Their Distribution and Elimination in Plasma of Exposed Population

In this study, we systematically investigated methyl siloxanes (D4–D6, L3–L16) exposure to workers from and residents living near a siloxanes manufacturing facility by measuring their concentrations in both environmental matrices (air, dust/soil, n = 62) and human plasma samples (n = 201). For the seventeen target compounds, the average concentrations in indoor matrixes from six workshops of the facility ranged from 0.6 μg/m3 to 2.7 mg/m3 in air samples and from 0.36 μg/g to 1.16 mg/g in dust samples, which were 3–5 orders of magnitudes higher than those levels at the reference zone. In plasma samples from the current workers in six workshops and residents living near the facility, the average concentrations of methyl siloxanes were 5.61–451 and 4.56–13.5 ng/g, respectively, which were 1–2 magnitudes higher than those in the reference group. Plasma methyl siloxanes concentrations of people from different workshops were positively correlated with their exposure levels, indicating that high occupational exposure in siloxane production process elevated human plasma concentrations. However, there was no significant correlation between human plasma concentrations with their duration of occupation. These methyl siloxanes were eliminated from human plasma with half-lives ranging from 2.34 to 9.64 days, which increased with the increasing number of Si–O bonds for most analogues.