Methyl siloxanes in environmental matrices and human plasma/fat from both general industries and residential areas in China

- Siloxanes are detected in additives/products from general industries in China.
- Their plasma concentrations in industrial workers were higher than reference group.
- Siloxanes are more likely to distribute in human fat than plasma.
- Linear but not cyclic compounds had an apparent accumulation in human fat.
- Population's half-lives of L8-L10 in human fat were about 1.49-1.80 years.

We investigated human exposure to methyl siloxanes in three general industries (building, automobile, and textile industries) and residential areas in China. Usage volumes of methyl siloxanes per capita in these industries were 2-5 orders of magnitudes higher than those in residential areas. Methyl siloxane concentrations in indoor air and dust samples from industrial facilities were 1-3 orders of magnitudes higher than those in residential houses. Both cyclic (D4-D6) and linear (L5-L16) siloxanes were detected in plasma of industrial workers (1.00-252 ng/mL, detection frequencies = 3.7-71%, n = 528), while only cyclic compounds (D4-D6) were detected in plasma of general population (n = 519) with much lower concentrations (1.10-7.50 ng/mL) and detection frequencies (1.7-3.7%). During the occupational exposure, anti-dust mask can reduce 30% of intake of cyclic siloxanes and 74% of intake of linear siloxanes, respectively. In addition, PM-10 could elevate intake of linear siloxanes. Calculated fat-plasma partition ratios of methyl siloxanes (D4-D6, L6-L11) in the present study were 5.3-241 mL/g. Linear rather than cyclic siloxanes had an apparent accumulation in abdominal fat. Population's half-lives of L8-L10 in abdominal fat of general population were approximately 1.49-1.80 years.