In view of their vast global usage in both consumer products and industrial processes, environmental emission and fates of siloxanes have become concerned issue. This review summarized the research progress, especially in the last decade, on production/consumption data, toxicities, analysis methods, environmental distribution, migration and degradation/transformation of both dimethylsiloxanes and modified siloxanes in atmospheric, aquatic and terrestrial compartments from various areas (especially in China). In spite of their fast degradation (hydrolysis and hydroxylation, etc) in various matrices (except sediment), dimethylsiloxane oligomers have been found in various environmental matrices from many countries due to their constant usage and emission. Moreover, recent literatures have paid attention to behaviors of dimethylsiloxanes in industrial areas, e.g., their higher residual levels compared with residential areas and unique transformed products (such as halogenated products) arose from special industrial production scenarios. Meanwhile, although most prior studies focused on dimethylsiloxanes, identification of modified-siloxanes with other functional groups in environment have been beginning to attract the attention of scientists. Furthermore, related literatures indicated that compared with dimethylsiloxanes, both halogenated-dimethylsiloxanes and modified methylsiloxanes (phenylsiloxanes and trifluoropropylsiloxanes) could have stronger persistence due to their weaker volatilization and degradation, especially in terrestrial matrices.

High concentrations (1.08 ng/g-3.61 mg/g) of methylsiloxanes, including cyclic analogs [octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6)], and linear analogs with 3-14 silicon atoms (L3-L14), have been detected in crude oil, additives and petroleum products from one petroleum refinery facility in China. Overall, the total mass load of Σmethylsiloxanes (1320 kg/day) in crude oil and additives was 1.5 times higher than that in petroleum products (857 kg/day), indicating their potential emissions in this facility, which were further confirmed by the find of their obvious emission through exhaust-gas (89.4 kg/day) and wastewater (4.70 kg/day). Σmethylsiloxanes emission from exhaust-gas discharge outlets of deep catalytic cracking units (60.6 kg/day) took up 68% of their total emission from all gas outlets. Overall, Σmethylsiloxanes in air (17.1-743 μg/m3) and soil samples [311 ng/g dw (dry weight) - 34.2 μg/g dw] from this facility were up to four orders of magnitude greater than those from surrounding areas, and plasma concentrations of Σmethylsiloxanes in current workers from this facility (7.4-609 ng/mL) were up to two orders of magnitude larger than those from reference group (