Helping WWTP managers to address the volatile methylsiloxanes issue-Behaviour and complete mass balance in a conventional plant

Volatile methylsiloxanes in beauty and personal care products sold in India and human exposure assessment

This study investigated the presence of cyclic and linear volatile methylsiloxanes in 174 beauty and personal care products (PCPs) sold in India. Siloxanes were detected in all the samples with a detection frequency of 20 to 99 %. The cyclic siloxanes viz. decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) were predominant in all the samples, and the total concentration of cyclic siloxanes was as high as 773,000 μg g-1. About 40 % of the samples exceeded the European Union guideline value (0.1 %) for wash-off and leave-on products. The estimated per-capita run-off emissions of total siloxanes from beauty and PCPs were between 158,000 and 2,680,000 μg day-1 (average: 988,000 μg day-1). Hair serum, makeup remover, body wash, face wash, and shaving foam showed higher average per-capita run-off emissions for total siloxanes (range: 2950 to 505,000 μg day-1). The estimated per-capita air emissions of siloxanes were between 42,600 to 1,950,000 μg day-1 (average: 551,000 μg day-1). Hair serums, moisturizers, deodorants, foundation, primers, lip colour, makeup removers, and aftershaves were the major contributors to air emissions (0.44 to 56.3 %). The average dermal and inhalation exposure to siloxanes from using beauty and PCPs was 4020 and 642 μg kg-bw-1 day-1, respectively. The average daily dermal and inhalation doses for ∑octamethylmethycyclotertrasiloxane (D4) + D5 were 16.9 and 172 μg kg-bw-1 day-1, respectively, which is higher than the chronic reference dose for inhalation exposure. Among the studied siloxanes, cyclic siloxanes predominantly contributed to consumer exposure from applying beauty and PCPs.

Distribution and spatial variation of volatile methylsiloxanes in surface water and wastewater from the Yangtze River Basin, China

Volatile methylsiloxanes (VMSs) earned serious concerns due to their detection and toxicities after their release to the environments. They were also detected in rivers around the globe, but their distribution remained to be explored in larger rivers with longer length, higher water volume and wider watershed. In the present study, 8 cyclic VMSs (cVMSs) and 7 linear ones (lVMSs) were investigated in 42 water samples (27 surface water (including 7 drinking source water) and 15 wastewater) from the Yangtze River Basin, China. Results showed that VMSs were detected in all sampling sites. In surface water, the concentrations of total cVMSs ranged from 17.3 to 4.57 × 103 ng/L, while those of lVMSs ranged from 1.72 to 81.6 ng/L. In wastewater, the total concentrations of cVMSs and lVMSs showed ranges of 17.6-1.66 × 103 ng/L and 2.59-252 ng/L, respectively. Apparently, cVMSs showed significantly higher concentrations than lVMSs. The concentrations of cVMSs followed an order of lower > upper > middle reaches, while those of lVMSs did not show clear distribution patterns. Among cVMSs, those with less Si numbers were dominant, while those with more Si numbers were dominant in lVMSs. Notably, the VMSs were also detected in 7 surface waters that served as drinking source waters, which earned them further concerns. In addition, the VMSs in surface water showed positive correlation with those in wastewater, which led to necessity in management on industrial emissions in the future.