Occurrence of Cyclic and Linear Siloxanes in Indoor Dust from China, and Implications for Human Exposures

Abstract

Siloxanes are used in a wide variety of personal-care and other consumer products. Although there is clearly a potential for contamination of indoor dust with siloxanes, reports of occurrence of siloxanes in indoor dust were not available, prior to the present study. Here, we have determined the concentrations and profiles of four cyclic siloxanes, octamethylcyclotetrasiloxane (D(4)), decamethylcyclopentasiloxane (D(5)), dodecamethylcyclohexasiloxane (D(6)), and tetradecamethylcycloheptasiloxane (D(7)), as well as 11 linear siloxanes, from L(4)-L(14), in 100 dust samples collected in China. Cyclic and linear siloxanes were found in all dust samples, with the linear siloxanes L(9)-L(14) being the predominant compounds. Concentrations of total siloxanes in dust ranged from 21.5 to 21,000 (mean: 1540 +/- 2850) ng g(-1). The highest concentration of the individual linear siloxanes, L(9)-L(14), ranged between 2680 and 6170 ng g(-1). Concentrations of total linear siloxanes (TLS) were 1-2 orders of magnitude higher than concentrations of total cyclic siloxanes (TCS), in all indoor dust samples. Siloxane concentrations in dust were associated with the number of electrical/electronic appliances, number of occupants, and smokers living in the house. Based on the measured siloxane concentrations and on estimated daily ingestion rates of dust by toddlers and adults, we calculated the daily intake of siloxanes. For adults, daily exposure to total siloxanes, based on an average dust intake rate and median exposure concentration, was calculated to be 15.9 ng day(-1); the corresponding value for toddlers was 32.8 ng d(-1).

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

“…The pretreatment referred to one previous study (Lu et al, 2010), with some modifications. Dust/soil samples were sieved through a 500 μm mesh sieve.…”

“…It should be noted that besides the studied samples, other additives/ products potentially containing methyl siloxanes were not investigated, which could result in the estimated V c values in these industrial facilities lower than the true values. cating that PCPs could be one important source of methyl siloxanes in indoor environment of residential houses (Lu et al, 2010;Lu et al, 2011).…”

“…It should be noted that besides PCPs, there should be other exposure sources of siloxanes in residential houses. For examples, as we discussed in Section 1, home paints can contain siloxanes; in addition, siloxanes are widely used in home electrical/electronic devices as insulating agent (Lu et al, 2010). Siloxanes in these products could also volatilize into air and distribute in dust.…”

“…The total annual production volumes of cyclic methyl siloxanes in USA and China, including octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6), were approximately 470 and 800 million kg, respectively (CNKI, 2009;EPA, 2002). Recently, methyl siloxanes have been detected in aquatic, terrestrial, and atmospheric compartments (Dewil et al, 2007;Lu et al, 2010;Mclachlan et al, 2010;Zhang et al, 2011;Bletsou et al, 2013;Pieri et al, 2013;Lee et al, 2014).…”

“…In view of their toxic effects on human reproductive, immune, and nervous systems (Liebierman et al, 1999;He et al, 2003;OEHHA, 2007), human exposure to siloxanes has become a public health concern (Horii and Kannan, 2008;Lu et al, 2010). One previous study demonstrated that plasma concentrations of methyl siloxanes in workers from one siloxane production facility in China were much higher than those in general population (Xu et al, 2012).…”