Survey of Organosilicone Compounds, Including Cyclic and Linear Siloxanes, in Personal-Care and Household Products

Yuichi Horii, Kurunthachalam Kannan

The determination of organosiloxanes in consumer products is important for the evaluation and characterization of sources of human and environmental exposures. In this study, we determined concentrations of cyclic siloxanes [octamethylcyclotetrasiloxane (D(4)), decamethylcyclopentasiloxane (D(5)), dodecamethylcyclohexasiloxane (D(6))], tetradecamethylcycloheptasiloxane (D(7))] and linear siloxanes (L(4) to L(14)) in a variety of consumer products (n = 76), including hair-care products, skin lotions, body washes, cosmetics, nursing nipples (i.e., pacifiers), cookware, and household sanitation products such as cleansers and furniture polishes, using gas chromatography-mass spectrometry with selected ion monitoring. Prior to the analysis of samples, a method was developed to reduce the contamination arising from organosiloxanes present in certain gas chromatograph (GC) parts, such as the inlet septum; use of a Restek BTO septum at an inlet temperature of 200 degrees C gave the lowest background level (D(4): 0.8 pg; D(5): 0.3 pg; D(6): 0.2 pg). Concentrations of cyclic siloxanes in consumer products analyzed ranged from <0.35 to 9380 microg/g, from <0.39 to 81,800 microg/g, from <0.33 to 43,100 microg/g, and from <0.42 to 846 microg/g for D(4), D(5), D(6), and D(7), respectively. Concentrations of linear siloxanes varied from <0.059 to 73,000 microg/g. More than 50% of the samples analyzed contained D(4), D(5), or D(6). Cyclic siloxanes were predominant in most of the sample categories; D(5) was predominant in hair-care products, skin lotions, and cosmetics; D(6) or D(7) was predominant in rubber products, including nipples, cookware, and sealants. Potential daily exposure to total organosiloxanes (sum of cyclic and linear siloxanes) from the use of personal-care products by adult women in the United States has been estimated to be 307 mg. Significant positive correlations (p < 0.01) existed in our study between D(4) and D(7), D(4) and linear siloxanes, D(5) and D(6), and D(5) and linear siloxanes. The correlations can be related to the composition of organosiloxanes used in consumer products. The results of our study suggest that a wide variety of consumer products that are used on a daily basis contain cyclic and linear siloxanes and these products can contribute considerably to human exposures.