Volatile methylsiloxanes of 141 personal care products in Korea: An adult exposure assessment

The widespread use of personal care products (PCPs) and subsequent exposure to their volatile methylsiloxane (VMS) content are often overlooked worldwide. Moreover, regulatory measures addressing VMS levels are sparse, and research on VMS levels in PCPs is limited. Therefore in this study, 141 PCPs from Korea, one of the biggest PCP markets in the world, were extracted and analyzed for seven VMSs using gas chromatography-mass spectrometry. Overall, cyclic VMS (cVMS) compounds were found at higher concentrations than linear VMS (lVMS) compounds, accounting for more than 93% of the total VMS concentration. The highest VMS content in PCPs was observed for octamethylcyclotetrasiloxane (D4) and hexamethylcyclotrisiloxane (D3), at approximately 130,000 and 110,000 μg g^-1, respectively. Additionally, the total VMS (∑VMS) concentration were in the order of face > hair > body products. PCPs were classified as non-rinse or rinse products based on their retention time on the body of the consumer. Non-rinse body products had more than twelve times the ∑VMS content of rinse body products (341 and 26.8 μg g^-1). Rinse hair products are three times the ∑VMS content of non-rinse hair products (576 and 191 μg g^-1). Furthermore, the principal component analysis suggested that PCPs can be grouped according to their cVMS content, with D3 and decamethylcyclopenatsiloxane (D5), D4, and D5 co-occurring. Notably, daily dermal exposure to VMSs in PCPs was largely determined by the retention time of the PCP on the body, followed by the VMS concentration. Although exposures to cVMS compounds were generally higher, exposure to the lVMS content of some PCPs was higher depending on the product type. Therefore, it is crucial to consider the significance of all VMS compounds, not solely cVMS, in exposure calculation and regulations. This study provides a database for regulatory bodies to implement in their exposure and toxicity studies.