Nylon Bristles and Elastomers Retain Centigram Levels of Triclosan and Other Chemicals from Toothpastes: Accumulation and Uncontrolled Release

摘要

Triclosan (TCS), a broad-spectrum antimicrobial, is used in commercial toothpastes with reported dental benefits. Our studies on 22 popular manual toothbrushes in the U.S. showed that common toothbrush head components can accumulate substantial amounts of TCS after brushing with TCS-formulated toothpastes (TCS-TPs). After simulated 3-month brushing with a commercial best-selling TCS-TP, over one third of the adults' toothbrushes showed a cumulative TCS uptake of 21—37.5 mg, equivalent to 7— 12.5 doses of the TCS used per brushing. Similar results were observed on children's toothbrushes with small pea-size heads. Elastomer components were found to be the main contributor while both nylon bristles and elastomers could act as absorptive sinks for TCS during brushing. Studies on six different TCS-TPs containing 0.3 wt% TCS showed similar profiles of TCS accumulation. The absorbed TCS was gradually released into toothpaste slurries after switching to TCS-free alternatives. Release of TCS, which typically measured at a fraction (<75%) of the standard dose using the TCS-TPs, continued for over 2 weeks and occurred most rapidly in peroxide-containing "whitening" toothpastes, followed by alkaline and surfactant-rich toothpastes. The accumulating effect was not exclusive to TCS but was commonly observed on several chemicals identified in TCS-TPs and a range of regular toothpastes.