Discovery of Hindered Amine Light Stabilizers in Dust from Automotive Repair Shops in China

Hindered amine light stabilizers (HALSs) are polymer additives that are widely used in plastics, synthetic fibers, and adhesives. However, research on the environmental presence and related exposure risk of HALSs remains limited. In this study, a wide range of HALSs were analyzed in indoor and outdoor dust from multiple environments, and nine HALSs were detected. Relatively high concentrations of HALSs were detected in the dust of automotive repair shops (median = 1.05 × 105 ng/g), while urban residential apartments (median = 1.53 × 103 ng/g), rural houses (median = 301 ng/g), and the rural outdoors (median = 75.9 ng/g) showed much lower concentrations. The estimated daily intake of ΣHALSs via dust ingestion for automotive repair workers under median exposure scenarios reached 35.4 ng (kg of body weight (bw))−1 day–1, which was 80 times higher than that for residential exposure. Despite elevated exposure in repair shops, current HALS concentrations do not appear to pose a significant threat to human health via dust ingestion. This is the first study to report the presence of HALSs in automotive repair shops and rural environment settings. Moreover, three HALSs, 2,2,6,6-tetramethyl-4-piperidinyl stearate, N,N′-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexane-1,6-diamine, and 4-hydroxy-1-(2-hydroxyethyl)-2,2,6,6-tetramethylpiperidine, are reported for the first time in the environment.