Identifying the sources of mercury exposure in dental workers

Dental professionals who handle dental amalgam are at risk of mercury exposure, though the prevalence and severity of elevated mercury levels from non-occupational sources are not well characterized. We report two dental workers who had elevated urinary mercury levels (37 and 25.6 mcg/L) during routine health screenings. Their previous mercury tests were normal, and no symptoms or abnormal findings were identified on clinical examination. Mercury exposure in these two workers occurred both occupationally through amalgam contact and non-occupationally via unregulated facial creams and seafood consumption. Their urine mercury levels normalized within 2 months after transitioning to amalgam-free roles and discontinuing the use of the facial products. No chelation or medication was administered in these cases. The identified primary source was inorganic mercury from unregistered facial creams, with levels measuring 18 302.17 and 6221.53 mcg/g surpassing the Thai regulation's maximum limit of zero.