Exposure of Inorganic Mercury in the General Population and Ethnic Minorities in New York City and Its Associations with Skin Lightening Practice

Abstract

Skin lightening practice (SLP) was identified as a source of inorganic mercury exposure among Caribbean-born blacks and Dominicans, who had geometric mean urine mercury concentration ([GMuHg]) ≥1 ng/ml compared to 0.69 ng/ml among the general population in the 2004 New York City Health and Nutrition Examination Survey (NYC HANES). We assessed such a pattern using the 2013-2014 HANES (n=1408), which also asked about the usage of skin lightening cream in the past 30 days. In addition, we present the preliminary results from a pilot study on SLP among NYC women of African and Afro-Caribbean ancestries (n=74) who have been bleaching their skin for a year.The population-weighted SLP prevalence was 5.5% overall and 8.1% among the Caribbean population (n=355). The overall [GMuHg] and its 95th percentile was 0.37 and 1.7 ng/ml, similar to the levels found among subgroups such as participants with SLP, the Caribbean population, or the Caribbean participants with SLP. Among those with SLP (n=75), 70% were female, 37% were Hispanic, 36% were Caribbean, and their [uHg] ranged from 0.063 ng/ml to 11ng/ml. Significant factors (p<0.05) associated with [uHg] were being non-US born, higher family income (≥$100,000), having silver-colored dental fillings and frequent fish or shellfish consumption (≥3 times in the past 30 days). In our pilot study, 81% participants were non-US born, about 50% from Jamaica or the Ivory Coast, 89% reported more than 3 years of SLP, 77% used daily, and 12% used while pregnant/breastfeeding.We observed an overall decrease in the population level [GMuHg] in NYC compared to the previous study, and did not find elevated [GMuHg] among the Caribbean or SLP population. Our SLP-focused pilot study showed that SLP is a habitual practice, and the existence of prenatal and postnatal exposures related to SLP may warrant further investigation especially among vulnerable subgroups (e.g., Jamaicans and West Africans) where SLP is more prevalent.