BACKGROUND: Mercury is commonly found in imported skin-lightening creams, and can cause dermatitis, renal impairment, and neurological damage. FDA considers cosmetics adulterated if they contain at least 1 part per million (ppm) mercury; Minnesota also prohibits the sale of cosmetics containing mercury. Measuring concentrations of mercury in cosmetics using laboratory methods can be time-consuming and expensive. We sought to estimate the sensitivity and specificity of a portable mercury analyzer to determine whether cosmetics contained mercury. We also sought to characterize the content of other heavy metals in skin-lightening creams.
METHODS: Samples of cosmetics were obtained during an investigation of products being sold in a market in Minnesota during April, 2016. Mercury vapor content was tested on-site using a portable mercury analyzer. Samples were selected based on mercury vapor content or because of a history of the brand containing mercury; laboratory analysis was performed at the Minnesota Department of Health laboratory for arsenic, cadmium, chromium, lead, and mercury. Wilcoxon rank sum test was used to compare distributions of test results, and sensitivity and specificity were calculated for the portable mercury analyzer.
RESULTS: A total of 47 samples were collected from the market. No products contained arsenic above the limit of detection. One product contained detectable chromium (1.0 ppm). Three products contained detectable levels of cadmium (maximum 6.2 ppm). Four products contained detectable lead (maximum 2.5 ppm). The majority of products tested (32/47; 68.1%) contained detectable levels of mercury (maximum 54,000 ppm). Products with detectable levels of mercury had significantly higher mercury vapor readings than products without detectable mercury (P < 0.01). Using a threshold of 200 ng/m3 to consider a sample positive resulted in a sensitivity of 96.9% (95% Confidence Interval [CI] 84.3–99.5) and specificity of 73.3% (95% CI 48.1–89.1).
CONCLUSIONS: We determined that measuring mercury vapor content with a portable mercury analyzer is a sensitive method for detecting mercury in cosmetic skin-lightening creams under field conditions. Because of the moderate specificity at a mercury vapor threshold of 200 ng/m3, confirmatory testing or a higher threshold may be warranted if environmental investigations will result in legal action. Although heavy metals were detected, mercury remains the primary contaminant of concern for these products. The continued availability of skin-lightening creams containing mercury indicates that additional resources need to be devoted to both enforcement of bans on sale of mercury-containing cosmetics and education of customers on the health risks of using these products.