Spectrometric analysis of mercury content in 549 skin-lightening products: is mercury toxicity a hidden global health hazard?

BACKGROUND: Cosmetic skin lightening is practiced worldwide. Mercury is a well-documented melanotoxin added to some lightening products. However, mercury can cause many dermatologic, renal, and neurologic problems. The Food and Drug Administration limits the amount of mercury in cosmetic products to trace amounts, 1 ppm. OBJECTIVE: The objective of this study was to quantitatively evaluate a large international sample of lightening products for mercury content, focusing on products available to US consumers either online or in stores. METHODS: A total of 549 skin-lightening products, manufactured in 32 countries, were purchased online in the United States, Taiwan, and Japan and in stores in the United States, China, Taiwan, Thailand, Japan, and Sri Lanka. Cosmetics were screened for mercury content above 200 ppm using a low-cost portable x-ray fluorescence spectrometer. RESULTS: Of the 549 tested products, 6.0% (n = 33) contained mercury above 1000 ppm. In all, 45% of mercury-containing samples contained mercury in excess of 10,000 ppm. Of lightening products purchased in the United States, 3.3% were found to contain mercury in excess of 1000 ppm. LIMITATIONS: Our study did not evaluate creams for other melanosuppressive ingredients. Only 1 sample of each product was tested. CONCLUSION: Our study confirms the national and global presence of mercury in skin-lightening products.

A comparative study of allergic contact dermatitis by patch test versus reflectance confocal laser microscopy, with nickel and cobalt.

Few studies have reported on the accuracy of reflectance confocal laser microscopy (RCLM) in observing allergic contact dermatitis in vivo. However, distinction of skin reactions from different reagents is not well understood. We sought to diagnose allergic contact dermatitis by RCLM images and compare with routine, visual patch test (PT) reading for 2 major allergen metals in Japan. The PT was performed on the upper back skin with 5% nickel sulfate (Ni) and 2% cobalt chloride (Co) in eight healthy volunteers and eleven patients. RCLM was used to calculate the thickness of the suprabasal epidermis after visual assessment of PT. Comparison of clinical scoring versus suprabasal epidermal thickness was observed. RCLM images of positive PT showed increased suprabasal epidermal thickness on day 2 (D2), and D3 for Co, whereas there was vesicle formation and an overall increase suprabasal epidermal thickness for Ni. In two of 3 doubtful positive PT to Co, RCLM images presented characteristics of irritant reactions; and one characteristic of a positive reaction. The frequency of Co doubtful-positive PT was higher than that of Ni. We found advantages in using RCLM for visualizing features of allergic contact dermatitis and found it a useful tool as an objective parameter in grading severity and types of PT reaction.