Mercury Exposure Among Household Users and Nonusers of Skin-Lightening Creams Produced in Mexico — California and Virginia, 2010

Mercury exposure has been reported among users of skin-lightening creams produced outside the United States but not among nonusers in their households (1–4). Mercury exposure can result in irreversible renal and central nervous system damage or death (4,5). In March 2010, coordinators of a health study notified members of a Mexican-American family in California with four study participants that they had elevated blood mercury levels and also notified the local health department, which in turn asked the California Department of Public Health (CDPH) to investigate. CDPH interviewed the four study participants and a fifth household member and identified unlabeled skin-lightening creams with mercury content measured at 2.0%–5.7% by weight as the likely source of mercury exposure. CDPH also interviewed friends of the study participants in California who had used similar skin-lightening products, and the Virginia Department of Health (VDH) interviewed relatives in that state who had used skin-lightening products. In all, investigators in the two states collected information and urine specimens for 22 persons in five households. The results indicated that 15 persons had elevated urinary mercury concentrations, including nine users of the cream (six with nonspecific symptoms) and six nonusers. Mercury vapor concentrations as high as 50 µg/m3 were measured in spot household locations; however, the overall concentration for each room in all five households was <1.0 µg/m3, considered a safe level. Both health departments advised users and the public to stop using these creams and issued clinical health alerts notifying physicians about this potential cause of mercury toxicity.

Epidemiologic and Environmental Investigations

CDPH interviewed the four health study participants and a fifth household member by using a questionnaire to assess potential mercury exposures from thermometers, fluorescent light bulbs, occupational activities, pharmaceuticals, personal care products, and spiritual practices. An unlabeled skin-lightening cream produced in Mexico was identified as the likely source of mercury exposure for persons who reported its use. After learning that the health study participants had Virginia relatives using skin-lightening creams from the same source, CDPH contacted VDH, which used a questionnaire more focused on skin-lightening creams because they were the suspected source of mercury exposure.

In both states, cream users and nonusers in each household were asked about symptoms associated with chronic mercury exposure and asked to identify other known users of similar skin lighteners. In California, household A included a woman and her three children who had participated in the health study and her husband who had not. Interviews with members of household A identified friends who used a similar cream and lived in two separate households in California. In addition, members of household A reported they had relatives who lived in two separate households in Virginia and some of them also used the same cream.

In all, 22 persons in five households were identified with potential mercury exposure. Ten of the 22 reported use of skin-lightening creams. The users were aged 16–62 years, and six were females. Household members reported no other potential exposures, except a broken fluorescent light bulb. Reported reasons for using the cream included skin-lightening, fading freckles, and treating acne. Frequency of use ranged from intermittent to twice daily, and duration of use ranged from months to 5 years. Cream typically was applied to the face. Two mothers used skin-lightening creams during three pregnancies and subsequent lactation.

Six users had nonspecific symptoms consistent with chronic exposure to mercury, including numbness, tingling, dizziness, forgetfulness, headaches, and depression. Users stored and applied their creams either in a bathroom or a bedroom. Members of household A in California received their cream from Virginia relatives who had purchased it in Mexico. Members of household B and household C purchased their cream in California, although it was produced in Mexico. Among the 22 persons with potential mercury exposure, the 12 nonusers were aged 8 months–67 years and included two females and 10 males.

All residents provided first-morning–void urine specimens, which were tested by commercial laboratories in each state by inductively coupled plasma mass spectrometry. Exposure to mercury (defined as ≥5 µg/g creatinine*) was confirmed for nine of 10 users (range: 26–317) and six of 12 nonusers (range: 20–276 µg/g) (Table). Exposed users were aged 29–62 years. One adolescent user, who used the cream to treat acne, had a concentration of only 4 µg/g. Exposed nonusers were aged 8 months–26 years and were asymptomatic. Concentrations were higher among younger children, compared with older children (Table).

Users turned over their skin-lightening creams to the health departments. To ensure comparability of results, creams collected in Virginia were sent to CDPH for testing. CDPH's laboratory tested 12 creams for mercury content by using inductively coupled plasma mass spectrometry. Eleven of the 12 creams collected in California and Virginia contained mercury (range: 2%–5.7%). One cream, intended for use around the eyes, contained only 0.0003% mercury.

The Environmental Protection Agency (EPA) measured mercury vapor concentrations throughout all five homes. Concentrations above background were found near cleaning supplies, clothing, and furniture where creams were stored, and near items frequently touched by cream users (range: 17–50 µg/m3). Mercury vapor measured near one user's hands remained elevated (6 µg/m3) even after repeated washings. Despite these focal elevations in mercury concentration, overall mercury vapor concentrations were within acceptable limits for each room in the households,† and EPA declared all households safe for occupancy.

Control Measures

The 15 residents with urinary mercury concentrations ≥5 µg/g creatinine were advised to seek medical evaluation. Five of the 15 were evaluated, and all received diagnoses of mercury poisoning (none were advised to undergo chelation therapy). In July 2010, VDH collected additional urine specimens from the eight Virginia residents with urinary mercury concentrations ≥5 µg/g creatinine and determined that their urinary mercury concentrations, although still elevated, had decreased by an average of 45%.

EPA advised residents of the five households to 1) discard contaminated items, 2) clean contaminated surfaces with disposable wipes, 3) treat washing machines with sulfur powder to bind residual mercury, and 4) ventilate their homes thoroughly. Return visits by EPA confirmed that mercury contamination in household areas tested previously had decreased or dissipated.

In May 2010, CDPH and VDH issued alerts in English and Spanish advising the public to discontinue using unlabeled skin-lightening creams or products that list mercury as an ingredient. CDPH also produced a Spanish-language public service announcement for statewide radio broadcast. The two state health departments were unable to collect information identifying cream producers. CDPH and VDH worked with CDC to alert federal health authorities in Mexico to the exposures, and CDPH also communicated with Mexico through the California Office of Binational Border Health.

Reported by

Lori Copan, MPH, Alyce Ujihara, MA, Carrie Jones, MD, Rupali Das, MD, Richard Kreutzer, MD, Rachel Roisman, MD, Robert A. Haas, PhD, Germelina Perez, Bahman Moezzi, PhD, California Dept of Public Health. Mark D. Miller, MD, Gina Solomon, MD, Univ of California, San Francisco, California Pediatric Environmental Health Specialty Unit. Rosilyn Ryals, MD, Larry Vitale, Muntu R. Davis, MD, Alameda County Public Health Dept. Michelle Rogow, Environmental Protection Agency. Rebecca V. LePrell, MPH, Dwight Flammia, PhD, R. Dana Bradshaw, MD, Kelly E. MacLaurin, MPH, Susan F. Davis, MD, Jessica Watson, MPH, April Achter, MPH, Angela Myrick-West, MPH, Virginia Dept of Health. Christopher P. Holstege, MD, Victoria F. Norwood, MD, Univ of Virginia School of Medicine. Thomas J. Bender, MD, EIS Officer, CDC. Corresponding contributor: Thomas J. Bender, [email protected], 919-286-3232.

Editorial Note

In this report, unlabeled skin-lightening creams produced in Mexico were the source of mercury exposure for users and nonusers living in the same households. Absorption of mercury through the skin and inhalation of mercury vapor generated by these creams likely were the modes of exposure. Among young children, contact with adult cream users' skin and with contaminated household items might have contributed to nondietary ingestion via hand-to-mouth behavior; breastfeeding also might have contributed to exposure.

Inorganic mercury (often mercurous chloride) is used in some skin-lightening creams produced outside the United States because it inhibits melanin formation when absorbed by the skin (6). Inorganic mercury, which differs from elemental mercury and organic mercury (e.g., methylmercury in fish), enters the body by inhalation, ingestion, or absorption through the skin and is excreted in urine, sweat, and breast milk (4). The half-life of inorganic mercury is 1–2 months (4). Consequently, mercury levels can increase gradually with repeated application of skin-lightening creams (1).

Urinary mercury concentration is measured to assess inorganic mercury exposure because blood mercury levels reflect exposure to both organic and inorganic mercury. Although 24-hour urine collection is the preferred method to confirm exposure to inorganic mercury, a first-morning–void urine specimen is easier to collect and correlates well with a 24-hour test (7). The risk for toxicity increases with increasing urine mercury but varies from person to person. Indicators of renal function, including urinalysis, creatinine, blood urea nitrogen, urine microglobulin, and microalbuminuria, should be assessed among persons with elevated urinary mercury concentration (5).

Chronic exposure to inorganic mercury can affect the kidney, producing oliguria, proteinuria, edema, and nephrotic syndrome (3) and can cause neuropsychologic effects, including nervousness, irritability, decreased cognitive function, headache, tremor, memory loss, depression, insomnia, paresthesias, fasciculations, ataxia, and fatigue (4,5). Occupational exposures causing urinary concentrations of 50–100 µg/g creatinine have been associated with tremor (4). Among children, prolonged exposure to inorganic mercury also might cause acrodynia, irritability, anorexia, and poor muscle tone (4). Effects of inorganic mercury on neurologic development are not well understood (8).

Mild-to-moderate symptoms of mercury toxicity typically resolve in 2–6 months without further therapy after exposure ends. Patients with elevated urinary mercury concentrations (≥5 µg/g creatinine) should be tested every 1–2 months to confirm that levels are decreasing.

Chelation therapy can have adverse effects, and no urinary mercury concentration has been determined to necessitate chelation. Treatment with dimercaptosuccinic acid (DMSA) or 2,3-dimercapto-1-propanesulfonic acid (DMPS) can accelerate excretion of limited amounts of inorganic mercury from the body, mainly the kidneys, but evidence is limited regarding enhanced recovery of renal or neurologic function among humans (9).

When mercury toxicity is identified, clinicians should consider exposure to mercury-containing creams, even for children or other household members who might not use such creams themselves. Clinicians should not begin treatment for mercury toxicity without consulting a medical toxicologist, who can help evaluate the type of mercury, blood or urinary concentrations, clinical symptoms, comorbid conditions, and other factors. Clinicians seeking guidance can consult their regional Pediatric Environmental Health Specialty Unit (telephone: 1-888-347-2632)§ or the American Association of Poison Control Centers (telephone: 1-800-222-1222).

Acknowledgments

Margaret Tipple, MD, Ingrid Costello, Linda Tripi, Virginia Dept of Health; John Savory, PhD, Laura K. Bechtel, PhD, Nathan P. Charlton, MD, Jennifer S. Boyle, MD, Univ of Virginia School of Medicine; Grier Mills, Shane Wyatt, Div of Consolidated Laboratory Svcs, Virginia Dept of General Svcs. Don McLaughlin, Christine Wagner, Environmental Protection Agency. John F. Risher, PhD, M. Olivia Harris, MA, Agency for Toxic Substances and Disease Registry. John Osterloh, MD, Joshua G. Schier, MD, Jerry D. Thomas, MD, Mary E. Mortensen, MD, Richard Y. Wang, DO, National Center for Environmental Health; Sheryl B. Lyss, MD, Scientific Education and Professional Development Program Office, CDC.

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