California woman suffers severe neurological damage from highly toxic mercury in skin lightening cream
The cream contained methylmercury, a form of organic mercury, making it the first known case of such poisoning in the US
A skin lightening cream has left a California woman with severe damage to the central nervous system. The cream, which the 47-year-old got from Mexico, had methylmercury — a form of organic mercury — making it the first case of such poisoning in the US in nearly 50 years, according to a report.
"This is the first known case of contamination of skin lightening cream with methylmercury (or any congener, including methylmercury iodide," say researchers in the Morbidity and Mortality Weekly Report by the US Centers for Disease Control and Prevention (CDC).
The team comprised experts from the University of California, San Francisco (UCSF), California Poison Control System (CPCS), San Francisco Division, California, Department of Public Health (CDPH), and the CDC.
Many weeks after the initial hospitalization and even after she has discontinued using the product, the patient is unable to speak or take care of herself.
She requires "ongoing tube feeding for nutritional support," say authors in their report. The California Department of Public Health is also investigating likely exposure to the same product in a family member.
According to senior study author, Dr. Paul Blanc, most harmful skin lightening creams are intentionally tainted with inorganic mercury.
"But in this case, the patient used a skin lightening product containing organic mercury, which is far more toxic. This form of mercury can cause profound damage to the central nervous system that may even worsen after cessation of use, "says Dr. Blanc from the UCSF Division of Occupational and Environmental Medicine and the CPCS.
Blood and urine tests confirmed mercury poisoning
In July 2019, a Mexican-American woman in Sacramento, California, sought medical help for involuntary muscle movements and weakness of her upper extremities. After two weeks of outpatient care, the patient's condition deteriorated.
Her symptoms progressed to blurry vision, unsteady gait and difficulty with speech, as a result of which she was admitted to a local hospital. "While hospitalized, her condition declined rapidly to an agitated delirium," says the study.
Mercury poisoning was confirmed after elevated blood and urine levels of the metal were found. However, the doctors did not know initially if inorganic or organic mercury was involved.
The hospital informed the CPCS and the CDPH. The patient's family disclosed that she had been applying skin lightening creams, which she obtained from Mexico, twice a day for seven years. The cream was analyzed and found to contain 12,000 ppm mercury.
"Two weeks into the hospitalization, screening blood and urine tests detected mercury concentrations exceeding the upper limit (UL) of quantification, indicative of abnormally high values of mercury (greater than 160 μg/L [blood] and greater than 80 μg/L [urine])," says the report.
"The hospital notified the CPCS and the CDPH. CDPH interviewed the patient’s family and learned that the patient was a long-term user of skin lightening creams obtained from Mexico."
The patient underwent chelation therapy, a treatment for heavy metal poisoning in which a chelator drug binds to the metal in the bloodstream and is excreted in the urine. While the therapy corresponded with a drop in blood mercury, the patient's condition did not improve.
The patient was transferred to UCSF, where clinicians raised suspicions of organic mercury poisoning. Further testing by the California Department of Public Health indicated that the skin-whitening cream had been contaminated with methylmercury iodide; methylmercury was confirmed by the CDC.
"Analysis of the cream performed at CDPH identified a possible match with methylmercury iodide, an organic mercury compound. Thus, organic mercury poisoning was suspected. CDC confirmed values of blood total mercury 528 µg/L, and blood methyl mercury 460 µg/L," the report confirms.
It says, "Health risks associated with inorganic mercury exposure are well-recognized from such products; levels up to 200,000 ppm (typically mercurous chloride) have been reported. The relatively lower 12,000 ppm mercury content of the cream, in this case, underscores the far higher toxicity of organic mercury compounds."
Methylmercury's toxic impact
According to the World Health Organization (WHO), methylmercury is toxic to the central and peripheral nervous systems.
"Neurological and behavioral disorders may be observed after inhalation, ingestion or dermal exposure of different mercury compounds. Symptoms include tremors, insomnia, memory loss, neuromuscular effects, headaches and cognitive and motor dysfunction," says WHO.
Central nervous system toxicity typically manifests after weeks to months of exposure and progresses rapidly thereafter.
"Central nervous system toxicity, as in this case, is the hallmark of organic mercury – it typically comes on after weeks to months of exposure," says Blanc.
"Once manifested, it quickly progresses and often worsens, despite the removal of any further exposure. Unfortunately, chelation therapy, which is effective in inorganic mercury poisoning, has not been established to be efficacious for methylmercury," Blanc adds.
The researchers recommend that while buying any skin cream, consumers must do due diligence and check if the product has a protective foil seal under the lid. The researchers warn that people should buy creams from well-known sources and avoid those which do not have proper labels, listing all the ingredients.
"The original source of the methyl mercury adulterant and its marketing chain remain to be identified (in the current case). CDPH is actively working to warn the public of this health risk, actively screening other skin lightening cream samples for mercury, and is investigating the case of a family member with likely exposure but less severe illness," says the report.