Skin-bleaching: got mercury?
The Minnesota Health Department yesterday issued a warning that skin-lightening cosmetic products sold in the area contain concentrations of inorganic mercury high enough to warrant their disposal as hazardous chemical waste.
Details on the warning can be found in this Star Tribune article by Maura Lerner with intern Alejandra Matos (hurray for summer student interns!).
State technicians tested 27 products, including 23 creams and four soaps, and found that 11 had mercury levels ranging from 135 to 33,000 parts per million. Federal law permits only “trace amounts,” less than 1 part per million.
Ramsey County officials said they became suspicious about the lightening creams when a staffer came across a blog about the mercury dangers.
The staffer, who worked with immigrant groups, knew the creams were popular among Somalis and others and thought it was worth checking out, said Zachary Hansen, the county’s director of environmental health.
Skin-lightening creams are popular in African nations as well as in some Asian cultures. A truly excellent 2008 review from a group of clinical dermatologists at the University of Lagos College of Medicine appeared in the International Journal of Dermatology.
The authors present therein some of the reasons why dark-skinned individuals might use such products:
Some of these are to look more attractive; to go with existing fashion trend; to treat skin blemishes like acne or melasma; to cleanse or “tone” the face and body; or to satisfy the taste of ones spouse. Although the men also use the products for the above reasons, some of them claimed they use the creams because their wives use them; and some male marketers of female cosmetics and toiletries claim they use the products to advertise their wares. Some of the men are homosexuals. The habit of bleaching the skin is most rampant among commercial sex workers who camouflage their occupation in the clinic data as “fashion designer” because of the opprobium attached to prostitution. It is noteworthy that even some people who are naturally fair in complexion, still use the bleaching creams to “maintain” the light skin color and prevent tanning or blotches from sunlight.
Currently, the Minnesota warning has not yet been associated with any illnesses or toxicity events. However, mercury-containing skin-lightening creams have been associated with typical, inorganic mercury nephrotic syndromes as early as this 1972 BMJ report from Nairobi where the disease was most commonly seen in “young sophisticated African women.”
But the risks associated with these skin-bleaching creams are not only due to mercury. More commonly, these products employ hydroquinone (benzene-1,4-diol). A naturally-occurring antiseptic compound – and carcinogenic hepatotoxin – found in the herbal product, uva ursi or bearberry, hydroquinone is used at concentrations up to 2-5% in some bleaching products where it can cause severe dermatological reactions.
Hydroquinone-containing skin creams have been most commonly associated with ochronosis, a skin and connective tissue disorder characterized by accumulation of homogentisic acid (or melanic acid). In an attempt to bleach the skin, the user experiences altered or hyper-pigmentation.
Ochronosis as a naturally-occurring condition was first described in 1865 by the famed German pathologist, Rudolf Virchow, and most typically occurs in individuals with alkaptonuria (black urine disease), an autosomal recessive defect in tyrosine and phenylalanine metabolism caused by a mutation in homogentisate 1,2-dioxygenase.
Hydroquinone mimics this disease by apparently inhibition several enzymes involved in degradation of these amino acids. Come to think of it, the Minnesota public health officials may care to re-analyze their products for hydroquinone as well. The International Journal of Dermatology review cited above listed nine Nigerian products with high concentrations of both inorganic mercury and hydroquinone.
And while we’re on metabolic diseases, long-term use of hydroquinone-containing products is associated with “fish odor syndrome,” an accumulation of trimethylamine from dietary choline and lecithin.
Other skin-bleaching products can contain high concentrations of corticosteroids whose prolonged use can cause thinning of the skin locally. Use of skin-bleaching products containing the corticosteroids has been shown to cause adrenal suppression.
Lastly, use of skin-bleaching products is not restricted to individuals on the dark end of the human pigmentation spectrum. As discussed in this 2006 article from the Asian Pacific Post, skin bleaching is also popular among young Asians where a porcelain complexion is valued. Region-specific bleaching of the anogenital region has also been a common practice among actors and actresses in the pornography film industry, exotic dancers, and sex workers.
The takehome message here is two-fold:
1. Consumers should be aware that skin-bleaching products likely contain high levels of potentially-toxic chemicals that can cause adverse reactions not just locally, but systemically as well. The skin is a remarkable absorptive organ. Putting large amounts of a mercury-containing cream on your skin can cause kidney damage.
2. Health care professionals should be vigilant for cases of unexplained renal toxicity and dermatological disorders that resemble inherited metabolic diseases. These cases may be more common among individuals of African descent but can also appear in patients from other cultural subsets.
Olumide YM, Akinkugbe AO, Altraide D, Mohammed T, Ahamefule N, Ayanlowo S, Onyekonwu C, Essen N (2008) Complications of chronic use of skin lightening cosmetics. Int J Dermatol 47:344-353. DOI: 10.1111/j.1365-4632.2008.02719.x
Findlay GH (1982) Ochronosis following skin bleaching with hydroquinone. J Amer Acad Dermatol 6: 1092-1093. DOI: 10.1016/S0190-9622(82)80104-7
Barr RD, Rees PH, Cordy PE, Kungu A, Woodger BA, Cameron HM (1972) Nephrotic syndrome in adult Africans in Nairobi. BMJ 2(5806):131-134. DOI: 10.1136/bmj.2.5806.131