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The UK Department of Trade and Industry (now the Department of Business, Enterprise and Regulatory Reform) characterizes nitrosamines as more toxic in more animal species than any other category of chemical carcinogen (i). Nitrosamines are common in cosmetics, but because they are impurities, they are not listed on product labels.

Products That May Contain Nitrosamines

Nitrosamines are a potential impurity in 53 ingredients and more than 10,000 of the products listed in the Environmental Working Group's Skin Deep database as of July 2008. Due to the common nature of this impurity, nearly every kind of personal care product, including mascara, concealer, conditioner, baby shampoo, pain relief salve and sunless tanning lotion, can contain nitrosamines as an impurity. Nitrosamines have been banned from use in cosmetics by Canada and the European Union (ii).

Where It Comes From

Nitrosamines are created in cosmetics when nitrates and various amino acids (the building blocks of proteins) are in favorable conditions to combine. Specifically, nitrosamines form when certain proteins, such as diethanolamine (DEA) or triethanolamine (TEA), are used in the same products as preservatives that can break down into nitrates. As these various compounds break down over time, they can recombine into nitrosamines. Both DEA and TEA are common additives used to adjust the pH or act as wetting agents (iii). The inadvertent creation of this carcinogenic compound can add a whole new challenge for consumers reading labels for safety, since nitrosamines do not appear on a label, and the precursor building blocks are not clearly noted.

Health Effects

Numerous studies and databases link nitrosamines to cancer. They are listed as possible human carcinogens by the U.S. Environmental Protection Agency, the International Agency for Research on Cancer, the U.S. National Toxicology Program Report on Carcinogens and the California EPA Proposition 65 list of chemicals known to cause cancer or birth defects. Several other databases cite strong to moderate evidence regarding the cancer-causing properties of nitrosamines. In addition, there is some evidence of endocrine disruption at very low doses. Studies have also linked nitrosamines to developmental or reproductive toxicity, immunotoxicity, neurotoxicity and systemic toxicity.

The FDA began watching personal care products for nitrosamines in 1979, and published a report stating that products containing nitrosamines could be seen as adulterated and subject to FDA enforcement. This led to a striking drop (from 150 ppm to 3 ppm) in concentrations of one form of nitrosamine n-nitrosoethanolmaine (NDELA) in testing 12 years later (iv). NDELA accumulates in the liver, bladder and other organs and leads to chronic toxic health effects. It is readily absorbed through the skin (v).

In 1996, the FDA encouraged cosmetic manufacturers to voluntarily remove ingredients that could combine to form NDELA and to conduct testing to understand why cosmetics become contaminated with NDELA. Despite these encouragements, the Environmental Working Group found that one in every 10 products contains ingredient that can combine with others to form nitrosamines. A 1998 study by the UK Department of Trade and Industry showed that nitrosamine levels in some products actually increase in the months after a product is opened (vi).

More Information

Skin Deep ingredient information: Nitrosamines

i Department of Trade and Industry, UK (DTI) (1998). A survey of cosmetic and certain other skin-contact products for n-nitrosamines.

ii Environmental Working Group. Skin Deep. Nitrosamines. Available online: Accessed July 28, 2008.

iii Malkan, S (2007). Not Just a Pretty Face: The Ugly Side of the Beauty Industry, pp. 58. Gabriola, BC, Canada: New Society Publishers.

iv Environmental Working Group (2007). Impurities of Concern in Personal Care Products. Available online: Accessed July 28, 2008.

v Matyaska MT, Pesek JJ, Yang L (2000). Screening method for determining the presence of N-nitrosadiethanolamine in cosmetics by opn-tubular capillary electrochromatography. Journal of Chromatography A. 887: 497-503.

vi Department of Trade and Industry, UK (DTI) (1998). A survey of cosmetic and certain other skin-contact products for n-nitrosamines.


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