Cosmetic Products May be Over-preserved

Researchers, led by Michael Dyrgaard Lundov from Gentofte University Hospital, Denmark, in a study published in the journal Contact Dermatitis, have suggested that concentrations of preservatives may be too high in some cosmetic products. For example, the preservative Kathon CG was found in concentrations of up to 15 parts per million (ppm) even though this preservative is a potent sensitiser and concentrations as low as 2.5 ppm have elicited allergic reactions in sensitised individuals.

Preservatives are added to cosmetic products with a high water content to minimise product spoilage and the proliferation of undesirable
micro-organisms, such as Staphylococcus aureus and Pseudomonas aeruginosa that can pose a health risk to consumers.

There are a range of preservatives at manufacturers’ disposal but most rely on parabens, formaldehyde, formaldehyde releasers (e.g. DMDM hydantoin, diazolidinyl urea, imidazolidinyl urea, bronopol, sodium hydroxymethylglycinate and benzylhemiformal) and methychloroisothiazolinone/methylisothiazolinone (also known as Kathon CG). An ideal preservative would be colourless, odourless, water soluble, non-allergenic, non-irritating, effective over a broad range pH range and capable of effectively preventing the growth of a wide range of bacteria and fungi. Unfortunately there is not preservative that can meet all these requirements.

The researchers note that “allergy to preservatives is one of the main reasons for contact eczema caused by cosmetics. Concentration of the same preservative in similar products varies greatly, and this may indicate that some cosmetic products are over preserved. As development and elicitation of contact allergy is dose dependent, over preservation of cosmetics potentially leads to increased incidences of contact allergy.”

Around 6 percent of the general population has a cosmetic-related contact allergy. They also point out that the results of studies looking into the antimicrobial efficiency of preservatives in cosmetics indicate that formulations could be adequately preserved with much lower concentrations than the maximum allowed under EU and US legislation.

Although products in the EU and US must carry lists of ingredients in descending order of concentration, three studies on preservatives in cosmetics found that around a quarter of the skin creams evaluated were labelled incorrectly. A Swedish study investigating 9 preservatives which should not be present in the moisturisers assessed according to the manufacturers, detected at least one of the preservatives in 17 percent of the formulations. This begs the question, how on earth are consumers supposed to avoid specific ingredients when the manufacturers don’t even provide an accurate description of the ingredients? Furthermore a study investigating the ability of patients with allergic contact dermatitis to avoid exposure to allergens in cosmetics, found that 46 percent of the patients had difficulty understanding the ingredients labelling of cosmetics.