Any water-containing cosmetic product is at risk of contamination during the consumer use, and these contaminating micro-organisms can alter the composition of the product and may pose a threat to human health.
To avoid this, cosmetics manufacturers add preservatives; however, according to a review in the journal Contact Dermatitis, some manufacturers may be adding higher concentrations of preservatives than are really needed.
Large range of preservative concentrations
According to the researchers, led by Michael Dyrgaard Lundov from Gentofte University Hospital, Denmark, a number of studies point to a large range of preservative concentrations in cosmetics products, although none were higher than permitted limits set by the relevant US or EU authorities.
A number of reasons could explain the fact some products contain significantly higher levels of preservatives than others, including the use of multiple preservatives which lower the concentration of each, but according to Lundov and the team excessive use of preservatives cannot be ruled out.
Furthermore, there are ways of reducing the concentration of preservatives needed such as dispensing and packaging systems that keep water and air out during consumer use.
The researchers argue that manufacturers may not be taking this into account when calculating the amount of preservation a product will need, consequently using more preservative than is really necessary.
Before a product hits the market the manufacturer has to perform a challenge test to show that it can withstand microbiological contamination. This test is labour intensive and expensive making it likely manufacturers will test only one preserving system, rather than experimenting with different combinations and concentrations in order to find the minimum efficient levels.
Preservatives can cause contact allergies
Excessive use of preservatives may not, at first glance, seem to be a problem, better safe than sorry, but the researchers argue such compounds elicit contact allergies in a significant percentage of the population.
It is estimated that 6 percent of the population has a cosmetics related contact allergy, and the two main culprits are fragrances and preservatives. Out of the more common preservatives (parabens, formaldehyde, formaldehyde releasers and MCI/MI) it is formaldehyde that seems to illicit the most reactions ranging from 2 per cent in Europe to 9 per cent in the US.
Individuals with known allergies to preservatives are told to avoid certain products but the researchers argue surveys conducted in the past show only half of the affected individuals can successfully read and understand ingredients lists, due to long chemical names and small print.
For Lundov and the team, optimising preserving systems and reducing concentrations to a minimum, may be one way to reduce cases of contact allergies.