Synthetic musk could pose toxicity risk

Synthetic musk fragrance is commonly used in a variety of cosmetic and personal care applications, including soaps, shampoos and skin care products. Although the compound has been proven as non-toxic, a study conducted on mussels by the US-based California Sea Grant has shown that it can have a cumulative effect in organisms, but that it can increase sensitivity to toxic agents in the environment.

The study, which was reported in the January edition of the journal of Environmental Health Perspectives, raises concerns that these very common household compounds may also pose unanticipated environmental risks.

Headed by professor David Epel from Stanford University, the study shows that mussels have a defense system that normally prevents toxins from entering cells. However, the research found that synthetic musks intensify the toxicity of other pollutants by interfering with proteins in the cell membranes.

Normally these proteins pump toxins out of the cells but when overwhelmed by foreign compounds such as the musk, toxins can begin to accumulate leading to cellular damage.

Synthetic musks do not degrade in sewage and are often pumped into the sea in significant amounts because they are commonly added to personal care products. This means that the compound often accumulates in a variety of marine life, although their non-toxicity has so far led to few concerns.

But one type of synthetic musk, xylene, has proved a particular exception to this rule. Human health concerns mean that its use has been discontinued in both Japan and Germany, but in the US it is still commonly used in a variety of cosmetic and personal care products, although not lipsticks and other such products that are easily ingested.

Epel's experiments took into account six different types of synthetic musk on a particular type of mussel commonly found on the Californian coast. Exposure to varying levels of the compound found in polluted water was said to impair cell function for 24 to 48 hours.

Epel said this result was 'troubling' since it implies lasting environmental impact from polluted water.

Further to this Epel believes that these results have further implications for human life, as human cells use the same transporter mechanisms as mussels. This leads to the conclusion that exposure to musks in people might impair defense systems, which in turn increases the risk of exposure to normally excluded toxins.

"This is the first study to show that some personal care products do have an effect in water, even in low concentrations,"​ said Epel. "Our results indicate that the effects on the first line of defense might be irreversible or continue long after the event. It's a warning sign. It's a smoking gun."​

Industry's reaction to the study has been relatively muted. However, the Fragrance Materials Association in the US stated that testing carried out under lab conditions such as this is difficult to extend to human life and that there is very little evidence to support such a claim.