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Should we worry about benzene in personal care spray products?

The publicity given by the media to the benzene issue in personal care products has been extensive and may have alarmed consumers more than warranted. However, when it comes to carcinogens, we should look to reduce any unnecessary exposure.

Probably not, but such products should not contain benzene and can be formulated without this contaminant. The issue arises because a number of products, including some deodorants, sunscreens, aerosol dry shampoos and athlete’s foot treatments have recently been recalled because they were found to be contaminated with trace amounts of benzene.

Let’s start with the basics. Benzene is an established carcinogen. And what does that mean exactly? It means that there is enough evidence to prove that at some dose, under some condition, benzene is capable of causing cancer. This has been determined via several lines of evidence. Feeding benzene to test animals, or exposing them to benzene vapour, causes cancer. Also, workers occupationally exposed to inhaled benzene have been shown to have an increased risk of leukemia. Add to this knowledge about how benzene is metabolized, and how some of the metabolites such as benzoquinone and muconaldehydes can produce free radicals that alter DNA, and we have pretty conclusive evidence that it is desirable to avoid benzene exposure.

The problem, however, is that total avoidance is impossible. Benzene occurs naturally in petroleum, and therefore in gasoline. Indeed, automobile exhaust is the largest source of benzene in the environment. The compound can also be found in numerous other products that are derived from petroleum including paints, glues, detergents, varnish removers and as we have seen, consumer spray products. The source of benzene in the latter is not clear. It may be a contaminant in the propane, butane or isobutene used as propellants, since these may be produced from petroleum distillates. “Carbomers,” which are polymers of acrylic acid used to stabilize suspended solids in liquids as well as to prevent emulsions from separating are another possible source. These polymers are sometimes synthesized using benzene as a solvent and as a result may contain some residue, although these days benzene has mostly been replaced by ethyl acetate or cyclohexane. The degradation of sodium benzoate, used as an antifungal preservative, may also give rise to traces of benzene.

Given that exposure to benzene cannot be totally eliminated, the question comes down to analysis of risk. For this, we look to data gleaned from occupational exposure. When researchers studied some 30,000 workers in 233 different factories where exposure to benzene was likely, they found roughly one case of leukemia for every 1000 workers. Consider, though, that this was constant exposure over years, quite a different situation from using a sunscreen spray when going to the beach. Exposure to benzene from such products is very likely too small to pose a risk, but if anyone is really concerned, they can just avoid spray products.

The publicity given by the media to the benzene issue in personal care products has been extensive and may have alarmed consumers more than warranted. However, we also learned that not all spray products are contaminated, so it is certainly possible to produce such items without any benzene present. The manufacturers of the products that have been recalled are all looking to alter their methodologies to eliminate benzene. While the risk may be small, when it comes to carcinogens, we should look to reduce any unnecessary exposure.


@JoeSchwarcz

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