Presence does not prove causality. Just because something can get into your system and can be found in your urine doesn't automatically make it a toxin. Vitamins? Minerals? Beneficial medications? Again, it can be about dosage and appropriate use.

For example certain apparently benign over-the-counter health supplements can cause liver damage and serious medical complications if used inappropriately.

I went to the Channel 4 website to check what they'd written about their own programme. I found this [emphasis added]:

Parabens are related to a chemical called benzoic acid which was discovered in the 16th century, and subsequently used to preserve products against moulds, yeasts and some bacteria. The most commonly used parabens have been methylparaben (E number, E218), ethylparaben (E214), propylparaben (E216), and butylparaben. But E216 is one of two parabens (the other being sodium propylparaben, E217) which have recently been withdrawn under revised EC regulations on food additives. While some parabens are found naturally in plants, those used as preservatives are made in the laboratory.

Recent worries about parabens are based on a series of British studies linking the chemicals to breast cancer. In one study, laboratory tests showed that parabens weakly mimic the activity of the natural female hormone, oestrogen. While all women need oestrogen, the hormone is known to help some breast tumours to grow, and part of breast cancer treatment aims to stop the effects of oestrogen.

In another study, parabens, especially methylparaben (E218), were found in 18 out of 20 samples from breast tumours. While there is no proof, it has been suggested that parabens contained in deodorant products may be absorbed through the skin under the arm and be involved in development of cancer in nearby breast tissue.

Neither of two leading cancer charities, Cancer Research UK and Breakthrough Breast Cancer, support this theory. Instead, they point out that it was a very small study, and it did not compare parabens levels in breast tissue from women who did not get breast cancer. Instead, they quote a large US study which failed to show that women who use deodorants or antiperspirants were more likely to get breast cancer.

Cancer Research UK points out that over 90% of today's deodorants and antiperspirants don't contain parabens. So if you are worried about a possible link with breast cancer, you should be able to find products which are parabens-free.

I found it interesting that the content on Channel 4's own microsite presented the subject with a different slant. The above text was not included in the script of the TV show. Instead the programme was almost devoid of real content. An interesting addition to the television show, for example, would have been to report that The European Commission had planned a technical hearing on behalf of the Scientific Committee on Consumer Products (SCCP) on the safety evaluation of "Parabens in cosmetic products", in order to follow-up the SCCP opinions on the subject. The hearing was on 23 October 2007 in Brussels.