There are NOT only the colors under the magnifying glass – for more than 40 years – of epidemiologists. Other substances contained in cosmetic hair products have also been investigated for a long time, to understand whether or not there is a correlation with the onset of breast cancer. And the message coming from the latest published data on the subject, particularly on the use of relaxing products, is reassuring: no clear association was observed. Well, that was exactly what was expected, and we understand why on the newsletter Breast Health this week here is the link to register for free
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Saluteseno: women who have cancer tell
by Tiziana Moriconi
The first suspects of the 70s
“The attention to hair products, in particular for dyes, had emerged very strongly in the mid-70s – he says Carlo La Vecchia, professor of Medical Statistics and Epidemiology at the State University of Milan – a new mutagenesis test had just been introduced – the Ames test, invented by Bruce Ames – which made it possible to test any substance in a very simple way to understand whether it could damage DNA and potentially induce the development of tumors in vitro. Many substances were tested: it was discovered that some hair dyes contained mutagens and, consequently, were considered suspected carcinogens “. These compounds were taken off the market and replaced, but at that point population studies began to see if the women who had used them up to that point were at greater risk of cancer. In particular, breast cancer, mainly for two reasons: breast cancer was (and is) the most common female cancer, and the breast has a large percentage of adipose tissue, in which some substances can accumulate. “Understanding whether dyes increased the risk of breast cancer was one of the reasons why the Nurses’ Health Study, one of the largest and most famous observational cohort studies ever conducted, was born in the United States,” La Vecchia points out.
Breast cancer, it’s time to talk about sex
by Tiziana Moriconi
New data and an old (unconfirmed) hypothesis
Another similar study is the Black Women’s Health Study, conducted on the population of 59,000 women of color, which started in 1995. Also in this case, the aims were to investigate a possible increase in the risk of breast cancer, both linked to dyes and smoothing substances. The new data collected, analyzed by Boston University School of Medicine epidemiologists and recently published in Carcinogenesis, come from this cohort and put other chemical compounds under the lens, including i paraben he phthalates, due to their potential role as endocrine disruptors, therefore capable of interacting – in theory – with the hormonal system. “The study is well done – continues the epidemiologist – and it started from a hypothesis: that these endocrine disruptors could be associated with breast cancer. There was therefore a reason to investigate, although the studies conducted so far have not provided support for this hypothesis ”.
In recent years in the Black Women’s Health Study there have been 2,311 cases of breast cancer that do not appear to be related to the use of straighteners with parabens and phthalates: there is no relationship either with the duration or with the frequency (the effect of a substance on the body, in fact, depends not only on its action, but also on the dose and the exposure time). A possible slight increase in risk resulted from very frequent use (greater than 7 times a year for over 15 years) for relaxing products containing lye, but – as the researcher who coordinated the study also remembers, Kimberly Bertrand, “Solid results from numerous studies are needed before we can conclude that the use of certain straighteners influence the development of breast cancer.” The fact that the study is conducted on a black population makes the results particularly interesting, since these women make more use than Caucasian women of relaxing products for curly hair, as well as dyes of dark color and therefore, theoretically , are more exposed to possible toxicity.
“In general, what emerges from the data of all these studies, which continue to be correctly analyzed, is that even for those who used dyes and straighteners before the 1980s, there does not seem to be an increase in risk, and even more so after”, he says. La Vecchia again. As the website of the Airc Foundation also reports, in fact, for the substances currently in use “there seems to be a single study (albeit on large numbers), the results of which revealed a higher risk than the norm, but limited to women who use them. frequent and have familiar with breast cancer. However, the study was conducted in the USA where the regulations on the chemical components of dyes are different from those in Europe and, in general, less restrictive ”.
Endocrine disruptors, parabens and phthalates
The discourse on endocrine disruptors, however, is different from what can be done for toxic substances in general. “These compounds have the potential to interfere with hormone receptors,” he explains Angelo Moretto, toxicologist, director of the Operating Unit of Occupational Medicine of the University Hospital and of the Department of Cardio-Thoraco-Vascular Sciences and Public Health of the University of Padua: “There is, therefore, a supposed mechanism of action. But parabens and phthalates are thousands of times less potent than our hormones. And since the endocrine system is able to keep itself in balance, I don’t expect any effects from such underpowered substances. And, in fact, there is no evidence of negative effects on human health ”. Add to this that in Europe we have a very stringent chemical evaluation system. “The amount of information we have on these substances is really very high and the evaluations that are made are always very precautionary”, Moretto emphasizes.
Research on environmental causes, Tos and alcohol
The two experts agree: apart from the prolonged use of hormone replacement therapy (Tos) for women in menopause, to date we have no evidence of exogenous substances – except for alcohol – that increase the risk of breast cancer, a unlike what we know for other cancers, such as that of the bladder or lung. “Research on environmental causes is carried out, although they are underfunded and in fewer numbers than clinical studies”, concludes La Vecchia: “However, strong modifiable environmental causes have never emerged, beyond overweight in post-menopause, therapies substitutes in menopause and alcohol. And this is demonstrated by the fact that breast cancer is the only common cancer in women all over the world ”.
More data on hair products will be published in the coming years from these and other population studies. They will be partly contradicting and inconclusive, as is normal because cohort studies are complex. But they will add new pieces of information and continue to investigate, also in the light of new knowledge on the molecular biology of tumors.
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