Antiperspirants and deodorants linked to breast cancer
A new study, which investigated whether the use of antiperspirants and deodorants increase the risk for breast cancer, relieved some concerns about a relationship; however, it also raised some questions and concerns. Researchers at the University of Reading, United Kingdom investigated parabens (alkyl esters of p-hydroxybenzoic acid), which are widely used as antimicrobial preservatives in pharmaceuticals, foods, and cosmetics. The study was published online January 12 in the Journal of Applied Toxicology.
About 10 years ago, studies began to surface that reported that parabens had estrogenic properties; it is known that estrogen plays a central role in the development, growth, and progression of breast cancer. In this new study, the researchers examined 160 breast-tissue samples obtained from 40 patients who had undergone a mastectomy for primary breast cancer. They found that 99% of samples had traces of at least one paraben, and that 60% had traces of five different parabens. Of significance, seven of the women reported never having used underarm products. In view of this finding, the authors suggested that the parabens originated from another source. They noted that the source of the parabens measured in the current and previous studies could not be identified; furthermore, they reported that it was unclear if the paraben traces came from long-term accumulation, current exposure, or a combination of both. “I do think that the parabens are only one part of a much bigger picture," said lead author Philippa D. Darbre, PhD, a reader in oncology at the university. She added, “That is not to say that they do not contribute, but the issue is bigger." She added that parabens are only one component of personal care products and what is now needed is a map of what chemicals there are in a human breast in the modern world and how they distribute across the breast, especially in relation to the site of the tumor.
The researchers found a disproportionate incidence of breast cancer in the upper outer quadrant of the breast. In all 40 women, paraben levels were higher in the axilla (armpit) region than in the mid or medial regions. The authors noted that this finding is not unusual; a number of studies over the past several decades have reported that a disproportionately high number of breast tumors in women originate in the upper outer quadrant of the breast for which a definitive explanation is lacking. This disproportionality has been increasing in the U.K. and currently exceeds 50% of breast cancers.
Personal care products have been used since antiquity; however, unprecedented quantities are being used currently, and are ultimately being released into the environment, explained Dr. Darbre. Investigations have shown that there is widespread aquatic environmental pollution stemming from their use, and therefore little doubt that these chemicals are entering human tissues. The human breast has "become a sink for lipophilic compounds due to its high adipose tissue content," she said.
However, in a previous study, Dr. Darbre and her team noted that it remains to be determined whether there is any causal relation between individual or combinations of chemicals and the development of breast cancer. The researchers noted that the real environmental impact of estrogenic chemicals needs to comprise the entire chemical load in the breast. They added that an increasing number of environmental chemicals with estrogenic properties have been measured in human breast tissues, which shows that the human breast is exposed to many estrogenic compounds in low doses and over a long period of time. These chemicals could act synergistically to "produce an estrogenic stimulus even at concentrations at which each alone would be ineffective."
The authors noted that a gap exists in our understanding of the combined effect of different chemicals in a single human breast because reports of measurements to date have generally evaluated only single groups of chemicals in any one study group. "In the meantime, I remain rather ambivalent about hounding just one chemical," said Dr. Darbre. "My advice remains as always: to cut down on, or cut out as much as possible, overall use of personal care products, especially those left on the skin around the breast area." She added, "When even the water systems are now having to remove personal care product compounds from them, we must be simply using too much in the modern world — too much for our own bodies and too much even for the environment. The only way forward at the moment is for us all to cut down."
In the current study, the researchers measured the concentrations of five parabens at four serial locations in the human breast, from the axilla to the sternum (breast bone), using tissue samples collected in from 2005 to 2008. They found that at least one paraben ester was quantifiable in 158 of 160 specimens (99%), and that allfive5 esters were quantifiable in 96 of 160 specimens (60%). The overall median value for total parabens in the breast tissue was 85.5 ng/g (range, 0.0 to 5134.5 ng/g). This level is four times higher than the 20.6 ng/g seen in a smaller previous study, which was also led Dr. Darbre. The highest values were observed for n-propylparaben, at 16.8 ng/g (range, 0.0 to 2052.7), and methylparaben, at 16.6 ng/g (range, 0.0 to 5102.9). They were much lower for n-butylparaben, at 5.8 ng/g (range, 0.0 to 95.4), ethylparaben, at 3.4 ng/g (range, 0.0 to 499.7), and isobutylparaben, at 2.1 ng/g (range, 0.0 to 802.9).
Reference: Journal of Applied Toxicology