MANCHESTER, England—Researchers at the Genesis Breast Cancer Prevention Center at the University Hospital of South Manchester measured the concentrations of five esters of p-hydroxybenzoic acid (parabens) at four serial locations across the human breast, from axilla to sternum, using human breast tissue collected from 40 women undergoing mastectomies for primary breast cancer in England between 2005 and 2008 (J App Toxicol. Jan. 12, 2012). They found one or more paraben esters were quantifiable in 158/160 (99 percent) of the tissue samples and in 96/160 (60 percent) all five esters were measured. Variation was notable with respect to individual paraben esters, location within one breast and similar locations in different breasts.
The 2004 study that found intact esters in human breast tumor tissue at a mean level of 20.6 nanograms per gram-1 tissue sparked international debate because, although parabens were thought to possess low toxicity (Golden et al., 2005; Soni et al., 2005), studies from 1998 onwards (Routledge et al., 1998) had begun to show parabens as possessing oestrogenic properties (reviewed in Darbre and Harvey, 2008), and oestrogen is known to play a central role in the development, growth and progression of breast cancer (Miller, 1996). Although the source of the paraben could not be identified in the human breast tissue, it was suggested that low-level dermal absorption from personal-care products applied to the breast region over the long term might have contributed.
The current study found overall median values in nanograms per gram tissue for the 160 tissue samples were highest for n-propylparaben [16.8 (range 0–2052.7)] and methylparaben [16.6 (range 0–5102.9)]; levels were lower for n-butylparaben [5.8 (range 0–95.4)], ethylparaben [3.4 (range 0–499.7)] and isobutylparaben 2.1 (range 0–802.9). The overall median value for total paraben was 85.5 ng g-1 tissue (range 0–5134.5). The source of the paraben could not be identified, but paraben was measured in the 7/40 patients who reported never having used underarm cosmetics in their lifetime. No correlations were found between paraben concentrations and age of patient (37 to 91years), length of breast feeding (0 to 23 months), or tumour location or tumour oestrogen receptor content.
In view of the disproportionate incidence of breast cancer in the upper outer quadrant, paraben concentrations were compared across the four regions of the breast: n-propylparaben was found at significantly higher levels in the axilla than mid (P=0.004 Wilcoxon matched pairs) or medial (P=0.021 Wilcoxon matched pairs) regions (P=0.010 Friedman ANOVA).
Philippa D. Darbe, M.D., leader in oncology, School of Biological Sciences, Biomedical and Pharmaceutical Sciences at the University of Reading, England, told Inside Cosmeceuticals: "There is no proven link with breast cancer either of parabens or any personal care product; however, absence of evidence is not evidence of absence; we simply do not know one way or the other. If these chemicals did not enter the human breast, then there would be no question. The fact that they are there needs more research to find out if they can cause any adverse effects from their presence either alone or in combination. Personally, I have always felt that the issue is bigger than parabens alone—that is not to say that I do not hypothesise that parabens play a role, but rather that the overall picture involves more than just parabens."
