The concentrations of five
esters of p-
hydroxybenzoic acid (
parabens) were measured using HPLC-MS/MS at four serial locations across the human breast from axilla to sternum using human breast tissue collected from 40
mastectomies for primary
breast cancer in England between 2005 and 2008. One or more
paraben esters were quantifiable in 158/160 (99%) of the tissue samples and in 96/160 (60%) all five
esters were measured. Variation was notable with respect to individual
paraben esters, location within one breast and similar locations in different breasts. 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 cannot 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 (37-91 years), length of breast feeding (0-23 months), 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).