Measurement of paraben concentrations in human breast tissue at serial locations across the breast from axilla to sternum.

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).