Background: The rising incidence of breast cancer suggests lifestyle and environmental causes. During the last decade many chemicals, among which parabens and aluminium, have been shown to express estrogenic properties in in-vitro and animal studies. A causative relationship theory between chemicals and breast cancer has been proposed. Another theory has linked the use of underarm cosmetics with the increased prevalence of breast cancer in the upper outer quadrant.Purpose: We conducted this study to investigate the presence and distribution of five commonly used esters of para-hydroxybenzoic acid and aluminium, in the female breast and their possible relationship with breast cancer development. We attempted to shed light into the link hypothesis between underarm cosmetics and breast cancer. Materials and methods: Fourty breast cancer patiens who would undergo mastectomy, completed the study questionnaire with information about underarm cosmetics use and other lifestyle and epidemiological parameters. Histological information was retreived from their medical records. We obtained tissue samples from four different regions across every mastectomy specimen, from the axilla to the sternum and analysed them for parabens and aluminium.Results: Parabens and aluminium were found intact in almost all samples. The distribution in the four regions across the breast from the axilla to the sternum was homogenous and independent of the patient’s age, tumor location and hormone receptor status. There were no significant differences in the concentrations between women who had used underarm cosmetics and those who had not, or those who had used them in the past but have now stopped using them. There was no correlation between the length of underarm cosmetic use and the the concentration of parabens and aluminium across the breast.Discussion: This is the first study to demonstrate the presence of five commonly used p-hydroxybenzoic acid esters and aluminium in the healthy female breast tissue. The measured concentrations are low and the pattern of distribution is homogenous but universal in the studied population, thus allowing the expression of their weak estrogenic properties for a lifelong period. We did not find a causative relationship with breast cancer. However, our findings can be added to those from other in-vitro, animal and human studies on the presence, properties, and combined effect of several widely used chemicals with hormonal properties. In the light of this relatively recent evidence there is an urge for developing biomonitoring techniques, determining the total chemical burden, and investigating the mixture effects in humans. Prevention policies should support the reduction of exposure to artificial chemicals, especially to those categorised as endocrine disrupters and for vulnerable groups.Conclusions: Parabens and aluminium can be found intact in the healthy female breast. Underarm deodorants or antiperspirants do not constitute the main source of parabens and aluminium for the female breast and cannot be… Advisors/Committee Members: Barr, Lester.