Data of the European Cancer Registries indicate that the incidence of breast cancer, which is the most common cancer among women, tends to increase not only in postmenopausal but also in very young women. The potential causes of breast cancer are genetic predisposition, long -term hormonal replacement therapy, alcohol, environmental pollution, and possibly modern lifestyle. The controversial results of several studies suggest that certain everyday-use products (including cosmetic ingredients) may be linked to breast cancer. Some of these ingredients, such as ethylene oxide, have recently been classified by the International Agency for Research for Cancer as carcinogenic and mutagenic to humans, with sufficient evidence of carcinogenicity for breast cancer. Other ingredients, such as xenoestrogens, are chemicals which have an estrogen -like effect or disrupt the normal metabolism of the natural estrogen and thus act as carcinogens. Some of them have been shown to result in DNA damage in animal and human mammary epithelial cells and, therefore, have the potential to generate genomic instability in the breast tissue. Examples of xenoestrogens with such properties include parabens, aluminium salts, phthalates, or bisophenol A. No sufficient epidemiological data on humans have been published so far, and the effects of a mixture of chemicals to which women are exposed during lifetime on the incidence of breast cancer have not been investigated. However, the results of the available studies emphasize the need for analysis of adverse environmental factors, which, in addition to a genetic predisposition and natural aging, may contribute to the increased incidence of breast cancer.