Breast Cancer and Endocrine Disruptors

environmentally pervasive xenoestrogenic chemicals have also been associated with human breast cancer. The connection between xenoestrogenic exposure and human breast cancer is a circumstantial one. It is based on the following nine parameters  

Parabens, which are used as preservatives in a multitude of food, cosmetic, and pharmaceutical products, have been shown to exhibit estrogenic properties and to accumulate chemically intact in human breast tissue 

Fetal exposure of mice to low doses of bisphenol A results in mammary gland effects, including neoplasias that are manifested in adult life. I73 74 Both bisphenol A sulfate and bisulfate have been shown to stimulate the growth of receptor-positive breast tumor cells. F51 

The compounds that have been identified as xenoestrogens vary widely in chemical nature. Many are highly lipophilic and slowly metabolized (TCDD, chlorinated hydrocarbon pesticides). Others are less lipophilic and more labile (phthalates) and some are hydrophilic (methyl paraben, aluminum chloride, and aluminum chlorohydrate). It is known that lipophilic chemicals are more readily absorbed through the skin than hydrophilic chemicals, but as has been pointed out repeatedly in this book, lipophiles facilitate the absorption of hydrophiles and contribute to unexplained mixture effects. Table 22.3 lists some of the known xenoestrogens, types of products they are used in, and their K)w values. 

The role of cosmetics in promoting the onset of breast cancer has received considerable attention. Xenoestrogens from environmental sources (PCBs and organochlorine pesticides) have been found in breast adipose tissue and in human breast milk. The breast, however, is also exposed to xenoestrogens that are applied topically to underarms and breast skinJ77,81 These include 

---