The results of an animal study suggest that infants exposed to BBP, a chemical additive used in pipes, vinyl floor tiles, carpet-backing, and other household items, may affect mammary gland development and perhaps increase the susceptibility to breast cancer. BBP (n-butyl benzyl phthalate) is a "plasticizer," which is added to substances such as cement, concrete and clay to increase fluidity.
This study is the first "demonstrating that exposure to this compound soon after birth results in alterations in the expression of genes present in the mammary gland," senior author Dr Jose Russo, from Fox Chase Cancer Centre in Philadelphia, told Reuters Health.
"Our findings are unique in the sense that we are studying the lifetime effect of BBP on the mammary gland, long before it starts developing under the influence of the hormones of puberty," he added. Russo's group originally observed genetic changes induced by BBP that occur very early in life, which may "result in significant modifications in the risk of the mammary gland to develop cancer later on in life."
The researchers fed BBP to lactating rats, and their offspring absorbed the chemical in breast milk. According to the report, the amount of BBP ingested by the offspring was roughly equivalent to the safe dose limit for humans established by the Environmental Protection Agency.
BBP exposure increased the uterine and body weight ratio in female offspring and decreased the body weight.
Lasting genetic effect
Although exposure to the chemical did not affect the appearance of the mammary gland, it did increase the proliferation of cells in lobules and other breast tissue compartments. Genetic analysis revealed that BBP exposure also increased the expression of several genes related to cell proliferation and differentiation, communication, and signal transduction.
Many of these effects seemed to disappear after BBP exposure was removed; however, the subtle genetic changes may have a lasting effect, the report indicates.
"The take-home message is that for preventing breast cancer in adulthood it is necessary to protect both the newborn child and the mother from exposure." BBP has an effect on oestrogen and may disrupt hormone production, Russo emphasized.
His group is currently conducting studies to evaluate the influence of these early changes in gene expression induced by BBP and the response of breast tissue to exposure to chemical carcinogens later in life, he added. - (Anthony J. Brown, MD/Reuters Health)
SOURCE: BMC Genomics