Environmental Exposure to Brominated Flame Retardants: Unraveling Endocrine and Mammary Gland Effects That May Increase Disease Risk.

Brominated flame retardants (BFR) are molecules added to consumer products to reduce fire hazards. They were banned in North America and Europe because of their persistence and biomagnification. However, BFR are still released in the environment due to continued use of products manufactured before restriction, and from waste and recycling processes of those products. As a result, they remain sources of chronic environmental and human exposure worldwide. BFR are well-characterized endocrine disruptors. They have been associated with a wide range of alterations in endocrine and reproductive systems both in humans and experimental models in vivo and in vitro. Paradoxically, the effects of BFR on mammary glands, whose development and carcinogenesis are mainly under hormonal dependency are poorly known. There is increasing weight of evidence that exposure to endocrine disruptors promotes breast cancer, especially if the exposure occurs during sensitivity windows. For the mammary gland, these windows include the perinatal life, puberty, and pregnancy, as important remodeling of the organ happens during those periods. The peak of exposure to BFRs happened during late 1990s and beginning of 2000s in most countries. Women who were pregnant at that time are reaching menopause while their daughters are 20-30 years old. It is thus important to better understand the effects of BFRs on mammary gland development and breast cancer to determine whether these women are more at risk. Thus, this review aims to propose a comprehensive review of data reporting the effects of exposure to BFR on female endocrine and reproductive systems, with a particular focus on mammary gland development and of a potential increased risk of breast cancer.