Chemical Exposures and Breast Health

Article Author: Jade Wagner, Public Health Major, Class of 2024, Co-Director 

In our daily lives, we reach for personal care products that cater to our unique needs, from moisturizing lotions to fragrant shampoos and makeup essentials. These products help us feel and look our best, but what many of us don’t realize is that they often contain chemicals that can have lifelong effects on our breast health. 

A study published last summer,  “Chemical Effects on Breast Development, Function, and Cancer Risk: Existing Knowledge and New Opportunities,” examines the potential impact of chemical exposures on breast development, function, and cancer risk. The study discussed trends of concern pertaining to earlier breast development, breastfeeding difficulties, and rising breast cancer rates in young women, all of which were associated with chemical exposures, particularly endocrine-disrupting chemicals (EDCs). EDCs can affect hormonal regulation, however “since EDCs and mixtures are unavoidable in daily life, it is difficult for epidemiological studies to pinpoint effects of any single chemical, making controlled experiments in rodents imperative to identify harmful exposures.” The authors emphasize the need for a more rigorous approach to identify effects of harmful chemical exposure. 

The mammary gland (MG) is a hormonally regulated organ that undergoes changes and transformation throughout development, from prenatal development to puberty, pregnancy, and beyond. The constant changes to the MG allows for potential hormonal disruption for development and function – “with monthly cycles of proliferation and regression, full differentiation at the first full-term pregnancy, and more extensive regression after menopause—mak(ing) the organ vulnerable to disruption, with the potential for persistent effects for both a woman and her offspring.”

A comprehensive examination of scientific evidence reveals four crucial aspects of breast health that can be affected by chemical exposures:

1. Lactation: Environmental exposures have been associated with decreased breastfeeding duration, leading to impaired offspring weight gain. These exposures can interfere with the development of the mammary gland and can affect the hormonal processes that control breast milk production. Other “chemicals with evidence of effects on lactation in rodents include (PFOA), atrazine, BPA/S,  TCDD, triclosan and the pharmaceutical ziracin.”

2. Pubertal Development: Certain chemicals can alter the timing of pubertal development, leading to changes in the breasts. “In recent decades, girls have been achieving pubertal milestones at increasingly earlier ages, with larger shifts in breast development (thelarche) compared to circulating sex hormone levels and age at menarche.” Early thelarche has been linked to an increased risk of breast cancer.

3. Breast Density: Chemical exposures have been associated with increased mammographic density (MD). High MD “can have a greater than four-fold higher risk of breast cancer than those with low MD.” It has also been linked to more aggressive tumors. 

4. Breast Cancer: Studies show that there is a connection between chemical exposures and an increased likelihood of developing breast cancer. More than 200 chemicals have been shown to induce mammary tumors in rodent cancer studies, meaning that they may also elevate human breast cancer risk.

Assessing key windows of susceptibility (WoS) is vital for identifying the effects of EDCs on the developing MG. These chemicals can have adverse effects during any of the WoS, from gestational to menopausal periods, with early developmental changes potentially predisposing breast tissue to adverse outcomes later in life. “Increasing the rigor of MG assessment would improve our ability to identify chemicals of concern, regulate those chemicals based on their effects, and prevent exposures and associated adverse health effects.”

As seen from the review of other research, the authors point out that we  know that chemical exposures from EDCs are associated with breast cancer and other health issues. These exposures are not only affecting us – there is a multigenerational effect of harmful chemical exposure. By understanding the impact of chemical exposures on breast health, we can make educated decisions when it comes to preventing health issues, such as breast cancer. Now equipped with this knowledge about the potential risks associated with chemical exposures, we can make more informed choices when selecting beauty and skincare essentials as well as  other products and packaging.


Kay, J. E., Cardona, B., Rudel, R. A., Vandenberg, L. N., Soto, A. M., Christiansen, S., Birnbaum, L. S., & Fenton, S. E. (2022). Chemical Effects on Breast Development, Function, and Cancer Risk: Existing Knowledge and New Opportunities. Current Environmental Health Reports, 9(4), 535–562.

Aided by ChatGPT, human-checked and edited content for accuracy and clarity.

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