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Leena Hilakivi-Clarke, PhD, professor at The Hormel Institute, University of Minnesota, is the author of a paper appearing in the scientific journal iScience titled “Aromatics from fossil fuels and breast cancer.”

In a review of existing scientific literature, researchers identified links between exposure to benzene, toluene, ethylbenzene and xylene (BTEX) aromatics and polycyclic aromatic hydrocarbons (PAHs) from fossil fuels and breast cancer risk in humans.

Breast cancer rates continue to rise, especially in young women. Years of scientific research has shown breast cancer risk which runs in families is often caused by germline mutations — mutations in parental cells that are passed down to offspring. BRCA1 and BRCA2 are two of the most commonly known genetic mutations linked to inherited breast cancer risk.

At the same time, more than 80% of breast cancers develop sporadically without any inherited mutations — and causes for these breast cancers have remained unknown. Several risk factors have been identified, such as timing of puberty onset and menopause, age at first pregnancy, diet and lifetime exposure to estrogens. However, these factors do not cause breast cancer, but alter vulnerability to environmental carcinogens that then can cause breast cancer.

The Biofuels Research Project researchers have studied the carcinogenic (cancer-causing) effects of compounds originating from burning fossil fuels.

In their newly published review of existing scientific literature, researchers identify exposure to PAHs from fossil fuels as key mutagens (compounds that can lead to DNA mutations) causing breast cancer in humans.

Among their key findings:

• Exposure to BTEX aromatics in fossil fuels may add to the adverse effects of PAH exposure.

• Exposure to BTEX compounds early in life, including in utero, may increase susceptibility to PAH-initiated breast cancer.

• Early life exposure to BTEX compounds may increase later breast cancer risk by silencing DNA repair mechanisms, increasing the number of targets in the breast that are known to be the sites where breast cancers are initiated (terminal lobular ductal units or TLDUs), and causing persistent gut dysbiosis (imbalance of healthy and harmful gut bacteria) which in turn impairs immune responses in the tumor microenvironment, preventing effector CD8+ T cells from killing cancer cells.

“It is essential to reduce exposure to the products from burning fossil fuels to prevent breast cancer. We are studying if reducing BTEX exposure will reduce susceptibility to PAH induced breast cancer. One way to reduce BTEX compounds is to reduce exposure by adding ethanol to gasoline,” Hilakivi-Clarke said.

The Hormel Institute researchers Theresa Jolejole, PhD candidate; Joas Lucas da Silva, PhD, post-doctoral associate; and Fabia de Oliveira Andrade, PhD, senior scientist, are among the authors of the paper.

The research project is supported by 15 different ethanol and biofuels funding agencies.