Electromagnetic fields such as electrical transmission lines, micro-wave towers. EMF's also reduce production of melatonin of which deficiencies are linked to increased breast cancer. Petrochemicals such as gasoline, kerosene, formaldehyde and benzene may be linked to breast cancer. Habitual sunscreen users have very low levels of Vitamin D which is an anti-oxidant and inhibits the initiation phase of breast cancer. Underwire bras are the worst.
Pesticides collect in fatty tissue and the breast can become a reservoir.
Pesticides can have an estrogenic effect. Avoid imported produce as it tends to be more heavily sprayed. Fiber binds to estrogen in the bowel and eliminates it. Soy products are quite rich in phytochemicals, including genistein, which prevent the initiation and promotion of breast cancer. Tomatoes, rich in lycopene, strongly correlate with a lower risk of breast cancer.