Environmental chemicals are widely distributed chemicals that have been shown to disrupt hormones, although it is not clear which hormones in humans are being disrupted. These chemicals may also cause reproductive abnormalities, birth defects and type 2 diabetes. Most chemicals are associated with industrial pollution.
Dioxins and PCB's are two of these chemicals. Because they persist in the environment and are not metabolized when consumed, they are not excreted from the body. Therefore these chemicals accumulate in body fat and breastmilk of lactating mothers. Some of these chemicals are known to promote the growth of cancer cells although humans may not be at significant risk unless one consumes excessive quantities of meat, milk, and fish. 90 to 95% of our exposure to these chemicals comes from consuming animal products!
A second group of these environmental chemicals also perceived to be significant causes of breast and other cancers are called PAH's (Polycyclic Aromatic Hydrocarbons). They are found in auto exhaust, factory smoke stacks, petroleum tar products and tobacco smoke. While PCBs and dioxins cannot be metabolized and excreted, PAH's in food and water can be. Here's the caveat, they produce intermediate products that react with DNA to form tightly bound complexes or adducts which is the first step in causing cancer. In fact, these chemicals have recently been shown to adversely affect the BRCA-1 and BRCA-2 gene's of breast cancer cells grown in the laboratory.
Here is what so many people do you not realize. When carcinogens enter our body, the rate at which they cause problems is mostly controlled by nutrition. Long story short, consuming a westernized type diet will increase the rate at which chemical carcinogens like PAH's bind to DNA to form products that cause cancer. Environmental chemicals seem to play a far less significant role for breast cancer than the kind of foods we choose to eat every day.