Depending on where you live and work, you’re likely to be exposed to a number of chemicals every day. Plastic food and beverage containers, personal care products, sunscreen, cleaning products, and lawn and garden products all contain chemicals. Chemical pesticides are used in many commercially grown fruit, vegetable, and grain crops to protect them from insects, weeds, diseases, and other pests.
A study suggests that exposure to certain chemicals in the environment, especially early in life, is linked to a higher risk of breast cancer.
The study was published online on Oct. 6, 2017 in the journal Environmental Research. Read “Environmental chemicals and breast cancer: An updated review of epidemiological literature informed by biological mechanisms.”
In 2007, the researchers that did this study published a review paper on the link between environmental chemicals and breast cancer. The review identified 216 chemicals that are linked to mammary tumors in animals and offered guidelines for studying the chemicals in people.
To do the study reviewed here, the same researchers searched through studies on the 216 chemicals linked to mammary tumors in animals published between 2006 and 2016. The researchers reviewed 158 of the studies in light of new information on the biology of breast cancer, including the influence of genetic variations and hormones on the development of the disease.
The results of the studies reviewed suggest that exposure to certain chemicals early in life -- in the womb, during puberty, and during pregnancy -- increases the risk of developing breast cancer later in life. The chemicals included:
- DDT, a pesticide banned by the U.S. Environmental Protection Agency in 1972; still, the chemical persists for long periods in the environment and some residues still remain
- dioxins, which are formed when fuels such as wood, coal, or oil are burned; like DDT, dioxins persist for long periods of time in the environment
- air pollution
- organic solvents used in industry, including benzene and dimethylformamide (DMF)
Differences in people’s genetic make-up also can affect how they respond to certain chemicals. One study reviewed found that among women exposed to polycyclic aromatic hydrocarbons (PAHs), a chemical in vehicle exhaust, women with certain genetic variants had a higher risk of developing breast cancer.
"During these so-called windows of susceptibility, the body is changing, breast cells are dividing quickly, and the breast tissue becomes vulnerable to damage from chemicals," said lead author Kathryn Rodgers, a research scientist at the Silent Spring Institute, a nonprofit organization dedicated to studying links between environmental chemicals and women’s health, especially breast cancer. "Every day, we come into contact with many different chemicals, and new ones are constantly being introduced to the market," she added. "Unfortunately, it's hard to measure exposures to multiple chemicals at multiple times in a person's life."
It’s important to know that the hazards of chemical exposures depend on a lot of things, including the amount of exposure, the frequency of exposure, the duration of exposure, and your age when exposed. Chemicals considered carcinogens usually require regular exposures over long periods of time to contribute to the cause of cancer. It can be a regular, low exposure over time or a large exposure for brief periods of time. Most of the information we have comes from laboratory animals, not people.
At Breastcancer.org, we look at things in your life that go in, on, and around you. If there is a significant concern about a substance, we want to help you make the best choices. If something may pose a hazard, in the absence of solid research in people, we lean on the Precautionary Principle. Basically, it means that it’s better to be safe than sorry. Our goal is to help you make the best choices for you and your family.
In the Breastcancer.org Breast Cancer Risk Factors section, you can read about chemicals in cosmetics, chemicals in plastic, chemicals in sunscreen, chemicals in water, and chemicals used on lawns and gardens and steps you can take to keep your exposure as low as it can be.