Common Chemicals May Act Together to Increase Cancer Risk

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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.

Depending on the type of chemical and the way it is used, chemical use in the United States is regulated by the Food and Drug Administration, the Environmental Protection Agency, or the Department of Agriculture.

Each of these agencies sets safe levels of exposure for the chemicals it regulates.

A study suggests that common chemicals in the environment that are considered safe at low doses may act together synergistically to increase cancer risk.

The study was published in the July 20, 2015 issue of the journal Carcinogenesis. Read “Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead.”

In the study, the researchers studied the effects of low doses of 85 common chemicals classified as non-cancerous to humans. The chemicals included bisphenol A (BPA), which is used in many rigid plastic products and on the shiny side of paper cashier receipts; rotenone, a chemical used to kill many insects; and triclosan, an antibacterial compound used in soaps, hand sanitizers, and cosmetics.

Using large databases of cancer information and models that predict cancer development, the researchers compared the chemicals’ activity in the human body to 11 cancer “hallmarks” -- patterns of cell and gene activity linked to the early development of cancer tumors.

The researchers found that 50 of the 85 chemicals were linked to one or more of these cancer hallmarks, even at low doses that have been considered safe. For 13 of the chemicals, the researchers found what is called a “dose-response threshold.” This means that there was a level of exposure that disrupted cell function so much that it would be considered toxic by the regulating agencies.

"Our findings also suggest these molecules may be acting in synergy to increase cancer activity," said Dr. William Bisson, assistant professor and cancer researcher at Oregon State University and a team leader on the study. "For example, EDTA, a metal-ion-binding compound used in manufacturing and medicine, interferes with the body's repair of damaged genes.

"EDTA doesn't cause genetic mutations itself," Bisson continued, "but if you're exposed to it along with some substance that is mutagenic [changes DNA], it enhances the effect because it disrupts DNA repair, a key layer of cancer defense."

The researchers said the study wasn’t meant to scare people, but to highlight gaps in our knowledge of cancers influenced by our environments and to create a research agenda for the next few years. More studies are needed to further investigate early exposure to chemicals and to understand how low doses of chemicals may work together to increase cancer risk.

It’s important to know that the hazards of chemical exposures depends 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.



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