Chemicals not thought to be carcinogenic may still cause cancer when combined


It’s well-known that certain substances like asbestos cause cancer. Now, new research shows that combined effects of chemicals not thought to be carcinogenic on their own may be a significant cause of the deadly disease.

That’s according to the Halifax Project, a group of hundreds of researchers from around the world that recently published a series of ground-breaking papers in a special issue of the journal Carcinogenesis.

Between seven and 19 per cent of cancers are due to toxic environmental exposures, the study says. Many chemicals are known to accumulate in the body over time, and when combined, they may work together to cause cancer.

Given the thousands of chemicals that people are exposed to every day, the findings of the Halifax Project are cause for concern, according to the Washington, D.C.–based Environmental Working Group.

“We know that cancer is a multistep process,” EWG senior scientist Curt DellaValle tells Yahoo Canada.  “Of the 85 chemicals they looked at, 50 were able to disrupt cancer-related pathways at low doses. This means we might have to reconsider what we consider carcinogens.

“Research has been focused on looking at individual chemicals that can cause cancer on their own, but now we’re learning that might be only one piece of the puzzle,” he says. “It may be that combinations of those chemicals may initiate enough hits against our cells that they help develop cancer.”

A new EWG report called Rethinking Carcinogens found that 23 of the 85 chemicals investigated by Halifax Project—including phthalates and pesticides—have been measured at detectable levels in the bodies of people participating in the U.S. Centers for Disease Control and Prevention’s annual National Health and Nutrition Examination Survey.

Among the chemicals known to disrupt certain cancer-related pathways found in people’s bodies, including umbilical-cord blood, were:

  • Acrylamide

  • Bisphenol A (BPA)

  • DDT

  • Dibutyl phthalate (DBP)

  • Lead

  • Mercury

  • Phthalates

  • Triclosan

 Not only that, but there are other chemicals that are quickly eliminated from the body and unlikely to be analyzed or detected in a survey like the one above, according to the EWG. Just because a chemical passes quickly through the body, doesn’t mean it poses no health risk. The pesticide glyphosate, for instance, which the World Health Organization recently classified as probably carcinogenic, remains in the body for only a few hours after exposure. 

“Even if chemicals aren’t necessarily accumulating in the body for long periods, they could be interacting in our body in ways we hadn’t predicted,” DellaValle says. He adds that while exposure to toxic chemicals play a lesser role in causing cancer than factors like smoking, sun exposure, poor diet, and lack of exercise, avoiding chemicals as much as possible can help prevent the disease.

Earlier this year, New York state held its first Cancer Prevention Summit, where Dr. Graham Colditz, deputy director of the Institute for Public Health at Washington University in St. Louis, presented eight ways to reduce cancer risk: 

  •  Maintain a healthy weight.

  • Exercise regularly. Walking just 30 minutes five or more days a week and not sitting for extended periods can dramatically improve health.

  • Don’t smoke, and avoid second-hand smoke.

  • Eat a healthy diet rich in plant-based foods, low in processed foods and red meats, and not too high in calories.

  • Drink alcohol only in moderation, if at all.

  • Protect yourself from the sun.

  • Avoid sexually transmitted infections. Practice safe sex and get recommended vaccinations, particularly for human papillomavirus (HPV) and hepatitis A and B.

  • Get screened for cancer. Consult your physician to determine what screenings are recommended, and when.

To that list, the EWG recommends people minimize their exposure to toxic chemicals in everything from personal-care and house-cleaning products to food and plastics and more.

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