Many healthy people are concerned about potential risks from exposures to air and water pollution, household chemicals, pesticides, and substances in the workplace. And for cancer patients, it can raise even more anxiety, with people wondering whether something in their environment triggered their disease.
However, links between environmental exposures and cancer have been difficult to prove on an individual level.
“There is a lot of misinformation or incomplete information about what’s going on with the environment and cancer,” says Timothy Rebbeck, PhD, professor of cancer prevention at Dana-Farber and director of the Zhu Family Center for Global Cancer Prevention at Harvard T.H. Chan School of Public Health. “Some people may be overly concerned, while many policy makers and industry are under-concerned.”
Rebbeck moderated the first in a three-part Cancer and Environment Forum 2022, sponsored by Dana-Farber, Mass General Brigham, and other organizations. Held over three days in February and March, the sessions were aimed at clinicians, researchers, and members of the public, with the theme “the new science on the influence of environmental chemicals on cancer.” One of the goals was to help prepare clinicians for conversations with patients about environmental causes of cancer based on emerging scientific research, and for how to contact public health professionals about suspected unusual occurrences of cancer in communities.
The first session discussed tools available to identify carcinogens, and how environmental exposures and genetic susceptibility can interact to cause cancer. Multiple streams of evidence, including experimental studies in animals and laboratory cell lines as well as observational epidemiology used by the International Agency for Research on Cancer, can categorize chemicals as known or suspected carcinogens.
One of the panel discussions was based on a cluster of childhood cancer cases in Wilmington, Mass., which has been traced to prenatal exposure to chemical contamination of drinking water in the 1990s. A Wilmington resident who spoke at the panel was diagnosed with Hodgkin lymphoma in 1991, believed to have been caused by his exposure in utero to tainted water from Wilmington wells. A study recently released by the Massachusetts Department of Public Health strongly suggests associations between the development of childhood cancers and maternal exposure to the carcinogenic compounds that had contaminated the Wilmington public water supply.
The disparities of air pollution
The second session, on air pollution and cancer, was moderated by Polly Hoppin, ScD, research professor of public health at the UMass Lowell Center for Sustainable Production. Hoppin said that the science linking air pollution to cancer is well-documented, and that clean air regulations have helped reduce pollution in the United States, mainly in particulate matter. However, she noted that exposure to air pollution is higher for many members of populations who are marginalized economically or racially, or who live nearer sources of pollution such as heavily traveled highways.
“Individuals can’t completely control what they breathe, and so population-level action is needed to give individuals — and their health care providers — resources to do what they cannot,” such as call on elected officials and others to take action, said Hoppin.
Roseann Bongiovanni, MPH, an environmental activist and executive director of GreenRoots in Chelsea, shared how certain communities can be dramatically more affected by pollution than the average community. She explained that Chelsea is extremely densely populated, with 73% of its residents being ethnic minorities, and disproportionately affected by exposure to jet fuel, heating fuel, gasoline, salt from road salt piles, and public health burdens.
Environmental exposures can be especially risky for cancer survivors, who may have long-term damage to their lungs and immune systems from treatment, said Judy Ou, PhD, MPH, of the University of Utah. “After diagnosis, cancer survivors live in the same environments that likely contributed to their cancers,” she noted.
Chemicals in the environment, women’s health, and sowing seeds of doubt
A prominent immunologist, Margaret Kripke, PhD, professor emeritus at the University of Texas MD Anderson Cancer Center, said that most clinicians minimize the importance of environmental causes of cancer, and that she herself had been a skeptic, believing that most chemicals were tested for cancer-causing properties and strongly regulated. “But none of the assumptions I had were entirely true,” she said. “We live in an ocean of chemicals, and no one is protecting us. People must act by being advocates for clean air, food, and water.”
Adding to the problem of insufficient regulation is that “corporations manufacture scientific uncertainty about potential harms caused by their products or activities,” said David Michaels, PhD, MPH, of the Milken Institute of the School of Public Health at George Washington University. He is the author of a book, The Triumph of Doubt: Dark Money and the Science of Deception. Michaels contended that companies hire “product defense” consulting firms that recruit scientists to say their products are not dangerous. “We need a system so that producers must pay for research but not control it,” he said.
You can access video recordings, speaker slides, Q&A transcripts, and additional resources from all three Cancer & Environment Forum sessions here.
Among the speakers were scientists from the National Cancer Institute, the Centers for Disease Control Division of Cancer Prevention and Control, the National Institute of Environmental Health Sciences, Silent Spring Institute, the UMass Lowell Center for Sustainable Production, the Cancer Free Economy Network, Massachusetts General Hospital, and activists from communities disproportionately impacted by environmental pollution.
The forum grew out of initial talks between Rebbeck, Cynthia McKeown, MS, of the Department of Communications, and David Read, MBA, MPH, vice president of Medical Oncology.