Cancer concerns from everyday products

In the span of a few days last summer, the simple act of sipping a diet soda became a bit more fraught.

Why? International health authorities issued a statement classifying aspartame — an artificial sweetener widely found in diet drinks and foods like gum, yogurt, and ice cream — as possibly carcinogenic in humans. But limited evidence supports any cancer-causing effects of aspartame, especially at the amounts most people consume, the International Agency for Research on Cancer noted.

Nevertheless, the announcement spurred much confusion and consternation—most of it needless, says Timothy Rebbeck, a professor of cancer prevention at Harvard-­affiliated Dana-Farber Cancer Institute. "A lot of people thought that statement meant they'd better not use aspartame, that it causes cancer. But that's not what it said, or how to interpret it," Rebbeck says. "There's not much meaningful evidence that aspartame confers cancer risk at all."

The muddle also reignited simmering concern that products we use every day — what we eat or drink, apply to our skin, or live with in our homes — might raise our risks for cancer, which causes one in every six deaths globally each year. But Rebbeck says fear may trump knowledge when it comes to knowing which products we routinely use pose a meaningful cancer risk.

"Most consumer products people are exposed to confer very low cancer risks, if any," says Rebbeck, who is also director of the Zhu Family Center for Global Cancer Prevention at the Harvard T.H. Chan School of Public Health. "People's estimate of the risk is probably higher than it actually is."

What other household goods might prompt cancer concerns? Rebbeck offers context around the evidence gathered for an array of products.

Nonstick cookware

Some pots, pans, and other cookware are coated with a synthetic chemical called polytetrafluoroethylene, commonly known as Teflon and one of a group of related chemicals known as perfluoroalkyl and polyfluoroalkyl substances, or PFAS.

The evidence: PFAS can be found at very low levels in just about everyone's blood worldwide. Research examining cancer rates in people living near or working in PFAS-related chemical plants, as well as in the general population, suggest — but don't prove — a link between PFAS exposure and certain cancers. And not all studies have found such links, according to the American Cancer Society (ACS).

Expert take: "The interesting thing about nonstick compounds is, because they're nonstick, they don't really react with very much when they're in their solid state. They don't cause DNA damage," Rebbeck says. "There's not much evidence that nonstick cookware is carcinogenic in humans, but some compounds related to Teflon in other forms have been associated with cancer."

Mattresses

Some mattress manufacturers add flame retardants to prevent burning or slow the spread of fire. This may mean the mattress you're sleeping on every night is coated in those chemicals.

The evidence: Certain flame retardants contain chemicals known as volatile organic compounds (VOCs), which means they can become airborne. Some research suggests these flame retardants can interfere with hormone levels and may be associated with cancer, according to the National Institute of Environmental Health Sciences.

Expert take: One pitfall of linking cancer risk with flame retardants is there aren't reliable measures of exposures to these chemicals in people and populations, Rebbeck says. "Epidemiological studies in people are limited, and these studies either offer mixed messages or say they have no effect on cancer risk," he adds. "But in any case, the effects are really small. I personally see no reason for people to change their behavior."

Cleaning products

Some household cleansers, dish soaps, and detergents contain chemicals known as endocrine disruptors. These are substances that interfere with human hormones and the reproductive and other biological processes they regulate.

The evidence: A November 2022 study in the journal Indoor Air suggested that using household cleaning products can expose us to potentially hazardous VOCs. Some VOCs, such as benzene and formaldehyde, have been linked with cancer, according to the American Lung Association. And a study published online Sept. 18, 2023, by the Journal of Exposure Science and Environmental Epidemiology suggested that exposure to certain endocrine-disrupting chemicals may contribute to cancers of the breast, ovaries, skin, and uterus.

Expert take: "Our ability to measure these relevant exposures is very limited," he says, "so the studies we do in humans cannot estimate risks accurately. We believe that if the effects were large enough, we'd have already seen them — like we did with cigarette smoking and lung cancer."

Personal care products

Some cosmetics, skin care, hair dyes, deodorants, hair relaxers, and other personal care products contain chemicals such as parabens, formaldehyde, coal tar dyes, and more.

The evidence: Research is scant that examines the long-term effects of most cosmetics on health, so there's little evidence to suggest using them increases cancer risk, according to the ACS.

But certain chemicals stand out. In October 2023, the FDA proposed a ban on formaldehyde in hair relaxers, products used to smooth or straighten hair. Repeated exposure has been linked to certain cancers, according to the National Cancer Institute. And a 2023 study of 33,000 women conducted by the National Institutes of Health suggested that those who used hair-straightening chemicals more than four times in the prior year were twice as likely to develop uterine cancer — the most common malignancy of the female reproductive system—compared to women who didn't use them.

Expert take: Most personal care products today contain lower amounts of potentially toxic chemicals than in years past, Rebbeck says, "so your past exposure may still matter to your cancer risk, but those exposures have really changed."

For people who work around these chemicals, the risks may climb. Earlier studies suggested that hair stylists, for example — who work with hair dyes and related chemicals in large amounts — faced higher odds of cancer. "If you're exposed to gallons of hair dye a month, that's very different from the small amounts most women are exposed to," he says. "The amount and way you're exposed is very relevant. But even with occupational exposure, the risk is still quite low."

Cancer prevention basics

If you're worried about your exposure to any of these common substances, Rebbeck's advice is simple: find alternatives. A back-to-basics approach to cancer prevention is also paramount.

"There are so many things you can do to reduce your cancer risk that are really meaningful and measurable and large: stop smoking, don't drink alcohol, get exercise, and maintain a healthy weight," he says.

To stay updated on new evidence emerging on cancer risks associated with everyday products, Rebbeck also advises visiting reputable websites such as the Harvard T.H. Chan School of Public Health's Cancer FactFinder, the ACS, and the National Cancer Institute.

"There's a lot of misinformation out there," he says. "That's why it's so important to turn to the right sources of information — not social media or what your neighbor tells you. There's much you can do to lower your cancer risks and empower yourself to make better decisions."

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