A Prop 65 Crash Course: What You Need to Know (2026)
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Photo-Illustration: Wired Staff; Getty Images Comment Loader Save Story Save this story Comment Loader Save Story Save this story My first encounter with a Prop 65 warning was on the back of my TV.
I was selling it on Facebook Marketplace , and when the buyer arrived to pick it up, he spotted a warning I had never noticed. “California Proposition 65 Warning: This product contains chemicals known to the state of California to cause cancer and birth defects or reproductive harm.” Neither of us had seen such a label before, and for a moment, he didn’t want the TV anymore. We did what anyone would do in this situation: We Googled it. He ended up taking the TV. I kept Googling.
California’s Proposition 65 , officially called the Safe Drinking Water and Toxic Enforcement Act, applies to a dizzying range of products, from food and cosmetics to electronics and household goods. Passed in 1986, the law turns 40 this year, yet that ominous little label still confuses the average consumer.
So, should you steer clear of all products with a Prop 65 warning? Not necessarily. Here’s what you need to know before you panic-buy a new TV .
Courtesy of Stephen Osman/Getty Images Proposition 65, Explained In November 1986, California voters approved Proposition 65 by a landslide margin of about 63 percent to 37 percent. It’s a right-to-know law, meant to inform Californians about potential exposure to chemicals that may cause cancer or reproductive harm over a lifetime.
It doesn’t ban those chemicals; instead, it requires businesses to provide a warning when their products could expose people to a listed chemical at levels above specific thresholds.
“At that time, it was part of a broader effort to address a growing concern that the public had about toxic chemical exposure,” says Megan Schwarzman, environmental health scientist at UC Berkeley’s School of Public Health .
The idea is that consumers can use that information to make their own decisions. A warning might prompt someone to choose an alternative, use a product less frequently, or take other steps to reduce their exposure. Prop 65 also gives businesses an incentive to reformulate products or change manufacturing practices to avoid issuing a warning that may deter customers.
And because California is such a massive consumer market, products often need to comply with Prop 65 requirements even when they’re manufactured or sold by companies elsewhere. Some large retailers, such as Target and Amazon , also require their vendors to comply with Prop 65 warning requirements.
Prop 65 covers a broad range of products and potential exposures. You can find warnings on fortified foods, smartphones, and appliances. The law is concerned with exposure, not simply whether the chemical is detectable. California's Office of Environmental Health Hazard Assessment (OEHHA) establishes the so-called safe-harbor levels for many listed chemicals. Generally speaking, a warning is required when anticipated exposure exceeds these levels.
The Prop 65 list contains both naturally occurring and synthetic chemicals that California has determined are known to cause cancer or reproductive harm. Supplements , for example, can contain trace amounts of naturally occurring or environmental contaminants, including lead, cadmium, and arsenic. The list is updated at least annually, and chemicals can also be removed from the list as scientific evidence evolves.
Chemicals can be added to the Prop 65 list through four mechanisms : through California’s Labor Code; through evaluations from California’s Carcinogen Identification Committee (CIC) or Developmental and Reproductive Toxicant Identification Committee (DARTIC); through identification by certain authoritative bodies, like the US Food and Drug Administration (FDA); or through identification by a state or federal agency.
Mariana C. Stern, cancer epidemiologist and member of the CIC, says the committee includes epidemiologists, toxicologists, molecular biologists, and cancer scientists who review the available literature before deciding whether a chemical belongs on the list.
“We may spend the whole day trying to dissect one chemical,” Stern says. “It’s not uncommon that we end up deciding we don’t have enough evidence to add this compound to the list.”
But seeing a warning doesn’t necessarily mean a product contains a dangerous amount of a chemical, or even that the product itself has been tested. According to Schwarzman, “some companies have opted to warn rather than test or reformulate, but from our research, I believe that is much less common than when companies post a warning because of the actual presence of the chemical above a certain threshold.”
From a consumer standpoint, the ubiquity of Prop 65 labels also means that it can be harder to prioritize which ones actually warrant attention. “We definitely have a concern with over-warning,” says Tina Cox, section chief of the OEHHA’s Proposition 65 Implementation Program. “Any unnecessary warnings do make it difficult for consumers to identify where the real exposures are, and it does dilute the value of Prop 65 warnings.”
As a result, California has started trying to make them more useful by requiring short-form warnings to name at least one chemical, rather than relying on the generic “may cause cancer or reproductive harm” language. Businesses have until January 2028 to fully comply with the new requirement. The state is also conducting more outreach to help companies understand when a warning is required and when it is not.
Courtesy of zimmytws/Getty Images The Warning Isn’t a Verdict Prop 65 was meant to inform consumers, not to tell them which products to buy. By the same token, a product without a warning isn’t necessarily free of hazardous chemicals.
“You’re never going to be zero exposure, even if you avoid all Prop 65 labels,” says air pollution scientist Shahir Fouad Masri . “If you have a product that doesn’t have a label, it’s one of two things: It was…
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