Cancer Warning Labels Based on California’s Proposition 65

Labels warning that a product contains compounds that may cause cancer, birth defects, or reproductive harm are now required on many household items sold in California. But people all over the country see them because many companies put the labels on all items that contain these compounds, even if they’re to be sold in other states. The warning labels can be found on many kinds of products, such as electrical wires, jewelry, padlocks, dishes, flashlights, and pesticides, to name just a few.


California’s Proposition 65, also called the Safe Drinking Water and Toxic Enforcement Act, was enacted in 1986. It is intended to help Californians make informed decisions about protecting themselves from chemicals known to cause cancer, birth defects, or other reproductive harm.

As part of the law, the state is required to publish a list of chemicals that are “known to the State of California to cause cancer or reproductive toxicity.” The list is updated at least once a year and now contains about 800 different chemicals. The complete list can be found on the California Office of Environmental Health Hazard Assessment (OEHHA) website.

Some of the substances listed by OEHHA can affect the reproductive systems of men and/or women. Others are thought to cause cancer. Scientists classify all of these cancer-related substances at least as probable carcinogens, meaning that they might cause cancer in some people. But not all of them are known carcinogens (known to cause cancer) by groups and experts outside the state of California. This means that not every compound labeled as a possible cancer-causing substance has been proven to the worldwide scientific community to actually cause cancer.

About the labels required by Proposition 65

As part of the law, businesses selling products to people in California must provide “clear and reasonable warnings” before knowingly exposing people to any chemical on the list, unless the expected level of exposure would pose no significant cancer risk. This warning is often in the form of a label on the product or its packaging.

The law defines “no significant risk” as a level of exposure that would cause no more than 1 extra case of cancer in 100,000 people over a 70-year lifetime. So a compound can be unlabeled if a person exposed to the substance at the expected level for 70 years is estimated to have a 1 in 100,000 chance or less of getting cancer due to that exposure. The law also has similar strict cutoff levels for birth defects and reproductive harm.

Businesses decide whether to put warning labels on their products based on their knowledge of the types of chemicals in them. Manufacturers are not required to provide the OEHHA with any information about the products. That means the OEHHA doesn’t know which chemical the warning refers to, how exposure could occur, or how much of the chemical a consumer is likely to be exposed to. All of these factors are critical when determining how much risk it might pose. The OEHHA cannot offer information to help consumers figure out what the potential risk is and how to avoid it. These kinds of details can only come from the product’s manufacturer.

What the labels don’t say

The Prop 65 labels only tell you that a product has something in it that might cause cancer or affect reproduction. They don’t say what the substance is, where it is in the product, how you might be exposed to it, what the level of risk is, or how to reduce your exposure.

How to get more information about what is in the product

If you find a warning label on a product and want more information, you will need to:

  • Find the name of the manufacturer by checking the package and any written information that comes with the product. The contact information is often on or in the package as well, but if it isn’t, you can look it up online by searching the manufacturer’s name.
  • Call, email, or write to the manufacturer about that specific product to find out what potentially hazardous substance is in the product. You might also want to ask what part of the product it’s in.
  • Ask the manufacturer how a person might be exposed to it in this product. Some common exposure routes include inhalation, contact with food, transfer to food or drink from unwashed hands, or a baby or child putting the product in his or her mouth. Different routes are important for different substances.
  • Find out what the manufacturer knows about the hazards of the substance that is in the product. Is it a possible cause of cancer, might it cause reproductive harm, or both?
  • Ask the manufacturer what you can do to reduce any risk of exposure to the hazardous substance while using the product.

Once you learn exactly what the substance is, you can usually find more information about it from other sources as well. The OEHHA has fact sheets on many common chemicals on its website. Sometimes you can find specific information on the OEHHA website, such as news about jewelry that contains lead or cadmium, or about kids and hand-to-mouth transfer.

Unlabeled products

Products that are sold outside of California are not required to have the warning label even if they contain substances that might cause cancer. Some companies that sell products all over the US only label those sent to California, even though all their products contain the same compounds.

Lead-containing wire

The required labels on electrical wires such as computer cables, power cords, and holiday lights sold in California are slightly different from the labels on other products.

Why are my wires labeled with a cancer warning? The state of California keeps its own list of cancer-causing substances. It requires manufacturers who know that a consumer might be exposed to one of these substances from using their product to label that product with a clear warning. These labels are slightly different from other California Proposition 65 warning labels because of a lawsuit settlement in 2002.

Lawsuits filed in 2000 charged that electrical manufacturers were selling covered electrical wires and cable products in California without labels, despite the fact that the wires and cables had lead in their coverings. (Lead is a substance on the California list.) As part of the lawsuit settlement, manufacturers were directed to start attaching warning labels to electrical cords as of late 2003. Unlike other California warning labels, these labels actually name at least one of the risky substances. People who buy new electrical products are often concerned when they see these warning labels, but cords have contained lead for many years. Only the labels are new.

Will I be exposed to lead if I use this product, and if so, how? Many electrical wires and cables have small amounts of lead in their outside insulation (surface covering), which can rub off on the hands of people who touch the wires. People can be exposed to lead by ingesting it, so if they handle these wires and then eat or put their hands in their mouths without washing them first, they can take in small amounts of lead. The bigger hazard is likely to be for toddlers and babies who put wires or cables in their mouths. Since babies and toddlers crawl around on the floor, it can be challenging to keep them away from wires and cables.

Can using this product cause cancer? Lead is a probable carcinogen, meaning it can probably cause cancer in some situations. But there is no way to assess the risk or even level of exposure for any one person handling electrical cords or cables.

The amount of lead a person might absorb will depend on what the person does with the cord and how long they handle it. People are exposed to lead mainly by swallowing or breathing powdered lead. The lead found in cords is not powdered, so users are not at risk of inhaling it.

Studies that looked at lead’s potential ability to cause cancer looked at people with high exposure levels on a constant, daily basis. This means that the effects of less frequent exposures to tiny amounts may not have any observable effects. It may also help to know that, in case of larger exposures, there are other symptoms of lead toxicity that would likely be a concern long before cancer could develop.

How can I avoid exposure (and protect children in the house)?

  • The most important point to avoid exposure is to wash your hands after handling the cords or cables to avoid swallowing any lead that rubbed off onto them.
  • Don’t eat or allow children to eat while handling lead-containing cords or stringing holiday lights.
  • Since small children are more likely to put cords, fingers, and other objects in their mouths, keep lead-containing wires and cables out of their reach.
  • Children are more affected by lead, and should always have their hands washed before handling food and eating.

Labeling requirements

Most electrical cords and cables that contain more than 300 parts per million of lead by weight in their covering (“surface contact layer”) are required to be labeled if they are to be sold in the state of California (see also “Exempt cords” below).

Label statements: Label statements on lead-containing wire or cable to be sold in California may have slightly different wording, but they all say something like this:

    WARNING: Handling the cord on this product will expose you to lead, a chemical known to the State of California to cause [cancer, and] birth defects or other reproductive harm. Wash hands after handling.

The word “cancer” (in brackets above) is optional, at the judgment of the manufacturer. Many of them use it, possibly to avoid liability.

Exempt cords: Cords that are not often plugged and unplugged do not have to be labeled. Cords with lead inside their covering, and cords that are in places that make them inaccessible to consumers during ordinary use do not have to be labeled. (But keep in mind that, other than wires, there are many other types of materials that must be labeled by the manufacturer if they are sold in California.)

Hazards on the job: There is a different warning system for electrical cords that are not sold in California and are handled in a work setting. The US Occupational Safety and Health Administration (OSHA) requires detailed information to be provided for employees who work with hazardous substances and materials. Known hazards must be listed on a standard form called a Material Safety Data Sheet (MSDS). Many materials must have an MSDS, including solids, liquids, and gases that people work with. Supervisors or safety officers should be able to get you an MSDS for any potentially hazardous material at work, no matter which state you’re in.

What about wires and cords with no labels?

You can’t assume that wires and cords without warning labels are lead-free or exempt. It’s possible that the product isn’t sold in California – the only state that requires this warning label. And some companies only put the labels on products that will be sold in California, so you won’t see them unless you buy the product there. Finally, older cords, cables, and wires that have not been labeled may also contain lead.

More about cancer warning labels that mention California

For more information and frequently asked questions about Proposition 65, go to OEHHA’s website at:

Proposition 65 is reviewed in plain language at:

For a fully updated list of all the chemicals and compounds that are known to the State of California to cause cancer or reproductive toxicity, go to:

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: July 14, 2015 Last Revised: July 14, 2015

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