In California, it is a requirement to label products that contain chemicals that may cause cancer, birth defects, or reproductive harm. Products sold outside of California are not required to have the warning label, even if they contain the same substances.
What Is Proposition 65, and Why Are These Warnings Everywhere?
Federal vs Californian Law
Under federal law, artists’ materials such as oil paints are exempt from the general ban on lead in consumer paints, provided they are clearly labelled and meet ASTM D4236 safety standards. This is why brands which use traditional lead-based whites can still sell their products legally to artists.
However, while these products may be fully compliant with federal safety regulations, California’s Proposition 65 imposes stricter labelling requirements. Even trace amounts of certain chemicals — including naturally occurring ones in pigments — can trigger a mandatory warning if exposure exceeds the state’s very low thresholds. This helps explain why a product may be considered ‘non-toxic’ under federal standards but still carries a cancer or reproductive harm warning in California.
Warning Label Requirements
Companies often label such products, irrespective of whether they will be sold in California or transported outside of the state. This is why if you live outside of California, you may encounter two different art products containing the same chemicals, but only the one that has been produced in California will have the warning label.
California’s Proposition 65, also called the Safe Drinking Water and Toxic Enforcement Act, came into law in 1986 and is intended to help people make informed decisions about protecting themselves from chemicals that could cause 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 contains nearly 1000 chemicals. The complete list can be found here on the California Office of Environmental Health Hazard Assessment (OEHHA) website. This list ranges from obvious industrial toxins to some naturally occurring minerals.
Why Some Products Have Carcinogen Labels and Others Don’t
As part of the law, most manufacturers selling products in California must provide ‘clear and reasonable warnings’, unless the expected level of exposure would pose no significant cancer risk. Businesses decide whether to put warning labels on their products based on their knowledge of the types of chemicals in them.
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 world might only label those sent to California, even though all their products contain the same compounds.
Why Do So Many Products Have Prop 65 Warnings?
California’s standards for requiring a warning are very strict. The threshold for many chemicals is extremely low (often far below what federal safety regulations consider dangerous).
Many businesses choose to label out of caution, even if the actual risk is minimal. This is because failing to warn when required can lead to costly penalties (up to $2,500 per day per violation!)
As a result, Californians see Prop 65 warnings on a wide variety of items – electronics, jewellery, foods (like coffee or canned goods), furniture, and art and craft materials, among many others.
Why Do So Many Art Supplies Have This Warning?
If you’re an artist or hobbyist, you’ve probably noticed harm warnings on paints, pigments, clays, and other art supplies. Artists’ materials often carry Prop 65 warnings because of certain things in them. For example, heavy metals in pigments, solvents in painting mediums, or other chemicals used in art products. Many mineral pigments (like Cadmium Reds, Cobalt Blues, or earth colours) naturally contain trace amounts of metals that are on the Prop 65 list.
The law makes no exception for ‘naturally occurring’ versus added chemicals – if using the paint could expose you above the limit, it needs a warning. Even tiny trace levels of a listed chemical can trigger a Prop 65 warning label.
For example, Golden explained why its Zinc White oil paint carries a warning for cadmium and lead: the zinc oxide pigment is mined from the earth and contains extremely low impurities of lead and cadmium (under 12.5 ppm cadmium and 2.5 ppm lead).
These levels are so low that toxicologists consider them insignificant under federal art material safety standards. In fact, ingesting a pea-sized amount of that paint would only expose you to about the same amount of lead and cadmium as what’s allowed in a day’s worth of drinking water.
The product is considered safe to use and meets all national art product safety guidelines, but because those metals are present even in trace amounts, California requires the warning.
This illustrates a common situation. The warning doesn’t automatically mean the art supply will harm you, only that it contains a chemical that, in high enough exposure, could be a concern. Often, the chemicals are bound up in the product (like metals in solid pigment) and only pose a risk if the product is mishandled (e.g. sanding or spraying without ventilation, or ingestion).
The bottom line for artists:
Don’t panic when you see a Prop 65 warning on your art supplies. The label is there because California errs on the side of caution. Even natural ingredients (earth pigments, minerals, etc.) can contain known trace carcinogens or toxins.
It doesn’t necessarily mean the product is ‘toxic’ in normal use. Use it responsibly (avoid creating dust or fumes, don’t ingest it, etc.), and you can continue to create art safely.
Prop 65 Requirements in 2025: What’s New?
Short-Form Warnings Now Name the Chemical
In the past, the short-form warning didn’t have to list a specific chemical (it could just say ‘Cancer’ or ‘Reproductive Harm’). Under the 2025 amendments, any short-form warning on a product must include the name of at least one chemical that triggers the warning.
It also must indicate the type of hazard. For example, a new short-form might say ‘Cancer risk from exposure to Lead’ or ‘Can expose you to Toluene, a reproductive toxicant’, instead of the old generic statement.
‘CA WARNING’ Language Option
The traditional wording still starts with ‘WARNING:’, but businesses now have the option to use ‘CA WARNING’ or ‘CALIFORNIA WARNING’ instead. So don’t be surprised if you see ‘CA WARNING:’ on some labels – it’s legally equivalent to ‘WARNING’ in this context. The text still needs to be in bold and all caps to grab attention.
Triangle Symbol Still Required (except for foods)
The ⚠️ triangle icon continues to be a required element for most Prop 65 warnings. You’ll still see it on product labels next to ‘WARNING’.
One notable exception is with food product labels: for food items, the new regulation allows short-form warnings without the triangle symbol. For non-food consumer products, assume the triangle will be there.
Internet Sales – New Clarity
If you’re shopping online, the seller must provide the Prop 65 warning on the website before you complete the purchase, typically on the product page or at checkout.
The 2025 update clarified that for online purchases, a business can comply by giving an electronic/website warning and doesn’t have to also include a physical warning on the product package when it’s delivered. Many companies still do put it on the package, but legally the online warning covers the requirement for that sale.
Other Labelling Changes
The new rules removed some old font-size requirements that tied the warning font to other text on the package. Now, the main rule is that the warning text (short or long form) must be at least 6-point font and prominent enough to be noticed.
Additionally, there are now specific tailored warnings for certain products (like vehicle parts, furniture, etc.) However, for most consumer goods, including art materials, it’s the standard warning that applies.
Transition Period Until 2028
Don’t worry if you still see the ‘old’ style short-form warnings (the ones that just say ‘Cancer/Reproductive Harm – www.P65Warnings.ca.gov’) on some products. Businesses have a grace period to adjust: products made before Jan 1, 2028 can use either the old or new warning language and still be considered compliant.
This means that through 2027, companies can phase in the new labels. By January 2028, any short-form warnings should be using the new format with the chemical name. So during 2025–2027, you’ll likely encounter a mix of warning styles on store shelves. Both are legally valid for now. The difference is just that the newer ones give you more specifics.
How to Get More Information About What’s in The Product
While manufacturers are required to put Prop 65 warning labels on applicable products sold in California, they are not required to report those details to OEHHA (the Office of Environmental Health Hazard Assessment). As a result, OEHHA cannot provide product-specific information to help consumers understand which chemical is present or the potential risk it poses.
Since August 30, 2018, Prop 65 long-form warnings must name at least one listed chemical and indicate whether it can cause cancer, reproductive harm, or both. Manufacturers aren’t required to list every chemical present, but the warning must be clear, reasonable, and include a reference to www.P65Warnings.ca.gov.
Short-form warnings, often used on small packaging or where space is limited, originally didn’t need to name any chemical. However, this is changing. From January 1, 2025, all newly manufactured products using short-form warnings must also name at least one chemical of concern. Businesses have until January 1, 2028, to fully comply with this updated requirement.
If you find a carcinogen warning label on a product and want more information:
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- Find the name of the manufacturer by checking the package and any 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.
- Contact the manufacturer to find out what potentially hazardous substance(s) the product contains.
- Ask the manufacturer how a person might be exposed to the chemical(s) of concern from this product. Some common exposure routes include inhalation, contact with food, transfer to food or drink from unwashed hands etc. How a chemical is ingested can have a bearing on the level of risk, which depends on each individual chemical.
- Find out what the manufacturer knows about the hazards of the chemical(s) in the product. Do the risks include cancer, reproductive harm, or both?
- Ask the manufacturer if there are ways to reduce any risk of exposure to the hazardous substance while using the product (this information may be found on the product label, or on an accompanying material safety data sheet, or MSDS).
Once you know which chemical(s) the product contains, you can usually find more information about it from other sources. For example, the OEHHA has fact sheets on many common chemicals on its website at www.p65warnings.ca.gov/fact-sheets. You can also find information on some specific products on the OEHHA website.
For more information and frequently asked questions about carcinogen labels and Proposition 65, go to: www.p65warnings.ca.gov.
Disclaimer: This article is for general informational purposes only and does not constitute legal advice. For specific guidance, please consult a qualified legal professional or regulatory expert.
Further Reading
Understanding Safety Data Sheets
