Prop 65 Compliance: Chemicals, Warnings, and Penalties

A product is Proposition 65 compliant when exposure to every listed chemical it contains stays at or below California’s safe harbor level, or when the product carries a warning that meets the state’s content and format rules. That’s the whole test. Everything else — testing, labeling decisions, supply-chain paperwork — exists to answer one of those two questions for each listed chemical in your product.

Proposition 65, formally the Safe Drinking Water and Toxic Enforcement Act of 1986, applies to any business with ten or more employees that sells into California or operates there.¹ Penalties run up to $2,500 per violation per day, and any private citizen can sue to enforce the law, so getting compliance right matters well before a product ever ships.

Does Proposition 65 Apply to You

The warning requirement reaches any business with ten or more employees, counting full-time and part-time workers alike, that makes, distributes, or sells products in California.² Each link in the supply chain — manufacturer, distributor, retailer — has an independent duty not to knowingly expose someone to a listed chemical without a warning.³ A small retailer being exempt doesn’t lift the obligation off a larger manufacturer upstream.

A few categories sit outside the law:

Businesses with fewer than ten employees.
Local, state, and federal government agencies.
Public water systems, which are regulated separately.
Exposures where a federal law governs warnings and preempts state authority.⁴

If none of those apply, the compliance work begins with knowing what’s in the product.

Step 1: Identify Which Listed Chemicals Are in Your Product

The California Office of Environmental Health Hazard Assessment (OEHHA) maintains the list of chemicals known to cause cancer or reproductive harm. It currently contains more than 875 substances, and state law requires OEHHA to revise and republish it at least once a year.⁵³ If a chemical is not on the list, Proposition 65 does not apply to it. If one of your ingredients or contaminants is on the list, the next question is how much of it a user actually encounters.

Figuring that out usually means laboratory testing. A lab identifies and measures listed substances at parts-per-million or parts-per-billion concentrations. Testing a single product for a standard panel runs a few hundred dollars, more for complex products or wider panels. The result is a chemical profile you can measure against California’s thresholds.

Watch the list over time. When OEHHA adds a chemical, businesses have a 12-month grace period before the warning requirement kicks in for that substance.⁴ A product that was compliant last year can fall out of compliance when a new listing takes effect.

Step 2: Compare Exposure to the Safe Harbor Levels

OEHHA publishes safe harbor levels for many listed chemicals, and staying below them is the clearest route to compliance without a warning.⁶ They come in two forms:

No Significant Risk Levels (NSRLs) apply to cancer-causing chemicals. An NSRL is the daily exposure calculated to produce no more than one additional cancer case in 100,000 people over a 70-year lifetime.⁷
Maximum Allowable Dose Levels (MADLs) apply to reproductive toxicants. A MADL is the highest dose that produced no observable reproductive harm in studies, divided by 1,000.⁸

To use these thresholds, convert your lab results into a realistic exposure estimate. That calculation accounts for how long and how often a person uses the product, whether the chemical migrates out of the material, and whether exposure happens through skin, inhalation, or ingestion. If estimated exposure sits at or below the NSRL or MADL for every listed chemical present, no warning is required.⁹ If any chemical exceeds its threshold, you’ll need a warning. Keep the test results and exposure calculations on file; they are your primary defense if someone later challenges your compliance.

Not every listed chemical has a published safe harbor level. When none exists, you can still avoid a warning by performing your own risk assessment with comparable scientific methods, but the burden of proof falls entirely on your business.⁴ That work generally requires expert toxicologists, so most businesses treat chemicals without safe harbor levels as warning-required unless testing shows very low concentrations.

A Narrow Defense for Food Businesses

Food businesses sometimes find listed chemicals that appear naturally, such as lead in root vegetables grown in mineral-rich soil or acrylamide formed during roasting. Proposition 65 recognizes a naturally occurring defense, but the bar is high. The business has to prove the chemical exists at natural background levels for the growing region, that it did not result from any human activity (including indirect contamination like agricultural runoff), and that the business followed good manufacturing practices to keep levels as low as feasible. The defendant carries the full burden, and courts have required extensive scientific evidence to sustain the defense.

Step 3: If a Warning Is Required, Make It Compliant

Title 27 of the California Code of Regulations, Section 25603, sets the formatting and content standards. A compliant consumer product warning has four required elements:¹⁰

A warning symbol: a black exclamation point inside a yellow equilateral triangle with a bold black outline. The symbol may appear in black and white only if no other yellow ink appears on the label or shelf tag.¹¹
A signal word: “WARNING” (or “CA WARNING” or “CALIFORNIA WARNING”) in bold, all capital letters, placed to the right of the triangle.
The name of at least one listed chemical in the product that triggered the warning.
The URL www.P65Warnings.ca.gov.

The hazard language changes with the chemical. For cancer-causing chemicals, the label states that the product can expose you to a named chemical “known to the State of California to cause cancer.” For reproductive toxicants, the chemical is “known to the State of California to cause birth defects or other reproductive harm.” Products containing chemicals in both categories must cover both risks.¹⁰

Short-Form Warnings

Products with limited label space can use a short-form warning. It still needs the triangle, the bold “WARNING” signal word, and a brief risk phrase, and type cannot be smaller than 6-point. Under amendments effective January 1, 2025, the short-form must now name at least one chemical; the earlier version allowed a generic statement with no chemical named.¹² Products manufactured and labeled before January 1, 2028, may still use the older short-form language; anything produced after that date must use the new format.

Online and Catalog Sales

When a buyer never sees the physical package before purchase, the warning has to reach them on the product display page or during checkout. A clearly labeled hyperlink to the warning text is enough, provided the buyer encounters it before completing the transaction. Catalog sales work the same way: the warning must appear while the buyer can still choose not to buy.

Workplaces, Rental Housing, and Physical Spaces

Proposition 65 is not only about products. If your business creates chemical exposures in a workplace, parking garage, apartment building, or retail store, you have to warn the people in that space.¹³ Methods include posted signs, distributed notices, or employee communications. Rental housing with known exposures such as lead paint in older buildings requires warnings to tenants. If any signage at the facility appears in a language other than English, the Proposition 65 warning must be posted in both English and that language.¹⁴

What Non-Compliance Costs

The civil penalty for failing to warn is up to $2,500 per violation per day. On a product that has been on shelves for months, that figure climbs quickly. Defendants also typically pay the plaintiff’s attorney fees, and a private plaintiff keeps 25 percent of any civil penalty collected.¹⁵ That bounty is what drives the volume of Proposition 65 litigation.

The attorney general, district attorneys, and some city attorneys can enforce the law, but most cases come from private citizens and organizations suing “in the public interest.” A private enforcer must first serve a 60-day notice of violation on the alleged violator, the attorney general, and relevant local prosecutors.¹⁶ That window is your opportunity to correct the problem; it also gives the attorney general room to take over the case. If no public prosecutor steps in, the private plaintiff proceeds. Most cases settle, with the business agreeing to reformulate, add compliant warnings, and pay penalties plus the plaintiff’s legal costs.

Testing, exposure calculations, and label review are much cheaper than defending a 60-day notice. If your product reaches California and you employ ten or more people, treat compliance as a required line item, not an optional one.

1
Office of Environmental Health Hazard Assessment. Proposition 65
2
Proposition 65 Warnings Website. Frequently Asked Questions for Businesses
3
California Legislative Information. Health and Safety Code – Safe Drinking Water and Toxic Enforcement Act of 1986
4
California Legislative Information. California Health and Safety Code 25249.10
5
Office of Environmental Health Hazard Assessment. The Proposition 65 List
6
Office of Environmental Health Hazard Assessment. Proposition 65 No Significant Risk Levels (NSRLs) and Maximum Allowable Dose Levels (MADLs)
7
Legal Information Institute. Cal. Code Regs. Tit. 27, 25703 – Quantitative Risk Assessment
8
Legal Information Institute. Cal. Code Regs. Tit. 27, 25801 – General
9
Office of Environmental Health Hazard Assessment. Priority List for the Development of Proposition 65 No Significant Risk Levels for Carcinogens
10
Legal Information Institute. Cal. Code Regs. Tit. 27, 25603 – Consumer Product Exposure Warnings – Content
11
Proposition 65 Warnings Website. Warning Symbol
12
Office of Environmental Health Hazard Assessment. Proposition 65 – Clear and Reasonable Warnings – Safe Harbor Methods and Content
13
Office of Environmental Health Hazard Assessment. About Proposition 65
14
Legal Information Institute. Cal. Code Regs. Tit. 27, 25607.26 – Methods of Transmission
15
California Legislative Information. California Health and Safety Code 25249.7
16
State of California – Department of Justice – Office of the Attorney General. Proposition 65 Enforcement Reporting