Proposition 65, Prop 65 Warnings, Chemical List, Prop 65 Compliance
Sunday, April 22, 2018

California Proposition 65 Made Simple

An overview of California's Proposition 65 for those seeking basic information about what is required under Proposition 65, and how the law works.

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California Proposition 65 Made Simple

What Is Proposition 65, and Why Does it Apply to My Company?

Proposition 65, commonly known as Prop. 65, is a ballot initiative that was passed by California voters in 1986 to provide warnings about potential exposures to carcinogens and chemicals known to cause reproductive harm in drinking water, air or in consumer products. The law is formally referred to as the Safe Drinking Water and Toxic Enforcement Act of 1986.

One common misconception about Prop 65 is that it bans listed chemicals. The law does not impose a ban on chemicals listed under the statute.  Instead, Prop. 65 requires clear and reasonable warnings for exposures to chemicals on the state’s list under certain circumstances.

Proposition 65 is administered by California’s Office of Environmental Health Hazard Assessment (OEHHA), which is part of Cal/EPA. Enforcement of the statute is supervised by the California Attorney General's office. Enforcement is discussed in more detail below.

Prop. 65 applies to companies and organizations employing ten or more employees.

How Does Proposition 65 Work?

Prop. 65 requires the State of California to publish its list of chemicals known to cause cancer or reproductive harm at least once every year.  In practice, OEHHA publishes a new list each time a new chemical or substance has been listed.  The original list was published in 1987 by Governor Deukmajian.  The most current chemical list contains more than 800 distinct chemicals and substances, some of which are found in consumer products and common household supplies such as cleaning products, pet products, foods and building materials.  Other chemicals on the list are used in manufacturing, or are by-products of chemical processes.

How Are Chemicals Added to the List?

Chemicals and other substances are added to the Prop 65 list in four different ways, each ensuring scientific review of chemical candidates.

The Authoritative Bodies Mechanism relies on the identification of a chemical or substance as causing cancer or reproductive harm by a designated federal agency or scientific body to trigger the listing of a chemical or substance. The designated authoritative bodies are:

§  U.S. Environmental Protection Agency

§  U.S. Food and Drug Administration

§  National Institute for Occupational Safety and Health

§  National Toxicology Program

The State’s Qualified Expert Mechanism utilizes scientific experts appointed by the Governor to the state’s Science Advisory Board, which evaluate the scientific evidence about chemical candidates to determine whether a chemical is clearly shown to cause cancer and/or reproductive or developmental toxicity.  The chemicals considered by the state’s expert panels are generally those where the findings of federal agencies and/or authoritative bodies differ.

The state’s Science Advisory Board is comprised of two independent expert panels of scientists and health professionals with specific scientific expertise.   The expert panels include:

§  Carcinogen Identification Committee (CIC)

§  Developmental and Reproductive Toxicant Identification Committee (DART-IC)

Staff scientists from OEHHA assist the expert panels by compiling information related to the hazards and potential toxicity of chemicals being considered by panel members.

The Labor Code Mechanism lists certain chemicals identified by the California Labor Code, which in turn takes the chemicals from a section in the federal Occupational Safety and Hazard Safety Code, and the Federal Hazard Communication Standard.  There has been controversy concerning which federal lists are triggered by this list.  A recent Court of Appeal opinion and change to the federal Hazard Communication Standard have recently limited listings by this method.  The Labor Code listing mechanism is the only method that lists chemicals based on an international body, which is also controversial.  The international body is the World Health Organization's  International Agency for Research on Cancer(IARC).

The Formally Required to be Labeled Mechanism is used when a state or federal government agency requires that the chemical be labeled or identified as causing cancer or birth defects or other reproductive harm.  The majority of chemicals listed by this method are prescription drugs required by the U.S. FDA to carry a specific warning about the potential risk of cancer or birth defects.

Proposition 65's Requirements

Warning Requirement

Businesses and non-governmental entities have a duty to provide a “clear and reasonable” warning before knowingly and intentionally exposing anyone to a listed chemical.  Depending on the nature of the potential exposure the warning can be given in several different ways.  For example, a warning could be given in a consumer product by a label or an insert into the product packaging.   A warning at a facility would be best conveyed by signs, however in some cases it can be done by a warning in a local newspaper.   Many businesses have opted to include Prop. 65 warnings out of an abundance of caution to avoid liability under the statute without evaluating whether exposures to their products or facilities would be required under the statute.  Performing a risk assessment to evaluate whether a warning would be required is outside of the budget of all but the largest companies, making this scenario common.  Product manufacturers, distributors and retailers selling products in the State of California are subject to Prop 65’s warning requirements regardless of their location.  The warning requirement for listed chemicals takes effect one year after the chemical is added to the list.

Discharge Prohibition

One of the purposes of Prop 65 is to protect drinking water.  The statute prohibits the discharge of any listed chemical into a source of drinking water.  The term “source of drinking water” is defined as "either a present source of drinking water or water which is identified or designated in a water quality control plan adopted by a regional board as being suitable for domestic or municipal uses."  Significant for the purposes of the discharge prohibition means any detectable amount, unless the discharging party can show the chemical poses no significant risk (discussed below).  The discharge prohibition is triggered for a chemical 20 months after it is added to the Prop 65 chemical list.


Businesses and organizations with less than 10 employees are exempt from Prop. 65’s warning requirements and discharge prohibitions.   Exposure from chemicals naturally occurring in foods such as oranges and tomatoes are also exempted.  An exemption also applies if an organization can show that exposures to a listed chemical poses no significant risk of cancer or reproductive harm.  Since establishing that a chemical poses no significant risk would require a risk assessment, it is an option rarely used.

When Does a Product or Facility Require a Warning?

OEHHA has developed threshold levels for approximately 300 of the more than 800 substances on the Prop. 65 list.  These levels are commonly known as the “Safe Harbor Level.”  The levels for listed carcinogens are known as No Significant Risk Levels (NSRLs).  The levels for Reproductive and developmental toxicants are known as Maximum Allowable Dose Levels (MADLs).  If there is no safe harbor level for a chemical, the business or organization has the burden of establishing there is no risk from exposure. 

The No Significant Risk Level for carcinogens is the level of exposure that would result in no more than one excess case of cancer in 100,000 individuals exposed to the chemical over a 70-year lifetime.

For reproductive and development toxicants, organizations must demonstrate the chemical  is below the No Observable Effect level (NOEL), a level that has been established where the chemical in question poses no harm to human or laboratory animals.  Because Prop. 65 requires a 1,000 fold margin of safety, a MADL for a reproductive or developmental toxin is 1/1,000th of the NOEL, making it the most stringent safety level in the United States.

What Should My Warning Say?

Prop 65 warning language varies depending on circumstances, such as whether the warning is for a consumer product, a facility, or in an occupational setting.  Nevertheless, there is core language  that must be used to provide a Prop 65-compliant warning.

For carcinogens: "WARNING: This product contains a chemical known to the State of California to cause cancer."

For reproductive toxins: "WARNING: This product contains a chemical known to the State of California to cause birth defects or other reproductive harm."

As previously mentioned, warnings for exposures from facilities, or in an occupational setting will vary, but only to the extent that it will say “this facility” instead of “this product.”  Nothing prevents the warning party to identify the chemical or chemicals present triggering the warning.

At present OEHHA is making several changes to its regulations about the language used in warnings, consequently the warning requirements discussed here may soon change.

How is Proposition 65 Enforced?

Unlike most environmental laws and regulations, Prop. 65 violations are not enforced by a government agency.  OEHHA, is responsible for maintaining the Prop. 65 chemical list, and performing risk assessments to develop NSRLs and MADLs, but has no role in the enforcement of the statute.  This vital role is shared by public prosecutors and citizens and citizen groups, which are often maligned as bounty hunters.   The primary public prosecutor enforcing Prop. 65 is the California Attorney General.  However, the statute is also enforced by county district attorneys, and city attorneys, where the city has a population greater than 750,000.  Because public prosecutors only have the resources to prosecute a fraction of the cases that would merit their attention, and because at the time the initiative passed mistrust of state agencies that failed to enforce environmental laws was widespread, voters approved citizen enforcement. This remains the most controversial component of Proposition 65.

Penalties for violation(s) of Proposition 65 can be as high as $2,500 per day, making non-compliance potentially very expensive.

My Company Received a 60-Day Notice of Violation – What Now?

  • Do not ignore the notice.
  • Hire  an attorney with Prop. 65 defense experience
  • In some cases, a company executive can successfully negotiate with citizen enforcers.
  • But in most cases it is wise to hire an experienced Prop. 65 defense attorney immediately.
  • Where Can I Find More Information?

Prop 65 News has been dedicated to providing information to help companies with Proposition 65 compliance since it took effect in 1987.  We would be happy to help answer your questions and discuss your concerns.

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