1. Scientific Committee Determination: A chemical can be listed if either of two independent, governor-appointed scientific committees – the Carcinogen Identification Committee (CIC) or the Developmental and Reproductive Toxicant (DART) Identification Committee – finds it has been clearly shown to cause cancer, birth defects, or other reproductive harm. These committees, designated as the “State’s Qualified Experts” and part of OEHHA’s Science Advisory Board, base their decisions on the most current scientific evidence, compiled by OEHHA staff scientists. Public comments are also considered before final determinations are made.

2. Authoritative Body Identification: Listing can occur if an organization formally designated as an “authoritative body” by the CIC or DART Identification Committee has identified the chemical as causing cancer, birth defects, or other reproductive harm. Currently designated authoritative bodies include the U.S. Environmental Protection Agency (U.S. EPA), U.S. Food and Drug Administration (U.S. FDA), National Institute for Occupational Safety and Health (NIOSH), National Toxicology Program (NTP), and International Agency for Research on Cancer (IARC).

3. Government-Mandated Labeling: A chemical must be listed if a state or federal agency requires it to be labeled or identified as causing cancer, birth defects, or other reproductive harm. Most chemicals listed via this pathway are prescription drugs that the U.S. FDA mandates carry such warnings.

4. California Labor Code Specification: The fourth mechanism mandates the inclusion of chemicals meeting specific scientific criteria and identified in the California Labor Code as causing cancer, birth defects, or other reproductive harm. This method established the initial Proposition 65 list in 1986 and continues to serve as a basis for listing when applicable.

Businesses are required to provide a “clear and reasonable” warning prior to knowingly and intentionally exposing individuals to a listed chemical. This warning obligation can be fulfilled through various methods, including product labeling, posting workplace signs, distributing notices in rental housing complexes, or publishing notices in newspapers. Businesses have 12 months from a chemical’s listing date to comply with warning requirements.

Furthermore, Proposition 65 prohibits businesses operating within California from knowingly discharging listed chemicals into sources of drinking water. Compliance with this discharge prohibition must be achieved within 20 months of a chemical’s listing.

Exemptions:

1. Business Size: Businesses with fewer than 10 employees and government agencies are exempt from both the warning requirements and the discharge prohibition.

2. De Minimis Exposure: Businesses are also exempt if the exposures they cause are sufficiently low as to pose no significant risk of cancer or pose no observable effect level for birth defects or other reproductive harm.

Health risks associated with these exposures are explained in more detail below.

Basis for Warnings:
The presence of a Proposition 65 warning on a product label, at a workplace, business, or in rental housing signifies the issuing entity’s awareness or belief that one or more listed chemicals are present. Businesses must provide such warnings unless exposures fall below established “safe harbor” thresholds:

• No Significant Risk Level (NSRL) for carcinogens, or

• Maximum Allowable Dose Level (MADL) for reproductive toxins.

Defining Safe Harbor Thresholds:

1. For Carcinogens:
   The NSRL represents the exposure level estimated to result in not more than one excess cancer case per 100,000 individuals over a 70-year lifetime of exposure. Exposure at or below the NSRL corresponds to a lifetime cancer risk of ≤1 in 100,000.

2. For Reproductive Toxins:
   The MADL is derived by taking the “No Observable Effect Level” (NOEL) – the highest dose level at which no reproductive harm is observed in humans or laboratory animals – and applying a 1,000-fold safety margin (MADL = NOEL ÷ 1,000). A warning is required if exposure exceeds the MADL.

Safe Harbor Numbers & Compliance Options:
OEHHA develops numerical “safe harbor levels” (NSRLs and MADLs) to assist businesses in determining when warnings are mandatory or discharges prohibited.

However, businesses retain flexibility:

• They may issue warnings based solely on knowledge or assumption of a listed chemical’s presence, without conducting exposure assessments.

• OEHHA does not maintain records of warnings issued or their justification, as businesses are not required to report this information.

For specific warning details – including the identity of chemicals, their concentrations, and exposure pathways – contact the business that issued the warning.