California lists Bisphenol S as female reproductive toxin under Prop 65

On December 12, 2023, the Office of Environmental Health Hazard Assessment’s (OEHHA) Developmental and Reproductive Toxicant Identification Committee (DARTIC) voted unanimously to list Bisphenol S (BPS) as a female reproductive toxicant under Proposition 65 (Prop 65).

Starting on December 29, 2024, companies doing business in California are required to provide a clear and reasonable warning under Prop 65 for exposures to BPS, including for exposures from products manufactured or distributed prior to this date. Unless OEHHA adopts a favorable safe-harbor exposure level, companies that cannot reformulate out of BPS or reduce BPS concentrations to below detectible limits may become targets for litigation.  

Background on Prop 65

Prop 65 requires businesses to provide “clear and reasonable” warnings before knowingly and intentionally exposing California consumers to one of over 900 chemicals listed as “known to the State” to cause cancer or reproductive harm. Once a chemical is listed, businesses with 10 or more employees, or their downstream customers, have 12 months to comply with warning requirements.

OEHHA has also established safe-harbor levels to assist businesses in determining whether a Prop 65 warning is required, but not for BPS. Without an adopted safe-harbor level – a Maximum Allowable Dose Level (MADL) for reproductive toxins – any detectible exposure to BPS is sufficient to issue a notice of violation, which is the precursor to a lawsuit.

Background on Bisphenol S

BPS is chemically and functionally similar to Bisphenol A (BPA), which was added to the list of chemicals known to the state to cause female reproductive toxicity in 2015. Both BPA and BPS are used in items such as food cans, beverage containers, and toys. BPS is also a common component in hard plastics and synthetic fibers for clothing and other textiles, and is used to preserve color in fabrics.

Outlook and risks similar to BPA listing

The Prop 65 warning requirement for BPA took effect in May 2016. In April 2016, OEHHA proposed an emergency regulation calling for Prop 65 warnings for food and beverage products posted at all physical points of sale. The warning read as follows:

WARNING Many food and beverage cans have linings containing bisphenol A (BPA), a chemical known to the State of California to cause harm to the female reproductive system. Jar lids and bottle caps may also contain BPA. You can be exposed to BPA when you consume foods or beverages packaged in these containers. For more information, go to: www.P65Warnings.ca.gov/BPA.

OEHHA allowed this point-of-sale warning, which became ubiquitous in California grocers, movie theaters, and other retailers, until late 2017. 

OEHHA has also established an MADL of 3 micrograms of BPA per day but limited the safe harbor to dermal exposures. This means that companies were without, and are still without, a safe harbor for alleged hand-to-mouth transfer causing oral exposure to BPA.

Further, in 2020, the Vision Council, an eyewear industry association, secured a Prop 65 Safe Use Determination (SUD) for exposure to BPA from certain polycarbonate eyewear products. In the SUD, OEHHA concurred with the proposed BPA concentration thresholds, which were between 25ppm and 302ppm depending on the eyewear component. OEHHA also adopted the Vision Council’s proposed testing methodology. Whether OEHHA will establish safe harbor levels or SUDs for BPS is currently unclear.

Additionally, the listing of BPA triggered substantial litigation and payments to Prop 65 plaintiff’s attorneys. Starting in 2016, plaintiffs’ attorneys issued approximately 400 Notices of Violation (NOVs) for BPA. Common targets were, and still are, athletic clothing, phone and laptop cases, shoes, socks, food and beverage containers, among others.

Next steps for compliance

Given Prop 65's active and litigious enforcers, companies doing business in California that suspect their products may cause an exposure to BPS are encouraged to review their compliance options now, including an assessment of whether BPS is used in any accessible components of finished goods. Where BPS cannot be replaced, Prop 65 warnings or other protective measures should be considered.

For more information about the implications of this development on your business, contact the authors.