Bisphenol S Added to Proposition 65 List After 2023 DARTIC Meeting

Effective December 29, 2023, the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) has added bisphenol S (BPS) to the Proposition 65 list as a reproductive toxicant, specifically targeting the female reproductive endpoint. The decision, made through the "State's Qualified Experts" mechanism, follows the conclusive findings of the Developmental and Reproductive Toxicant Identification Committee (DARTIC) that BPS is a contributor to female reproductive toxicity.

The listing of BPS under Proposition 65, effective from December 29, 2023, highlights the potential hazards of the substance and necessitates warning requirements for significant exposures.

During the DARTIC meeting, OEHHA staff presented a comprehensive review of the scientific evidence regarding the female reproductive toxicity of bisphenol S. Following the presentation, the DARTIC voted unanimously (9-0) in favor of the determination that BPS induces female reproductive toxicity based on scientifically valid testing according to widely accepted principles. This led to the addition of BPS to the Proposition 65 list, specifically for female reproductive toxicity.

Proposition 65

Proposition 65, established in November 1986 as a ballot initiative, protects California’s drinking water sources from contamination by chemicals known to cause cancer, birth defects, or other reproductive harm. It requires businesses to inform Californians of potential exposure to such chemicals and to provide warnings.

These chemicals may be present in products, homes, workplaces, or released into the environment. Proposition 65 empowers Californians to make informed decisions about their chemical exposures and prohibits businesses from knowingly discharging significant amounts of listed chemicals into drinking water sources.

Understanding Bisphenol S

Bisphenol S (BPS) is a constituent of polyethersulfone (PES) plastic, commonly used in the manufacture of rigid plastic products and synthetic fibers used in clothing and textiles. Beyond its application in curing fast-drying epoxy glues, BPS serves as a corrosion inhibitor and is frequently used as a reactant in polymer reactions. BPS can improve color longevity in fabrics and is often chosen as a substitute for BPA in certain paper receipts. It can also be found in the protective coatings that line some food cans, and consumers should be aware that products labeled as "BPA-free" may contain BPS. The common characteristic of BPS and BPA as endocrine disruptors lies in the presence of the hydroxy group on the benzene ring, enabling them to mimic estradiol.

These developments highlight the ongoing efforts to identify and regulate potentially harmful substances. As stakeholders navigate these changes, it is increasingly important to stay informed about chemical listings and associated warnings.