After a unanimous 9-0 vote by the Developmental and Reproductive Toxics Identification Committee (DARTIC), the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment (OEHHA) announced to add bisphenol S (BPS) to the list of chemicals known to cause reproductive toxicity (female reproductive endpoint) under California Proposition 65. This chemical has therefore been added to the Proposition 65 list of chemicals, for female reproductive toxicity, effective December 29, 2023.
Identify of bisphenol S (BPS)
Bisphenol S, or BPS, consists of two hydroxyphenyl groups connected by a sulfonyl group and has the molecular formula C12H10O4S. It is an analog of bisphenol A (BPA) and its IUPAC name is 4-4hydroxyphenyl sulfonylphenol. BPA is also known as 4,4'-sulfonyldiphenol, 4-hydroxyphenyl sulfone, and 4,4'-sulfonylbisphenol. The CAS number for BPS is 80-90-1.
BPS, which is commonly used to produce plastics and is a part of PES plastic, which is used to make hard plastic items and synthetic fibers for clothing and other textiles. It is also utilized as a color developer for thermal paper and as a protective coating for some food cans. BPS can even be detected in personal care products, food, baby bottles, and other items.
Recent researches reveal that exposure to BPS is widespread and can be rapidly distributed throughout the body. It can be detected in human cord blood, amniotic fluid, breast milk, semen and skin. BPS can also be measured in human breast milk and there is maternal-fetal transfer of BPS via the placenta in humans.
Female reproductive toxicity of BPS
While BPS was previously thought to be a safe substitute for BPA, recent researches demonstrated that it has a wide range of toxic effects on neuroendocrine function in animals. The DARTIC’s research has indicated that BPS can be just as damaging to the reproductive system as BPA, and that even relatively low levels can cause damage to female eggs.
- Effects on ovarian development and maturation of oocytes: BPS can alter germ cell nest breakdown and meiotic progression in oocytes. BPS can cause alternations in spindle morphology and chromosome alignment in oocytes. BPS can cause changes in follicular cell communication and proliferation.
- Effects on the placenta: BPS may alter autocrine and paracrine signaling in the placenta.
- Effects on the endocrine system (hormone levels, receptor levels, mRNA): BPS can alter hormones involved in reproduction and development in whole animals. It can also induce changes in steroid hormone receptor expression in vivo and in vitro.
The addition of BPS to California's Proposition 65 list of reproductive toxins is an important step in the state's efforts to protect public health and the environment. This decision enhances the warning to consumers and will prompt manufacturers to find safer alternatives.
