Maternal health milestone: California mandates toxic metal testing in supplements

The non-profit organization, the Environmental Working Group (EWG), touts Governor Gavin Newsom’s signing of SB 646, a law that requires manufacturers of prenatal multivitamins to test for and publicly disclose levels of toxic heavy metals, including lead, arsenic, cadmium, and mercury.

The measure — authored by democratic Senator Dr. Akilah Weber Pierson and co-sponsored by the EWG, Unleaded Kids, and the American College of Obstetricians and Gynecologists District IX — marks the first time any US state has passed a mandate allowing for this amount of transparency.

The law will take effect on January 1, 2027, giving the supplement industry two years to prepare for the coming testings and accountability.

“With Governor Newsom’s signature, California has taken a monumental step to protect maternal and fetal health,” says Susan Little, EWG’s California legislative director. “Even trace amounts can interfere with a baby’s brain development, raising the risk of lifelong health and learning problems.”

“It’s unacceptable that pregnant women are unknowingly exposed to toxic metals in the very supplements they take to protect their health and their baby’s health.”

Protecting maternal health

The move comes amid mounting evidence that prenatal supplements, which are designed to safeguard maternal and fetal health, are often contaminated with trace metals known to interfere with neurological development and pregnancy outcomes.

A recent peer-reviewed study in Environmental Research found that most of the 150 popular prenatal multivitamins contained detectable levels of lead and cadmium, with one product showing as much as 900 parts per billion of lead. The study appears to confirm the contested findings of a similar study published in the American Journal of Clinical Nutrition at the end of 2024.

While these concentrations fall below the FDA’s daily exposure limit of 8.8 micrograms, scientists warn that no level of lead is truly safe for developing fetuses. Even low-dose, chronic exposure can affect brain development and future cognitive function.

Under SB 646, manufacturers must list both the names and levels of any heavy metals detected, and include a clear reference on product labels directing consumers to a website where full testing results are published. The law builds upon Assembly Bill 899, passed in 2023, which established similar requirements for baby food.

According to the EWG, the implications of the law extend beyond California. By setting enforceable standards for transparency and safety, the legislation could reshape how prenatal supplements are manufactured and marketed nationwide. It may also give healthcare professionals critical data to guide patients toward cleaner, safer options.

This comes at a time when US food safety confidence is reportedly at an all-time low. It also comes on the heels of several health and nutrition enforcement laws passed by the Governor, including one banning the sale of ultra-processed foods in the state’s schools.

“Right now, there’s no federal requirement even to test prenatal multivitamins for lead, cadmium, mercury, or arsenic, let alone inform the public,” Little underscores. “That’s unacceptable — SB 646 ensures accountability from supplement makers.”

Safety through transparency

The Environmental Research study found that the type of supplement may influence contamination risk. It also uncovered that gummies and soft gels contained little to no measurable lead, while traditional tablets and capsules frequently did.

The EWG supports that, for expectant mothers navigating the maze of prenatal supplements, SB 646 offers reassurance and empowerment through information. As testing becomes mandatory and disclosures public, families will have clearer insight into what they are taking and what they are avoiding.

“It’s outrageous that prenatal multivitamins, which are meant to support healthy pregnancies, may contain toxic heavy metals,” Bernadette Del Chiaro, EWG’s senior vice president for California, asserts. “Thanks to Gov. Newsom’s signature, California is once again at the forefront of protecting maternal and infant health.”

“Consumers have a right to know exactly what they’re putting in their bodies. SB 646 brings long-overdue transparency to the supplement industry, and peace of mind to families,” she concludes.