California's SB 646: A Landmark Law Requiring Heavy Metal Testing in Prenatal Multivitamins
California has taken a historic step toward protecting maternal and fetal health with the passage of Senate Bill 646 (SB 646) authored by Senator Akilah Weber Pierson and signed into law in October 2025. This legislation establishes the first statewide U.S. requirements for testing and publicly disclosing heavy metal levels in prenatal multivitamins. The law goes into effect January 1, 2027, giving manufacturers time to prepare for new testing, reporting, and transparency obligations.1
Why SB 646 Was Introduced
SB 646 responds to mounting evidence that prenatal vitamins may contain detectable levels of toxic heavy metals, including lead, cadmium, arsenic, and mercury. A peerreviewed study cited in legislative discussions found that many of 150 prenatal multivitamin products tested contained lead and cadmium, with one product containing 900 parts per billion of lead.2
These findings echo earlier concerns that led California to pass AB 899, a law requiring heavy metal testing and disclosure for baby foods. SB 646 extends that consumerprotection framework to prenatal supplements, recognizing that exposure to toxic elements during pregnancy can impair fetal neurodevelopment and contribute to longterm health risks.
Read more about law AB 899 here
What SB 646 Requires
SB 646 introduces a comprehensive set of testing and transparency requirements for manufacturers and brand owners of prenatal multivitamins.3
1. Mandatory Heavy Metal Testing
Manufacturers of both bulk and packaged prenatal multivitamins must test a representative sample of each lot for four toxic elements:
- Arsenic
- Cadmium
- Lead
- Mercury
This requirement applies to all prenatal multivitamins sold in California, regardless of where they are manufactured.
2. Laboratory Standards
Testing must be conducted by laboratories that meet strict quality and sensitivity criteria:
- ISO/IEC 17025:2017 accreditation
- Demonstrated proficiency in detecting metals at 10 µg/kg
These standards ensure that testing is both scientifically rigorous and consistent across manufacturers.1
3. Public Disclosure Requirements
Brand owners must publish the following information on their websites:
- Heavy metal levels detected in each prenatal multivitamin product
- Nutrient information
- A required statement about toxic elements and ingredients
This disclosure must appear on the same webpage as the nutrient information, ensuring consumers have easy access to safety data.
4. Reporting to the State
Manufacturers and brand owners must provide test results to the California Department of Public Health upon request.
How SB 646 Protects Consumers
The law is designed to:
- Increase transparency in a supplement category where contamination has been repeatedly documented
- Reduce exposure to toxic heavy metals during pregnancy
- Align California’s standards with emerging scientific consensus on prenatal supplement safety
- Encourage industrywide improvements in sourcing, manufacturing, and quality control
As the first law of its kind in the nation, SB 646 is expected to influence regulatory discussions beyond California, much like Proposition 65 and AB 899 did in their respective domains.
What Manufacturers Should Do Now
With January 1, 2027, effective date approaching, manufacturers should begin:
- Reviewing and updating their heavy metal testing protocols
- Ensuring partnerships with ISO/IEC 17025:2017accredited labs
- Preparing for public disclosure requirements
- Evaluating raw material sources to reduce contamination risk
Early preparation will help companies avoid compliance challenges and demonstrate leadership in consumer safety.
Conclusion
California’s SB 646 represents a major advancement in prenatal supplement safety. By mandating rigorous testing and transparent reporting of heavy metal levels, the state is setting a new benchmark for protecting pregnant individuals and their developing babies. As scientific scrutiny of supplement quality continues to grow, SB 646 may serve as a model for future national standards.
If you’re preparing for compliance, our team is here to guide you through every step.
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