Why Refluxter Has a Prop 65 Warning | What It Really Means

Last updated: June 12, 2026. Originally published March 15, 2025.

Understanding California Proposition 65 and Its Implications for Dietary Supplements

California’s Proposition 65, officially known as the Safe Drinking Water and Toxic Enforcement Act of 1986, is a regulation intended to inform California residents about exposure to chemicals identified by the state as causing cancer, birth defects, or other reproductive harm. While the intention behind Prop 65 is laudable, its implementation is often criticized for triggering warnings on products whose chemical levels are comparable to those found in everyday foods.

One area where Prop 65 has significant implications is the labeling of dietary supplements, particularly those with naturally occurring trace elements like lead. Understanding what a Prop 65 warning on a supplement label does and does not signify requires a closer look at the regulation itself and the context of naturally occurring lead in the everyday diet.

The Stringency of Prop 65

Prop 65 covers more than 900 chemicals identified by California as hazardous. For lead, the state uses a very conservative “safe harbor” value for reproductive toxicity, the Maximum Allowable Dose Level (MADL) of 0.5 micrograms (mcg) per day, to determine when a warning is required. The MADL is set 1,000 times below the highest exposure level at which no observable effect was found. If a product’s suggested daily use can exceed this amount, a warning is required, such as: “Consuming this product can expose you to Lead, which is known to the State of California to cause birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov/food.”

This threshold reflects California’s approach of erring far on the side of caution. It is worth noting that California updated its short-form warning rules effective January 1, 2025 (with a compliance deadline of January 1, 2028); among other changes, short-form warnings must now name at least one listed chemical, and businesses may use “CA WARNING” or “CALIFORNIA WARNING” to make clear the notice stems from California law.

How Prop 65’s Threshold Compares with Federal and International Reference Levels

The FDA’s Interim Reference Level (IRL) for dietary lead is 8.8 mcg per day for females of childbearing age, and a level of 12.5 mcg per day has been recommended for adults generally (Flannery et al., 2020). The FDA derives the IRL by converting the CDC’s blood lead reference value into an estimated dietary intake and then dividing by 10 as an additional safety factor. The CDC’s blood lead reference value (BLRV) is a population-based screening benchmark used to guide follow-up actions; it is not a health-based safety threshold, and the IRL therefore sits well below it by design. The current IRLs, set in 2022, are 2.2 mcg per day for children and 8.8 mcg per day for females of childbearing age (FDA: Lead in food and foodwares).

For international context, the European Food Safety Authority (2010) has estimated typical adult dietary lead intake at roughly 25–87 mcg per day for a 70 kg adult from ordinary foods, which is roughly 50 to 170 times California’s 0.5 mcg per day warning threshold.

Naturally Occurring Lead in Foods

Many naturally derived ingredients, including botanical extracts, marine ingredients, and minerals, contain trace amounts of lead absorbed from soil and water. Published analyses of everyday foods illustrate how common this is. Peer-reviewed testing has found lead in chocolate and cocoa products at levels ranging from 0.5 to 230 micrograms per kilogram (Rankin et al., 2005). A published ICP-MS analysis found up to 75 micrograms per kilogram of lead in dark chocolate, roughly 3 mcg in a typical 40-gram bar, and up to 170 micrograms per kilogram in dark tuna, roughly 39 mcg in an 8-ounce uncooked portion; the same analysis reported up to 2,800 micrograms per kilogram in cinnamon, although typical use amounts are small (Atkins, 2017). These figures represent the highest samples tested in each analysis rather than typical values, but they show that trace lead in foods derived from natural sources is the norm rather than the exception.

Lead levels in common foods and beverages from published analyses. Tuna, cinnamon, and chocolate values are the highest (“up to”) levels found in each analysis; wine is the mean across 472 internationally sampled wines (Rankin et al., 2005; Atkins, 2017; Towle et al., 2017).

Where Refluxter Stands

Refluxter’s key ingredient, sodium alginate, is derived from brown seaweed, and like other marine ingredients it naturally contains trace minerals. Based on testing of each production lot, one serving (2 capsules) of Refluxter contains less than 0.5 mcg of lead, which on its own is below the Prop 65 daily warning threshold.

So why does the label carry a warning? Because we tell customers they can take Refluxter after every meal and before bedtime if desired, up to 8 capsules per day, an amount of use that can exceed the 0.5 mcg daily threshold. California’s framework requires the warning to reflect the maximum suggested daily use. If our directions had simply said “take once daily,” no warning would have been required. We chose to keep the flexible directions and provide the warning rather than limit how you can use the product.

For perspective, a full day’s maximum use of Refluxter (8 capsules) contains roughly 1 mcg of lead or less, below the published maximum for a single 40-gram dark chocolate bar (roughly 3 mcg), below the mean for a 5-ounce glass of internationally sampled wine (roughly 5 mcg), and a small fraction of the published maximum for an 8-ounce portion of dark tuna (roughly 39 mcg).

Interestingly, some research suggests alginates can bind certain metals in the gut and may support their elimination rather than increase exposure. Savchenko and colleagues (2015) reported that oral calcium alginate supplementation in rats was associated with increased removal of lead from the body. This was an animal study, and its relevance to humans has not been established, but it is a notable direction in the alginate research literature.

The Implications for Dietary Supplements

Dietary supplements made from natural ingredients may carry Prop 65 warnings due to trace lead content. The key takeaway is context: the lead levels that trigger these warnings are often comparable to, or lower than, the levels found in common foods, and far below federal and international dietary reference levels. A Prop 65 warning indicates that a product’s maximum suggested daily use can exceed California’s uniquely conservative 0.5 mcg threshold; it does not, by itself, indicate how the product compares with the rest of the diet. That is a judgment each consumer can make with the numbers in front of them, which is why we publish ours.

Some Prop 65 chemicals, such as lead, are prevalent in the soil of the natural environment and unavoidably end up in products that contain natural ingredients. Products made with synthetic or heavily processed ingredients can more easily avoid or remove natural trace elements. This is a structural disadvantage Prop 65 imposes on natural products, and it is why warnings are disproportionately common on supplements with botanical and marine ingredients.

Conclusion

California’s Proposition 65 plays a role in informing consumers about potential chemical exposures, but its thresholds sit far below federal and international reference levels, and warnings frequently appear on products whose trace lead content is in line with the everyday diet. Understanding where the threshold comes from, how it compares with FDA and EFSA reference levels, and what your actual products contain allows you to put a Prop 65 warning in context. We test every production lot of Refluxter, and we would rather explain a warning honestly than restrict our directions to avoid one.

References

Atkins, P. (2017). Our daily dose of poison: A look at lead in the food supply. Spectroscopy, 32(10), 12–17. https://www.spectroscopyonline.com/view/our-daily-dose-poison-look-lead-food-supply-0

European Food Safety Authority. (2010). Scientific opinion on lead in food. EFSA Journal, 8(4), Article 1570. https://doi.org/10.2903/j.efsa.2010.1570

Flannery, B. M., Dolan, L. C., Hoffman-Pennesi, D., Gavelek, A., Jones, O. E., Kanwal, R., Wolpert, B., Gensheimer, K., Dennis, S., & Fitzpatrick, S. (2020). U.S. Food and Drug Administration’s interim reference levels for dietary lead exposure in children and women of childbearing age. Regulatory Toxicology and Pharmacology, 110, Article 104516. https://doi.org/10.1016/j.yrtph.2019.104516

Rankin, C. W., Nriagu, J. O., Aggarwal, J. K., Arowolo, T. A., Adebayo, K., & Flegal, A. R. (2005). Lead contamination in cocoa and cocoa products: Isotopic evidence of global contamination. Environmental Health Perspectives, 113(10), 1344–1348. https://doi.org/10.1289/ehp.8009

Savchenko, O. V., Sgrebneva, M. N., Kiselev, V. I., & Khotimchenko, Y. S. (2015). Lead removal in rats using calcium alginate. Environmental Science and Pollution Research, 22(1), 293–304. https://doi.org/10.1007/s11356-014-3324-7

Towle, K. M., Garnick, L. C., & Monnot, A. D. (2017). A human health risk assessment of lead (Pb) ingestion among adult wine consumers. International Journal of Food Contamination, 4, Article 7. https://doi.org/10.1186/s40550-017-0052-z

U.S. Food and Drug Administration. (2022). Lead in food and foodwares. https://www.fda.gov/food/environmental-contaminants-food/lead-food-and-foodwares