If you live in the state of California and have ever purchased dietary supplements from Fullscript, you might have noticed that certain products have a warning label indicating the presence of chemicals linked to cancer, birth defects, or other reproductive harm. This warning label is known as California Proposition 65, commonly referred to as Prop 65 for short, and it’s commonly displayed on a range of products from furniture to dietary supplements. Although this warning may be disconcerting, it’s important to understand the basics of Prop 65 and how its guidelines relate to dietary supplements.

What is Proposition 65?

Proposition 65, also known as the Safe Drinking Water and Toxic Enforcement Act of 1986, is a California law that requires companies to display a warning label on any product containing certain chemicals with levels above a predetermined threshold. (6)

Prop 65 does not restrict the sale of products containing harmful chemicals, its purpose is to inform consumers about the potentially hazardous contents of the products they’re purchasing. The Prop 65 list is continually updated with new additions based on the most recent research and occasionally delists existing chemicals that are no longer considered to be a concern to consumers. (7)

Where is the Prop 65 warning label required?

The Prop 65 warning label is required on many products we use and are exposed to every day. Examples of common products requiring this label include:

  • Alcoholic beverages
  • Dietary supplements
  • Furniture
  • Petroleum products (e.g., crude oil, diesel fuel, gasoline)
  • Wood products (10)

Additionally, some physical locations are required to post Prop 65 warning signs:

  • Amusement parks
  • Apartment buildings and rental properties
  • Dental offices
  • Designated smoking areas
  • Gas stations
  • Hotels
  • Office buildings
  • Parking garages
  • Restaurants and coffee shops (10)

What does it mean if a product has a Prop 65 warning label?

Products labeled with the Prop 65 warning contain certain levels of one or more chemicals known to cause cancer, birth defects, or other reproductive harm. (6)

By law, a business must include a warning label if their product contains a chemical known to cause cancer unless the amount is minimal enough that it poses no significant risk. “No significant risk” means that the likelihood of developing cancer is no more than one in 100,000 over the course of a 70-year lifespan as a result of the chemical exposure. (3)

Chemicals known to cause birth defects, or other reproductive harm, undergo thorough research to determine the level at which the chemical poses no threat to humans or animals . This level is known as the “no observable effect level”. Out of an abundance of caution, Prop 65 divides this level by 1,000 to ensure an adequate margin of safety. In other words, a warning label is required if the product contains more than 1/1000th of the “no observable effect level” for a particular chemical known to cause other reproductive harm and birth defects. (3)

The Office of Environmental Health Hazard Assessment (OEHHA) is responsible for reviewing and evaluating current scientific evidence to determine whether or not a chemical should be included in list of chemicals in Prop 65.

Chemicals of concern

Approximately 900 chemicals, some naturally found in nature and others man-made, are included on Prop 65’s list. Examples of these chemicals include:

  • Arsenic
  • Asbestos
  • Benzene
  • Bisphenol A (BPA)
  • Cadmium
  • Carbon monoxide
  • Glyphosate
  • Lead
  • Nitrous oxide (11)

For a complete list of chemicals, visit California’s Proposition-65 website.

What does the California Prop 65 warning label look like?

Products containing certain chemicals with levels above a predetermined threshold are required to carry a Prop 65 warning label similar to the warning label below.

Prop 65 warning labels may also include the name of the specific chemical found in the product.

Manufacturers are also required to indicate the name of the chemical or chemicals contained in any product produced after August 30, 2018. If a product was produced before August 30, 2018, they are not required to include the chemical as long as the company meets all requirements determined at the time of manufacturing. (9)

Woman looking at label on supplement bottle

Proposition 65 warning labels are often found on supplement bottles if they contain any chemicals linked cancer, birth defects, or other reproductive harm.

What are the benefits of Prop 65?

The primary objective of Prop 65 is to reduce harmful chemical exposure in California. Information provided in Prop 65 warnings allow individuals to make informed decisions about the products they purchase, helping them reduce their exposure to potentially harmful chemicals. (3)

As a result of Prop 65, many businesses have entirely removed harmful chemicals from their products. Several other improvements have been made in the state of California including reductions in harmful air emissions, decreased lead content found in jewelry and many personal care products (e.g., toothpaste, hair dye), and reductions in arsenic levels found in bottled water. (8)(12)

Are products labeled with a Prop 65 warning dangerous?

Not necessarily. When used as directed, chemical exposure is minimal. (4) Chemical exposure does not necessarily mean a particular product will cause cancer, birth defects, or other reproductive damage.

Prop 65 guidelines are much more rigorous than many of the Environmental Protection Agency’s (EPA) and the U.S. Food and Drug Administration’s (FDA) guidelines for chemical exposure. For example, the EPA’s limit for lead in drinking water is 15 mcg/L, while the Prop 65 threshold for any product containing lead is 0.5 mcg. (5)(2) The FDA’s limit for daily lead exposure, also known as the Interim Reference Level (IRL), is 12.5 mcg per day. (18)

For further perspective, many foods naturally contain levels of heavy metals commonly found in soil and water and are exempt from Prop 65 regulations. (15) Dark chocolate, for example, contains an average of 0.92 mcg of lead per ounce, which exceeds Prop 65 guidelines. (14) Additionally, grape juice contains approximately 2.6 mcg of lead per serving, which is over five times the limit advised by Prop 65. (16)

Prop 65 and supplements

Unlike food, supplements containing certain chemicals are required to carry a Prop 65 label even if all ingredients in a supplement are naturally occurring. Heavy metals, including arsenic, cadmium, lead, and mercury, are prevalent in the soil and water. These metals can then accumulate in plants commonly used in the production of dietary supplements. (13)

Most vegetable, fruit, and herbal matter is likely to contain some level of contaminants, whether that’s from pesticides, herbicides, or heavy metals. (17) Keep in mind that the level of exposure to these substances is minimal and average daily intake is well below the tolerable limits determined by the EPA and FDA. (1)

The supplement brands provided on Fullscript take precautions to ensure the safety of their products. You may notice some of your supplements carry a Prop 65 warning label on the packaging and this is a clear sign that the manufacturer is compliant with California law. The warning label simply means that the supplement contains small amounts of certain chemicals that may pose a small risk.

Furthermore, certain products in the US Fullscript catalog are restricted for sale in the state of California. This means that the ‘California Only’ products can only be shipped to an address in California and are the only option available for those in California. ‘California Only’ products are identical to the original product; the only difference is the presence of a Prop 65 warning on the packaging.

The bottom line

While receiving a product with a Prop 65 warning label may cause alarm, chemical exposure is generally low when products are used as directed. Prop 65 regulations are particularly stringent and exceed guidelines established by the EPA and FDA. Use supplements as directed and speak to your integrative healthcare practitioner if you have any concerns. If you have questions about a specific product, you can also reach out to the manufacturer directly or contact the Fullscript support team.

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  1. Abdulla, N. M., Adam, B., Blair, I., & Oulhaj, A. (2019). Heavy metal content of herbal health supplement products in Dubai – UAE: a cross-sectional study. BMC Complementary and Alternative Medicine, 19(1), 276.
  2. Agency for Toxic Substances and Disease Registry. (2019, July 2). Lead (Pb) toxicity: What are the U.S. standards for lead levels? Retrieved from https://www.atsdr.cdc.gov/csem/csem.asp?csem=34&po=8
  3. American Cancer Society. (2019, June 26). Cancer warning labels based on California’s Proposition 65. Retrieved from https://www.cancer.org/cancer/cancer-causes/general-info/cancer-warning-labels-based-on-californias-proposition-65.html
  4. American Herbal Products Association . (n.d.). Answers to frequently asked questions about California Proposition 65. Retrieved June 9, 2020, from http://www.ahpa.org/Consumers/CaliforniaProposition65FAQ.aspx#:%7E:text=Is%20Prop%2065%20intended%20to,above%20a%20very%20low%20threshold.
  5. California Office of Environmental Health Hazard Assessment. (2019, March). Proposition 65 no significant risk levels (NSRLs) for carcinogens and maximum allowable dose levels (MADLs) for chemicals causing reproductive toxicity. Retrieved from https://oehha.ca.gov/media/downloads/proposition-65//safeharborlist032519.pdf
  6. California Office of Environmental Health Hazard Assessment. (2020a). About Proposition 65. Retrieved from https://oehha.ca.gov/proposition-65/about-proposition-65
  7. California Office of Environmental Health Hazard Assessment. (2020b). How chemicals are added to the Proposition 65 list. Retrieved from https://oehha.ca.gov/proposition-65/how-chemicals-are-added-proposition-65-list
  8. California Office of Environmental Health Hazard Assessment. (2020c). Informing Californians’ choices and reducing chemical exposures. Retrieved from https://www.p65warnings.ca.gov/informing-californians%E2%80%99-choices-and-reducing-chemical-exposures
  9. California Office of Environmental Health Hazard Assessment. (2020d). New Proposition 65 warnings. Retrieved from https://www.p65warnings.ca.gov/new-proposition-65-warnings
  10. California Office of Environmental Health Hazard Assessment. (2020e). Products & places. Retrieved from https://www.p65warnings.ca.gov/products-places
  11. California Office of Environmental Health Hazard Assessment. (2020f). The Proposition 65 list. Retrieved from https://oehha.ca.gov/proposition-65/proposition-65-list
  12. Cox, C., & Green, M. (2010). Reduction in the prevalence of lead-containing jewelry in California following litigation and legislation. Environmental Science & Technology, 44, 6042–6045.
  13. Hu, B., Jia, X., Hu, J., Xu, D., Xia, F., & Li, Y. (2017). Assessment of heavy metal pollution and health risks in the soil-plant-human system in the Yangtze River Delta, China. International Journal of Environmental Research and Public Health, 14(9), 1042.
  14. 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.
  15. State of California Department of Justice Office of the Attorney General. (2019, June 20). Frequently Asked Questions. Retrieved from https://oag.ca.gov/prop65/faqs-view-all
  16. U.S. Food & Drug Administration. (2018a, February 23). Total diet study. Retrieved from https://www.fda.gov/food/science-research-food/total-diet-study
  17. U.S. Food & Drug Administration. (2018b, March 21). Foods and analytes in the total diet study. Retrieved from https://www.fda.gov/food/total-diet-study/foods-and-analytes-total-diet-study
  18. U.S. Food & Drug Administration. (2020, February 27). Lead in food, foodwares, and dietary supplements. Retrieved from https://www.fda.gov/food/metals-and-your-food/lead-food-foodwares-and-dietary-supplements