Prop 65 and Dietary Supplements

What is Proposition 65?

In 1986 – almost 30 years ago – due to concern over exposure to toxic chemicals, California voters passed a citizen initiative, the Safe Drinking Water and Toxic Enforcement Act, or, as it’s now universally known, Proposition 65.  This citizen-based initiative, which is now the law in California, requires the State of California to publish two lists of chemicals – one list of chemicals that have been shown to have a risk of causing cancer in animals or humans, and a second list of chemicals that have been shown to have a risk of causing birth defects or other reproductive harm in animals or humans.

Even if a chemical has not been shown to cause these kinds of harm in humans, if the harm has been shown in animal testing, then the State of California is required to put the chemical on the appropriate Proposition 65 list.  The two lists, which are updated once a year, have grown to more than 800 chemicals since they were first published in 1987.

Proposition 65 also requires any company doing business in California to notify California consumers about the presence of a Proposition 65-listed chemical in any product the company is offering for sale in California.

If a product sold in California could expose a California resident to the specified minimum amount of one of these 800+ chemicals, then the product must include a warning notice.  Proposition 65 does not ban the sale of a product that contains a listed chemical; it simply requires that the product have a “clear and reasonable” warning notice on it.

What Kinds of Chemicals Are on the Proposition 65 Lists?

The two Proposition 65 lists encompass a wide range of both naturally-occurring and man-made chemicals.  Listed chemicals include ingredients found in pesticides, insecticides, and construction materials, as well as ingredients in common household products like foods, drugs, and alcoholic beverages.

Proposition 65 applies to all consumer goods sold in California, including food, although naturally occurring chemicals that are in food are not counted for purposes of determining if a warning notice is required.  Since 2013, as a result of litigation to determine their status, dietary supplements are categorized in California as foods for purposes of Proposition 65.

Some chemicals on the two Proposition 65 lists, such as lead, cadmium, and arsenic, are naturally found in the environment, literally all over the world.  Therefore, some products that naturally contain these chemicals can be required to carry a Proposition 65 warning notice, although, as noted above, not in the case of foods.

Are All States Affected by Proposition 65?

Proposition 65 only applies in California.  Manufacturers, distributors, and retailers who sell consumer goods in California are subject to Proposition 65’s warning notice requirement, whether or not the company is located in California.  However, it is certainly possible that a product originally intended for sale in California that has a Proposition 65 warning notice on it could find its way to another State and be offered for sale there, even though Proposition 65 doesn’t apply in that State.

Does Proposition 65 Apply to Dietary Supplements?

Proposition 65 does apply to dietary supplements sold in California.  If a dietary supplement contains a chemical on a Proposition 65 list, and the chemical is present in an amount above its Proposition 65 threshold – and the chemical is not naturally occurring in an ingredient in the dietary supplement – then a warning notice must be on the product to inform California consumers the chemical is present.

Are Products with a Proposition 65 Warning Notice Unsafe?

When a manufacturer includes a Proposition 65 warning notice on a product it does not mean the product is unsafe.  Rather, the notice is intended to inform California consumers of the presence of a listed chemical so the consumer can make an informed decision when purchasing the product.

How Concerned Should I Be about a Proposition 65 Warning Notice?

A bit of background information is needed to understand what Proposition 65 warning notices really mean.  It’s important to understand that a Proposition 65 warning notice does not mean a product is dangerous or harmful.  The threshold exposure limits that the State of California has set for many chemicals on the two Proposition 65 lists are far below the “safe” limits set by other regulatory agencies, such as the U.S. Food and Drug Administration, the U.S. Environmental Protection Agency, various European health agencies, and the World Health Organization.

For example, for lead, for children under the age of six, the U.S. Food and Drug Administration has established the “provisional total tolerable intake level” at six micrograms of lead per day.  Consuming less than this amount of lead daily is an amount the U.S. Food and Drug Administration deems to be safe for children in this age group.  By contrast, Proposition 65 requires a warning notice on any product that provides 0.5 micrograms of lead daily – an amount 12 times lower than the U.S. Food and Drug Administration’s “provisional total tolerable intake level” for daily lead consumption in a six-year-old.  For pregnant women, the U.S. Food and Drug Administration’s “provisional total tolerable intake level” for lead is 25 micrograms daily, which is 50 times greater than the amount requiring a Proposition 65 warning notice.  Finally, the U.S. Food and Drug Administration’s “provisional total tolerable intake level” for non-pregnant adults is set at 75 micrograms of lead daily, which is 150 times greater than the amount requiring a Proposition 65 warning notice in the State of California.

How Does Proposition 65 Determine the Threshold Levels for Which a Warning Notice Is Required?

Proposition 65 establishes two criteria to define the level of exposure risk.  One criterion applies to cancer risk and the other criterion applies to the risk for birth defects or other reproductive harm:

  • The maximum daily exposure threshold for a cancer-risk chemical is determined using the “no significant risk level.” The “no significant risk level” is defined as the maximum daily level of exposure that would result in not more than one additional case of cancer in 100,000 individuals exposed to that specific chemical every day for 70 years.  In other words, a person who was exposed for 70 years to the maximum daily limit of the chemical at the “no significant risk level” would have no more than a one-in-100,000 chance of developing cancer as a result of that 70-year exposure.
  • The maximum daily exposure threshold for a birth defect-risk chemical is determined using the “no observable effect level.”  The “no observable effect level” is defined as the maximum daily level of exposure that has been shown to not cause any birth defects or reproductive harm in laboratory animals or humans.  In addition, as a margin of safety, the “no observable effect level” is divided by 1,000 to establish the threshold for requiring a Proposition 65 warning notice for that chemical.

How Is California’s Proposition 65 Enforced?

Ultimately, the California Attorney General is responsible for enforcing Proposition 65.  In addition, the 53 district attorneys in the State of California can also enforce Proposition 65.  However, any private citizen who states that he or she is “acting in the public interest” can file a lawsuit against a company alleged to be violating Proposition 65 — this is the part of Proposition 65 commonly referred to as its “bounty hunter” provision.

Although Proposition 65 lawsuits have been filed by the California Attorney General and by California’s district attorneys, because the penalties for not including a Proposition 65 warning notice on a product are as high as $2,500 per violation per day, it is easy to understand why consumer advocacy groups, private citizens, and private plaintiff’s law firms have filed the vast majority of Proposition 65 lawsuits.  In fact, most lawsuits brought under Proposition 65 are filed by a very small number of consumer groups and law firms – some of these law firms do no other legal work but represent the plaintiffs who sue companies for allegedly violating Proposition 65.

Why Is There a Proposition 65 Warning On Some Thorne Research Products?

A California consumer advocacy group called Environmental Research Center tested a number of Thorne Research products and found that, based on a product’s recommended daily use, 18 (out of 300) Thorne Research products contained levels of lead higher than the extremely conservative Proposition 65 threshold limit for lead for birth defects or other reproductive harm.  In addition, two products were over the Proposition 65 threshold level for cadmium.

Environmental Research Center notified Thorne Research of their findings in December 2013, and subsequently filed a lawsuit against Thorne Research in March 2014 in Alameda County, California.  Since 2010, Environmental Research Center has done this hundreds of times to hundreds of other dietary supplement companies.  A single law firm usually represents Environmental Research Center in filing these lawsuits.

As noted above, previous litigation against several other dietary supplement manufacturers resulted in a decision by a California trial court in February 2013, in which the court held that dietary supplements are foods, and as such, dietary supplements can qualify for the exemption from the warning notice requirement when a Proposition 65-listed chemical (such as lead) is “naturally occurring” – meaning the presence of lead does not come from human activity such as pesticide application, industrial air pollution, or contaminated groundwater.

After losing this litigation in 2013, the private plaintiffs and the law firms that represent them in Proposition 65 lawsuits against dietary supplement manufacturers have sought to impose an almost impossible standard for manufacturers to meet to prove the “naturally occurring” status of the ingredients in their products.  Thorne Research believed when it was first contacted in December 2013 – and we still believe now – that any lead in an ingredient in our products is naturally occurring.

However, we could not reach agreement with Environmental Research Center on how to define “naturally occurring” so Environmental Research Center sued us in March 2014 for failing to include the Proposition 65 warning notice on the 18 products.  We settled this litigation in January 2015.  The California Attorney General and the trial judge have approved the settlement.

Thorne Research settled the lawsuit because we did not want to go to trial to try to defeat an unreasonable definition of “naturally occurring” and risk not being able to do so.  That is why we negotiated the settlement agreement to have a provision in it for determining how we can prove the lead in several of the ingredients in our products – like pea protein powder and rice protein powder – is naturally occurring, meaning, as noted above, the lead does not come from sources such as pesticide application, industrial air pollution, or contaminated groundwater.

As part of the settlement Thorne Research will notify California consumers of those products that contain levels of lead or cadmium above their respective Proposition 65 limits.  Meanwhile, we will try to prove the “naturally occurring” status of these substances in our products, as well as search for alternative ingredients that contain lower levels of these two substances.  When we’re successful it will mean a Proposition 65 warning notice isn’t required on our products.

Is Proposition 65 Meeting Its Goal of Reducing the Exposure of California Residents to Toxic Chemicals?

In the 30 years since it became law, Proposition 65 has provided California residents with information that has helped them limit their exposure to toxic chemicals.  For example, more women are aware of the dangers associated with alcohol consumption during pregnancy.  And Proposition 65 has prompted the removal of known carcinogens, such as trichloroethylene and methyl chloride, from a number of consumer products.

However, due to what many experts believe are unnecessarily low exposure thresholds to so many chemicals, Proposition 65 warning notices are very nearly ubiquitous in California.  They can be seen in almost every supermarket, restaurant, and convenience store.  Consumer products such as electrical wiring, jewelry, and flashlights are just as likely to carry a Proposition 65 warning notice as are insecticides and paint strippers.  The near-universal posting of Proposition 65 warning notices has led to a general sense of apathy among California residents, which has significantly blunted Proposition 65’s effectiveness.  And Proposition 65 has come at great cost to companies that do business in California and their customers.  The cost and expense involved in product testing and reformulation, providing warning notices, and otherwise complying with Proposition 65 is inevitably passed on to consumers.

How Can I Learn More about Proposition 65?

For information about the chemicals listed under Proposition 65 go to or  

Or do an online search using “Proposition 65” as the search term.