Prop 65 Warning

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What is the Prop 65 Warning?

The Proposition 65 warning is officially known as the California Proposition 65 warning or the Safe Drinking Water and Toxic Enforcement Act of 1986. It is a law that prohibits companies from intentionally releasing large amounts of harmful chemicals that could cause cancer, birth defects, or reproductive harm into sources of drinking water.

It also requires companies to ensure that any products containing listed chemicals do not expose individuals to amounts above a specific safety threshold. If exposure is likely to exceed that limit, the company must either reformulate the product to reduce or eliminate the chemical, or provide a clear warning to consumers in advance.

Even though it's a California law, many companies apply the warning nationwide to avoid legal risk and simplify packaging, which may be why you see a product with this warning outside of California. But also keep in mind, if a product is not sold, distributed, or used in California it does not have to include a Prop 65 warning. 

Pros of Prop 65

Proposition 65 offers several advantages, including raising public awareness, promoting the use of less hazardous products, and contributing to environmental preservation. By requiring warnings on products that contain potentially dangerous chemicals, the law helps inform consumers about possible health risks they might not have known about. This enables people to make more conscious choices about the items they purchase and use. As a result, companies are often motivated to reformulate their products to reduce or eliminate toxic ingredients in response to consumer demand.

For example:

Under Prop 65, 4-Methylimidazole (4-MEI), a byproduct in certain caramel colorings used in soft drinks, was listed as a chemical known to cause cancer. California required warning labels if beverages exceeded safe exposure levels. To avoid the need for Prop 65 warnings and to address consumer concerns, Coca-Cola reformulated its caramel coloring in products like Coke and Diet Coke to reduce 4-MEI levels well below the Prop 65 limit. (This is not me telling you to go and drink Coke everyday. Ha!)

In addition, Prop 65 regulations cover California’s water sources, which has led to stronger protections for drinking water and broader efforts to safeguard the environment.

Cons of Prop 65

Some of the main criticisms of Proposition 65 include excessive warning labels, public confusion, and the potential for misinformation. Because the Prop 65 warning appears on such a vast array of everyday products, its impact is often diluted. Rather than serving as a meaningful health alert, the label can become background noise—something many people overlook entirely.

The warning can also trigger unnecessary worry. The presence of a label doesn’t always indicate a significant health risk, as the threshold for required warnings is set extremely low. As a result, people might avoid products that are, in reality, completely safe, simply because they contain trace amounts of a listed substance well below harmful levels.

Prop 65 doesn't provide context about the amount of exposure, or how dangerous the chemical is compared to others.

A 2016 study from Harvard Kennedy School criticizes the current government warning systems, including Prop 65, for their inability to clearly differentiate between serious and minor risks—comparing the confusion to mixing up wolves with puppies. When consumers are overwhelmed with warnings about relatively insignificant hazards, they may start tuning them out. This desensitization becomes risky when genuine threats emerge but warnings are no longer taken seriously. Prop 65 labels alert shoppers to the presence of potentially harmful chemicals, but they don’t provide context about the amount of exposure or how dangerous the chemical is compared to others. Because of this lack of clarity, the researchers conclude that Proposition 65 warnings often fail to deliver meaningful or helpful information to consumers.

Redmond Bentonite Clay

Let's look at heavy metals. Heavy metals are found in so many things—food, water, soil, supplements, cosmetics—because they're naturally present in the Earth's crust and have become more widespread through human activity. Because of this, products that have a higher chance of containing naturally occurring trace minerals (like mineral salts, bentonite clays, etc), are most likely going to include a Prop 65 warning. In these cases, brand transparency and communication speaks more to me than a warning label. Do not ever hesitate to reach out to a company and ask the hard questions. You can tell a lot by their response! You can read more about brand transparency here.

I am not negating the severity of heavy metal exposure, but we also can't let toxicity paranoia consume us. Unfortunately, it's nearly impossible to escape toxins entirely. Do the best you can, and then hug your kids tight, get outside, stay active, and enjoy life. Keep yourself as healthy as you can, support your immune system, and trust in your body's natural detoxification system. It's powerful!

How Are Safety Levels Determined?

As noted earlier, one of the major concerns with Proposition 65 is that its warning labels are often applied to products that are, by practical standards, safe. This is largely due to how the law defines safety thresholds, which are extremely conservative. So, how exactly does Prop 65 determine what counts as a “safe” level of exposure?

According to the plain language summary of Prop 65:

• For chemicals linked to cancer, the “no significant risk level” is the amount of exposure that would cause no more than one additional case of cancer in 100,000 people over a 70-year lifetime. In simple terms, someone exposed to this level every day for 70 years would have a 1 in 100,000 chance of developing cancer due to that exposure.

• For chemicals associated with birth defects or reproductive harm, safety is based on the “no observable effect level”—the highest level of exposure shown to cause no harm in humans or lab animals. Prop 65 then adds an extra buffer by dividing that amount by 1,000. So, businesses must issue a warning if exposure goes beyond one-thousandth of that already-safe level.

Summary of Prop 65 Risk Thresholds:

• Cancer Risk: A chemical is considered a potential cancer risk under Prop 65 if exposure to it over a 70-year lifetime increases the risk of developing cancer by more than 1 in 100,000.

• Reproductive Harm Risk: For chemicals linked to birth defects or reproductive harm, exposures must be 1,000 times lower than the safe level.

Prop 65 vs FDA Regulation

Proposition 65 sets much stricter limits on chemical exposure than federal agencies like the FDA.

Take lead, for example—a heavy metal with well-documented health risks that’s commonly found in the environment. In June of 2022 the FDA tightened its Interim Reference Levels for lead to 2.2 micrograms/day for children and 8.8 micrograms/day for females of childbearing age - applying a tenfold safety margin. By comparison, Prop 65 sets a far more cautious limit of just 0.5 micrograms per day, using a 1,000-fold safety buffer.

If those numbers seem inconsistent, that’s because they are. Different agencies often rely on varying studies, methods, and assumptions to define what counts as “safe,” which can lead to conflicting guidelines.

In fact, the FDA has occasionally pushed back against certain Prop 65 warnings, arguing that they don’t always align with scientific evidence. A well-known example is the controversy over coffee. Prop 65 required a cancer warning due to the presence of acrylamide—a compound formed during the roasting process. While acrylamide has been shown to cause cancer in high doses in animal studies, the amount found in coffee is extremely low. In contrast to the warning, research has actually linked coffee consumption to a reduced risk of several cancers. Keep in mind, not all coffee is created equally.

Due to public pressure and scientific review, coffee was officially removed from the Prop 65 list in 2019. While that change marks progress, it also highlights the need for broader updates to the regulation so that it can serve the public more accurately and effectively.

I am not here to tell you what the "safe" number is. Obviously, the "safest" number is 0, but I think it's important to look at these topics as a whole, with as much context as possible.

Prop 65 & Dietary Supplements

As the coffee example shows, many natural products—including foods, drinks, herbs, and dietary supplements—can contain trace amounts of substances that may be harmful in large doses, but are not necessarily dangerous at the extremely low levels commonly consumed.

A similar issue arises with dietary supplements, where Prop 65 warnings frequently mention lead or other heavy metals. While it’s true that heavy metal exposure at high levels is a serious health concern, it’s also important to recognize that trace levels of these elements are naturally present in the environment. Because they exist in the earth’s crust, small amounts can be found in nearly all plant-based foods—fruits, vegetables, herbs, roots, nuts—especially those grown in soil.

In most cases, when these foods are grown in uncontaminated environments, the benefits of consuming them far outweigh the risks posed by naturally occurring heavy metals. However, the situation becomes more concerning with certain dietary supplements—especially those sourced from regions with polluted soils or loose regulatory oversight.

To reduce risk, choose supplements that are certified organic (such as USDA Organic), verified by organizations like the Clean Label Project, or tested by trusted third-party labs (not online influencers)! These markers indicate that a company is actively working to ensure its products are free from harmful levels of heavy metals and other contaminants.

Questions to Ask

Despite its limitations, Proposition 65 can still serve as a helpful tool for consumers, businesses, and environmental health. While the warnings may not always reflect meaningful risk, they can still prompt more thoughtful decision-making. If you see a Prop 65 label on a product, consider the following before deciding whether to buy it:

• Do you really need this product? If it’s not essential, it might be worth skipping.

  
  

• Can you find a safer alternative? Look for options that don’t carry a Prop 65 warning.

  • This can be tricky, though, since if a product is not sold, distributed, or used in California it does not have to include a Prop 65 warning. 

    
    

• Look into the listed chemical. Research what it is, how it might affect your health, and whether the level of exposure is concerning to you.

  
  

• Think about how often, and how, you’ll use it. 

  • Prioritize products used daily, especially ones:

    • you ingest (foods/drinks)

    • come into contact with food, especially hot food (cookware, tableware)

    • leave on skin products (lotions/makeup)

  • Occasional-use items or rinse off products like shampoos may pose less risk

    
    

• Look for trustworthy certifications. Labels like USDA Organic or third-party verified non-toxic seals often indicate stricter testing and lower contaminant levels.

  
  

• See what the manufacturer says. Reputable companies often share more details about their ingredients and safety practices. Never hesitate to contact a brand if you have questions, or can't find what you're looking for!