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Prop 65 – What Supplement Consumers Need to Know

What is Prop 65?

Prop 65 is a legislation that is entirely bespoke to the state of California formed for the purpose of informing consumers about potentially harmful ingredients.  Prop 65 is something consumers are coming across more and more with the international purchase of supplement goods especially within the USA.  Since its birth about 30 years ago, it has been annually updated to currently contain approximately 900 chemicals.

On this list is a range of substances from herbicides and pesticides to some of the most common forms of heavy metals. Initially, this was a safety concern warning against potentially contaminated water supplies in the state of California, which may leach into soils and plants.  It was developed and voted for by the residents of California pre-internet era over 30 odd years ago, with genuinely good intentions. However, the implementation can hinder the importation of products into the state of California, that can be provided into other parts of America without concern.

What the Proposition 65 warning looks like…

Proposition 65 requires businesses to provide warnings to Californians about significant exposures to chemicals that cause cancer, birth defects, or other reproductive harm. harm. When you come across the Prop 65 warning if you are a resident of California, here is what it looks like:

Warning: Consuming this product can expose you to chemicals including lead, which is known to the state of California to cause birth defects or other reproductive harm. For morning information go to

This is the official warning required on labeling only by the state of California. However, it can be difficult for companies to produce labels and advertising that state-specific. Additionally, the company is unable to prevent their products from being physically purchased in another American state and taken into California by the consumer, but yet the Company remains liable (and in breach) for the label not being on the product in such circumstances. With this, because of importation and transit, many companies just apply this Prop 65 warning and produce one standard label to be applied nationwide for the USA. This leads to many consumers becoming concerned and confused by the warning due to the lack of knowledge on the complexities of Prop 65, which remains only relevant outside of California.

The “Safe Harbor Level”

The “safe harbor level” is deemed by a committee of scientists as the threshold of safe consumption when used as directed.  Even in this case where a product is well within safe harbor levels, companies generally still apply the claim to avoid potential lawsuits in the state of California. Better to be safe than sorry right?

However, here is where it gets a bit grey – the Committee is deeming new products be added to the list annually, and subsequently, not all compounds have been allocated a “safe harbor level”. It’s believed that as many as 60% of the items on the list may not have been allocated this safe harbor threshold for safe consumption and interaction. So, the Prop 65 warning gets labeled on the product, which can be anything organic or inorganic in nature, if it contains one of the items on the Prop 65 list. Even if the chemical is barely detectable, because there is no “Safe harbor” level allocated, the warning must be present. Which can be very alarming to consumers.

An example of confusion around Prop 65 Warnings…

Alcohol – yes, alcohol is on that list of 900 or so Prop 65 chemicals. So, if you are buying a bottle of wine for a dinner party to celebrate that new position at work. There will be a proposition 65 warning label on that bottle of wine, only for Californians, because the consumption of alcohol has been linked with the increased risk of cancers. However, this is not information limited to just California. Around the globe, the World Health Organisation has made it very clear that the consumption of alcohol should be done in moderation and is linked with risk factors or early mortality.

Similarly, what is normally deemed as a healthy superfood, Matcha Tea, also contains this warning only for Californians as it may contain traces of lead. To drink or not to drink?

What science are the warning claims based on?

California’s Office of Environmental Health Hazard Assessment (OEHHA), the International Agency for Research on Cancer (IARC) do not need to test a compound in humans to see if there are carcinogenic properties to humans. Animal studies are sufficient to deem a compound as carcinogenic or harmful. Which from a human ethics aspect makes sense, except that in most animal studies, the doses are far higher than what a human would actually consume or accumulate in most instances through their diet or general exposure.

This is where we can see a lot of grey areas and concern for compounds that may elicit little to no effect in humans but have been deemed as harmful in animal studies. A great example of this is the famous news headline “French fries cause cancer”, a great eye-catching headline and excellent scare tactic to get people to read your article (clickbait 101) – but this turned out to be debunked shortly after. Ahh yes, the big Acrylamide scandal, which saw us looking at our French fries and coffee a little differently.

Acrylamide is a naturally occurring compound that can be formed in foods exposed to heat or cooked – making it unavoidable and linking cancer and coffee together for instance was more hindering and misleading than anything. Studies done on rodents showed little to no effect in correlation with various cancers and the exposure assessment, in general, has been deemed inadequate.[1] There was a follow-up call from the FDA to reassess the threshold for naturally occurring compounds like this.

Supplements and the big target on Heavy Metals

Prop 65 isn’t limited to just foods, however understandably, no one wants to be ingesting large amounts of heavy metals in any form, they are notoriously difficult to remove from the body. But again, we find ourselves in a grey area of concern with Prop 65 and commonly administered dietary supplements.

You will commonly come across this Prop 65 warning on items that are food-based, think dietary protein supplements, fish oils, natural food supplements, etc.  The consumer can take comfort that they contain food at least, but this warning can be confusing. Of course, being of food origin there is a chance it comes in contact at some stage with by-products of human pollution – fossil fuels, pesticides, and geological leeching from active or inactive volcanic soil areas. We see this in commonly bought grocery goods; rice for example is renowned for having traces of arsenic and your mushrooms have traces of cadmium. So, if you’re buying even the highest quality of organic food-based products, there is a fair chance”, it will have some form of minuscule traces of metals, well, unless it was synthetically produced in a “franken-food” lab.

Should you take the Prop 65 label seriously?

For the company/producer – Yes, it is better to be safe than sorry, even if there are grey areas, It would be nice if safe harbor thresholds could be indicated on all of the substances on this extensive list. That is not the case, unfortunately, so we work with what we have; even if the product contains one speck of a trace, it’s better to have the warning on your product and save yourself as a company rather than face a potential lawsuit later down the track.

For the consumer – all we suggest is to do thorough research. Limit purchasing from companies where the price is a little too good to be true, that cannot provide testing documents or certificates of authenticity if requested. If their manufacturing isn’t up to the highest grade possible for food manufacturers which they should be able to present also their grade. Lastly, especially don’t assume that because they don’t have the warning label, they are safe.  Most high-quality manufacturers still apply the warning because they care about the consumer and it’s about helping them to make informed decisions not hiding behind faulty or misleading labeling.