Prop 65 Guide
A Prop 65 warning doesn't tell you whether a product is actually harmful for three reasons: companies often over-label for legal protection rather than because a chemical exceeds meaningful exposure limits. The label relies on hazard, not personal risk, meaning it flags a chemical's potential to cause harm without accounting for whether you're ever actually exposed to it, how much, or through what route. Whether a warning matters depends on what the product is made of, how readily that material's chemicals move into air, dust, or skin contact, and how often you're in contact with it, so a warning on sheets you sleep in nightly carries different weight than one on the sealed metal components inside an air purifier. The right response is neither panic nor dismissal, but a material-by-material assessment of whether the exposure pathway is even plausible before deciding if it's worth acting on.
By Dr. Meg Christensen | Physician-founder of Interior Medicine, a non-toxic home resource built on her background in medicine, biochemistry, epidemiology, and clinical research.
Published August 12, 2026 | Updated August 12, 2026
What This Guide Covers
Table of Contents
What does a prop 65 warning mean? Why is Prop 65 on everything?
Why won’t brands tell you what chemical their Prop 65 warning is for?
Intro to Prop 65
If you spend any time on Reddit, Facebook, or other forums, you’ve probably seen this exact conversation many times:
Original Poster: “Does anyone know why does X product has a Prop 65 warning?”
Commenter 1: “Ugh no, and I liked that brand. I can’t believe it’ll cause cancer now, I’m depressed.”
Commenter 2: “I emailed them and they wouldn’t tell me any details”
Commenter 3: “I wouldn’t waste your time worry about it, literally everything has a Prop 65 warning, it’s meaningless.”
Alcohol, aspirin, arsenic, whole-leaf aloe vera, asbestos, formaldehyde, vinyl chloride, wood dust, red dye no. 8, cadmium, fluticasone propionate (Flonase), lead, DDT, cannabis, BPA, blood pressure medications like ACE inhibitors and atenolol, and many more substances are listed as Prop 65 chemicals.
Some of the substances listed feel truly worth concern, some are surprising, and some you might expose yourself to on purpose regularly, like medications, wood dust from woodworking, or alcohol.
By the end of this guide, you’ll be able to see a Prop 65 warning and make a decision about it in a skeptical, calm, and confident way, rather than resorting to fear, defeat, or dismissal.
What does Prop 65 mean?
Prop 65 is a law in California that requires businesses with 10 or more employees to label any product that contains at least one of ~950 chemicals in an amount above a set safety limit. These are chemicals that a committee in California has identified to have the potential to contribute to cancer, reproductive harm, or both. It was originally started in 1986 as a “right to know” act to protect people from chemicals getting into the water supply during product manufacturing.
Why is Prop 65 on everything?
In short, companies over-label because it is easier or legally protective. A Prop 65 Warning can mean three things:
The product contains a chemical that consumers are likely to be exposed to above set limits.
The product contains a chemical that consumers are not likely to be exposed to above set limits, but they’re labeling with a warning anyway for ease, or to cover themselves legally. This includes companies that have a tiny amount of lead solder deep inside of their electronics, which you will never be exposed to. But, instead of trying to prove to California that they meet the requirement, they just add the warning instead.
The product does not contain a Prop 65 chemical but the company has decided to add a warning anyway in case of trace contamination during manufacturing out of their control. This is done to avoid lawsuits as well. For example, some furniture is made with entirely PFAS free materials, but a consumer could test it and finds PFAS that were actually transferred onto the furniture from their rain jacket. It can be legally easier to just label instead.
Aside from the surprisingly normal substances we use daily, this is another reason Prop 65 is so confusing. A warning can mean three wildly different things, and it’s impossible to tell which, even if you ask the company. This actually is such a problem that California now has a term for it:“prophylactic overwarning.” They are taking steps to reduce it, though it will take a few more years (likely 2028) for it to roll out.
What are the set limits for Prop 65 chemicals?
The limit chemicals have to stay under to avoid a Prop 65 warning varies. These are called Safe Harbor Levels (an old maritime sailing term that is still used when talking about legal protections!)
For most carcinogens, the NSRL (No Significant Risk Level) is used. NSRL isn’t a very useful way to think about your personal risk. It’s a measure of risk in a population overall over 70 years. Something that meets an NSRL limit means that a lifetime of daily exposure to it should add no more than 1 extra cancer case per 100,000 people, on top of the cancer that happens anyway for all sorts of other reasons.
For most reproductive toxicants, the MADL (Maximum Allowable Dose Level) ÷ 1000 is used. Unlike the NSRL, this is a personal limit. If something is below the regular MADL limit, it means it doesn’t have any bad reproductive effects for you. Prop 65 takes it way farther and divides that by 1,000 to be extra cautious and respect the uncertainty of what we don’t know about chemicals yet. Exposure at or below this level doesn’t require a warning.
Sometimes, a chemical doesn’t have an NSRL or MADL yet. In this case, a company has to make their own consumer exposure case. Some will just choose to use a warning label instead of doing this.
This is a third reason Prop 65 is confusing: whether a product in your home will have a cancer effect on a population over 70 years, and how that actually applies to you, is impossible to wrap your mind around.
What chemicals are Prop 65?
Naturally occurring and synthetic chemicals are both included on the list. Aside from the ones listed in the intro above, the most common chemicals are from pesticides, household cleaning products, solvents, drugs, dyes, construction materials or even byproducts of processes, like car exhaust. You can see the full searchable list here.
What does Prop 65 Compliant mean?
This just means that the company is labeling correctly. It does not mean that the product is free of Prop 65 chemicals, though it’s often used that way. I’ve even used it that way because it can be a shortcut for “this product doesn’t contain any Prop 65 chemicals” but that’s technically incorrect. A company that labels their Prop 65 chemical-containing product with a Prop 65 warning is also “Prop 65 compliant.”
Prop 65 in California
Is Prop 65 only in California? Technically, yes. Only products that are sold in California have to be labeled. But, because the vast majority of international and US businesses make products for many countries and all states, including for sale in California, they label everything the same way. This is why you might live in Tennessee but still see the CA Prop 65 warning or sticker.
Why won’t brands tell you the chemical they have the Prop 65 warning for?
Mostly for legal and practical reasons.
Many companies use what’s called the short-form warning, which before 2024, didn’t require naming the actual chemical of concern. Now, short-form warnings should name at least 1 of the chemicals of concern, but businesses have a transition period, running through 2028, to comply. Disclosing less than more while still meeting legal requirements is generally a good business strategy.
I'd also guess that companies benefit from the fact that most people are overwhelmed by Prop 65 warnings and won't bother to dig in.
Consider asking the company what chemical their Prop 65 warning is for anyway. You probably won't get an answer, but it sends a message that you care, and as the new rules phase in, you'll start getting real answers by default. More people understand how we have the power to make our homes healthier now. They're thinking about material health and choosing non-toxic options. Every time you ask, it tells a company that may actually be using a harmful chemical that people notice and that they should stop. If the original intent of the law is realized through this reform, transparency will theoretically start to drive competition between companies to make healthier products.
You can also look up a brand on the Attorney General’s 60 Day Notice page to see if they've ever had a formal notice filed against them for a Prop 65 violation, and how it turned out. It may not apply to the specific product you're interested in, and one notice doesn't always tell you about a brand's practices overall. But it's a useful data point on whether a brand has had exposure allegations before.
Why a Prop 65 warning doesn’t necessarily mean something is harmful
There are two reasons a Prop 65 warning doesn’t mean you should worry.
First, it may be over-labeling because it’s easier or legally protective for a company. We covered this above, but to quickly recap, a Prop 65 warning can mean that the product contains a chemical that consumers are not likely to be exposed to above set limits, but instead of trying to prove to California that they meet the requirement, they just add the warning instead. It’s also possible that the product does not contain a Prop 65 chemical but the company has decided to add a warning anyway in case of trace contamination during manufacturing out of their control. A label can mean the presence of a potentially harmful chemical, but it may not.
Second, hazard is not the same as risk. Prop 65 relies on hazard to make calls, not your actual personal risk. Hazard is the intrinsic property for something to cause harm in some situation, but it requires you to be exposed to it for it to become a risk. That exposure also has to get into your body somehow, and it has to accumulate at a high enough dose for you to have a negative response to it. You have to be susceptible to it and not able to clear it. And then it’s still…just a risk, not a guaranteed bad outcome.
A specific example of hazard vs. risk: an air purifier might have a Prop 65 warning on it because it contains a small amount of lead in the metal in the electronic components on the inside. You will never be exposed to it because lead does not spontaneously volatilize into your air. Even if you were to open it up and touch it, lead does not pass through skin. Even if you were to lick it, you would get a very small dose of it. If you were a baby, that could be bad, but if you are an adult, lead is less risky for you because you’re not developing. (If you’re interested in a deep dive, I cover Hazard vs. Risk and how to make decisions about risk in depth my free course.)
But, this doesn’t mean you should completely blow off a Prop 65 warning, either.
Why a Prop 65 warning shouldn’t be completely blown off
Over-labeling has caused us a lot of confusion. Untangling the concepts of hazard, exposure, and risk is difficult, too. It’s so hard to know if a Prop 65 warning will actually affect our health, and the expertise required to figure it out is one more thing we shouldn’t all have to learn. Deciding to ignore it all is a reasonable strategy when dealing with a law that’s not working well for us. That said, I still think it’s worth caring just enough about to make an informed decision instead. I think so for three reasons:
Even though it's nearly impossible to tell which labels are meaningful, some products really do have harmful ingredients in them above set levels. The California Attorney General’s 60 Day Notice page is a public database of formal notices alleging a specific chemical exposure in a specific product. You can look up any brand, chemical, or case, and see whether they were non-compliant or just accused of being so.
The law is being reformed, not thrown out. The underlying concepts and original intention are really good, and when they work, they do protect us. Instead of throwing out the law entirely, it’s being reformed now. Companies over the next few years will have to submit to product testing and be more clear in their disclosures, telling us exactly which chemicals of concern are present. This in itself is a signal that it matters, and just needs to be done better.
Long-term, low-dose exposures do add up. Yes, a single product with a Prop 65 warning will probably not harm you. But one of the basic philosophies of Interior Medicine is that we are never exposed to a singular product. “Levels are too low to harm you” doesn’t work in the context of real life and the thousands of exposures we encounter daily and bioaccumulate.
Reasoning instead of panicking or dismissing is harder to do, but I think it’s worth it. How to do it is next.
How to know if a Prop 65 label matters
Right now, in 2026, asking a company what their Prop 65 label is for will probably not get you an answer (though I still think it’s worth doing.) I also still think it’s worth considering taking a few logical steps to decide if a product has a chemical concern that poses a risk to you.
The simplest version of this is:
Consider what materials the product is made out of.
Consider how chemicals might move out of a product into your home or body, and how much that would happen.
Decide whether the risk is worth the benefit to you.
To be honest, it isn’t simple. This is hard. It requires understanding materials and how chemicals move, and how our bodies process them. I go over this whole thought process in great detail in Part 7: How Do Toxins in Products Reach You? Exposure Routes Explained and cover the risk-benefit thinking in Part 9: What Does “Non-Toxic” Actually Mean? of my course, if you’re interested in the deep dive. Here is a shortened version:
1. Consider what materials the product is made out of.
For example: a couch is a combination of wood, glue, foam, and fabric. An air purifier is a combination of plastic and metal. A plate is ceramic and glaze. Using that, look up the most common reasons for a Prop 65 warning for each material. I have a guide for each, with a list of the chemical possibilities, plus context about whether or not you should be concerned or not:
Common reasons for a Prop 65 warning on plastic
2. Consider how chemicals might move out of a product into your home or body, and how much that would happen.
Can the chemical leave the product? Can it get into your house? Can it get into your body?
Chemicals are generally classified as VOCs, sVOCs, particles, or heavy metals, and they move from products into your house in predictable ways:
VOCs are chemicals that spontaneously volatilize into your air as gas, or odors and smells.
sVOCs are substances that migrate slowly on their own
Particles are physical fragments of things that come off with friction
Heavy metals generally stay locked inside of products but can be coaxed out with friction, heat, or acid
There are three ways chemicals get into your body:
Inhalation: VOCs, sVOCs, and fine particles all move through indoor air, and we breathe constantly
Ingestion: we eat a lot of dust. We touch surfaces, then touch our faces, and small amounts of settled sVOCs, particles, and heavy metals end up swallowed
Dermal absorption: sVOCs like flame retardants and phthalates, especially when contact is prolonged
And then of course, is how often and how much you’re exposed.
For example: a set of sheets is made of fabric, and might be dyed or finished with wrinkle-resistant coatings. You’re in constant, close contact with them overnight every night. A Prop 65 warning on sheets is a high exposure. On the other hand, back to our air purifier example from the beginning of this article: these are made with plastic and metal. A Prop 65 warning for lead very likely refers to the small amount of lead in the electrical components inside. Lead doesn’t volatilize into the air, since it’s a heavy metal. You’ll never come into contact with it, so a Prop 65 warning here would represent a low exposure.
3. Decide whether the risk is worth the benefit to you
Ultimately, there are no absolutes or yes/no answers about whether you personally should avoid something with a Prop 65 label on it. That ambiguity is strange to deal with, and I think causes so much of the confusion in those Reddit conversations. A Prop 65 on one object could cause several different reactions depending on your situation:
The benefits outweigh the risks: taking aspirin or a blood pressure medication like atenolol (both on the Prop 65 list) may be worth it for health reasons. Even for the benefit of fun, people choose to use alcohol and cannabis, which are carcinogens and reproductive toxicants, all the time.
The risks outweigh the benefits: A product with a Prop 65 warning may not alarm a healthy adult male, but would be a legitimate concern for a new baby. Susceptibility, vulnerable health status, and life stage can change the calculus of a Prop 65 decision.
Regardless of logic, people have different levels of risk behavior. What matters most is understanding that yours may be different than someone else. If you want, Part 5: Why We Disagree About Risk: The Psychology of Risk Perception goes into detail about this.
Conclusion
If you have the bandwidth, consider logically thinking through a Prop 65 label based on the materials and how your body interacts with them. If you don’t have the bandwidth, that’s OK, too: there is hope! Reforms are coming to make this easier to navigate for all of us.
In the meantime, just know that neither panic nor dismissal is the answer. There is always some ambiguity present and the best thing you can do is to take care of yourself in a well-rounded way all across your life wherever you can.
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