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Learn ➜  Course ➜  Part 6

What Household Chemicals Should I Avoid?

By Dr. Meg Christensen

Dr. Meg Christensen is the physician founder of Interior Medicine, a non-toxic home resource built on her background in medicine, biochemistry, epidemiology, and clinical research.

Published May 2026   |    Updated May 2026

Welcome to What "Non-Toxic" Actually Means, a free course on how to read product claims and navigate healthier materials more clearly. Stay here, or if you'd like the full arc, the Intro is the best place to start.

Part 6 takes ~10 min to read

The household chemicals most worth avoiding are PFAS, phthalates, formaldehyde, flame retardants, lead, cadmium, combustion particles from gas stoves and chlorination byproducts in water. These substances appear in our home products, indoor air, and water, and have well-documented hazard evidence at residentially relevant levels. The full database below covers 70 substances organized by where they show up in at home. A reminder that this is a hazard list, not a risk list, and the two aren’t the same. You can read more about why in Part 2 of the course.

Is It Non-Toxic? A Clear Process You Can Use

This half of the course is all about the tools you can use to decide whether a product is non-toxic. I can't make that decision for you, because doing so would collapse the six-step frameworkinto one step, and I'd be projecting my susceptibility assumptions, my precautionary stance, and my risk tolerance onto a decision that should be yours. Instead, we sort the six steps by who can answer them. Hazard, exposure, and dose are knowable from outside data, so I'll show you how those fill in the framework. Susceptibility is partly knowable from outside data and partly knowable only to you. Risk tolerance and precautionary stance are knowable only to you, so you'll bring those.

If it feels like a lot, there's a tool at the end of the course in Part 10 that walks through the framework for you on any specific product. If you'd rather see the tool first and decide whether you want the background, that works too.

Otherwise, let's get started with step 1: Hazard!

What Household Chemicals Should I Avoid?

Below is the list of hazards in the home. Every institution, brand, and blog has a different set of chemicals to prioritize avoiding, and I didn't want to come up with another arbitrary set. So I built this using the methodology described below the list.

Before you scroll through, I recommend holding it lightly. This list matters. It's the working set of substances the rest of the course returns to, and Part 7 builds directly on it. But you don't need to memorize it or start auditing your home against it yet. Skim it, notice what's there, and move on. The point of seeing it now is so the next steps have something concrete to land on.

Hazard Database
Potential hazards common in home products, organized by the material category they appear in. Checkmarks show which hazard lists flag each one. Substances that appear in more than one material are listed under each.
Material:

Hazard lists: IARC = International Agency for Research on Cancer. NTP = National Toxicology Program. REACH = EU Substances of Very High Concern. CLP CMR = EU Carcinogenic, Mutagenic, Reprotoxic. ATSDR = US Agency for Toxic Substances and Disease Registry. WHO = World Health Organization 10 chemicals of major public health concern. EPA = US Environmental Protection Agency drinking water regulatory or candidate list (CCL 6 draft plus current Safe Drinking Water Act regulations). Six Cl. = Green Science Policy Institute's Six Classes framework. DTSC = California Candidate Chemicals List. Prop 65 = California Proposition 65. AB 1200 = California cookware labeling list. Blogs = commonly cited as a hazard in popular non-toxic and wellness blogs.

The Methodology Behind the List

Casting a Wide Net

I didn't want to miss anything important that just wasn't on my radar. So I started with the major institutions that address toxicants: IARC (the International Agency for Research on Cancer), the National Toxicology Program (NTP), REACH SVHC (the EU's Substances of Very High Concern list), CLP CMR classifications (the EU's harmonized list of Carcinogenic, Mutagenic, and Reprotoxic substances), ATSDR (the Agency for Toxic Substances and Disease Registry), the WHO Global Air Quality Guidelines and 10 Chemicals of Major Public Health Concern lists, Proposition 65, and AB 1200.

Then I expanded to additional sources that catch hazards the institutions haven't yet addressed, or that are emerging issues with good evidence we should keep an eye out for. For that, I turned to the Six Classes framework (the Green Science Policy Institute's grouping of chemicals of concern by function), DTSC's Candidate Chemicals List, and the EPA’s Drinking Water Contaminant Candidate List 6 that highlights emerging concerns that aren’t formally regulated yet.

Finally, I looked through to see if any substances commonly called out on wellness blogs were missing from these lists. A handful were, like bleach, ammonia, quats, and fragrance. Institutional lists miss these for structural reasons (bleach is acute rather than chronic, fragrance is a mixture rather than a single substance). They're still very present in most homes. Beyond that, sometimes wellness coverage catches what institutions miss, and that's worth taking seriously even when the rest of the methodology informing this list leans institutional. (Think of how long PFAS were being called out before they were formally recognized as a problem.)

I included substances found in products, and substances that end up in the air because of those products. I included other hazards in the air that don't come from products at all, like radon. I included substances in the water supply that reach our sinks. And I included hazards we treat similarly to substances by avoiding or reducing exposure, like blue light.

Hazard is just the first step. A substance being on this list, from any of these sources, only matters if the next steps show it does. We'll see how that plays out as we go.

Narrowing it Down

A lot of the substances overlap, and together, over 1,000 chemicals could deserve our attention. From that combined set, I made a few cuts and collapsed a few into categories to make it usable and applicable to our homes.

First, I ignored a lot of the hazards on lists that applied to things totally outside of home products. I didn't include hazards in automobile manufacturing, dry cleaning, or agricultural pesticides. They're important, but the scope of Interior Medicine is home products, so I'm keeping it tight.

Second, current-purchase products only. No asbestos, no pre-1978 lead-in-paint references, no legacy PBDE foam. These are important, but I dropped them for two reasons. First, most people are already aware of their dangers since they've been in public awareness for several decades. Second, this is about navigating the products we're currently faced with making decisions about. Couch and mattress brands aren't using PBDEs anymore; they've moved on to current flame retardants, so the focus is on those instead.

Third, I collapsed categories where subdividing wouldn't change your decision about a product. PFAS is one entry covering roughly 15,000 compounds. Current flame retardants are one entry. Biocides are one entry. Pesticide residues are one entry. Phthalates, by contrast, stay separated. The certifications that cover them treat them as a single pooled limit, not as individually evaluated substances. CertiPUR-US, for example, tests 13 phthalates and requires the combined weight to be ≤ 0.01%, but until January 1, 2026, only 8 of the 13 actually counted toward that limit. A product made in late 2025 could pass CertiPUR while containing measurable amounts of the other 5, including newer replacements like DCHP and DPENP. Collapsing all phthalates into one database entry would hide that distinction. I’ll drop this in a few months when late 2025 products aren’t likely for sale anymore.

What are UVCBs?

UVCBs is short for Unknown or Variable composition, Complex reaction products, or Biological materials, a regulatory category for substances that don't have a single defined chemical composition. Fragrance, essential oils, paraffin wax, and most botanical extracts all fall into it. They remain on the list because they're in nearly every home and they sit inside a larger unsolved problem in toxicology: assessing the risk of complex mixtures. Regulatory bodies have published guidance acknowledging that the field does not yet have settled methods for either UVCBs specifically or chemical mixtures generally.

Next: Part 7

Just because a hazard exists doesn’t mean it can get out of the material, into your home, and into your body. How to make an educated guess about whether or not these hazards become exposures is what the next section is about.

Start Part 7 now ➜‍ ‍

Part 6 References

The Hazard Database draws on regulatory listings, certification standards, indoor exposure science, and toxicology. The list below consolidates the sources used across all entries. Where many substances cite the same authoritative landing page (ATSDR Toxicological Profiles, IARC Monographs, EPA TSCA risk evaluations), the general resource is cited once. Specific monograph volumes and individual substance profiles are noted in the database itself.

Regulatory and Authoritative Bodies

Certification Standards and Test Methods

Peer-Reviewed Literature

Regulatory documents are updated periodically; readers should consult the linked landing pages for the most current versions.

Explore More Interior Medicine

Product Reviews

Tools and References

About Interior Medicine

Material Health Guides

Learn ➜  Course ➜  Part 6