Ingredient Glossary: What to Know

Not every ingredient deserves the same amount of concern. Explore this ingredient glossary to learn what’s in your products, what to watch for, and safer options to choose.

You can start with my list of 15 toxic ingredients to avoid in skincare products, browse the topics below for more depth, or jump straight to the Ingredient Glossary for a quick definition.

Ingredient Guides

BPA & Bisphenols

Dioxane (1,4-Dioxane)

Endocrine Disruptors

Also see: BPA, Parabens & Phthalates

Fragrance

Parabens

Phthalates

Retinol & Retinol Alternatives

Sunscreen & UV Filters

Mineral vs. Chemical

VOCs

Curious how these ingredients show up in real routines? Visit the Clean Beauty & Skincare Hub for product guidance, or the Non-Toxic Home Hub for room-by-room swaps.

Ingredient Glossary: Quick Lookup

Looking for a quick definition? Use the ingredient glossary below to look up ingredients and chemicals and why they’re worth knowing about.

A-F

A manufacturing byproduct that can contaminate cosmetics, soaps, detergents, and more. You won’t find it listed on the label.

1,4-dioxane is a cancer concern. It can form during the manufacture of certain ethoxylated ingredients, including some PEG compounds.

Want to know more? What Is 1,4-Dioxane?

A chemical UV filter used in sunscreens to absorb UVA rays.

It is unstable in sunlight on its own, so sunscreen formulas typically include ingredients that help stabilize it. 

An antimicrobial preservative used in cosmetics, personal care products, disinfectants, and household cleaners.

BAK can irritate the skin and cause allergic contact dermatitis, particularly with repeated exposure.

Want to know more? 15 Toxic Ingredients to Avoid in Skincare Products

Antioxidants used to keep oils and other ingredients from going rancid. BHA has been classified as reasonably anticipated to be a human carcinogen. Both BHA and BHT have raised concerns about endocrine disruption and other toxic effects.

Want to know more? 15 Toxic Ingredients to Avoid in Skincare Products

A chemical used to make certain plastics and epoxy resins.

BPA can disrupt hormone activity and has been associated with reproductive, developmental, and metabolic effects.

Research has also raised concerns about possible links to cancer.

Want to know more? Is BPA-Free Actually Safe?

Bisphenols used as substitutes for BPA, including in products marketed as “BPA-free.” BPS and BPF can disrupt hormone activity and have shown endocrine-disrupting effects similar to BPA. 

Want to know more? Is BPA-Free Actually Safe?

A black pigment used in eyeliner, mascara, and other dark cosmetics, made by burning petroleum products at high heat.

Carbon black can carry trace amounts of PAHs. These are chemicals linked to cancer.

The International Agency for Research on Cancer (IARC) classifies carbon black as a possibly carcinogenic to humans (Group 2B). 

Emulsifiers, surfactants, and pH adjusters used in personal care and household products.

MEA, DEA, and TEA can irritate the respiratory tract and affect organs.

DEA has also raised concerns about cancer and can react with nitrites to form carcinogenic nitrosamines.

Chemicals that can interfere with the body’s hormone systems.  Endocrine disruption can affect reproduction, development, metabolism, and other systems in the body.

Want to know more? What Are Endocrine Disruptors and Why Do They Matter?

A manufacturing process used to make harsh detergents and cleansers gentler on skin, common in ingredients you’ll spot by “-eth-,” “PEG,” “polyethylene,” or “-oxynol” in the name.

Ethoxylation can leave behind trace amounts of 1,4-dioxane, and because it’s a manufacturing contaminant rather than an added ingredient, the FDA doesn’t require it to appear on the label.

Want to know more? What Is 1,4-Dioxane?

A chemical used to bind metals and help stabilize products. It can cause skin, eye, and respiratory irritation.

May appear on labels as: EDTA, disodium EDTA, tetrasodium EDTA, trisodium EDTA, and other EDTA salts.

Preservatives used in some cosmetics, personal care products, household detergents, and other products.

Formaldehyde is a known human carcinogen and can be absorbed through the skin.

Formaldehyde and its releasers can also cause allergic contact dermatitis.

A mixture of natural and synthetic chemicals used to give a product its scent. 

“Fragrance” can represent dozens or even hundreds of individual chemicals. These can include allergens, phthalates, and VOCs.

Some fragrance chemicals are linked to hormone disruption and other health concerns. They don’t have to be listed individually on the label due to the fragrance loophole.

Want to know more? What Is Fragrance?

G-P

A chemical UV filter used in sunscreens to absorb UVB rays. Research has raised concerns about hormone disruption.

The European Union’s Scientific Committee on Consumer Safety has also raised concerns about systemic exposure and bioaccumulation

Want to know more? Mineral vs. Chemical Sunscreen: What’s Actually in Your SPF

A skin-lightening ingredient used to fade dark spots and hyperpigmentation. It can cause rashes, facial swelling, and ochronosis, a skin discoloration that may be permanent.

Animal studies have found kidney tumors and other toxic effects. The relevance of these findings to humans remains uncertain.

OTC skin-lightening products containing hydroquinone cannot legally be sold in the U.S. 

A toxic metal that can occur as an impurity in cosmetics, particularly products containing pigments and mineral ingredients. Lead has been detected in lipsticks, eye shadows, and other cosmetics. FDA testing has found lead in hundreds of cosmetic products.

Lead exposure can affect the nervous, cardiovascular, kidney, and reproductive systems.

There is no known safe level of lead.  

Preservatives used in cosmetics, personal care products, and household products. MI and MCI are potent skin sensitizers and can cause allergic contact dermatitis.

Emerging research has also raised concerns about possible endocrine-disrupting and neurotoxic effects. 

Tiny plastic particles created when larger plastics break down or intentionally manufactured at small sizes. They can be found in food packaging, plastic bags, tea bags, appliances, textiles, cosmetics, and other everyday products.

Microplastics have been detected in human blood, placenta, and gastrointestinal tissue.

Research has also linked exposure to inflammation, oxidative stress, and changes in the gut microbiome.

A petroleum-derived ingredient used as a moisturizer, emollient, and skin protectant. The safety of mineral oil depends on how highly it has been refined.

Less-refined mineral oils can contain polycyclic aromatic hydrocarbons (PAHs), which are linked to cancer. Highly refined mineral oil contains very little or no PAHs.

Look for white mineral oil or highly refined mineral oil on the label.

A chemical UV filter used in sunscreens to absorb UVB rays.

Research has raised concerns about hormone disruption.

A chemical UV filter used in sunscreens to absorb UVB rays.

It may increase the penetration of other substances through the skin. 

A chemical UV filter used in sunscreens to absorb UVB rays.

It can break down into benzophenone over time.

Benzophenone is classified by IARC as possibly carcinogenic to humans.

A chemical UV filter used in sunscreens to absorb UVA and UVB rays.

It’s shown high systemic absorption when sunscreen is applied to the skin. Research has raised concerns about hormone disruption. 

A group of synthetic preservatives used to prevent bacteria, mold, and yeast from growing in cosmetics and personal care products.

Research has raised concerns about their estrogen-like activity and effects on reproductive health.

Common names include: methylparaben, ethylparaben, propylparaben, and butylparaben.

Synthetic ingredients used in cosmetics as moisturizers, emulsifiers, and other formulation ingredients. Some PEG compounds may be contaminated with ethylene oxide and 1,4-dioxane during manufacturing.

Some PEG compounds can also increase the penetration of other substances through the skin.

May appear on labels as: PEG, polyethylene, polyethylene glycol, polyoxyethylene, and ingredients containing -eth- or -oxynol-

A petroleum-derived ingredient used as a moisturizer and skin protectant. The safety of petrolatum depends on how highly it has been refined.

Poorly refined petrolatum can contain polycyclic aromatic hydrocarbons (PAHs), which are linked to cancer.

Look for white petrolatum when choosing petroleum jelly.

A large family of synthetic chemicals containing fluorinated carbon chains.

Many PFAS don’t easily break down in the environment or the body. That’s why they’re often called “forever chemicals.”

Exposure to PFAS has been linked to immune, reproductive, developmental, and certain cancer risks. 

Commonly found in: Nonstick cookware, stain-resistant fabrics and carpets, water-resistant clothing, food packaging, some cleaning products, and some cosmetics. 

May appear on labels as: PTFE, perfluorononyl dimethicone, trifluoroacetyl tripeptide-2, and other ingredients containing fluoro- or perfluoro-. 

Used to make plastics flexible and in some fragrance formulations. Some phthalates can disrupt hormones and have been linked to reproductive and developmental concerns. They may also be hidden under “fragrance” on product labels.

Want to know more? What Are Phthalates and Why Do They Matter?

A synthetic ingredient used in cosmetics and personal care products to help products hold moisture and improve their texture.

It can cause skin irritation and allergic reactions in some people.

Q-Z

 A group of chemicals used as disinfectants, preservatives, surfactants, and fabric softeners.

Some quats can cause skin irritation and contact dermatitis and have been linked to occupational asthma in people with repeated workplace exposure.

May appear on labels as: Benzalkonium Chloride, Behentrimonium Chloride, and ingredients beginning with Polyquaternium- followed by a number (e.g., Polyquaternium-7), or Quaternium- followed by a number (e.g., Quaternium-15).

Vitamin A derivatives used in skincare products.

Research has raised concerns that retinyl palmitate can damage skin cells when exposed to UV light.

Another study found that topical retinyl palmitate increased skin tumor development in mice exposed to simulated sunlight.

Retinoic acid has also been associated with developmental toxicity in experimental studies.

May appear on labels as: Retinyl Palmitate, Retinoic Acid, Retinol Palmitate, or Tretinoin.

Want to know more? Side Effects of Retinol Cream

 A cleansing and foaming ingredient used in personal care and household products.

SLES is an ethoxylated ingredient that may contain trace amounts of 1,4-dioxane, a potential human carcinogen, as a manufacturing byproduct.

A cleansing and foaming ingredient used in personal care and household products. SLS is a well-established skin irritant that can also damage the skin barrier.

May appear on labels as: Sodium Lauryl Sulfate or Sodium Dodecyl Sulfate.

Synthetic fragrance chemicals used to give products a musky scent. Some synthetic musks are persistent and can accumulate in the environment. Research has raised concerns about endocrine activity.

May appear on labels as: Musk Xylene, Musk Ketone, Galaxolide, or Tonalide.

A naturally occurring mineral used in products to absorb moisture and improve texture.

In 2025, the International Agency for Research on Cancer (IARC) classified talc as probably carcinogenic to humans. 

Talc can also be contaminated with asbestos, a known carcinogen.

A mineral UV filter used in sunscreens to protect against UVB and some UVA rays.

Particle size matters, and research on the long-term effects of nanoparticles is still developing. Look for non-nano titanium dioxide on the label.

Synthetic antimicrobial chemicals used in some personal care and household products.

Research has raised concerns about hormone disruption and breast cancer progression. They can also persist in the environment and affect aquatic organisms.

A mineral UV filter used in sunscreens to protect against UVA and UVB rays.

Particle size matters, and research on the long-term effects of nanoparticles is still developing. Look for non-nano zinc oxide. Look for non-nano zinc oxide on the label.