The "Toxic 20": Meet the Ingredients a Green Cosmetic Chemist Would Never Use

Originally published in June of 2020, we found the information to still be valid. The website Byrdie worked with Yashi Shrestha, the research scientist and green cosmetic chemist behind clean beauty retailer NakedPoppy. She’s an expert in the field of toxic beauty ingredients and has built a career out of spotlighting the toxic ingredients that aren’t doing our bodies or the planet any favors. “A study by EWG notes that a woman applies about 168 different chemicals everyday,” she says. “This exposure accumulates over time and so it is important for people to opt for products that are cleaner and better for our health.”

Formaldehyde. Despite decades of research that classifies formaldehyde as a known carcinogen, it’s still a fairly common ingredient in hair straightening products, nail polish, eyelash glue, and an array of other cosmetics. Thankfully, some retailers (including Whole Foods, CVS, and Target) are starting to ban products that contain formaldehyde from their shelves.

But there’s a catch. “While formaldehyde has become a well-known toxic ingredient to avoid in beauty products, many don’t know about the lesser known ingredients that release formaldehyde which are formulated in cosmetics today,” says Shrestha. In other words, while it’s unlikely that you’ll see the word “formaldehyde” on an ingredient label, it might be hiding behind another name.

Formaldehyde releasers. “Bronopol, DMDM hydantoin, diazolidinyl urea, imidazolidinyl urea, and quaternium-15 are cosmetic preservatives that slowly form formaldehyde,” says Shrestha. In other words, steer clear if you can.

Synthetic fragrances. A heads-up: When an ingredient label simply says “fragrance” or “parfum,” it’s often an umbrella term for hundreds of chemicals that brands aren’t required to disclose. (That makes it a heck of a lot harder to discern what’s hazardous and what’s not.)

Phtalates. One such sneaky compound hiding under the “fragrance” umbrella? That would be phtalates, which are sometimes used to help perfume stick to skin, as well as eyelash adhesive and nail polish. That’s bad news, because phtalates have been shown to be pretty significant endocrine disruptors—in some cases facilitating early puberty in girls and boys, and reduced sperm count in men. Oh, and did we mention they’re also harmful to the environment? The EWG reports that some retailers have started to ban phtalate-containing products from their shelves, but we still recommend a healthy dose of skepticism when it comes to added fragrance.

Parabens. “Butyl, propyl and ethyl parabens have been linked to hormone disruption,” notes Shrestha. These are preservatives that are found in a white variety of cosmetics—which is why many cleaner brands have taken the initiative to label their products “paraben-free.” Parabens are probably the most well-known ingredient to avoid due to a 2004 research paper that that appeared to find traces of parabens in breast cancer tissue samples. According to EU and FDA regulations, parabens in their current form are officially considered safe to use, since cosmetic products only use a very small concentration of these ingredients in their formulas (up to around 0.4 percent, though measurements do differ for each paraben). However, we say better safe than sorry. (You can read more about parabens here.)

Mineral oil. File this under “ingredients that seem perfectly innocuous.” But while mineral oil is a common additive to lip gloss, concealer, eyeshadow, SPF, and balm cleansers, it’s actually pretty iffy from a health and environmental standpoint. As a byproduct of petroletum, mineral oil (which also goes by the name of paraffin—sneaky!) can carry carcinogenic impurities.

Polyethylene glycol (PEGs). On a similar note: Polyethylene glycol, “propylene glycol (PG) and butylene glycol (BG) could potentially be petroleum derived and irritating to the skin,” says Shrestha. These are chemical thickeners and can sometimes be found in cream-based products.

Siloxanes. Also known as cyclical silicones, these compounds are found in a variety of cosmetic and skincare products—but they’re not great for the environment, and have been linked with endocrine disruption as well.⁷ (Dimethicone, on the other hand, is considered safer when used sparingly.)

Triclosan. This antimicrobial ingredient (often found in hand sanitizers and antibacterial soap) has been linked to such a significant impact on the thyroid and reproductive hormones, that it’s banned in several countries.⁸ The US has moved to ban it from antiseptic soap, but it might still show up in deodorant, mouthwash, shaving cream, and toothpaste, says the EWG.

Ethanolamines. While these compounds (which are emulsifiers found in foundation, mascara, and skincare products) are technically classified as safe for cosmetic use by the EWG, they’re also shown to be allergens—something to keep in mind if you have sensitivities to certain ingredients.⁹ They might be listed as monoethanolamine (MEA), diethanolamine (DEA), or triethanolamine (TEA).

Oxybenzone. “This well-established endocrine disruptor can be found in many skincare products that contain sunscreen, including lotions, lip balms, cleansers, fragrance, and even baby products,” says Shrestha. Yikes.

Octinoxate. This common sunscreen ingredient was thought originally to be harmful to coral reefs, and although that may have been recently proven false, it’s still somewhat irritating to sensitive skin.

Homosalate. “This is another chemical that’s commonly used in sunscreens as a UV absorber,” says Shrestha. While regulations are starting to wisen up to octinoxate and oxybenzone, homosalate is still pretty commonly used. Read your labels!

Toluene. This chemical (which also goes by the name of Butylated Hydroxytoluene, or BHT), is a big no-no: It’s linked with brain toxicity and can be especially dangerous during pregnancy.¹⁰ While it’s banned in the EU and Southeast Asia (as well as by a few retailers in the US), you can still find it nail polish, nail treatments and hair dye.

Talc. While talcum powder (often used as a smoothing agent in mineral makeup) is generally safe, it also has the potential to be contaminated with asbestos, which is a known carcinogen and instigator of lung disease.¹¹

PFAs and PFCs. Remember how we said that the term “fragrance” can potentially be hiding hundreds of chemicals? Well, PFAs are a class of thousands. “They’re fluorinated chemicals that have been found in sunscreens, hair products, and shaving creams,” says Shrestha. “They’re linked to serious health effects, including cancer, thyroid disease, and even reduced effectiveness of vaccines.”

If you commonly use waterproof mascara or eyeliner, take note: PFCs are big culprits here, because they’re water repellents.

Teflon. Teflon is one specific PFA worth calling out—it’s the brand name for Polytetrafluoroethylene (PTFE), and is sometimes added to cosmetics to improve the texture. But like other PFAs, it’s linked to hormone disruption and reproductive issues.¹²

Resorcinol. “This common ingredient in hair color and bleaching products has been linked to skin irritation and immune system dysfunction,” says Shrestha. “In animal studies, resorcinol can disrupt normal thyroid function.”

Carbon black. The EWG has flagged this pigment (which is often found in mascara and eyeliner) because of its possible link to cancer with regard to inhalation (not topical application).¹³ For what it’s worth, the FDA has put some limits on the amounts used—but it’s still widely found in cosmetics at retailers everywhere.

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