Why Are These 6 Beauty Ingredients Banned in California?

Getty Images / Collage by Bella Geraci

California recently banned 38 beauty ingredients under the Toxic-Free Cosmetics Act, a law that starts taking effect as early as next year. And since beauty companies probably aren’t going to produce a lipstick they can’t sell to California’s 39 million-plus residents, these new regulations likely will change the way a lot of products are formulated and manufactured.

This certainly feels like a welcome move — regulation over beauty products has admittedly been lacking. When President Biden signed the Modernization of Cosmetics Regulation Act (MoCRA) into law on December 29, 2022, it was the first overhaul of beauty ingredient regulations since before WW II and there is a lot of optimism that MoCRA could mean safer manufacturing processes and ultimately safer products. But it’s also reassuring to know that a lot of big beauty brands already follow safe manufacturing processes. “Most reputable companies work hard to create safe products,” says cosmetic chemist Kelly Dobos. “It has always been against the law for a cosmetic to contain any ingredient that makes the product harmful when used according to the directions on the label or in the manner expected.” Certain ingredients are already banned and on the FDA’s list of Prohibited & Restricted Ingredients in Cosmetics.

But there’s a twist: When it comes to California’s laws, the majority of the 38 ingredients on the banned list “are just not used in modern cosmetics,” says Dobos. A lot — but not all.

Out of all the ingredients that California is banning, the six below are arguably the most concerning. We took a closer look at them to help answer questions like: How concerned should we be? What kinds of products contain these ingredients? And why are they in our mascaras, lotions, and shampoos to begin with?

Meet the experts:

In this article:


Where you’ll find it: Based on the name, it probably won’t come as a shock that lily aldehyde or lilial (sometimes called lysmeral or lysmal, depending upon on the manufacturer) might make an appearance in “any personal-care product that manufacturers want to smell like lilies,” cosmetic chemist Perry Romanowski says. That can include shampoos, soaps, moisturizers, and deodorants, as well as household cleaning products. And even if a product isn’t made to smell specifically like lilies, lily aldehyde “might find its way into any fragranced cosmetic,” says Romanowski. It’s likely to be lumped under the word “fragrance” on ingredient lists, so it’s almost impossible to know when it is present. Under MoCRA, allergens in fragrance will need to be listed (a change that is expected to go into effect in the next two years), but ingredients considered irritants will not necessarily be called out on ingredient lists.

Why it’s used: Quite simply, it adds a pleasant floral scent that’s popular with a lot of noses.

Why it’s being banned: There is some concern that lilial can cause skin irritation. That’s why its use was previously restricted in the EU — but they decided to ban it in March 2022 after classifying it as a reproductive toxicant and potential endocrine disruptor. But “there is no consensus in the literature regarding its toxicological properties. A number of authors contradict each other,” states the same Scientific Reports study. In it, lilial was tested in vitro (in test tubes) and did not display endocrine-disrupting abilities or cytotoxicity (the quality of damaging cells or causing them to die). However, the authors note that more may be happening when lilial interacts with the body. At the very least, the fact that lilial was banned in the EU means “conscientious beauty companies operating globally have phased out this compound,” says Dobos.

What brands could use instead: Romanowski says there are plenty of other fragrance ingredients that don’t cause irritation and are not suspected of being a potential health risk — and these could be used to create a soft floral scent in place of lily aldehyde, or brands could revamp the products to have an entirely different fragrance.


Where you’ll find it: It’s in some fruity-smelling beauty products, but it’s also used in other industries: Acetaldehyde may be a fruit and fish preservative or a solvent, for example, and it is emitted by wood-burning fireplaces and tobacco smoke, according to an Environmental Protection Agency (EPA) fact sheet on the colorless liquid. Brands have included it in a variety of personal-care products, like shampoos and conditioners, and, just like lilial and other fragrance components, it’s usually referred to as “fragrance” on ingredient lists, so you really can’t tell if it’s in a product.

Why it’s used: As a fragrance note, acetaldehyde gives a fruity, apple scent.

Why it’s being banned: "At high-enough levels, there is concern it can cause skin irritation,” Romanowski says. There’s also concern over carcinogenic risk: The EPA classifies acetaldehyde as a “probable human carcinogen,” though the agency notes “human data regarding the carcinogenic effects of acetaldehyde are inadequate.” It’s worth noting that exposure is much more likely and concentrated through sources like industrial emissions and residential fireplaces. The National Institutes of Health (NIH)’s PubChem Compound record on acetaldehyde takes a stronger stance, stating that it “is the most abundant carcinogen in tobacco smoke.” At high-enough levels, “there is also concern it can cause skin irritation,” Romanowski adds.

What brands could use instead: As with lily aldehyde, Romanowski says brands could use other, less-suspicious fragrance ingredients to create a similar scent or brands could “just change out the product scent for something else.”


Where you’ll find it: Also called D4, cyclotetrasiloxane is a silicon-based ingredient found in “lots of personal-care products like shampoos, conditioners, styling products, serums, skin moisturizers, et cetera,” Romanowski says.

Why it’s used: Cyclotetrasiloxane provides desirable shine, slip, and a smooth feel, “and it doesn't build up on the surface [of the skin or hair] like other silicones have the potential to do,” Romanowski says.

Why it’s being banned: Although it doesn’t build up on the skin or hair, there is concern about environmental buildup. Cyclotetrasiloxane is what is known as a cyclic silicone and these have been raising eyebrows for a while. (There are both cyclic, or round, silicone structures and linear ones, like dimethicone.) Allure previously reported that, in 2018, the EU limited the concentration of cyclotetrasiloxane and one other cyclic silicone (cyclopentasiloxane) in wash-off cosmetics to 0.1% because of concerns that they can accumulate in the water supply. (Cyclopentasiloxane is not on California’s list, although it is still found in some beauty products in the US.) “According to a recent study, in water, the half-lives of cyclic silicones was between 17 and 315 days and up to three years in soil and sediment,” Dobos explains. “For comparison, a material that's deemed ‘readily’ biodegradable can hit that threshold in less than 30 days.”

Environmental researchers are looking even more closely at the presence and potential effects of cyclotetrasiloxane, specifically in aquatic food webs, waters, soils, and in the air. One study, in collaboration with the Norwegian Institute for Water Research, found cyclotetrasiloxane in the country’s Oslofjord waterway but also found that concentrations became dilute as they moved up the food web. This is “an important criterion for assessing bioaccumulation and ecological risk,” according to the study. “There was no evidence to suggest biomagnification” in which materials build up in greater and more dangerous amounts in higher-level predators. Another recent review of data on cyclic silicones, published in the journal Environmental Science and
Pollution Research, found “no significant concentrations were observed in water, soil, and sediments except for wastewaters.”

As far as harmfulness toward human health, Romanowski says that while there are concerns that cyclotetrasiloxane could be an endocrine disruptor, they are “without evidence.”

So, if there’s no evidence, where do the concerns come from? A lot of it dates back to “a number of comprehensive toxicology studies of cyclic silicones between the late 1990s and 2000s,” Dobos explains. “Despite the overall conclusion that cyclotetrasiloxane was safe at hundreds of times the amount that you could possibly be exposed to from using a cosmetic,” she says that their usage virtually stopped due to negative perceptions. But while a lot of major beauty brands don’t use these specific silicones today, that doesn’t mean they’re totally gone: The Environmental Working Group (or EWG, a major sponsor of California’s Toxic-Free Cosmetics Act and a nonprofit organization focused on research, education, and policy advocacy surrounding the safety of chemicals used in everyday products like cosmetics, household products, and food) lists more than 120 products that still contain cyclotetrasiloxane, including all different kinds of formulas — primers, foundation, eyeliners, hair care, and more.

What brands could use instead: Various plant oils and esters or dimethicone could serve as suitable substitutes. “Nothing really works as well as silicones, however,” Romanowski notes.


Where you’ll find it: Phytonadione, regularly referred to as vitamin K1, is found in facial serums and — probably more than anything else — eye creams.

Why it’s used: It’s been suggested that phytonadione can reduce dark undereye circles, says Romanowksi. However, he isn’t particularly impressed with its capabilities.

Why it’s being banned: “There's a risk of allergic reactions or skin irritation in some people,” Romanowski says. Though some have suggested a potential toxicity risk, the NIH does not classify phytonadione as a health hazard (like it does acetaldehyde). Its compound summary sheet notes it is used in medicine (in the treatment of coagulation disorders) and that it is naturally present in Arabica coffee.

What brands could use instead: “It doesn't actually work to do anything, so to support a marketing story, a company could just throw in some antioxidant, peptide, or herbal extract with traditional ‘medicinal’ qualities [like vitamin K has] and tell the story with that,” Romanowski says. Dobos agrees that phytonadione probably doesn’t add much to a formula: “Research on topical application of phytonadione is fairly limited and it's not very stable. I suspect it doesn't really do much in a cosmetic product,” she says.


Where you’ll find it: The presence of formaldehyde and formaldehyde-releasing ingredients in hair-straightening formulas like keratin treatments and relaxers is a huge problem that’s been the subject of multiple FDA warnings and a proposed ban on a federal level. When these hair treatments are heated during the application process, formaldehyde is released as a gas, posing serious inhalation risks, especially when salons aren’t properly ventilated. You should never apply hair smoothers with formaldehyde — which may go by the names formalin or methylene glycol on ingredient lists — at home, cautions the FDA. In their proposed ban last year, the FDA stated the use of hair-smoothing products containing formaldehyde and formaldehyde-releasing chemicals “is linked to short-term adverse health effects, such as sensitization reactions and breathing problems, and long-term adverse health effects, including an increased risk of certain cancers.” Allure has previously reported that a study supported by the National Institutes of Health found that “women who used chemical hair-straightening products were at higher risk for uterine cancer compared to women who did not report using these products.” Relaxers and smoothing or straightening products are primarily used by Black women, putting them at higher risk for potential health issues.

There’s also formaldehyde in certain kinds of nail care, according to the FDA. (These are typically formaldehyde resins; formaldehyde itself is a gas, explains Dobos.) For the last decade, pretty much every nail polish brand has been considered to be at least “3-free” (meaning their polishes don’t contain formaldehyde, dibutyl phthalate, and toluene), so it may come as a surprise that formaldehyde is still used in some nail strengtheners and some polishes. To avoid it, scan ingredient lists for toluene sulfonamide/formaldehyde resin, formalin, and methylene glycol – all ingredients that indicate formaldehyde is either in the formula or released by the formula. Now, it’s true that nail polishes aren’t absorbed through your nails to reach the skin, but it’s also possible to ingest them, as anyone who bites their nails could probably guess.

Then there’s the third category of formaldehyde in beauty products: The ingredient was once used as a preservative in skin care, hair care, and makeup, says Romanwoski, but it’s not anymore. “These types of preservatives have not been used since the 1970s at least,” says Dobos. But beauty products may still contain “preservatives known as formaldehyde releasers that give off a tiny amount of formaldehyde over time,” she explains. These include DMDM hydantoin, imadazolidinyl urea, diazlidinyl urea, quaternium-15, bronopol, sodium hydroxymethylglycinate, glyoxal, and polyoxymethylene urea. “Preservatives releasing formaldehyde in the presence of water are widely used in many cosmetic products (shampoos, creams, etc.), topical medications, and household products (e.g., dishwashing liquids),” according to one study published in the journal Open Medicine. If you decide you want to scan ingredient lists for them, here’s a more complete list of formaldehyde-releasing preservatives.

Why it’s being banned: Formaldehyde is a known carcinogen, according to the US National Toxicology Program and the International Agency for Research on Cancer (IARC), which is part of the World Health Organization. The IARC, for one, has concluded that formaldehyde is "carcinogenic to humans."

There’s an argument to be made that the amount of formaldehyde released by preservatives is so small that it doesn’t have negative health effects — and bacteria growing in your products could be a lot worse for you. But it’s also true that data has shown formaldehyde-releasing preservatives can irritate skin: “Members of this class have been associated with allergic contact dermatitis, possibly due to the agents themselves, the formaldehyde they release, or both,” states one paper published in the journal Dermatitis. Another peer-reviewed paper out of Spain explains, “This condition often becomes chronic, given that these allergens are found nearly everywhere and it is difficult for patients to avoid them completely.” It’s estimated that 20% of our beauty products contain formaldehyde-releasers, explains an Open Medicine study from 2015, and even a small amount of formaldehyde (up to 0.2%) “is sufficient to provoke ACD [allergic contact dermatitis] in those allergic to formaldehyde and [when] using these products on healthy skin.”

In nail care, it may come as no surprise that “formaldehyde may also cause skin irritation, as well as allergic reactions to this ingredient,” as stated by the FDA.

Notably, California is not banning all formaldehyde-releasing preservatives — of which there are many — from products. Quaternium-15, for example, will no longer be allowed, but others are not on the list.

Why it’s used: Formaldehyde is an effective preservative (there’s a reason it’s in embalming fluid) and it is antibacterial. In hair straightening products, Allure has previously reported that formaldehyde locks hair into a straighter position that lasts beyond shampooing. And in nail strengtheners, formaldehyde is supposed to bond with the nail’s keratin. “Using these nail hardeners often, however, may make nails brittle and more likely to break or peel,” cautions the FDA.

What brands could use instead: Other preservatives do indeed exist — sodium benzoate, phenoxyethanol, and caprylyl glycol are three options — but “each has its own benefits and limitations in use,” says Dobos. While formaldehyde-releasing preservatives tend to be “effective over a broad range of bacteria and some are also active against fungi (yeast and mold),” other preservatives often are only effective against “gram-positive bacteria, gram-negative bacteria, yeast, or molds” and they may require low-formula pHs in order to work, “which isn’t deal for a lot of skin-care products,” explains Dobos. Short-chain parabens are effective like formaldehyde donors, “but negative perceptions have really removed those from the formulators tool kit,” she says.

In nail polish and nail care, “alternatives used today include toluenesulfonamide/epoxy resin (TSER), polyester resins, and methylsulfonylmethane,” says Dobos.

And in hair care, “thioglycolates are ingredients used in hair relaxers that are long-lasting, at least until the hair grows out. This is the same ingredient used in perms which breaks bonds in the hair and allows them to be reset,” says Dobos.

PFAS “Forever Chemicals”

Where you’ll find them: PFAS (which stands for Per- and Polyfluorinated Substances) is the umbrella term that refers to the hugely controversial category of “forever chemicals,” which are most commonly found in products that are not cosmetics, like stain-resistant fabric and carpeting, cleaning products, paint, firefighting foam, nonstick cookware, wire insulation, and more. PFAS may also be in beauty products — “things like long-lasting makeup; foundation, and mascara,” says Romanowski. Perfluorooctyl triethoxysilane and perfluorononyl dimethicone are two kinds of PFAS “that have been used in cosmetics, but have been reformulated out of many brands already,” adds Dobos.

Why they’re being banned: There’s a growing body of research dedicated to the potential health effects of PFAS. “There are thousands of PFAS with potentially varying effects and toxicity levels, yet most studies focus on a limited number of better-known PFAS compounds,” states the EPA. “Current scientific research suggests that exposure to certain PFAS may lead to adverse health outcomes. However, research is still ongoing to determine how different levels of exposure to different PFAS can lead to a variety of health effects.”

The most well-studied PFAS, Perfluorooctanoic acid (PFOA), was classified as a human carcinogen in 2023 by the National Cancer Institute Working Group. This is not, we repeat not, the type of PFAS found in cosmetics. “There have been few studies on the presence of PFAS in cosmetics… [and] not all PFAS that may be found in cosmetics can be readily measured because the specific ‘fingerprint’ or analytical standard for the specific PFAS may not be available, making their detection and quantitation challenging,” explains the FDA. “There is also limited research on whether PFAS in cosmetics are absorbed through the skin at levels that could be harmful to human health.” Because the data is limited, the FDA states that “additional research is needed to determine: 1) toxicological profiles for PFAS in cosmetics; 2) the extent to which various PFAS in cosmetics can be absorbed through the skin; and 3) the potential for human health risks from this type of exposure.”

PFAS are called “forever chemicals” because they take thousands of years to break down — and now they are persistent in our bodies and the environment. Because PFAS last so long, “they can build up in the environment,” adds Romanowski, and that includes our food supply and drinking water — although he thinks other industries contribute more PFAS to the environment than the beauty industry.

Why they’re used: PFAS “are highly water-resistant, so they are great for long-wearing products,” says Romanowski.

What brands could use instead: “[PFAS] are the best technology for what they are used for, so a ban will lead to products that don't work as well as current technology,” Romanowski says. Dobos agrees, explaining that “PFAS have incredibly unique properties that can't be matched by conventional chemistries.”

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Originally Appeared on Allure