Many of us have bathroom cabinets stocked full of hair products, but could some of them be affecting our health?

When it comes to choosing hair care, many of us are guilty of picking up bottles based on their colors or perhaps the smell of a certain formula. However, we should probably pay more attention to any harmful nasties hiding in our products’ ingredient lists. But which chemicals in particular should we be on the lookout for?

20. Sulfates

Sodium laureth sulfate (SLES) and sodium lauryl sulfate (SLS) are two ingredients that are commonly found in many personal care products, including shampoos. The widespread use of such sulfates in the cosmetic industry is down to the fact they’re cheap detergents that help formulas lather up. However, they may not be good for our health.

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David Felstead is the director of the Daniel Galvin Hair & Scalp clinic in the U.K. And in 2019 he told The Independent, “There is concern that this chemical may be carcinogenic or an irritant. So some manufacturers steer clear of it and use alternatives such as ammonium laureth sulfate which is gentler.”

19. Synthetic colors

If you notice the letters “D&C” alongside the name of a color and a number on your product’s details, then it contains artificial colors. Often, these ingredients are taken from coal tar or petroleum sources, which may come as a surprise to some people. And the potential risks associated with the chemicals are even more shocking.

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In fact, there’s evidence to suggest that synthetic colors can potentially cause cancer in humans. Some artificial colorings are banned in the European Union as a result, after they were classified as carcinogenic. Furthermore, the chemicals can cause irritation and have also been associated with childhood ADHD.

18. Retinyl palmitate

Retinyl palmitate is a kind of vitamin A. It is used in conditioners to enhance the appearance of hair by boosting shine and volume. Alternatively, it can be used to treat hair that has been harmed in some way. But while it may sound like a wonder product, its may create health risks.

When administered in high doses, in fact, retinyl palmitate has been seen to speed up the development of cancer in laboratory animals. Other studies have tended to focus on the use of the chemical in sunscreen, rather than in hair products. And to date there is no conclusive proof that it has a carcinogenic effect on humans.

17. Phenoxyethanol

This potentially nasty chemical is commonly used as a preservative in some hair products and many other cosmetics. However, the ingredient’s prevalence doesn’t guarantee its safety, as there’s conflicting scientific evidence regarding whether we should be using phenoxyethanol on a regular basis.

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There are concerns that phenoxyethanol can depress the central nervous system if consumed by young children, for example. And there are also instances of people developing nasty skin conditions after being exposed to the chemical. With that in mind, authorities in both Japan and the E.U. have lowered the legally permitted concentration of phenoxyethanol to just 1 percent in all beauty products.

16. Formaldehyde

Moreover, shampoos can include preservatives that release formaldehyde. According to the U.S. National Toxicology Program, this organic compound is “known to be a human carcinogen.” With that in mind, ingredients to be aware of include imidazolidinyl urea, diazolidinyl urea, bronopol, DMDM hydantoin and quaternium-15.

“Formaldehyde is known to cause DNA damage and cancer,” Dr. Trevor Cates, a top naturopathic doctor, told The Independent in June 2018. “It is most dangerous when inhaled and, in liquid form, can be absorbed through the skin. In addition to being carcinogenic, formaldehyde and its releasers can cause ‘allergic’ reactions, including skin irritations and asthma.”

15. Fragrance

We all want our hair to smell nice. In order to get those heady scents, however, cosmetic companies often rely on a concoction of potentially hazardous chemicals. And the Environmental Working Group (EWG) Skin Deep Database indicates that some of these can have detrimental effects on our health.

The EWG has stated that fragrance formulas have been linked to eczema, can cause respiratory distress and may aggravate asthma symptoms. They could even have an impact on the human reproductive system. Furthermore, due to their use of endocrine-disrupting chemicals, fragrances count as some of the most common allergens that we encounter.

14. Silicones

If you notice ingredients ending with “oxane” or “methicone,” it’s likely that your product contains silicones. These cover hair in a waterproof layer, therefore protecting it from humidity. With this in mind, silicones are often used in products designed for creating straight, sleek styles.

Silicone coatings also lock moisture in the hair, giving it gloss and making combing easier. But not all silicones are good. The use of dimethicone, for instance, may lead to hair appearing lifeless. Moreover, there are some concerns that cyclosiloxanes may be carcinogenic.

13. Methylene glycol

Methylene glycol is another popular ingredient among hair smoothing treatments, and it happens to emit gaseous formaldehyde if warmed up. As a result, the FDA has warned that products containing the chemical can cause headaches, rashes, eye issues, sickness and disorientation. Once again, then, formaldehyde-releasing ingredients may be worth avoiding.

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Scott Masten is the director of nomination and selection at the National Toxicology Program. And he advised a “know before you go” approach to hair care. In other words, researching ingredients before buying products. In 2018 he told Vice, “[It’s] easier to do your homework in advance rather than wait until you are in a store or business.”

12. Toluene

Toluene is another chemical that’s derived from coal tar or petroleum sources. It’s be a difficult substance to look out for, however, as it can also be denoted as toluol, benzene, methylbenzene, or phenylmethane in ingredients sections. And surprisingly, it’s a powerful solvent that can even cause paint to decompose.

When it comes to hair products, you’re most likely to some across toluene in bleaching agents or certain hair dyes. And it can pose a risk to health, especially by causing nausea and skin irritation. Toluene may also affect the respiratory system, and pregnant women should avoid the chemical altogether, as its vapors could potentially affect their unborn babies.

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11. Mineral oil

Yet another byproduct of petrolatum, mineral oil is used in products to protect the hair and prevent moisture from escaping. But due to the ingredient’s origins, there has been some concern that it may cause cancer. Indeed, raw mineral oil is a proven carcinogen.

But that being said, mineral oil has to be highly refined until it’s deemed suitable for use in cosmetics and hair-care products. If conducted properly, these processes should remove all carcinogenic materials. With that in mind, Masten told Vice that cosmetic-grade mineral oil is “generally of low concern.”

10. DEHP

While DEHP may not be used as frequently as other phthalates, it can still be found in some hair relaxers. It’s also employed as a fragrance carrier in a number of cosmetics and personal care products. However, exposure to DEHP has been linked to a number of health issues and can even potentially cause problems with male reproductive development.

With that in mind, several government agencies across the world have implemented policies to limit human exposure to DEHP. And when it comes to using products that contain the chemical, Masten told Vice, “There’s enough adverse health effects known or suspected with DEHP to be concerned.”

9. Parabens

Parabens are commonly used in cosmetics to stop the development of mold, yeast and the likes. And in the hair care industry, parabens such as propylparaben and methylparaben are contained in products that promote hair growth. However, there may be negative side effects that come with the use of parabens.

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That’s because there’s some evidence to link parabens to breast cancer. Furthermore, the chemicals have even been found in breast-tumor biopsy samples s. It’s not yet clear how the two things are connected, however. Nevertheless, Dr. Cate recommends avoiding parabens if possible.

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8. Phthalates

This group of chemicals can be found in hundreds of products as they’re used to soften plastics. Dimethyl phthalate is one example, which is sometimes used in hair spray. However, because phthalates are added to fragrances, they’re often not mentioned on ingredient lists in order to protect products’ “secret formulas.”

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Unfortunately, though, phthalates are something you’d probably want to know about given the health risks they may pose. The chemicals are endocrine disruptors, meaning they can interfere with the human hormonal system. As a result, they’ve been linked to early breast development and higher chances of contracting breast cancer in females, as well as birth defects in both genders.

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7. Silk protein

As its name suggests, silk protein is a protein produced by silkworms. It’s used in hair care as a conditioning agent but can also be added to formulas simply to bulk them out. However, while the ingredient may have a natural origin, that doesn’t mean it’s 100 percent safe to use.

While the Cosmetic Ingredient Review has approved eight silk proteins for use in cosmetics, Masten recommends that consumers exercise caution. He told Vice that known safety information on silk protein is “considerably less than for other common ingredients.” As such, he couldn’t tell consumers whether they should or shouldn’t use products containing silk protein.

6. Polyethylene Glycol

Polyethylene Glycol – often shortened to PEG – can be used to deep clean ovens, which entails stripping them of hard-to-remove baked-on grease. With that in mind, you’d think that they’d be way too harsh to use on our hair. But that doesn’t prevent many companies from adding it to shampoos, conditioners and the likes.

Nevertheless, PEG is generally considered a safe ingredient. However, some online sources have linked the compound to liver and kidney failures, brain problems and even heart attacks. So while the jury is out, some manufacturers have chosen to leave propylene glycol out of their products, just to be on the safe side.

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5. Lead

Lead is known to cause cancer. However, some companies have nonetheless included a compound of the substance – lead acetate – in a number of products, including progressive hair dyes. It’s toxic and has been banned for cosmetics in Canada and the European Union for some time. But it remained in use in the U.S. until fairly recently.

In 2018 the FDA announced it would ban the use of lead acetate in hair dyes 40 years after the substance had first been declared safe. A statement from the agency explained, “Our understanding of the hazards of lead exposure has evolved significantly. We now know that the approved use of lead acetate in adult hair dyes no longer meets our safety standard.”

4. Isopropyl

Isopropyl is a form of alcohol that’s commonly contained in antifreeze thanks to its oil-dissolving properties. However, the substance is also used in many hairsprays and hair gels, meaning it could potentially have the undesirable effect of stripping tresses of their natural moisture.

Without moisture, of course, hair can become brittle and snap easily. That isn’t the only problem isopropyl can pose, though, because breathing in this nasty chemical can potentially cause depression, dizziness, nausea and headaches. So it’s probably best to avoid the ingredient where possible.

3. Polyethylene glycol

Another glycol to maybe stay clear of is propylene glycol. This organic alcohol appears in shampoos, conditioners and hair sprays. When used in personal care products like these, the main function of polyethylene glycol is to maintain moisture levels and draw in excess water.

However, that isn’t the only way in which polyethylene glycol can affect users. The substance can irritate the skin as well, causing contact dermatitis. It may also damage cell membranes, dry out skin, cause rashes and prevent skin cell growth. Nevertheless, it’s classified as “generally recognized as safe” by the FDA.

2. Coumarin

Coumarin is used in hairspray but can be dangerous if inhaled. This plant-derived ingredient is known for its sweet-smelling scent, although that distinctive smell can cause irritation to the skin. But more worryingly, it can behave like a liver toxin and could therefore potentially cause cancerous tumors to form.

While the amount of coumarin found in hairspray is unlikely to have a detrimental effect on health, consumers should still be wary of the chemical. That’s because it’s used in a number of beauty products, meaning people could potentially consume the substance from many different sources, which in turn might cause them problems.

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1. Potassium sorbate

Many hair-care companies use potassium sorbate to prevent the growth of microorganisms, in order to preserve products and extend their shelf life. While some manufacturers are opting to use the substance in place of parabens, which – as we’ve already seen – come with risks of their own, the safety of potassium sorbate itself also isn’t clear cut.

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That’s because potassium sorbate is an eye, skin and respiratory irritant in its pure form. Furthermore, it’s said that the substance promotes toxicity in the organ system. Nonetheless, formulas that contain potassium sorbate concentrations that below 0.5 percent aren’t believed to be potent enough to irritate the skin.