Chemicals are hidden in everyday haircare with documented risks linked to relaxers and common shampoos.
The typical bathroom shelf holds far more chemistry than most consumers realize. Research from the Environmental Working Group shows that the average adult in the U.S. applies an average of six personal-care products each day containing as many as 112 different chemicals.
What often goes unnoticed is how prominently haircare contributes to this chemical load. From shampoos and conditioners to relaxers, masks, oils, gels, edge tamers, and heat protectants, hair routines create one of the most concentrated sources of exposure in the modern bathroom.
The cosmetics industry lacks proper oversight despite its massive growth. Sales have skyrocketed from $1 billion to over $169 billion since Congress last passed cosmetics legislation in 1938. The safety standards remain weak, and 595 cosmetics manufacturers now use 88 chemicals that scientists link to cancer, birth defects, or reproductive harm across more than 73,000 products. A 2021 study revealed that 52 percent of cosmetics contain PFAS (per- and polyfluoroalkyl compounds), and 88 percent of these products don’t list these substances on their labels.
Unlike skin care, which is often framed as a more curated and ingredient-conscious category, hair products remain among the least transparent. Many of the formulations sold in drugstores, beauty supply shops, and salons contain mixtures whose full composition rarely appears on a label. This lack of clarity has drawn increasing concern from toxicologists, particularly in a regulatory landscape that still allows most ingredients to enter the market without preapproval.
A review published in the Vermont Law Review emphasizes this point, noting that the United States has restricted or banned fewer than a dozen cosmetic ingredients, while the European Union has prohibited more than 1300.
Hair relaxers put the risks into sharp focus
Hair relaxers provide one of the clearest examples of how routine grooming can intersect with significant chemical exposure. A 2022 study found that women who used chemical straighteners more than four times per year had a higher risk of developing uterine cancer.
These formulas often rely on lye, parabens, phthalates, and formaldehyde-releasing preservatives — substances known to penetrate the scalp, where absorption can be higher than other areas of the body. The issue is especially acute for Black women, whose consumer choices have historically been shaped by social pressures around straight hair. More than 80 percent of products marketed to Black women contained at least one potentially hazardous ingredient, a recent study found. Legal cases connected to these products are increasing quickly, and recent reports show that hair relaxer lawsuit settlements could reach $120,000 to $150,000 based on the injuries.
Relaxers are not the only concern. Hair dyes, heat-styling treatments, and so-called “smoothing” products have repeatedly been found to contain formaldehyde or its releasers. Even items marketed as professional-grade may emit vapors linked to eye irritation, respiratory issues, and long-term sensitization. And as consumers combine products the risks of having a reaction increase. This layering effect — relaxer, neutralizing shampoo, leave-in conditioner, hardness-reducing mask, shine spray, edge control — creates a blueprint for repeated exposure well beyond a single application.
Where everyday haircare products hide harmful ingredients
Shampoos, conditioners, stylers, and serums often contain some of the most opaque ingredient mixes in the beauty aisle. The Environmental Working Group’s Skin Deep database shows that thousands of shampoos include fragrance mixtures that may legally contain dozens of undisclosed substances.
One of the most common surfactants, sodium lauryl sulfate, is used for its ability to lift oil and dirt with rich lather, yet it can strip the scalp of protective lipids. Preservatives such as methylisothiazolinone and methylchloroisothiazolinone, frequently found in rinse-off hair formulas, have been associated with allergic reactions in patch-testing studies.
PFAS, a class of fluorinated chemicals often called “forever chemicals,” have been detected in some hair products, especially sprays and treatments designed to increase shine or resist humidity. Researchers in 2021 found that more than half of the cosmetics it evaluated contained PFAS, many without disclosing them on the label.
Hair products, like other personal-care items, can affect the endocrine system. The Environmental Working Group warns that “exposure to these chemicals has been linked to endocrine diseases and some types of cancer.”
Some phthalates mimic estrogen, a mechanism that toxicologists believe may contribute to hormone-sensitive cancers. Researchers at Harvard T.H. Chan School of Public Health have connected long-term exposure to certain preservatives and plasticizers with elevated risks of breast cancer, impaired fertility, and developmental effects in children. Endocrine-disrupting chemicals do not follow the traditional idea of dose equals toxicity. Very low doses can have significant effects. Children and pregnant women remain especially vulnerable.
Dermatitis, contact allergies, and respiratory irritation also occur more commonly in individuals who use multiple haircare products daily or frequently visit salons, according to a 2024 report.
Can you reduce exposure without sacrificing performance?
For shoppers seeking safer haircare options, dermatologists recommend scanning ingredient lists carefully, especially for parabens, phthalates, formaldehyde releasers, synthetic fragrances, and PFAS indicators such as “fluoro” in names. Apps such as ThinkDirty and resources like INCIdecoder or Skin Deep help simplify this process.
Single-ingredient oils such as argan, almond, or jojoba offer alternatives to complex serums. Some consumers find that reducing the number of products in their routine lowers the likelihood of irritation.
Salons increasingly offer ammonia-free color systems, low-formaldehyde smoothing treatments, and sulfate-free cleansing protocols, although ingredient awareness remains essential. As reform accelerates, transparency — long overdue in the haircare category — appears poised to become standard rather than optional.
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