The hair dye industry was worth $18.59 billion in 2016 and is expected to grow by 8.56% between 2016 and 2024. Estimates from the National Cancer Institute also show that more than a third of adult women (and about 10% of men over 40) use some kind of hair coloring product. With such large market value and widespread use, we have to wonder:
What exactly are so many people putting on their bodies—and are these substances causing health problems?
Toxic Ingredients Found in Hair Dyes (Plus 3 Potential Health Problems They're Linked To)
Hair dyes were reformulated in 1980 to remove many known toxic and cancer-causing chemicals. To this day, however, most hair dyes still contain ingredients that have been shown to be toxic or even carcinogenic in humans. These toxins include:
- P-phenylenediamine: linked to cancer and skin hyper-sensitization (notably, the European Union has restricted its use)
- Resorcinol: a potential hormone disruptor that has been linked to organ toxicity and central nervous system dysfunction
- Lead acetate: a neurotoxin associated with everything from memory loss to behavioral problems—of note, lead acetate was just banned from hair dyes by the Food and Drug Administration according to the Environmental Working Group, but as recently as January of this year Consumer Reports warns that hair dyes and other products containing this toxin may still be available for purchase
- Toluene: also found in household products like paint thinners, this chemical has been linked with organ damage (especially to the liver and kidneys) as well as pregnancy loss and birth defects
- Ammonia: a common respiratory irritant and potential endocrine disruptor
Some factors appear to increase a person's risk for adverse health effects from using hair dye. These include genetics, frequency and length of use, and the type of hair dye used, with darker hair dyes tending to contain more chemicals which may be carcinogenic or toxic compared to lighter colored dyes.
And while the research is mixed, various studies have found links between hair dye use and specific health problems.
1. Non-Hodgkin's Lymphoma (NHL)
In June of this year, a meta-analysis and systematic review was published in Medical Principles and Practice; it evaluated the association between hair dye and the incidence of an immune system cancer called non-Hodgkin's lymphoma (NHL). 16 studies were included in the review.
Statistical analysis of the data showed that people (especially females) who frequently use hair dyes, or have been coloring their hair for more than two decades, have an increased risk of NHL.
2. Bladder Cancer
A 2011 paper published in International Journal of Cancer analyzed data from more than 2,600 people, 1,193 of which developed bladder cancer, to investigate the possible link between this diagnosis and hair dye use. The study's researchers also investigated the impact of certain genotypes.
They found an increased risk of bladder cancer in certain groups of women, including women who:
- Used permanent hair dyes
- Had certain types of genes, including NAT2 slow acetylation phenotype, and
- Had higher socioeconomic status (as indicated by a college degree)
Furthermore, the International Agency for Research on Cancer (IARC), which is part of the World Health Organization, cites occupational exposure to hair dyes as a hairdresser is "probably carcinogenic," specifically as it relates to bladder cancer.
Additional research, including a 2017 study published in Carcinogenesis, suggest additional links between hair dye use and breast cancer, particularly when darker tinted hair dyes are used in combination with hair relaxers.
3. Fertility Problems
In 2010, the Journal of Occupational Medicine and Toxicology published a systematic review of epidemiological studies exploring the link between fertility problems among hairdressers (who have a much higher exposure to hair dyes compared to typical consumers).
While the researchers say that the available evidence is inconsistent, they did find several studies linking occupational exposure to hair dyes (as a hairdresser) to an increased risk of infertility, congenital malformations, babies born with low birth weight, and children with pediatric cancers.
They conclude cautiously that "fertility disorders and pregnancy complications in hairdressers cannot be excluded" and that more studies should be done to clarify the impact.
Research isn't fully conclusive on whether mass-marketed hair dyes increase the risk for various health problems. There are studies available which both support and refute this hypothesis.
However, many professional organizations warn that hair dyes contain products that could be carcinogenic and advise at least some people (such as pregnant women) to avoid or limit their use of these products. Ultimately, and until there is more clarification from additional studies, it may be up to the consumer to decide whether using conventional hair dyes is worth the risk.