Strong link indicates a link between hair dye, chemical straighteners, and breast cancer

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Hair dying, whether to enhance a natural color or to hide grays, is ubiquitous in American culture, but a recent study published in the International Journal of Cancer showing a possible link between breast cancer and the use of hair dye and chemical straighteners, especially among African American women, could have people opting to go natural.

Do hair dye and straighteners cause breast cancer?

The study, published on Dec. 3, followed 46,709 women, ages 35 to 74, with enrollment lasting from 2003 to 2009. Each woman had at least one sister who’d been diagnosed with breast cancer, but none of the participants had been diagnosed at enrollment. 

The study’s authors looked at both the use of hair dye and chemical straighteners/relaxers and said 55% of participants reported using permanent dye during the 12 months prior to enrollment. Researchers followed up with the women after approximately 8 years and found 2,794 had been diagnosed with breast cancer.

“Permanent dye has been associated with 45% higher breast cancer risk in black women … and 7% higher risk in white women,” the study reads, noting the use of straighteners and non-professional use of semi-permanent dye also increased breast cancer risk. 

Additionally, the more frequently a product was used, the higher a person’s risk for breast cancer. The study concludes, saying, “We observed a higher breast cancer risk associated with any straightener use and personal use of permanent dye, especially among black women. These results suggest that chemicals in hair products may play a role in breast cancer carcinogenesis.”

The American Cancer Society, however, says studies such as this can be difficult to prove because many other factors, including lifestyle habits and environment, may be involved in developing cancer. ACS also says comparing different hair dyes can be difficult because no two are created equal, with each made of many different chemicals and others of the same brand changing formulas over the years.

Hair dyes developed before 1980, for example, contained chemicals known as aromatic amines. These were found in the late 1970s to be carcinogenic, or cancer-causing, in lab animals. Dye manufacturers, therefore, changed their formulas.

Does hair dye cause other cancers?

According to ACS, several earlier studies reported mixed results of risk associated with breast and other cancers, including leukemias and lymphomas, and not enough conclusive evidence to show a definite link. The studies that found an increased risk for non-Hodgkin lymphoma concluded the risk was especially high for those who used dye prior to 1980 and/or used dark colors as the chemicals are needed in higher concentrations to produce the dark color. “If there is an effect of hair dye use on blood-related cancers, it is likely to be small,” ACS concluded.

The National Toxicology Program has not listed hair dyes as carcinogenic. However, it has listed cobalt and cobalt compounds (a metal often found in hair dyes, especially brown tones, according to Unity Cosmetics) as “reasonably anticipated to be human carcinogens.”

A consistent link between hairdressers and bladder cancer

Unlike other cancers, bladder cancer studies have consistently resulted in an elevated risk among hairdressers and barbers, who are exposed to the chemicals daily, but not among those who have their hair dyed, ACS reported. The National Cancer Institute also says many studies show mixed results of cancer risk, but due to the consistent findings of bladder cancer risk and hairdressers and barbers, researchers will continue to keep a close eye on this and study whether those who dye their hair at home are also at increased risk.

The International Agency for Research on Cancer says chemicals used professionally by hairdressers and barbers are “probably carcinogenic to humans” in relation to bladder cancer, saying the evidence is “limited.” It also concludes the use of personal hair dyes “is not classifiable as to its carcinogenicity to humans,” due to “inadequate evidence.”

Whether cancerous or not, should you use hair dye?

Knowing the potential risk for cancer may be enough for some to err on the side of caution and limit their visits to the salon. But cancer isn’t the only health risk. 

Many health care professionals say the numerous chemicals found in hair dyes are known toxins and should be avoided, whether carcinogenic or not. Allergic reactions are common, including a burning and itching scalp and even blisters and hair thinning or loss, according to the Cleveland Clinic.

Hair dyes use a cocktail of chemicals to alter hair color, reports the Cleveland Clinic on its website. According to the clinic, they have often contained ammonia, hydrogen peroxide and paraphenylenediamine (PPDA) — a common allergen. Dyes have also included lead acetates, which the Food and Drug Administration recently repealed approval of. 

The Cleveland Clinic goes one to say despite many studies on the long-term effects of hair dye, including cancer risks, many findings are “inconsistent or inconclusive.” It is stated on the clinic’s website that essentially, this means experts don’t have a clear understanding of the possible hazards of these dyes over time.

The toxicity in these chemicals can cause havoc on the body’s various systems, throwing off hormonal balance among many others. Functional medicine practitioner William Cole, D.C., IFMCP, at, says the number of toxins to which people have been exposed in recent years has increased 10 times over, and the human body just can’t keep up. 

“The results [have] been an onslaught of inflammation, hormonal and autoimmune health problems,” 

– William Cole DC IFMCP

he says, listing several known toxins found in hair dyes, including formaldehyde, ammonia and coal tar.

Cole urges people to either go natural or to choose dyes (or salons that provide dyes) that are all-natural and non-toxic and to make sure they read the ingredients label when purchasing dyes themselves.

The truth about eyelash tinting

Just as there are dyes for your hair, there are dyes and tints for eyelashes. People may think eyelash tinting is a great way to enhance their lashes without having to use mascara every day. The Food and Drug Administration, however, says think again.

“Permanent eyelash and eyebrow tints and dyes have been known to cause serious eye injuries, including blindness,” writes the FDA on its website. “There are no color additives approved by the FDA for permanent dyeing or tinting of eyelashes and eyebrows. FDA has an important alert in effect for eyelash and eyebrow dyes containing coal tar colors.”

The Cleveland Clinic also warns of using hair dye to color eyelashes, citing the potential for permanent damage and blindness.

The American Academy of Ophthalmology, which also urges people to never have their eyelashes tinted, says the FDA cannot regulate salons. This job is left to the state and local governments, so every state varies as it relates to regulations. California prohibits eyelash tinting, while New York allows it as long as the dye is not permanent.

“Experts have long warned that dyes and other treatments are not safe,” AAO says.

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