For many years, people have been trying to find a link between hair dye and cancer. The reason most people find this so interesting is because “Many people in the United States and Europe use hair dyes. It is estimated that more than one-third of women over age 18 and about 10 percent of men over age 40 use some type of hair dye” Also, it has been found that some hair dyes can contain up to 5,000 different chemicals.

There are many different types of hair dyes: permanent, temporary, and semi-permanent. Permanent color is the most common and chemically changes the color of your hair for a long period of time before the hair starts growing out again. Temporary color lasts for a few washes and does not chemically change your hair, it just goes on top of the present color. Semi-permanent chemically changes your hair but only lasts for up to two weeks of washes.

Darker, permanent hair dyes are believed to have the strongest link to the possibility of cancer, and people who frequently color their hair or work around dyes are believed to be more at risk. Testing hair dye formulas on humans for cancer is completely unethical because it could end up killing people, so there have to be alternate forms of testing done. To test if hair dye can cause cancer, researchers test on animals and study large groups of people based on their exposure to the dyes.

In the animal testing, “animals are exposed to a substance (often in very large doses) to see if it causes tumors or other health problems.” Although some studies show that these animals are getting cancers, it is not reliable enough because scientists are unsure if humans would be affected in the same way as the animals being tested.

In the observational studies done on large groups of people based on their exposure, researchers are looking at the difference in cancer rates between those exposed and those not exposed to these dyes. These studies are not the most reliable because they do not take into account possible third variables that could be causing cancer in these groups of participants.

One of the hardest obstacles when testing dyes is the brand. Different brands have a wide variety of ingredients and levels of those ingredients within the dye. In the 1980’s there were studies performed that found that dyes consisting of two specific chemicals  increased cancer risk,”4-methoxy-m-phenylenediamine 2, 4-diaminoanisole, and 2, 4-methoxy-m-phenylenediamine sulfate 2, 4-diaminoanisole sulfate”, causing the FDA to release warning statements to consumers. Hair dye companies no longer use these chemicals in the making of their dyes. Since these two chemicals have been taken out of the hair coloring products, there are no links to the hair dyes for sale today and cancer, according to the FDA.

Some studies have found that the use of hair dyes can increase your risk for bladder cancer but most of these studies don’t include enough people and therefore cannot be reliable. Specifically, a study was conducted to find if the dyes caused an increase in NHL, or Non-Hodgkin’s Lymphoma, where there were about 4,800 women with and 5,800 women without it were studied. The results showed an increased risk prior to 1980, but no increased risk after. Also, there are just as many findings that show no link as there are studies that show possible links. The same issue is faced when talking about if it causes an increased risk between hair dyes and different types of blood cancers. There are many studies that show possible links, but just as many that show absolutely none.

Overall, no study has been compelling enough to show a strong relationship between hair dyes and cancer. Even when a study shows that there is a link, there are multiple other studies refuting that claim. Ultimately, there may never be sufficient evidence to show a strong link because of the fact that experiments on humans are unethical and in observational studies you can never completely rule out possible third variables.