Hair Dye: a choice between health and beauty

Hair color today is a matter of choice--but is it safe?
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Some people believe that nature has provided us with the hair color that is the most complementary to our skin tone. Others, however, feel differently and that perhaps nature did not quite get it right. Both men and women dye their hair these days; probably more so now than ever before. Whether the motivation to change our hair color stems from age, fashion, or beauty it remains a question as to whether the choice to do so results in a health risk that may outweigh the aesthetic advantage.

Three types of hair coloring products include temporary (does not penetrate hair shaft, lasts through 1 shampoo), semi-permanent (does not penetrate hair shaft, lasts through several shampoos), and permanent (penetrates the hair shaft, last until new growth occurs). Two types of hair dyes are progressive and oxidative. Progressive hair dyes contain lead acetate or bismuth citrate, which are metal salts that react with sulfur compounds in the hair resulting in a change of hair color. Oxidative hair dyes are mixed before they are applied and contain hydrogen peroxide and chemicals such as p-phenylenediamine or 2-nitro-p-phenylenediamine. Studies have found that there is an increased risk of cancer from the use of select types of hair dye; especially the darker dyes as they contain higher concentrations of carcinogens. [1]

Hair coloring products can readily be purchased off the shelf for home use.
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In 1993, the International Agency for Research on Cancer (IARC) issued a statement that hairdressers and barbers are exposed to carcinogenic compounds from hair coloring products; however, not enough information was provided from studies that were done on exposure to hair dyes to relate this to an increased risk of cancer. Many more studies have been conducted since IARC issued that report, but the data has been inconsistent and so a direct link between the use of hair dye and increased risk of certain cancers such as bladder cancer, blood cancer and other types has not been confirmed. For this reason, it is not considered a major public health concern. Lab animals that were fed high concentrations of ingredients found in hair dyes (4-methoxy-m-phenylenediamine or 4-MMPD, 4-MMPD sulfate, 4-chloro-m- phenylenediamine, 2,4-toluenediamine, 2-nitro-p- phenylenediamine, 4-amino-2-nitrophenol, C.I. Acid Orange 3 and C.I. Disperse Blue 1) developed cancer. But for animals that received doses applied to their skin, although some gets absorbed into the bloodstream, no direct link has been established with this application method and an increased cancer risk. [2]

In 2001, Health magazine published information that brought a public awareness about the risks of developing bladder cancer from the use of hair dyes. Researchers found that women who dyed their hair at home using products purchased over-the-counter increased their risk of bladder cancer in comparison with women who did not use those products. The study also found that professional hairstylists and barbers increased their risk of developing cancer by 50% through one year of occupational exposure to hair dyes. Since cigarette smoking has been linked to cancer, this study adjusted for that variable. In 1978, The Federal Drug Administration (FDA) issued a warning on hair dye labels regarding the use of coal tars in hair dyes. Since that warning, two coal car ingredients with carcinogenic properties, 4-methoxy-m-phenylenediamine (4MMPD) and 4-methoxy-m-phenylenediamine sulfate (4MMPD sulfate) have been removed from hair dye products. In spite of the reports from studies that have considered hair dye and bladder cancer to be in correlation with one another, researchers feel that larger and more controlled studies need to be done in order to make a fair evaluation. Although levels of occupational risk are significant, it is questionable as to whether other exposure causative factors may be considered as a possible influence. Professional hairstylists at one salon took notice of the potential health concerns and developed a non-contact technique to lessen the client’s exposure to hair dye. They do not bring the color mixture as close to the scalp as they did in the past. [3]

Mixing hair color before application results in an oxidizing process.
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In 2001, reports from several studies indicated that bladder cancer and blood cell cancers are the two most common types of cancers associated with the use of hair dye products. One study compared 897 patients with women who use hair dye and that also have bladder cancer with a group who use hair dye but do not have cancer. The results indicated that women, over the course of 15 years, who use hair dye on a monthly basis increased their risk of bladder cancer 3-fold. The study emphasized that although they found an association between the use of hair dye and bladder cancer it does not mean that its usage is the direct cause. [4]

A 2004 WebMD Health News report discussed a Yale scientist who conducted a study with a pool of 601 women. The results of that study indicated that women who used a dark color permanent hair dye for more than 25 years doubled their risk of non-Hodgkin’s lymphoma. For women who used hair dyes made after 1980, no increased risk was indicated. Also, no increased risk was noted for women who used semi-permanent dyes or temporary rinses. The Cosmetic, Toiletry, and Fragrance Association, however, points out that there is inconclusive evidence about the link between the use of hair dyes and cancer. Their view is based on select epidemiological studies conducted by prestigious institutions that did not find a link between the two. Although some researchers think otherwise, this does not necessarily mean that hair dye is safe to use if made after 1980. One study found that the more often a person uses dye products, the higher the risk of cancer. A chemical called 4-ABP is a known carcinogen and was found in hair dye purchased off the shelf at stores open to the public. The ingredient is not necessary to the product and so can easily be removed. However, one scientist notes that it is not necessarily the ingredients in the dye that are responsible for cancer but rather the reactions they undergo through an oxidizing process when mixed that results in potentially harmful chemicals. This is especially true for the darker color permanent hair dyes. The carcinogenic chemicals in the hair dyes are called aromatic amines. The body can naturally detoxify these chemical compounds; however, some people cannot detoxify them due to a genetic fault. [5]

Darker hair dyes have a higher chemical concentration of suspected cancer-causing agents.
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Another study published in 2004 (American Journal of Epidemiology) suggested that longer term use of dark hair dye may increase the risk of developing non-Hodgkin’s lymphoma. Hair dyes used before 1980 contained carcinogenic chemicals that caused cancer in mice. However, hair dyes no longer contain those carcinogenic ingredients. In 2005, The Journal of American Medicine (JAMA) published a meta-analysis on the research involving the use of hair dye and cancer. The results were that it was not likely that there is a correlation between the two. However, other studies revealed that there may be a link between the use of hair dye use and some types of blood cancers such as myeloma, lymphoma or lymphoblastic leukemia. In 2008, the World Health Organization (WHO) stated that there is evidence that the risk of bladder cancer is increased in males who work in professions such as hairdressing and barbering. [6]

1973 Miss Clairol Hair Color--Cybill Shepherd.
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In 2006, researchers from the University of Texas, Department of Epidemiology and Urology and the Cancer Center, published results from a detailed hospital-based case-controlled study of 712 subjects (712 healthy controls and 712 with bladder cancer). They found that occupational exposure resulted in a slight or moderate increased risk of bladder cancer and also that personal hair dye use and the risk of increased bladder cancer risk was not significant. The study adjusted for multiple variables that could correlate with hair dye use habits and cancer including age, gender, ethnicity, smoking, educational levels and household income. There was no evidence of joint effects of smoking and hair dye use and cancer and, overall, no evidence to support the idea that the use of permanent hair dye increases the risk of bladder cancer. [7]

In 2008, IARC reported that there was now enough evidence that hairdressers and barbers are at greater risk for bladder cancer from hair dye due to occupational exposure. This conclusion is based on evidence from epidemiological studies over a span of 15 years. It was reported that hair dyes with a benzidine base are carcinogenic and have been shown to cause bladder cancer and are more concentrated in darker hair dyes. A study conducted in the United States found a potential link between home hair dye use and the risk of cancer; however, another study in Spain that focused on the same topic did not find evidence of a link between the two. [8]

In 2008, HealthDay News reported that hairdressing professionals who used hair coloring products that are now banned have a slightly elevated risk of bladder cancer. The suspicion about the link between hair dye and cancer arose in the 1970s. The carcinogenic ingredients in the hair dyes were discontinued when lab animals that were tested developed cancer. However, there is question as to whether hair dyes used today result in the same cancer risk. Cancers take years to develop and so the more relevant exposure is from the past. Many of the reports on the use of hair dye and increased cancer risk that are published today are based on longitudinal studies, which are done over the course of many years. The exposures in the past may put a person at higher risk but the data do not provide evidence about the risk of exposure to newer dyes. [9]

The American Cancer Society publicized the following statistics for the United States.
•   In 2000, there were 53,200 diagnosed cases of bladder cancer, and 12,200 deaths. Bladder cancer represents 6% of new cancer cases in males and 2% of new cancer cases in females.
•   In 2008, it was reported that there would be 68,810 new cases of bladder cancer (51,230 in men and 17,580 in women) and an estimated 14,100 deaths (9,950 in men and 4,150 in women).
•   In 2009 it was reported that there will be approximately 70,980 new cases of bladder cancer (52,810 men and 18,170 women) and about 14,330 deaths from bladder cancer (about 10,180 men and 4,150 women).
Bladder cancer more commonly occurs in people over 55 years of age. The lifetime probability of developing this cancer is 1 in 27 for a man and 1 in 84 for a woman. Also, the survival rate is much higher today than it was in the 1970s and 1980s. More than 500,000 people in the United States are survivors of this type of cancer. And although there has been an increase in bladder cancer through the years, it is not directly correlated with one influencing factor, such as the use of hair dyes. [10][11][12]

The incidence of bladder cancer is increasing but the survival rate is higher than in the past.
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The FDA addresses concerns about the use of hair dyes by providing recommendations for precautionary measures: [13]
•   Don't leave the dye on your head any longer than necessary.
•   Rinse your scalp thoroughly with water after use.
•   Wear gloves when using hair dye.
•   Carefully follow the directions in the hair dye package.
•   Never mix different hair dye products, because you may cause potentially harmful reactions.
•   Be sure to do a patch test for allergic reactions before putting the dye in your hair. Do a patch test before every use.
•   Never dye your eyebrows or eyelashes.
•   Delay dyeing hair until later in life when it starts to turn gray.
•   Consider using henna, which is largely plant-based, or hair dyes that are lead acetate-based.

Read and follow the instructions for applying hair coloring products.
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Studies that have analyzed the use of hair coloring products and increased cancer risk differ in their results and conclusions. Some reports found significant evidence to link the two and other studies have not. Many reports show agreement, however, that hair dyes used before 1980 contained ingredients that are known cancer-causing agents. Also, darker dyes in comparison with lighter ones have a higher concentration of suspected carcinogens. The use of darker dyes increases the exposure to chemicals that have the potential for adverse effects. Since the 1970s, many of the cancer-causing compounds in hair coloring products have been removed as advancements have been made in their formulation. The mixing of the products before application results in chemicals that may cause harm. Taking precautionary measures when using these products may lower the risk of harmful effects. The hope is that safer hair coloring products and chemicals can be developed to protect consumers from dangerous carcinogens so that coloring your hair results in a safe balance between health and beauty and not a choice between the two.

Reference links:
1.   http://www.cancer.org/docroot/PED/content/PED_1_3X_Hair_Dye.asp
2.   http://www.cancer.org/docroot/PED/content/PED_1_3X_Hair_Dye.asp
3.   http://www.usatoday.com/news/health/spotlight/2001-04-10-blasi-dye.htm
4.   http://www.cancer.org/docroot/NWS/content/NWS_1_1x_Study_Finds_Possible_Link_Between_Hair_Dye_and_Bladder_Cancer_.asp
5.   http://www.webmd.com/skin-problems-and-treatments/news/20040126/hair-dye-linked-to-blood-cancer
6.   http://www.cancerhelp.org.uk/help/default.asp?page=4124
7.   http://cebp.aacrjournals.org/cgi/content/full/15/9/1746?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Use+of+Personal+Permanent+Hair+Dye+is+Not+Linked+to+Bladder+Cancer+Risk&searchid=1&FIRSTINDEX=0&volume=15&issue=9&resourcetype=HWCIT
8.   http://www.newscientist.com/article/dn13533-hair-dye-may-raise-cancer-risk-for-coiffeurs.html
9.   http://health.usnews.com/usnews/health/healthday/080326/now-banned-hair-dyes-linked-to-bladder-cancer.htm
10.   http://www.usatoday.com/news/health/spotlight/2001-04-10-blasi-dye.htm
11.   http://www.mass.gov/Eeohhs2/docs/dph/cancer/type_urinary_bladder_info.pdf
12.   http://www.cancer.org/docroot/cri/content/cri_2_4_1x_what_are_the_key_statistics_for_bladder_cancer_44.asp
13.   http://www.cancer.org/docroot/PED/content/PED_1_3X_Hair_Dye.asp