While there is no definitive scientific study that links cancer to hair dye, there are reports that show an increased rate of some types of cancer in people who are exposed to it. There are several non-chemical/vegetable dyes you can use.

According to the Food and Drug Administration's Office of Cosmetics and Colors, hair straighteners and hair dyes are among its top consumer complaint areas. Allergic reactions to dyes include itching, swelling of the face, and even difficulty breathing. The petroleum products used in hair dyes are known to cause allergic reactions in some people. Synthetic chemicals, including hair dyes and other color additives, were originally manufactured from coal tar, but today manufacturers primarily use materials derived from petroleum.

One problem is that people become sensitized. You may think that if you've been using a particular hair dye for years there's nothing to worry about. Actually, people in this category are most at risk. Years of using a chemical has increased your sensitivity and you may find that one day using your favorite hair dye will leave you with bald patches, swollen eyes, and/or irritated skin.

A study published in the January/February 2005 issue of Public Health Reports, the official journal of the US Public Health Service, found that the use of permanent hair dyes among men and women increases the risk of developing bladder cancer by up to 50 percent compared to those who don't use hair dye.

In 2004 a study by Yale researcher Tongzhang Zhen found that long-term use of permanent hair dye, in dark colors, doubles a person's risk of non-Hodgkins's lymphoma.

In the summer of 2004, the Environmental Working Group (EWG) analyzed 117 hair dyes. It found:

• 62 percent of products contained ingredients that are known or probable carcinogens, including dyes derived from coal tar
• One product contained lead acetate, a known reproductive toxin
• 79 percent of products contained ingredients that contained impurities linked to breast cancer
• 96 percent of products contained penetration enhancers that increase exposures to carcingongens and other ingredients of concern
• 73 percent of products contained ingredients that are known allergents
• Women who use permanent, hair dyes once a month for 1 year or longer have twice the risk of bladder cancer.
• Women who use permanent hair dyes for 15 or more years at least monthly have three times the risk of bladder cancer using permanent dyes for 15 or more years when the dyes are used monthly or more frequently.
• Those who have worked as hair dressers or barbers for 10 years or more have five times the risk of bladder cancer.

Here are links to safer alternatives. Notice I say safer and not safe because while these are better alternatives, you can develop sensitivities to natural dyes as well:

• Naturtint
• Surya
• Herbatint
• Light Mountain

Reference: 1,001 Chemicals in Everyday Products