It's the sad truth that the government does not regulate ingredients in hair dye. An astonishing number of these chemicals are linked with cancer, allergies, and other health problems. Toxicity for the immune system and the nervous system, all wrapped up in a pretty box.
"Chemicals may also cause seemingly unrelated problems, such as infertility that you will never associate with the beauty or cleaning products you were exposed to throughout your lifetime. When you use chemicals on or near your body, you are essentially performing a science experiment on yourself and your family that you will never know the results of."
There ARE other options that are gentler and more benign. One such option is henna for hair. While some henna products include unhealthy chemicals, it is possible to find henna hair coloring that contains none.
Henna highlights your natural color and covers gray. It provides a healthy coating that will protect your hair from the wear and tear of daily life, making it soft and lustrous.
Henna comes in shades of blonde to black. Colorless henna is also available that simply strengthens your hair.
http://www.ecomall.com/greenshopping/ewghair.htm