Article by Jim Thomas, http://www.livestrong.com
The health effects of hair coloring are, to a certain extent, unknown. And the link between hair coloring and cancer is controversial and, to date, inconclusive. But many of the chemicals contained in frequently used hair dyes have been shown to be dangerous. Such chemicals can cause allergic reactions and perhaps even neurological problems. There are alternatives to such hair dyes, such as plant-based henna and infrared techniques that open up hair shafts to allow coloring. Such "green" solutions are advisable for anyone who wants to avoid the risks associated with many hair coloring products.
Types of Chemically Based Hair Coloring
There are three main types of chemically based hair coloring products, as explained by Surviving-Hairloss.com. Temporary hair dyes are like surface paint: They don't penetrate the hair shaft and are easily washed off. Semi-permanent dyes contain smaller molecules that do penetrate the hair shaft. Permanent dyes use the harshest products, which break up the original color pigment in your hair and replace it.
Potentially Dangerous Chemicals in Hair Coloring Products
Chemicals in hair coloring products include PPD, or para-phenylenediamine, which can cause allergic reactions such as burning and headaches and is also a potential carcinogen; coal tar, which is in 70 percent of hair coloring products and can cause allergic reactions; lead acetate, which has been banned in European countries as a possible carcinogen and, as with, other lead products, may cause potentially serious neurological problems; DMDM hydantoin, a preservative that has been linked to immune system problems; ammonia, which can be toxic and corrosive and may cause respiratory problems; and resorcinol, which can be an irritant and is a potential carcinogen.
Further read at : http://www.livestrong.com/article/211736-the-health-effects-of-hair-colo...