I used to dye my hair when I had dreadlocks. I wanted to lighten my locks so that they looked "sun-kissed". I loved the look; however, I quickly stopped dyeing my hair because it didn't make any sense to spend that amount of money on my hair when I was living on a meager graduate student stipend in New York (well, I WAS married at the time and my husband was my Sugar Daddy! But, you get my point!). I no longer dye my hair and a recent flurry of events make me even happier with my decision to stop the dyeing habit. In fact, I'm now afraid to use do-it-yourself hair dye kits.
Several weeks ago a British teen eventually died in a hospital after first collapsing minutes after a do-it-yourself hair dyeing episode (http://abcnews.go.com/blogs/health/2011/10/20/hair-dye-allergy-suspected-in-teen-death/; http://www.dailymail.co.uk/femail/article-2051098/Does-YOUR-hair-dye-contain-chemical-feared-killed-woman.html. The teen, Tabatha McCourt, was apparently an avid hair-dyer who loved to experiment with different hair colors. It appears that Ms. McCourt had a severe allergic reaction to Paraphenylenediamine (PPD) a chemical widely used in hair dyes (this article talks about the teen, another woman who had a severe allergic reaction and provides detailed information about PPD: http://www.guardian.co.uk/lifeandstyle/2011/nov/28/could-hair-dye-kill-you?newsfeed=true). Here is some information on PPD from the Center for Disease Control (http://www.cdc.gov/niosh/ipcsneng/neng0805.html).
I am not a chemist, but it sounds like this stuff is noxious though it's been deemed safe as long as it doesn't touch the scalp. Wait a minute? How in the world can you dye your hair without any of the hair dye touching your scalp? That seems IMPOSSIBLE! Aren't the roots the main target of hair dyeing? It seems like we need to look into the safety of hair dye. I'm not the only one who thinks this is fishy. According to the British Medical Journal (2007): "Wider debate on the safety and composition of hair dyes is overdue—among medical and scientific communities, the public, and legislators. Cultural and commercial pressures to dye hair and, perhaps, the widespread obsession with the “culture of youth” are putting people at risk and increasing the burden on health services. It may not be easy to reverse these trends, however, as some patients have continued to use such dyes even when advised that they are allergic to them and risk severe reactions" (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1790769/).
Severe reactions that can lead to death. Folks, if you dye your hair or know of anyone who does, please be careful. I understand that natural henna and other plant-based dyes don't contain PPD. Again, I'm not an expert so please, check with your stylist, better yet your doctor.