Black Henna: A CON

I was thinking about dying my hair with black henna, assuming it was a good idea due its organic nature. I went to the shop and bought a package... While I was at home, I read the components and I jumped when I read it had barium peroxide in the formula, which is a bleaching agent.
I went back to the shop with the product, which was the blue one of this photo, and got my money back.
I went back home made a quick research, just to find out that black henna doesn't exist naturally. There are several brown to red tonalities of the original henna, but 'the black one' is mixed with strong chemicals, Para-phenylenediamine and can be very dangerous to the skin.
Surfing the blog community I found out the nightmare this woman suffered caused by a henna tattoo done in a vacation in Zanzibar. Black henna can cause severe allergic reactions, leave scars and further adverse reactions.