As a chemist I would like to warn people again about the phenylenediamines. They are suspected carcinogens and are capable of causing an extreme form of allergic dermatitis. They are also cross sensitizers that can sensitizze people to related developing agents such as Metol and the color developing agents. Skin absorption has been linked to liver and kidney damage. I speak from personal experience since I had to give up color processing. They are bad news and have no place in modern photography.