The only natural hair color is henna. There is no such thing as a true organic hair color either, here's an article about the subject by Dr. Said
A Chemist worked at Redken:
THE MYTH OF ORGANIC NATURAL HAIR COLOR
Q. Dr. Said I have been hearing a lot about natural and organic as well as PPD-free hair color. Is there such a thing as organic or natural hair color? And if so, could you recommend any of those? Lea, Indian Wells, CA.
A. First I cannot recommend a product because THERE ISN’T ANY. Unfortunately, some small manufacture’s try to play the fear factor in their advertisements to achieve a quick sale. Be aware of those. The only dye that you can find in hair color with truly organic nature is natural henna, but we all know the drawbacks of this colorant. There are many claims cleverly designed to confuse you into believing that a product is “natural” or “organic” or simply “good for you”. For example, many products on the market contain natural botanical extracts or other ingredients derived from botanicals. But as long as the active ingredients (in this case hair dyes) are chemicals synthesized in the lab, the product should in no way be described as a natural or organic product in the sense we understand “organics” to be..
On the other hand, there are hair products which do not contain PPD (para-phenylenediamine) free but again they are not organic or natural. A replacement for PPD is a dye called PTD (para-toluenediamine, or 2,5-Toluenediamine) which is very similar to PPD. The only difference is the presence of an extra chemical (methyl) group on the benzene ring. PTD delivers similar color combination to PPD when combined with various dye couplers, and is used as a replacement for PPD. PPD has been in use in hair color for several decades and has been subjected to intensive research along the way. Considering the billions of color applications involving PPD on humans and the number of reported toxic cases of the dye, the risks appear to be quite minimal. PTD, on the other hand has been in use for only a much shorter period and not enough studies have been conducted in relation to its safety. Long-term effects, if any, are yet to be seen. Remember that people can develop sensitivity to a number of things including food, flowers, and other things that are harmless to the greatest majority of people. Dye allergies should be viewed from this perspective."