The claim that natural dyes are inherently safer than synthetic dyes is the result of ignorance about the actual risks. Some natural dyes are very safe, and some synthetic dyes are dangerous (not the ones whose use I recommend!), but there are also natural dyes that are poisonous, even for those working only with the dyed fiber, and there are some synthetic dyes that are safe enough even to eat. (For some examples of unsafe natural dyes, see "Aren't natural dyes safer than synthetic dyes?".)

No hand dyer has ever been killed by exposure to Procion MX dyes. The mordants used with almost all natural dyes are far more dangerous. Even alum, the safest of all of the metal ion mordants, has caused fatalities, and more hazardous mordants such as copper and iron have caused many more. Alum, iron, copper, and tin may all be used safely by those who take all of the appropriate safety precautions, and who take care never to use them around those who might swallow them or splash themselves with the mordant, such as small children. However, chrome mordant, which makes beautiful colors when used as a mordant for natural dyes, is, in my opinion, too dangerous for use at home.

As Olli described, the real risk of working with Procion MX and other fiber reactive dyes is that of developing a respiratory allergy to the dye. You must be careful to avoid breathing the dye powder in order to reduce your risk of developing this problem. One well-known quilt artist developed an allergy to Procion MX dyes and had to switch to using Cibacron F dyes, which perform similarly. If you develop an allergy to any particular class of dyes, such as Procion MX dyes, you must then quit using it forever, as otherwise it can provoke serious asthma. It is easier to avoid the problem in the first place, by being careful. Doing so also avoids exposure to the possibility of dangers that are now unknown.

The Procion MX type dyes contain little or no metal, depending on color. You can easily check this by looking at an MSDS page, provided by your dye supplier. Turquoise MX-G and rubine MX-B each contain a small amount of copper, between 1% and 5% of the weight of the dye powder. A hand dyer does not need to worry about metals in these small quantities. (See "Toxicity of Procion Dyes".) If you are dyeing by hand, by yourself, there is no harm in the relatively small quantities of dye that you may dump down the drain. There is more danger to you and your children in the neurotoxins commonly applied to your neighbors' lawns as insecticides, and the fertilizers applied to your neighbors' lawns are far more harmful to the environment than the dyes you dispose of, as fertilizer run-off leads to the production of oxygen-free dead zones in the oceans and the Gulf of Mexico.

Many acid dyes, including some of the Lanaset dyes, contain a small amount of the more toxic metal, chromium. While I strongly recommend that home dyers strictly avoid the use of a separate chrome mordant, the amount of chromium bound to the Lanaset dyes is low enough that a single recipe of Lanaset dye paint will meet EPA requirements for drinking water, if diluted by fifty gallons of water. (See "What are the risks of exposure from using a dye that is premetalized with chromium?".) This means that it is safe to dispose of small quantities of Lanaset dyes down your drain.

Other types of dyes bring with them additional safety concerns. There have been direct dyes sold to home users in the past that contained probable carcinogens, based on the chemicals benzidine, o-tolidine, or o-dianisidine. These dyes were included in all-purpose dyes that were available to home dyers in the US through the 1970s. (See the safety section at the bottom of my page on all-purpose dyes.) You can still buy "tie dye cords" that contain an o-dianisidine-based dye, which should never be given to children to use. (See the post "o-dianisidine in dye-impregnated tie-dye cords".) There is no such thing as a fiber reactive dye that is based on benzidine, o-tolidine, or o-dianisidine, so this is not a concern for those using Procion MX, Remazol, and other fiber reactive dyes. Some popular acid dyes, such as Rhodamine B, have been listed as carcinogens in the past; I recommend that users of these dyes be particularly careful with their safety precautions, but I don't see a safety problem for those who do take care. It's interesting to note that the safest dyes for children to work with, the certified food colorings, are also acid dyes.

The naphthol dyes are more dangerous carcinogens than other dyes that hand dyers use, but they are not generally available to hand dyers in Europe or North America. Unlike many other potential carcinogens, some of the naphthol dye components can be absorbed directly through even unbroken skin, which makes any skin contact much more dangerous than contact with other types of dye. (Fiber reactive dyes tend to react with the dead surface skin cells and stay put, rather than entering the body through the skin.) I am very glad that the most dangerous dyes, such as the black dye that (or so someone said) killed all the Japanese master dyers who used it, are no longer available to artists, at least in most countries.

The safest dyes for the wearer are properly fixed fiber reactive dyes, because they form a permanent chemical bond to the fiber which does not break during use. Disperse dyes and basic dyes are occasionally reported to cause allergic reactions in the wearers, but the only report I have seen in the medical literature of a wearer's reaction to fiber reactive dyes involved inadequate wash-out; the problem was solved for the wearer by washing the garment. Of course, all excess unattached dye must be washed out, preferably using hot water; you can dampen your dyed fabric and then press it between two white cloths with a hot iron to see if you still have any remaining unattached dye. This is important for quilt-making, and for dyeing clothes for babies or anyone else who might chew on the fabric.

Claims for eco-safety are different, since a poorly-run factory can do great damage by dumping toxic chemical intermediaries. Dystar, the current owner of the Procion trademark, does not manufacture Procion MX dyes, but they still manufacture Remazol dyes and Procion H-E dyes. Their dyes have been certified according to both the EU label and the Oeko-Tex Standard 100; the standard includes approval for use in clothing for infants. See "Are Reactive Dyes eco-friendly?".

I have myself used the dry-dye-sprinkling method with Procion MX type dyes, as was recently discussed here [on the DyersLIST mailing list], but only when working outdoors, with a properly fitting dust mask. I would not like to have loose powder floating around inside the house; safe indoor use requires a suitable box set-up that contains all loose dye powder inside it. The fit of your dust mask is critical, even when you are working outdoors, since the wind may unexpected blow the dye back in your face. It is easier to breath if you are pulling in some air from around the edges of the dust mask, but that negates its usefulness. Never rely on a dust mask that allows you to breathe around it.

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