What do you have to say about the presence of benzene in fibre reactive dyes?
Country or region: Canada
Message: Paula, what do you have to say about the presence of benzene in fibre reactive dyes? I stopped using them thirty years ago after being warned about the carcinogenic nature of the dyes. I am very interested in trying them again but wondered if that warning is still valid. If so, how dangerous and what level of exposure are we talking about? I would not be making a career of dyeing yards of fabric! I am a fibre artist interested in making a little bit of hand dyed fabric for particular jobs. Thanks for your help.
I have a suspicion that your real question is about a different chemical, benzidine, rather than with the chemical benzene. Benzidine is a dangerous chemical that has been found in other dyes, though never in Procion dyes, while benzene is not found in most dyes. I'll discuss both, as well as the question of whether Procion dyes are carcinogenic in general. It's ironic that sometimes you see warnings by the ignorant that reactive dyes are too dangerous to use because of carcinogenicity, when in fact it's the all-purpose dyes sold in grocery stores that used to be a danger in this respect. It's unfortunate that you were given such a warning thirty years ago, because it's simply not true that fiber reactive dyes are too dangerous to use safely. They are certainly safer than ordinary all-purpose dyes were, at the time you were given this warning.
By law, in the US, the Materials Safety Data Sheets (MSDS) must contain the names of all ingredients which are health hazards that are present at a concentration of 1% or greater, but they must list all carcinogens even if the are present at only 0.1% or greater. I don't know if the law in Canada is the same, but in practice it appears that the same MSDS pages are used in Canada as in the US.
If you look at an MSDS for benzene, such as the one provided by ScienceLab, you can see that benzene is classified as a proven human carcinogen by the IARC (International Agency for Research on Cancer). This means that any MSDS for a dye that contains as much as 0.1% benzene must list its presence.
For each dye you are concerned about, you should look up its MSDS. There are about a dozen Procion MX dyes in common use, used to mix all of the different colors of Procion MX dyes that are commercially available to us. Any retailer should, on request, supply you with the MSDS for any dye or other chemical they sell to you. Two easy places to look for MSDS information for Procion MX dyes are at Dharma Trading Company's MSDS index and at PRO Chemical & Dye's online catalog (see the link on the individual page for each dye color). Jacquard Products also provides MSDS pages, but they often seem less informative to me than some MSDS pages from other sources. You can also see MSDS for some Procion dyes at the chemical supplier Sigma Aldritch; their MSDS for reactive red 2 (red MX-5B) includes the statement that "This product does not contain any chemicals known to State of California to cause cancer, birth defects, or any other reproductive harm." It is clear from looking at any of the MSDS for Procion dyes that benzene is not a significant component of any of them.
In contrast, an MSDS for Direct Black 38, formerly an ingredient in many all-purpose dyes (all-purpose dyes include different brands such as Rit and Tintex), clearly states,
The carcinogenicity in this case is not caused by benzene at all, but it's caused by another chemical with a similar-sounding name, benzidine.
C.I. Direct Black 38 - California: carcinogen, initial date 1/1/88
NTP: Known carcinogen
IARC: Group 2A carcinogen (listed as Benzidine based dyes)."
Benzidine, rather than benzene, is a carcinogen of great interest in dye safety. Both benzene and benzidine are carcinogens, but there is little or no benzene in dyes, while there are many dyes actually based upon benzidine, or on either of two other specific chemicals, o-tolidine, and o-dianisidine. Dyes that are made from these chemicals may be contaminated with traces of the chemicals; worse, when absorbed into the body, they are changed by the body back into the base chemicals, benzidine, o-tolidine, and o-dianisidine. I strongly advise all of my readers to avoid all dyes that are based upon these substances.
Fortunately, Procion dyes have never contained benzidine-, o-tolidine, or o-dianisidine. No fiber reactive dye has ever contained any of these three dangerous chemicals. Unlike fiber reactive dyes, all-purpose dyes have in many cases been based upon benzidine. However, since the 1970s when they were in common use, all-purpose dyes that are based on benzidine have been phased out, and replaced by other dyes that are not based on benzidine. All-purpose dyes are now safer than they were in the nineteen-fifties, sixties, and seventies.
Unfortunately, while benzidine-based dyes have been phased out, there are still dyes now being sold, in the US, for use by children, that contain a o-dianisidine-based dye, in one brand of the "tie dye cords" that are so inferior to Procion dyes. I always recommended against these cords because of the poor quality of the dye contained in them, but I particularly recommend against using the ones that contain o-dianisidine. They can be used safely by careful adults, but, in my opinion, are too likely to be used unsafely by children, who are the target audience. (See "o-dianisidine in dye-impregnated tie-dye cords".)
We don't know that any particular textile dye is safe to eat, of course. Only food dyes have been tested for safety with truly careless use. Sometimes a food dye which has been allowed in the food supply for decades will be banned due to new evidence that it might have a small tendency to cause cancer, in a very small fraction of the people who eat it. Since textile dyes have not been tested in this way, it's always possible that one might turn out to be carcinogenic when eaten; this doesn't matter much to us, since we're not going to be eating any of them. We should always be careful, with any household chemical, to treat it as though it is a hazard. Wear gloves to prevent it from getting on your skin, wear a dust mask and be careful when working with dust powder, so that you don't breathe it, and wipe up any spills immediately.
There are other dyes that are much more dangerous to work with than Procion MX dyes. Some of the components used in naphthol dyes, for example, can be absorbed through intact skin when spilled on it, in contrast to Procion dyes, which react with the dead cells that serve as a protective layer on our skin, and are not absorbed into living cells.
The true, known hazard with Procion MX dyes, and any fiber reactive dye, is that breathing the dye powder can cause respiratory allergies, similar to the dust allergies many of us have, but with potentially worse results. If you become allergic to a particular type of dye powder, then, when you continue to use it, you are likely to have an asthmatic reaction. These sorts of allergies are not uncommon in the textile industry; they are much rarer among dye artists who follow the recommended precautions. Once you have developed an allergy to a dye powder, you must quit using it, and substitute a different kind of dye (for example, using Drimarene K fiber reactive dyes instead of Procion MX fiber reactive dyes). It is better to take careful precautions from the beginning, so that the allergy never gets started.
Looking at Sigma Aldritch's MSDS for reactive orange 4 (orange MX-2R), you see repeated statements, attributed to various agencies, that "No component of this product present at levels greater than or equal to 0.1% is identified as probable, possible or confirmed human carcinogen". However, that doesn't mean that it's safe to spill dyes, get them on your hands or in your eyes, or allow them to dust up into the air so that you and others breathe them. This is true for any dye, not just fiber reactive dyes, and in fact is true for most household chemicals. The MSDS contains these warnings:
- Inhalation: May be harmful if inhaled. Causes respiratory tract irritation.
- Skin: May be harmful if absorbed through skin. Causes skin irritation.
- Eyes: Causes eye irritation.
- Ingestion: May be harmful if swallowed.
All of these potential dangers can be safely managed by taking care to wear a dust mask, wear gloves and (if necessary) safety glasses, and avoid doing anything that might cause you to breathe or eat any of the dye. That last sounds a little stupid, but I've many times seen artists eating a snack or smoking cigarettes while painting with oils; obviously that sort of carelessness is easy to avoid, and incredibly foolish to engage in. Of course, cigarette smoking is a particular hazard for bladder cancer, as it greatly multiplies the danger of benzidine-based dyes, even for someone who is reasonable about hand-washing; the use of benzidine dyes is more dangerous in people who also smoke. It's remarkable, though, just how much more careless than necessary some people choose to be. I've seen artists who didn't take even the most obvious precaution of not using hands covered with fresh lead-, cadmium-, and chromium-based oil paints to handle something they're putting in their mouths. I recall reading a description one supposed dye company employee (of a company that is no longer extant) of never bothering to wear gloves or a dust mask while measuring out dyes, and ending up breathing so much dye that it appeared in his handkerchief when he blew his nose.
Procion MX dyes are safe to use, as long as you are careful and follow the usual rules of safety for household chemicals. They are no less safe than many household chemicals people don't think much about, such as dishwasher detergents, and they are safer than many.
Answers to questions about dye safety in this blog
Posted: Tuesday - November 22, 2011 at 09:41 AM
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Published On: Aug 29, 2012 02:49 PM