Deadly Pyro?

[bert_krages1]

<p>A constant refrain seen in posts about pyrogallol is its toxicity. Out of curiosity, I did a quick search at Toxnet to see how it compares with other standard developers. I found it interesting, after reading some of the dire warnings posted on photo.net, that pyrogallol is considered safe when used as an ingredient (up to 5 percent) in hair dyes and seems to compare reasonably well to other developing agents in its toxicity.

 

<p>Here are some links:

 

<p><A HREF="http://toxnet.nlm.nih.gov/cgi-bin/sis/search/f?./temp/~qMJ9kr:1">Pyro</A>

<p><A HREF="http://toxnet.nlm.nih.gov/cgi-bin/sis/search/f?./temp/~Je5EBE:1">Metol</A>

<p><A HREF="http://toxnet.nlm.nih.gov/cgi-bin/sis/search/f?./temp/~OVNhek:2">Hydroquinone</A>

<p><A HREF="http://toxnet.nlm.nih.gov/cgi-bin/sis/search/f?./temp/~K2A21H:4">Amidol</A>

 

<p>I am not downplaying the need to act responsibly with regard to safety and photographic chemicals but it does not appear to me that pyro presents a significant risk above that encountered with other developers.

[kirk_keyes]

Bert -

You are right. The numbers just don't indicate that pyrogallol is significantly more hazardous than any of the other compounds you mention. In fact, numbers for LD-50 in rats indicate it is less toxic.

 

You're a lawyer, right? So you certainly understand that public perception of any issue is ultimately more important than actual facts. It's too bad things are like this. But I do believe that education is the best tool in situations like this. So thanks for rounding up these references and making them easily accessable for us.

 

Kirk

[rustys pics]

Anything will kill you in large enough amounts....

From those reports, Hydroquinone looks worse than Pyro.

But the dosage is what counts. Does anyone know what the percentage of

Pyro is in the average developer mix?

[john_murphy1]

Unfortunately, internet searches cannot provide the full story. I am a doctor, and I recall researching this subject once using the texts that are available to me. I came to the conclusion that pyro compounds are significantly more toxic than the others at the dilutions commonly used in photography. Hope this helps.

[peter_witkop]

John, just curious what conclusions you came to exactly? I've been experimenting with pyrocat-hd (pyrocatchol based), and thinking about trying pmk (pyrogalol based) but I haven't been able to find information I understand about the effects of either of these chemicals (my biology and chemistry experience is pretty limited, to what I took in high school). I've read quit often that inhalation is the worst for of exposure, and of course I wear nitril gloves to avoid skin contact, but how bad is skin contact, and how much contact would be dangerous? I'd really like to have a better understanding of the chemistry I'm working with, as I suspect from the responses this thread has generated so far.

 

Peter

[silent1]

When I was in high school (and before) learning to develop and print, we always used to just stick our fingers right in the Dektol and I did it a few times with HC-110 when using that as a paper developer. In those days, that was considered safe as long as you didn't bite your nails or lick your fingers, though I recall one girl in my high school photo class who got a bad rash from the Dektol (presumably a metol reaction).

 

These days, it's generally recognized that *everything* is toxic -- even water and oxygen. In this environment, something that's "more toxic" than the next substance that will do the same job is likely to wind up banned before too long; it's amazing to me that we're still allowed to buy some photographic chemicals over the counter, given the stuff we're *not* allowed to buy (a popular antihistamine, phenylpropanolamine, was taken off the market a couple years ago because something like a dozen people out of 280 million in the USA had strokes that were traced back to the drug -- and never mind the hundreds who probably died because they fell asleep and drove off the road under the influence of a "less hazardous" alternative drug).

 

So, in this environment, we have warnings about toxicity of pyro (which, though the LD-50 may be higher, has many more and worse effects at sub-lethal doses than hydroquinone), and then counterwarnings about metol, hydroquinone, phenidone, even sodium ascorbate, for heaven's sake!

 

Okay, thanks for all the warnings. Now, please let me get back to my darkroom (well, at least my changing bag and daylight tank) and get some developing done, while I still can. Call or e-mail if you need someone to petition some agency or other to keep HC-110 or Rodinal on the market -- maybe we can tell them about what's in oil paints! Meantime, even pyro doesn't worry me as long as I don't have to mix it from powder or put my hands in it, ungloved, to develop prints.

 

Now, if I can find a less toxic subsititute for mercury to develop Daguerreoptypes...

[sandy_king]

A liter of the 1:1:100 dilution PMK contains 1.0 g of pyrogallol. A liter of the

1:1:100 dilution of Pyrocat-HD contains 0.5 g of pyrocatechin.

 

Sandy King

[john_murphy1]

Peter,

This is the difficulty to which I referred: I need to go to a medical library to access the full body of literature on these chemicals. Medical libraries have cases of poisonings dating back centuries, which gives a better picture of a chemical's toxicity than an internet search can possibly provide. As I recall, the problem with pyro involved its ability to penetrate the skin and enter the bloodstream, while inhalation was not such a big deal. Don't quote me on this.

[garrylewis747]

well, let's ban Di-hydrogen Monoxide! Its killed more people than all developer agents combined.

[johnmarkpainter]

When dealing with Pyro......

 

Try to mix it from Liquid and not Powder. If you spill it clean it well because it will dry into

powder and become airborne as well as eventually get on your skin. Wear Gloves (many

people don't).

 

Selenium and Pyro are probably the worst chemicals that we use.

 

Bert...pyro is definitley nastier than the most common developers such as Xtol, D-76, HC

-110.

 

jmp

[kelly_flanigan1]

Doctors use to hawk cigarettes in commercials in the 1950's; along with Lucy and Ricky. Most of us worried about the atomic bomb; fallout; and Civil defense. Trains were a common toy. One doctor we had recommended smoking; to reduce ones weight; or reduce hay fever/ pollen; alergies. The shoe stores had an Xray deal/gismo; to "show" how ones foot "fit" in a shoe about to be sold. We drank from garden hoses; used mercury thermometers. The teachers would handle raw mercury in their handsl and pass it around from student to student; in by their hands.

[roger_hicks1]

Dear Bert,

 

A point seldom addressed is that many things are harmless (more or less) at the point of use, and pose no significant danger in a lab when handled with respect, but are still dangerous enough that you don't want them in large quantities in an industrial process where some workers may not be all that careful and even the careful ones may spill things occasionally. Then they can be a problem again in landfill, leaching into groundwater. Hence the disappearance of cadmium from film and paper, and mercury from batteries. I don't think I'd worry about handling pyro, but I'd certainly be careful with it. And then you have the pornography argument: "Of course I'm old enough/wise enough/sensible enough, but what effect will it have on children/simpletons/the unthinking."

 

Cheers,

 

Roger

[tim_curry]

My understanding of pyro's toxic effects has more to do with the benzene molecule's ability to penetrate the body's "normal" defenses than anything else. Benzene has the ability to zip right through the skin, enter the blood stream and then go anywhere in the body in seconds. The skin's normal defenses are useless with this type of invasion, because it will not prevent the entry at all, acts just like a sponge. This allows the molecule to affect all parts of the body, especially the brain and central nervous system. Cancer is also a possibility.

 

I agree that one must take precautions against this type of exposure and penetration. Use gloves. Wear a respirator and work with the dry chemical outside where it will dissipate rapidly if some does escape. This is just common sense.

 

I got a warning bulletin about the hazardous nature of sawdust when I was running my cabinet shop some years ago (1980's). It went into grave detail about the disposal of this toxic substance and how to clean up a spill. A haz-mat team should be called in the event of a spill, precautions must be taken if....... I shudder to think of how many times I was exposed to this toxin. It was on my skin, in my lungs, nose and clothing for 25 years. Now I'm just waiting to die from my exposure to it so please be careful, although so far, I've managed to dodge the bullet. I'm happy to have something as relatively "safe" as pyro to work with in the meantime.

[roger krueger]

LD-50 is far from the whole story--long term exposure is the issue with pyro, not sudden

death.

 

All I've heard are anecdotes of people with massive skin exposure (gloveless tray

development) for many,many years eventually having kidney issues.

 

Think of it like cigarettes--if you have one or two or even 200 they won't do any real

damage, but a couple of packs a day for 30 years is a problem.

 

I have a leaky tank that sometimes lets pyrocatechin-based TD-3 dribble down my arm

during agitation. It doesn't worry me enough to deal with the hassle of gloves. If I

developed 4-5 days a week I might think differently, though.

[kelly_flanigan1]

The pre WW2 photo books mention skin problems when using developers; and recommends the usage of gloves.

[john_stockdale2]

The fact that pyrogallol is still approved as an ingredient in hair dyes suggests that some skin contact should not cause great alarm. Regular contact would be more serious, so use a method that keeps it off your skin.

 

As far as inhalation is concerned, it should not be too difficult to find a place where a breeze blows it gently away from the user and his environment. One good thing about PMK is that it lasts so long that mixing need be done only once every 2 or 3 years.