View Full Version : Health Risk of Pyro

steve simmons
14-Jun-2004, 08:28
There has been so much BS about pyro posted all over the net and in some magazines that View Camera and CamraArts have posted a rational and considered essay on its health aspects. The article is in the Free Article section of both web sites



This article was written by Richard Knoppow and we have posted it with his permission.

steve simmons

Andrew O'Neill
14-Jun-2004, 08:41
Sorry Steve, but I looked and couldn't find the article in either site.

Ralph Barker
14-Jun-2004, 08:48
I couldn't find it indexed in the free section on either site, Steve. Do you have a direct link?

steve simmons
14-Jun-2004, 09:49
I sent it to our web master a couple of hours ago. It will be up soon.


ronald lamarsh
15-Jun-2004, 07:55
Steve: Thank you for being such a good member of the community

Andrew O'Neill
15-Jun-2004, 09:20
ain't there yet...

15-Jun-2004, 12:09
That's about the most uninformative article I've ever read. Basically it says that Pyro could be toxic in large quantities, but it may or may not be in small quantities, and no long term exposure sutdies have ever been done. Oh yeah, it stains everything brown, but don't use Latex gloves. That's about it.

Chad Jarvis
15-Jun-2004, 15:19
Pyro killed Weston! Or was it that Mikey kid from the Life cereal commercials? No wait. That was Pop Rocks...

15-Jun-2004, 17:38
Pyro must be deadly. Every photographer born before 1900 who used Pyro is now dead. This includes Weston, Burke-White, Steiglitz, Porter, and Brady.

steve simmons
15-Jun-2004, 22:15
That's about the most uninformative article I've ever read. Basically it says that Pyro could be toxic in large quantities, but it may or may not be in small quantities, and no long term exposure sutdies have ever been done. Oh yeah, it stains everything brown, but don't use Latex gloves. That's about it.

--Bill, 2004-06-15 11:09:02 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

You got it!! All of those people saying pyro causes this and that are blowing smoke. There is no evidence that when used as a developiong agent in liquid form that there is any greater risk than other common photo chemicals.

steve simmons

Paul Kierstead
15-Jun-2004, 23:34
I hate to be really pedantic, but...

"There is no evidence that XXX", although strictly accurate, is quite different in it's implications then "XXX has not been researched". When the latter is true, those who wish to take the view that XXX is OK will often couch their opinion in the form of the former. It is misleading. If you don't have the evidence, then the best that could be said is that "We don't know". This does not ensure safety, nor ensure our demise.

Donal Taylor
16-Jun-2004, 00:07
apart from the fact that the proof reading and editing are up to the usual View Camera standards e.g. "Pyro: Some Truthful Informaion About Health Considerations "

There is no actual information in there, truthful or otherwise.

No accurate research, facts or figures are detailed about the danger or otherwise of pyro, just some vague instructions about how to be careful when you mix it. This doesn't clear up any of the BS at all - it's merely more steaming BS added to the pile.

Paul's point is entirely accurate - the author concludes "There is no evidence that XXX" (that pyro is no more dangerous than anything else used in photographic processing) when he actually means "XXX has not been researched" (i.e. the dangers of pyro have not been researched - which he actually says early on and then goes on to completley ignore) - which should lead to an entirely different conclusion than the one we get:

"So, I don't know whether you would find PMK or some other Pyro formula worth while, but there is not really any special hazard to mixing or using it."

Which is an assertion based on... nothing more than Knoppow's assertion (and the fact that some people will take this seriously because it is written for Viewcamera).

Steve, you are doing no one a service by publishing such a badly written and poorly researched article.

Perhaps when someone becomes ill from pyro use they will sue? We can only hope

ronald lamarsh
16-Jun-2004, 08:06
This most certainly seems to be a tempest in a teapot. Some here have trashed the article that Steve posted but i have yet to here these folks offering something better! Also Gordon Hutchings gives some very detailed information on the health affects of PMK Pyro in his book. ( I have an original) I distinctly remember that Weston died from Parkinsons disease not chemical poisoning. The medical community still does not know what causes Parkinsons if it were by chemical poisoning I'm sure they would have found it! I am more afraid of amidol than pyro. I use the liquid PMK pre-mixed and will continue to do so without fear. Also some of the dichromates commonly used are much more hazardous. The effects of silver or gold nitrate splashed in the eyes is very very bad but many of us still use them? The caveat is use the proper pocedures and protective equip and you'll be ok its not cobalt 60! I would love to see one of the complainers here do a better article.

steve simmons
16-Jun-2004, 08:52
Here is a uote from the post on or website

"Pyrogallic acid is toxic but one must be careful in interpreting MSDS: mostly they are written for industrial users of substances who use and store them in very large quantity. Pyro is a sensitizer and can cause very strong skin reactions. It should be kept out of the eyes for the same reason. It is capable of causing life threatening damage if ingested in fairly large quantity. It will irrate the lungs and respiratory system if inhaled. Pyro can penetrate the skin but so can many other substances used in photography.

There have been NO studies of the chronic effects of Pyro exposure. Pyro is no more hazardous than several other developing agents. It should be treated with respect but there is no unusual hazard in using it. Since airborne Pyro is dangerous to breath in its wise to mix Pyro developers while wearing a dust mask and facial protection. You should wear nitrile gloves. Try to avoid getting the stuff into the air. It is in light flakes which become airborne easily so some care is needed. "

The point of this post is to countract the scaremongers who post such dire warnings about pyro. There is no evidene to suggest that pyro is any more dangrous than other chemicals found in the darkroom.

If the critics have some fresh info to share please do so as we can all learn something. Otherwise your postings criticizing the info in Knoppow's article are hollow.

It is easy to be critical. It is more difficult to be constructive.

steve simmons

Jorge Gasteazoro
16-Jun-2004, 09:27
This most certainly seems to be a tempest in a teapot. Some here have trashed the article that Steve posted but i have yet to here these folks offering something better!

Although not in this forum I did offer an analysis of the currenta available data that is far more useful than the article presented. The article is nothing more than an opinion from a photographer. The same way that Kim Weston says pyro is toxic and everbody beleives him because he is Weston's grandchild, it seems Simmons thinks we should beleive the author of the article because he is a knowledgeable photographer.

The problem lies in that we dont know the qualifications of either one that backs up their claims. The moment you say "there are no long term studies on the toxicity of pyro" you cannot say if it is harmful or not, you can only analyse the data available and make some educated guesses.

I have taken the liberty to copy my response on the other forum to this one, in the response you will see I make no statements about long term studies, I only use the present data to make some inferences about the toxicity of pyro based on my knowldege of risk assesment obtained by working in hazardous waste disposal for many years.

To judge toxicity you need to look at 3 important factors. Chemical concentration, length of time exposed to the chemical and route of entry into the system.

Lets start with the concentration. I dont recall exactly the LD50 of pyro, but I remember is somewhere around 250 mg/kg. With PMK you start with a 10% stock solution, so if we fudge a little and set the density of this solution to 1, you have in the stock solution 100,000 mg/kg. To use it you then dissolve the stock solution a 100 fold, leaving you with approximately 1000 mg/kg. Now, lets say the average person who uses this developer weights 176 pounds or 80 Kg. If you multiply 80 x 250 mg/kg, you find that a dose that would be harmful to you would be around 20,000 mg/kg. IOW 20 times more than what you use for developing and one fifth of what is contained in the stock solution.
Lets move on to the length of exposure time. The LD50 doses are arrived by feeding the subject big amounts of the chemical on a daily basis until 50% of the subjects die. This can take days, weeks or months, depending on the chemical. Unless you plan to add 20 grams of pyro to your diet on a daily basis, the chances that you will be exposed to pyro long enough to cause you harm are close to infinitesimal.
Now, finally we move on to the route of entry. Lets say you decide to develop with PMK and you put your hands in the developer without gloves. Lets further assume that you absorb all of the pyro through your skin (clearly impossible, the pyro would be gone and you would not have a developing action). At this time you have been exposed to a dose that is 20 times lower than the one determined to be harmful and if you stop developing, you have only been exposed for a small amount of time.

Of course, if you develop everyday, take no precautions and eat, drink and smoke in your darkroom, well then yes your chances of getting sick are greater, but it might not be only because of the pyro.

Now, the sentence about the pesticide. First, pyro is used in hair dye, I dont see people dropping off like flies after getting their hair tinted. Second, just because it is similar, does not mean it is the same, nor that it has the same effects on the body. Funny thing is, D76 has a developing compound that is very similar to pyro, yet we dont see Bond making any objections to it.

The Parkinson's statement is so ridiculous it chaps my hide. For one, Weston also used amidol, another benzene derivative, for another, there are millions of people who get Parkinson's without ever coming within 50 miles of pyro. His statement that people say "well nothing has happen to me" as proof of safety should not even be written, since he only offers the case of one person who happened to use pyro and get Parkinson's. How stupid is this?

Bottom line John, the article is a self serving ad for his unsharp mask and his workshops, he wrote about things about which he has no knowledge based on the flawed and alarmist research of a woman whose only merit was to read MSDS sheets and write about them on a terrible book.

It is unfortunate that people like him write these things and they become part of the "truths" of photography, just because Bond said it.

I cannot guarantee you 100% that nothing will happen to you, but with a little bit of care, good laboratory practices and a little bit of common sense I can guarantee you that if a drop falls on your arm, your gonads are not going to shrivel. All this based on careful analysis of the evidence, not on some hear say, or faulty information from from a woman that was too lazy to think.

So you see, is very simple, you use the data available and make some educated guesses, but as it stands nobody can say with definite certainty that using pyro as a developer will or will not cause harm. Both the article by Bond and the one in VC are wrong.

Paul Kierstead
16-Jun-2004, 09:31
There is no evidence to suggest that pyro is *safer* then other chemicals in the darkroom.

In fact, it would seem that there is essentially no evidence.

Sure, you can quote the "put up or shut up argument" but this is my health I am talking about, and sorry I happen to apply some critical thinking when someone tells me "go ahead, its ok, really". And that article does not pass the most cursory glance of critical thinking. Just a couple of highlights from Steve's post:

"Pyro is no more hazardous than several other developing agents." -- Completely, utterly useless information as said developing agents are not specified. For all I know those agents may not be used in any of the developers I currently use. In that case, Pyro would be a significant new exposure. Or the agents could be extremely common and Pyro would be no new exposure. But since the statement does not specify, I don't know. Hence it is a zero-use statement. Furthermore, since the agents are not specified, I am unable to even verify the validity of the statement.

"There have been NO studies of the chronic effects of Pyro exposure. " ... "There is no evidene to suggest that pyro is any more dangrous than other chemicals found in the darkroom.". -- By your own argument, the only reason the latter statement is true is that there are no studies. You are aware that the lack of studies does not imply it is safe, right? I really find it amazing that one could say both of those statements without seeing the problem.

"Pyro can penetrate the skin but so can many other substances used in photography." -- Again those mysterious other substances, unnamed. No need to hit all the problems with this statement, I am sure that anyone capable of rudimentary analysis can see that it is a pointless statement. We don't even know what dilutions, how easily, etc. those substances are absorbed. Or what the relative effects. If I was to tell you that Mecury was OK because although it can be absorbed through the skin, so can water and water is OK, what would you think.

Whatever. This article is no better then the scaremongers; both seem intent on making wildly unsubstantiated claims. I am sick of it. I still don't use Pyro because nobody can give me a thoughtful, well reasoned and substantiated argument that it is reasonably safe with normal darkroom handling procedures. Since it is my health, then I err on the no side.

Could somebody, please, write something that can pass scrutiny.

Paul Kierstead
16-Jun-2004, 09:33
Clarification: My post does not include Jorge's comments as they were posted while I was composing mine.

steve simmons
16-Jun-2004, 11:07
The point of posting the article was simply to say that no longterm ill effects from using pyro have ever been shown. This flies in the face of the doomsayers who claim all sorts of health hazards. To make such a claim they should have supporting data.They do not and are doing all of us a dissevice when they make such claims.

That is all I intended to do. To argue with me because I did not do something I never claimed to do seems like a lot of time taken that could have been usd for more constructive activities.

Tak my post for whatever you will. When someone finds data supporting longerm ill effects please share it.

steve simmons

Jorge Gasteazoro
16-Jun-2004, 11:35
The point of posting the article was simply to say that no longterm ill effects from using pyro have ever been shown

Not true, here is one study. Which by the way it makes my analysis even more relevant as the dosage I quoted for LD50 is way lower than what this study shows.


Perhaps the article should have read, "there are no long term studies that I am aware of"

Kirk Keyes
16-Jun-2004, 11:50
Just to clarify - Jorge you wrote: "LD50 doses are arrived by feeding the subject big amounts of the chemical on a daily basis until 50% of the subjects die. This can take days, weeks or months, depending on the chemical. Unless you plan to add 20 grams of pyro to your diet on a daily basis, the chances that you will be exposed to pyro long enough to cause you harm are close to infinitesimal."

The procedure for performing an LD50 test is usually done as an acute LD50, where a one-time dosage, not the amount being added to a daily diet, as you've said (although it can be done repeatedly like that). But most of the numbers that I see in MSDSs are for the acute LD50. It could also be pointed out that there are typically 3 ways the dose can be administered - orally, inhalation, and intravenous. Each different method usually has a differing LD50, and each different animal will typically give a different LD50 as well even when comparing the same method of dosage. It does sometimes make things a little confusing...

But ultimately Jorge is right. We need to assess the risks involved in the use of different chemicals by basing the risks on known hazards. Simply having each person assert opinions without giving any facts to support the opinion does not help.

An excellent resource on the health affects of pyrogallol (also known by the archaic name pyrogallic acid) can be found at http://ntp-server.niehs.nih.gov/htdocs/Chem_Background/ExecSumm/Pyrogallol.html This document is written by the National Institute of Environmental Health Sciences - I suggest that everyone take a look at this document and read through it at least once (I know it is pretty scientific looking, but scientifically derived information is what we need here, not more hearsay and wild speculation by people with know knowledge of the subject.)

It looks to me like several long term studies on the affects of pyro HAVE been performed - the above reference contains the following sentence: "Lifetime dermal exposure of mice and rabbits to low doses of pyrogallol did not induce toxic effects." This is really the kind of info that we need to be looking at, long-term dermal exposures. Using pyro in photographic processes is really a low doseage, dermal exposure.

And to all those people that are worried about breathing the dust - I think you would be suprised at how little dust would be breathed even if you were sloppy, just use some care when weighing out your chemicals and don't do things that will make dusts in the first place. Use a spatula or even a spoon to transfer the chemical from the container onto your weighing paper on the balance. Don't just dump a bunch out of the bottle onto the balance. Don't forget to wear gloves, and also wipe up yor work area when done to remove any materials that may have gone astray. It's really simple things like this that can greatly reduce your exposure to ANY chemical.

And Steve, I also didn't find Mr. Knoppow's article all that helpful. As the other have pointed out, without and references to actual research that has been done by an authoritative source, it is really just an opinion. Perhaps you could find someone that is medically trained to write an article for your magazine that does have the experience and training to look through the available literature and compile something (with references listed) that you could publish in the magazine. There must be a toxicologist or doctor out there that can help with this. I am waiting for the day that this happens.

Side Note: Speaking of putting hydroxybenzene compounds on your skin, people seem to have no problem putting Carmex on their lips, which contains phenol which is also known as 1-hydroxybenzene (1,2-dihydroxybenzene is pyrocatechol, 1,2,3-trihydroxybenzene is pyrogallol, 1,3-dihydroxybenzene is resorcinol). Everyone should read the MSDS on phenol - very water soluble, and can cause some serious nervous system problems if ingested in high-enough doses or after chronic application. But people seem to have no problem using this product on a daily basis.

Annie M.
16-Jun-2004, 12:17
Just a reminder for pregnant women....... Pyrogallol in many studies was found to be mutagenic for In Vitro Mammalian Systems ..... Some of these studies are mentioned in the link Jorge posted. Also, the amount of material necessary to damage the fetus is much smaller than the amount which can injure an adult. The most sensitive time for chemical interference with normal development is from the 18th to the 60th day after conception. Although people are not dropping like flies from dying their hair most doctors do recommend that women not dye their hair during pregnancy. So be careful.... and stay out of the darkroom if there is a possibility you are pregnant.

Michael Kadillak
16-Jun-2004, 12:22
There seems to be a distinct polarity of those that find pyro as one of many tools to express themselves with their photography and accept and deal intelligently with the issues by using gloves, breathing security apparatus, adequate darkroom ventilation and performing all of your chemical mixing outdoors and those that do not want to go there. Great. Do what you want to do.

I guess setting aside the technical studies (or lack thereof), I find that in the common era of which we have been a part of there are just to many intelligent people in this art form that have been using various forms of pyro safely for years and they use their head when doing so to become overly stressed out about it. Many photographic chemicals have some degree of risk associated with them and common sense in using them is the key.

I just completed a basement and darkroom and when I consider all of the dangerous materials that I used in my project and construction workers use every day in the business such as bag cement and mortar (silica), liquid nails, adhesives for carpets and other chemicals, I would never have done the work myself if I did not feel that the risk in using them could not be safely mitigated. I feel the same about photographic chemistry and that includes pyro.

If you chose to continue to be excessively concerned about your personal health or safety you do have a choice. Go digital or have someone do all of your processing for you. All I ask is that we as a group leave innuendo and half truth out of this discussion so that those that are coming into this forum can draw their own conclusion on the subjects that we cover.


Paul Kierstead
16-Jun-2004, 13:42
"If you chose to continue to be excessively concerned about your personal health or safety you do have a choice. Go digital or have someone do all of your processing for you. All I ask is that we as a group leave innuendo and half truth out of this discussion so that those that are coming into this forum can draw their own conclusion on the subjects that we cover."

I am guessing that you believe that your first sentence does not contain innuendo? Or are you not subject to your own request? In any case, your argument sounds eerily like the "I know people who have smoked for years and they are ok" kind of argument. If you want some reasoned discussion, then don't imply that those who are concerned have "excessive" concern. You are a guilty as the naysayers.

Mr. Keye's offers some useful information. Thank you for that.

Kirk Keyes
16-Jun-2004, 14:54
Your welcome Paul, I'm glad you found some useful information in my post.

After reading all the opinions of people in print and on this and other internet forums, I've come to the conclusion that what we really need to do is try and better educate people when it comes to handling chemicals of any kind. I'm an analytical chemist, and I have a good amount of experience handling hazardous materials. I realize that most people doing darkroom work are not forutunate enough to have a background like mine.

First off, Mr. Kadillak's statement above "Many photographic chemicals have some degree of risk associated with them and common sense in using them is the key" is not quite right. It should say "ALL chemicals have some degree of risk..." Even simple and common chemcials such as water, oxygen, sand, and sodium chloride (table salt) have risks, however low they typically are, but in the right conditions and amounts, they are also deadly and hazardous materials.

So whether there is a percieved hazard or not, we all need to assess the level of risk we are willing to accept. In order to assess that risk, that means also putting the risk into the proper context. Things that need to be considered are: What are the intrinsic hazards of the chemical? What are the types of exposure that will be encountered? What is the lenght of time to which we will be exposed? What is the actual amount of material to which we will be exposed? And even special conditions like Annie mentioned above like pregnancy or other medical conditions such as allergies/sensitivities should be considered.

Then we need to think about what level of personnal protective equipment (PPE) could we use while handling the chemical? Simple things like gloves, safety glasses, lab coats, and particle masks are easily available to all of us. We can all greatly increase our level of personal safety by wearing these simple things.There are times where we would only need one or two of those items, and other times where we would want to wear all of them. And like I said above, if there are special conditions that are more hazardous than others, say if dust inhalation has greater risks, then we can combine the use of PPE with techniques such as I mentioned in my previous post above to reduce the hazard in the first place. In our dust exposure example, we can use tools such as a spoon to transfer powders so that the amount of dust created is greatly reduced. By finding ways to reduce the hazard (decreasing the amount of dust generated), using PPE (to limit the amount of exposure), and cleaning up our work area afterwards (to limit the time of the exposure), we can greatly reduce many hazards.

None of the chemicals that are used in the vast majority of photographic processes are so hazardous that we can not handle them in the home darkroom, IF we take the proper precautions. By using the guidelines and the type simple techniques I mention above, we should all be able to handle these chemicals with very little risk. None of them are as hazardous as some other chemicals where a drop on the skin will cause serious injuries. (Or in the case of something like dimethyl mercury where a few drops on the glove of caused the rapid death of a researcher a few years ago.)

So if someone makes an educated choice and decides not to accept the risk of using a pyro developer, or any other photographic chemicals for that matter, that is fine. But let's help them make a decision that is based on facts and not opinions.

Jorge Gasteazoro
16-Jun-2004, 18:12
The procedure for performing an LD50 test is usually done as an acute LD50, where a one-time dosage, not the amount being added to a daily diet,

Kirk that was not how it was explained to me, but it does not matter, the truth is whether it is a one time dose or a periodic doses over a short period of time the studies show that pyro is not as toxic as it has been purported to be by that Susan Shaw woman, and that in the concentrations we use it really poses little risk of causing harmful effects.

The funny thing is that Simmons and most of us are on the same side on this issue. Pyro has gotten a bad rep mainly because of a few people who had little or no experience handling chemicals. Unfortunately we cannot unring the bell, so if we are to set the record straight we need to use the best possible analysis backed by scientific data, and here is where Simmons went wrong. The article, which contained no analysis and no data to back up the analysis was just another opinion by another photographer....people here and in other forums said so, and it seemed to have bothered Simmons...

Francis Abad
16-Jun-2004, 18:37
I am no chemist (I trade options for a living) BUT my negatives developed in Pyrocat HD are the best I have ever done! Long Live Pyrocat! Oh and wear gloves...please!

Jorge Gasteazoro
16-Jun-2004, 19:03
I am no chemist (I trade options for a living) BUT my negatives developed in Pyrocat HD are the best I have ever done! Long Live Pyrocat! Oh and wear gloves...please!

Oh! so you are the SOB that has all my money, uh?....that is it Francesco, you are on my shit list from now on... :-)

Kirk Keyes
16-Jun-2004, 19:18
Jorge, you are right! I was kind of nitpicking, but for a better, more accurate understanding, I hoped.

I agree with you about the Shaw book, it is quite poorly done, and it is the most "authoritative" book commonly available to photographers out there on this subject, and for 20 years now!

And yes, Mr. Simmons did not approach this issue well. And becoming defensive about it doesn't help his side of the arguement. And it reflected poorly on Richard Knoppow, who I'm sure you know is a wealth if good, valuable, and researched information. I get the feeling that Simmons simply cut and pasted a posting of Mr. Knoppow's from rec.photo.whatever. It is out of context and did not help with the issue at hand.


Paul Kierstead
16-Jun-2004, 20:24
Hmm...now, IMO, it is getting constructive.

One thing you left out on the risks are the ramifications of an accident. One of the things that concerns me with a powdered agent it what happens in the event of a serious spill. Lets face it, containers get knocked over. So, I have a few questions:

In the event of a serious spill, what would the procedure to clean up be? The particle size -- if small enough -- could be disastrous to vacuum (for example). The concern I have is kicking up the powder for a long time afterword be entering/exiting the room, etc. This is one of those instances where a liquid agent makes me considerably more happy.

What is the most effective method of reducing the severity of such a spill? Obviously splitting it into smaller containers helps...but is there accepted methods for this exact problem? (Other then don't do that :))

Although I imagine sensible procedures can help prevent kicking up dust, in the event of a spill (launching a lot of powder into the air) what would the best defense be?

For those who might think I am too cautious, hogwash. I am willing to take much larger risks (and have taken them), but take *informed* risks with a known value on the outcome and known parameters on the activity. I want to establish that for Pyro (or other photographic chemicals, for that matter).

Jorge Gasteazoro
16-Jun-2004, 21:31
Paul, the best answer, although you dont want it is dont spill it.....I am not being a smart ass, what I am trying to say is that you have to acquire sensible laboratory methods.

If you work at a chemistry lab and you measure something and leave the opened bottle next to the scale while you go do something else, the lab manager will hand you your ass along with with the bottle to close. If you get in the habit of opening the bottle, measuring out the amount you want, closing the bottle and replacing in the shelf before you do anything else I guarantee you, you will never have a spill....I have done this for years and never had one. Spills are not accidents, but events that occur due to carelessness.

Of course unforeseen causes might produce a spill, here once again sensible laboratory practices make all the difference. First, Pyro comes in different forms depending on how it was produced. Commonly it comes as a white fluffy powder, if you do spill it, put on some gloves, pick up the powder with a wet rag, wash the rag and then mop the area immediately and wipe all counter surfaces. Pyro does not go airborne easily so breathing massive amounts is not a worry, once again, take into consideration the doses that you will be inhaling, most likely if you clean up immediately, if there is any pyro left that you missed, the amount will be so small as to be able to be processed by your body.

Of course, if you do a weekly cleaning of your darkroom, wipe clean all surfaces and mop the floor, the chances of continuous exposure are greatly diminished. This once again is just common sense.

Now Paul, you are getting too paranoid about this. I dont say this to offend you, but tell me what do you do when you spill D76, or ID11? They contain developers which are in the same family as pyro, yet this does not seem to bother you. Your reaction is understandable given the misinformation that has been given about pyro. Bottom line, of you spill pyro you do the same you would do if you spill any other developer.

Kevin Kemner
16-Jun-2004, 21:43
For further info you all may want to review this website.


Kevin Kemner
16-Jun-2004, 21:52
I apologize but I forgot to add this one.


Jorge Gasteazoro
16-Jun-2004, 22:35
Ah hell, Kevin apparently you did not read all that has been said here, specially by Kirk and me.

Lets see, your arthazard link, shows pyro as "can be lethal, DONT USE." Once again these people apparently read an MSDS and copied it, probably to cover their ass and not be sued. This is no different than what Shaw did in her lousy book.

Your NIOSH link, now we are talking, NIOSH is a very credible source. They cite lowest oral lethal dose in human reported as 28 mg/kg. I am thinking: "damm, this crap might be more toxic than arsenic after all." But then you click on the reference and it is a study done in 1969. I dont know, but is seems to me that this person who died from such a small dose of pyro had far greater health problems already. All these numbers have to be taken into perspective of the possible contamination, concentration and method of introduction into the system as well as the general health of the subject. To any of you who read this link, when you come to the number lethal dose dog intravenous, please think, is it any wonder the damm dog died if they injected the pyro directly into the blood stream? Hell I am surprised it took 80 mg/kg!

I give up....in the end is just a developer. If you choose to think it is too dangerous to use, by all means it is for you and stay away from it.

Kirk Keyes
17-Jun-2004, 01:04
Paul - good question. Despite our best intentions, accidents do happen.

Jorge gave some excellent advise - pay attention to what you are doing, keep the lid on the bottle when not in use, and that the procedure used to clean up a pyrogallol spill is no different than what you would do for any other of your darkroom chemicals. Simply wipe up the material with a wet towel to help hold the powder together, and then wash the affected area with soap and water. The wetted pyro powder will not go into the air and also has the benefit that pyro is very water soluble and will be easily cleaned up with just water. One thing I do after every printing session is to wash down the area where may chemicals have been. I also to this when I'm weighing out chemicals when mixing solutions - I wash the area before I weigh things out, wiping up any spills as I go along, and then again wash the area when I'm finished.

I do have one comment on thing you suggested - tranfering what you buy into smaller bottles. If you are trying to minimze your exposure to something, this is not really a good idea. The act of transferring the material to a smaller bottle will increase your risk of causing a spill and increasing your exposure.

A better approach is to buy your stock reagents in smaller quantities if you want to minimize your risk. So only buy a 100g or 250g at a time, instead of 1 kg or more. You then have less material to spill in the first place so that will greatly minimize any exposure in case of an accidental spill. There will simply be less material to launch across the room. If for some reason you do spill a large amount and you do generate a lot of dust in the air, you can simply leave the area and allow the dust to settle before returning and then cleaning up.

Keep in mind that chemicals like pyro belong to the aromatic class of compounds and as you may have already figured out by that name, they typically have very distinctive and easily detectable oders. It doesn't take very much pyro dust in the air before you can smell it, but it is certainly a very small amount and not seriously hazardous.

And as I mentioned above, part of the arsenal of personal protective equipment that we should all have at our disposal should be gloves, a lab coat, safety glasses, and particle mask. A spill like this is probably one of those times that you may wish to wear them, to minimize your risk of exposure. As Jorge pointed out, pyro really is similar to many of our other commonly used developing agents - so that suggests that you may want to follow this scheme of PPE when cleaning up other developer agent spills as well. Other's may not feel that it is necessary. That's where I'm suggesting that you make a decision as to what level of protection you wish to take to minimize your risks.

Buying smaller amounts of your more hazardous chemicals can also have the benefit of having fresher reagents since you use the smaller amounts up faster. I know this goes against our penny-pinching urge to save money by mixing our own chemicals, but if you are serious about minimizing exposure to something, that is your best bet.

Here's a little anecdotal story for you. Accedents to happen to everyone sooner or later. I was working in the chem lab in a hood trying to dissolve some tin/lead solder in acid - a very difficiult thing to do as you have to use both nitric and hydrochloric acid in just the right ratio or the solder will not dissolve. Too much nitric and the tin drops out of solution, too much hydrochloric and the lead drops out of solution.

I was using a little glass 60ml dropper bottle for the nitric, slowly adding the acid to the beaker in a hood. Well, I set the bottle on the edge of the counter, and then proceeded to knock it off! I saw it go, and it was falling right next to me, so I did my best imitation of a hacky-sack move and stuck my foot out a little to deflect the glass bottle so it would not hit the floor straight on. The acid spilled on my pant leg, and went down in to my sock and shoe. While I did manage to keep the bottle from breaking(!), I got about 50 mls of concentrated nitric acid on me in the process. As I had been using nitric for some time at work by that point, I knew my flesh wasn't going to be melting off my bones, but I also knew that the simplest thing to keep things from getting worse was to just put my foot up into a nearby sink and run a lot of cold water on all the affected areas (lower leg, foot, and clothing). So that's what I did. I did not even get the yellow stain that one often gets from skin contact with nitric acid. My shoe did not fair so well - one, and only one, of the many layers of plastic in the sole of the shoe proceeded to fall apart during the rest of the day, but I escaped unharmed and no one else in the room was injured either. So I guess the point I'm trying to make is that by minimizing the amount of hazardous materials you are handling, you can greatly reduce the risks associated with them. That story would certainly have had a much more serious outcome if I have been using a 500 ml or 1 L bottle of acid. And going further with the lesson that can be gleaned from my story, if you did have a catastrophic accident where for some reason you did get a LOT of material on yourself, you should consider things like rinsing the affected area, removing the affected clothing, and proceeding to a shower. If time is of the essence in minimizing an exposure - proceed to the shower clothed and wash the material off and then remove the affected clothing. Remember, DON'T PANIC!!!

One nice thing about darkrooms, is that there is usually water readily available and that can be a great aid in reducing your exposure risk. Simply wash the material off before it has a chance to do any harm. But again, if you are spilling that much material on yourself, then you are probably buying too large of quantities in the first place.

Another thing for home darkrooms, do not ever prepare solutions in area where food are prepared. That means like in your kitchen. OK, some things would be fine, but it really is not a good practice in general.

So Paul, like you said, taking *informed* risks is the important thing.

Kirk Keyes
17-Jun-2004, 01:31
Kevin - thanks for posting those links. But the suggestions at the City of Tucson web site are really very conservative, and could be considered overly cautious, especially if you've been reading the info I've been giving on how to minimize your risks when handling chemicals.

I noticed that their list had Ammonium Hydroxide listed as highly toxic in all three categories of exposure, but they didn't go on to say that is should not be used. I personally consider ammonium hydroxide, at least in the concentrated form, to be a much greater health risk than pyrogallol when used in the average home darkroom. First off, concentrated ammonium hydroxide spontaneously evolves gaseous ammonia. it is a very strong, pungent, and choking gas - it wasn't used in WWI as a poison gas, but it has many similarities with gaseous chorine which was. Pyro is a solid in the lab and does not really have this gaseous hazard. If you've ever had a whiff of concentrated ammonia, you will quickly respect it for how hazardous it can be. Ammonium hydroxide is a strong caustic with a high pH and will damage your skin if exposed for long enough, and it is very dangerous to get into your eyes, like any other caustic material. But for some reason they did not see fit to recommend not using it, perhaps because most people are more familiar with ammonium hydroxide than pyro and there is less percieved danger from it.

I agree with Jorge about the NIOSH reference being much better info, but some of it is pretty hard to digest.

Keep in mind that when a reference says something has a lethal dose of 28 mg/kg, that means that if humans are affected at that concentration, and you wiegh 80 kg, then the lethal dose for you would be calculated at 2240mg (80 kg * 28 mg/kg). That's about 2.25 grams. That's quite a lot of pyro to be ingesting. And I really don't see how you are going to come anywhere close to ingesting that amount unless you intentionally ingested it, or perhaps you were working in industry and fell into a vat of the material and swallowed some. That's why Jorge is getting upset, it is really not a very likely thing to happen.

And as we pointed out above, everyone really need to be more concerned with dermal contact as that is your greatest pathway to exposure. And if you follow some of my suggestions above, you can pretty much eliminate any dermal contact with it by using items like gloves and still use pyro to your heart's content.

Jorge Gasteazoro
17-Jun-2004, 09:37
Just a small clarification as it may appear Kirk and I are at odds. I agree with him that 2.8 grams is a lot of pyro to ingest at one time, yet IMO it is a relatively small dose compared to other compounds we know are really dangerous.

As I said, many of these studies, specially old ones have to be read and the methodology examined.

The NIOSH study has a lot of numbers, many of them quite alarming if not examined carefully, for example; they cite lethal dose dog intravenous as 80 mg/kg, right below they cite lethal dose dog oral at 28 mg/kg. Am I the only one who sees something wrong here? Unless pyro has some property that causes the gastro-intestinal tract to turn to s*it when you swallow it, I dont see how the oral dose can be smaller than the intravenous dose. This could be possible, I admit I dont know anything about biology, veterinary or medicine. But I find this sort of strange.

I think I will shut up now, Kirk has said it all and better than I have.....

Paul Kierstead
17-Jun-2004, 09:58
Thank you very much, Kirk and Jorge. At least I feel considerably more informed now; I hope others do as well. Because of my particular handling procedures, dermal contact has always been very limited; it has always been the mixing process that concerns me most.

BTW, Jorge, you really shouldn't assume that I am not concerned about D-76. I understand that you are tired of the "Pyro is dangerous" crowd, but short of good data, outsiders like me have every right to be concerned about an agent we don't know. I am aware of D-76 and its hazards. One significant difference is that *I* don't mix D-76, so my exposure (in terms of strength) is more limited then if I was to mix Pyro from scratch. That being said, one of the irritating things about D-76 is that you tend to get some airborne when you mix it. Some of the particulate is very small. BTW, I was the "safety officer" for a photo lab for a while and am educated on many of the risks, though more in a highly prolonged exposure setting.

People's approach to life vary. My approach it certainly different than many peoples. I believe nothing is zero-risk. I believe I will commit evil acts. I believe lots of weird things. What I endevour to do is understand these things and weigh the value of the outcome. I have taken some extreme risks because the outcome pleased me greatly. I am actually fairly surprised to have lived this long, though my tolerance for risk has diminished over the years. Although I enjoy photography very much, I do not think the outcome of using one developer over another is sufficiently interesting to take any risk beyond minimal. If I am going to die, or get sick, I want it to be for something that I can say "at least it was a great ride". Mixing chemicals don't qualify. So, for me, it isn't paranoid; the chemicals really are dangerous and I just wanted to know those risks.

From what I have read here and a few other places, I would conclude that it is safe to mix if you use caution. I think for my particular darkroom circumstances, I would be better off using something pre-mixed or partially pre-mixed, but I would now be comfortable mixing it myself if necessary. For *me*, the handling of mixed photo chemicals has always been pretty circumspect, so it was not a big issue.

Now, Steve, hire a toxologist to write a real article. Really, I think it would be a great idea. And then on a web page, do a safe-darkroom practices page.

Kirk Keyes
17-Jun-2004, 10:58
Jorge - We ARE very much on the same side. Thanks for helping on this subject.

Chris Gittins
17-Jun-2004, 12:17
LD50 definition:

"An LD50 value is the amount of a solid or liquid material that it takes to kill 50% of test animals (for example, mice or rats) in one dose."

Source: http://www.ilpi.com/msds/ref/ld50.html

Jan Nieuwenhuysen
17-Jun-2004, 13:53
In addition to Jorges excellent lead: http://grants.nih.gov/grants/guide/notice-files/NOT-ES-02-009.html This relates to a grant being given "to evaluate the toxicologic and carcinogenic potential of (.... ), and pyrogallol".

Apparently a grant has been given to conduct this study. See here on page 17: http://www.hhs.gov/osdbu/read/nih.pdf

Estimation completion dates are given as 09/30/05 and 06/30/04. One of these dates is very soon. This could be interesting.

Kevin Kemner
17-Jun-2004, 15:08
I think all of the above comments about reasonable precautions when using toxic chemicals are right on. I used Pyro as my LF developer for some time, until I got married and had kids running around. I was fortunate that I was trained in the safe use of hazardous chemicals and worked with things much more hazardous and in greater quantities than one ever would in a darkroom. What I find interesting about this discussion is that there are some very clear knowns about the chemical. First, it IS toxic. It has a high degree of oral toxicity with the lowest known lethal human dose being roughly 4.5 grams for a two hundred pound individual (if I did the math right). Second, it is a skin irritant, but probably not lethal. What does that mean to us? As it can be absorbed through mucous membranes (nose) and is a dermal irritant in its dry form, it is inherently safer to work with it in liquid form wearing gloves and if you chose protective eyewear. What is not clear in the studies is how long it remains in the body and develops a cumulative effect. If it remains potent in the body for thirty days your exposure risk to powdered pyro is greater if you mix developer on a daily basis. In either case if you work following a safe protocol the toxicity of the chemical should not be a significant risk factor to the average photographer.

for even more info to muddle the discussion


Kevin Kemner
17-Jun-2004, 15:49

My math was wrong. The lowest known oral lethal dose is 2.8 grams for a 200 pound individual. For reference when mixing stock solution A when mixing Pyro you use 50 grams.

Its still a great developer.