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  #11  
Old 30th October 2018, 11:39 PM
NJHrs NJHrs is offline
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I forgot to say like everyone else I don't wear any gloves or other PPE when printing, I only use the nitrile gloves when preparing working solution from the concentrates and film developing.
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  #12  
Old 31st October 2018, 09:13 AM
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Printing: I use tongs to shift prints from tray to tray, and it's largely about protecting the print. RC paper is pretty hardy and will tolerate all sorts of abuse. However, I like fibre papers, and I have experienced staining after holding prints up by one corner whist they drain back into the tray. Not sure why, but completely eliminated by tongs.
Film: When I develop roll film in a tank I work in a well ventilated kitchen. I don't use any PPE as contact with chemistry is almost non-existent. Sheet film I process in open trays in the darkroom. I wear Nitrile gloves for this as I use PMK Pyro.
Pyrogallol is considered toxic, principally through inhalation of the dust during mixing, but I don't see any health benefit putting my fingers directly in the soup.
Currently I use pre-mixed PMK concentrate. When I used the 'Photographers Formulary' powdered kit I did wear a disposable dust mask whilst mixing up the concentrates. Why not?
Toning: I use two different toners, one of which (Selenium) is also considered toxic. Again, I choose to wear Nitrile gloves for this, and work at an open window. Partly for ventilation, but so I have decent light to judge print colour.

One of the main risks of contacting chemistry is contact dermatitis. Some of us have handled photographic chemistry for a long time (42 years for me) with no ill effect. Unfortunately, sensitivity varies between individuals and is hard to predict. I'd suggest anyone with asthma, dermatitis or other allergies should exercise greater caution handling chemistry.

To maintain a perspective most photographic chemistry is no more toxic or environmentally damaging than the kitchen cleaning products we all routinely accept. Many home hair colourants are considerably more likely to trigger dermatitis or severe allergy. People have been killed by hair dye, but I can't find a single story about death by developer. That's not to discourage caution, but the discussion about chemical safety on photo forums seems too often driven by unsupported rumour.
Don't wear your best clothes (dev and toner stain) exercise a little sensible caution, use print tongs consider gloves for some processes and just ENJOY yourself.
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  #13  
Old 31st October 2018, 09:38 AM
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Having just made the above post, I though t I'd better go further.
Main bogey-man on photo forums is Pyrogallol, 'known to be toxic'.

The LD50 (lethal dose in 50% of cases) for Pyrogallol is between 738 and 1700 mg per kilo of bodyweight.

https://ntp.niehs.nih.gov/ntp/htdocs...gallol_508.pdf
We will take the lower value, 700mg.
That means that if a person of 70 Kilos consumes 49 grammes of pyrogalol they stand a 50% chance of death.

The formula for PMK Pyro requires 50g of Pyrogallol per 500ml of solution A.

http://jeffreysoper.com/node/124

The Berrger and PF kits both make 250 ml of solution A.
250ml of solution A therefore contains 25g Pyrogallol.

Therefore, if at one sitting I consume two full bottles of Berger PMK Pyro solution A I stand a 50% chance of death. Taking the 1700mg/Kilo figure that rises to 5 bottles.
I do not suggest anyone tests this, but I personally am reassured about handling PMK.

Allergy/sensitivity is different. Some individuals may become sentisized by very small doses, and after very few exposures.

Later one I'll go looking for some numbers on Selenium I think.
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  #14  
Old 31st October 2018, 10:15 AM
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Colin do you happen to know if any of the chemicals are carcinogenic or could lead to disease and premature death?
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  #15  
Old 31st October 2018, 11:59 AM
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Hi Marty.
The link to the toxicology report on Pyrogallol is interesting, but a very lengthy read. In short, its carginogenity wasn't directly tested on humans (such tests would always be deemed unethical even on volunteers). Rather a number of different tests were made on rabbits, mice, rats and on tissue samples. The results showed Pyrogallol had the ability to damage DNA in some tissues of some species some of the time. It would therefore be prudent to conisder it a possible carcinogen. However, the lab tests involve high doses over a prolonged period on focussed areas- not the circumstances which we will encounter.
Again, not to belittle risk, but studies based on human population confirm that processed meats and alcohol are both confirmed carcinogens. My personal exposure to both is (considerably) higher than to Pyrogallol. I have made a conscious choice to accept some risk in my life as also know that no matter how careful I am, something is going to get me. I eat sausages occasionally, I consume alcohol more often, I willingly travel on aeroplanes despite the increased dose of cosmic radiation. I don't smoke though- tobacco kills 50% of those who use it. For me, that risk would be utterly unacceptable.
I am completely happy to continue using Pyro with gloves and (if mixing powder) a dust mask on the basis that from all of the evidence I can find the risk seems negligible.
Will Pyrogallol contribute to premature death? One would have to ask by what mechanism that would happen; acute poisoning is most unlikely. A tray of 500 ml working solution contains between 0.2 and 1% of LD50, depending on which figure you take. Accidental ingestion orally of 10ml working solution would give between 0.004 and 002% LD50.
It's carginogenity is not quantified clearly for humans, but exposure for the home darkroom worker is incredibly slight. Long term liver, kidney or other organ damage would be consequent upon repeated absorption or ingestion, and again he amateur worked simply isn't facing that kind of exposure.
However, since this is interesting, and I'm off work with a gammy eye (not photochemical related!) I'll continue looking at this.
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  #16  
Old 31st October 2018, 12:56 PM
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Seleium Toner.
Again, a substance which comes in for much discussion on the internet regarding its dangers.

The kodak data sheet:
https://www.freestylephoto.biz/pdf/m...nium_Toner.pdf

A couple of things I'd note;

Acute Toxicity Data:
• Oral LD50: 500 - 5,000 mg/kg
• Dermal LD50: > 10 mL/kg
• Skin irritation: slight
• Eye irritation: slight


For a dangerous substance its likelihood of causing eye irritation is 'slight', which is good. The LD50 is for the whole solution, and taking the low value of 500mg/kilo means our notional 70kg individual would have to consume 35 grammes of concentrate to be at 50% risk of death. 35g isn't actually very much- hence:

NFPA Hazard Ratings: Health - 3, Flammability - 1, Instability - 0


Kodak, being American, include a National Fire Protection Association (NFPA) risk rating. 3 means a severe risk to health.
I'll keep using selenium toner, and I'll keep on wearing my gloves. We don't have children round the place, but if I did I'd be extra careful about storing Selenium toner tightly closed and high up. Good news is that like most toners it's a bit stinky, so you'd be a bit desperate to want to drink it in the first place.
Also from the data sheet, some potential to cause allergy, but no evidence has been collected on its carcinogenity. Remembering of course that 'absence of proof is not proof of absence'. Of course it might be academic, as you just aren't going to want to ingest or dabble bare-handed in this stuff anyway.

You will also read comments in internet discussions that Selenium is a crucial trace element for life. Yes, but I don't think a quick top-up from skin exposure to Toner is the way to go. In fact the only cases I can find recorded of Selenium poisoning come from the use of Health supplements. It seems Selenium deficiency might be implicated in prostate cancer, and some individuals have now come to harm from over consumption of Selenium supplements.

https://www.mja.com.au/journal/2006/...nium-poisoning

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3225252/
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  #17  
Old 31st October 2018, 05:15 PM
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Thank you Colin.

It sounds like I should cancel my order for a hazmat suit and book a week at a health farm instead!
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  #18  
Old 31st October 2018, 07:14 PM
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Hi Marty.
A few simple precautions go a very long way. Spare a thought for our brothers and sisters involved in Gum Bichromate and wet plate collodion photography.
They are using some potentially dangerous substances, but once again by knowing and understanding the risks, and working responsibly they get by safely.
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  #19  
Old 1st November 2018, 04:15 PM
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If you would like a useful reference to all photo chemicals I can recommend this book

https://www.amazon.co.uk/Health-Haza.../dp/1558211810
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  #20  
Old 1st November 2018, 06:29 PM
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I too use Nitrile gloves but buy them on eBay a couple of hundred at the time. They’re not expensive- this lasts me a good few months. I use a tray for developing, Nova for Stop&Fix and tone a lot but I’ve never found tongs that work for me so it’s fingers all the time. I didn’t realise they could be washed and reused (thanks Alex) but I’m not sure I could be bothered with that.

Apart from that the only other precaution is I make sure I’ve the window open when using selenium and don’t get too close to the tray.

Michael
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