Click here to edit subtitle

Safety Aspects of Photography 

in the Digital Age

Traditional Darkroom Processing / 'Alternative' Photography

and Cyanotype

35mm SLR camera                                       B+W Enlarger (Paterson)       

sources:  Kiekeben (edit) | M. McCann, PhD | Center for Safety in The Arts | Spandorfer | Wikipedia

Photography now looks back

at nearly 200 years of development.

The lens-based medium has

taken the world by storm and

fundamentally changed the way

we picture things.

Over the years a multitude of chemicals and emulsions with photographic uses and light sensitive properties were discovered - ranging from relatively harmless silver halide compounds to extremely hazardous substances; various heavy metal salts and even uranium and other radioactive  agents were found in the toolkits of early photographers. 

The transition to digital processes is now nearly complete, and traditional film photography has become a niche market. Darkroom processes are still taught at art schools to convey a sense of historical continuity to today's tech-savvy students.

Joseph Nettis: 'Spanish Woman', 1957,
gelatin silver print.
The artist was concerned about chemical fumes
and installed extensive ventilation in his
darkroom. 'I also don't use toners or other

"After National Geographic published photos from his bicycle trip through Europe in 1955, he persuaded the magazine to sponsor a round-the-world journey in the spring of 1956. What originally was to be a three-month trip lasted more than a year. Mr. Nettis traveled mainly by scooter, mostly sleeping in people's homes, though he slept in a monastery and in a jail in Japan." ( After completing his work for National Geographic, he struck out across Spain, where he shot 10,000 photos for a book he eventually published, A Spanish Summer.

    A Short History of Photography, Cedric Green  

    Photographic Processing Hazards:  Overview

    Photo Processing Hazards in Schools

    National Press Photographers Association Health Survey

    The Decisive Moment    

'Alternative' or Historical Photography

Potassium Bichromate, the widely used staple ingredient of Alternative Photography
is highly toxic and is known to cause cancer

Potassium Ferricyanide, the main ingredient in Cyanotype printing is now used 
in large quantities by artists and in art schools. A common misconception, 
also supported by some chemists, suggests ferricyanide to be a 
harmless compound. Members of the art safety / industrial hygiene community 
have long contested this claim, 
(and warn against potential cyanide gas release due to to UV exposure, heat, or acid). 
Both the US agencies EPA and CDC have argued against the 
widespread use of the Cyanotype process since the late 1980s.

The rise of the digital age has also brought about a movement 
that tries to reconnect with early photographic means, 
chemicals and methods known as Alternative or Historical Photography, 
and many of these authentic processes yield outstanding 
photographic images.

Unfortunately, most of the historical processes 
are in a special league of toxicity. 

While many of the harmful substances of printmaking are 
in the toxicological class of 'toxins' (known more to cause 
medium or long term health effects, but not necessarily 
presenting immediate danger) many of the agents utilized 
in Alternative Photography are outright 'poisons' capable 
of harming or killing a person
through ingestion or vapor inhalation. 

A few decades ago there was still a debate if the widely used 'bichromate' (sodium or potassium bichromate, chromic acid, also known as 'dichromate') was toxic but now there is undisputed evidence that the chromium salts are highly toxic and are classed as 'poisons'; chromium salts have also be found to be highly carcinogenic. The casual attitude in the use of this highly reactive chemical amongst some users, schools, and photographers is of concern. Hazardous materials such as this should only be used with the most stringent precautions, and in our view, safer alternatives should be sought out as much as possible, especially in an educational setting.

        Cyanotype or Blueprinting

The popular process of Cyanotype is widely believed to be a fascinating and harmless photographic curiosity.
Various books and websites helped popularize the method amongst artists, hobbyists, and in art schools in recent years, and brought about a Renaissance. The artist's variety of cyanide compounds is based on a more hazardous molecule than the 'architect's blueprint' or the blue pigment. These are separate processes.

The English botanist Anna Atkins, born 1799, is regarded as the first female photographer.  She also pioneered the art of the photogram. 'Cyanotype: Algae' (Wikipedia)

The hidden dangers of Cyanotype

The deep blue prints made in Cyanotype are very alluring, but on reflection, the chemical hazards that are present (both in the process and in the prints) may outweigh the aesthetic benefits.

The key compound needed in Cyanotype chemistry -
potassium ferrocyanide - is falsely thought of as safe.
Many think of this common iron salt as harmless
because it can safely be ingested.
The US food agency (FDA) declared the chemical safe in the 30s,
based on knowledge available at the time.
Yet on contact with UV light or acids,
or heated to mid-summer temperatures the compound can break down
and release hydrogen cyanide gas (HCN)
that can be as toxic as nerve gas.
Ferrocyanide has even been implicated in terrorism

Ferrocyanide is not to be confused with the iron cyanide molecule of its relative Prussian Blue (or the printing ink Cyan) which has a very stable and much more inert chemical structure. The nontoxic compound is used in ink, paint, and pigment making, and in certain medications. Only experts can fully explain the subtle but highly significant differences between the various blue cyanides that are used for these different applications.

The professional use of small amounts of ferrocyanide in the food industry and for medical applications may not be of concern. However, it is questionable if amateurs should be advised to use dry ferrocyanide powders or bottled cyanotype formulations as a staple ingredient in their practice. Making photographic prints and decorated fabrics with the Cyanotype process, and the reactive chemistry it entails, carries very significant risks.
The EPA reported a case where an unsuspecting amateur photographer made printed quilts treated with cyanotype chemicals as a hobby, and then suffered permanent facial injuries as a result of what was believed to be possible exposure to cyanide vapors and/or chromium compounds. The EPA warns: '...the hexacyanoferrates used in cyanotype, blue print, and in Prussian blue pigment should be considered true cyanides.' (see pdf below)

In 1993 Merle Spandorfer wrote : '...Merle Spandorfer herself contracted breast cancer after practicing Historical Photography.'
From a prudent perspective it would seem advisable to avoid Historic photographic processes altogether, or to practice the medium with the strictest safety training and following very thorough precautions and safety routines.

EPA Environmental H&S Guide for Art Departments and Schools,
         Pratt (waste management guide)

'The most important information you can have about these processes is in this area, it could stop you becoming sensitized to the chemicals, getting sick or even save your life.Theodore Hogan makes a very relevant comment about experimenting with the limits of the materials in 'The New Photography', that illustrates the point well,: 'Just remember that you may exhaust your limits long before the materials reveal theirs'. 'Ignorance of how to safely handle the chemicals used in various printing techniques can put you out of the picture'. The chemical might still be on the shelf when you are in the grave!So a correct understanding of these materials, processes and environments to handle them in is essential.Almost all photographic chemicals can irritate the eyes, nose, throat and skin. Exposure to some chemicals such as cyanides and solvents (Turps and mineral spirits) may cause headaches, weakness, dizziness, and a sense of confusion. Prolonged exposure with chromate's may result in skin ulcers. Other chemicals can produce severe skin and lung burns, and if they get in your eyes, blindness (hydrochloric acid, oxalic acid, potash, silver nitrate).'


Alfred Stieglitz in 1902. Photo: Gertrude Käsebier  (Wikipedia)
       page continues below, scroll down for more in-depth content

A Safer Approach to
Black and White darkroom work

The most common form of darkroom photography -

B+W silver gelatine based processing and printing - is not entirely
without health concerns, but can be practiced with relative safety
if key safety measures are observed. 

The most common concern related to B+W photography are respiratory in nature, shallow breathing and asthma can be caused from the mists given off by the chemicals. Ensure good air flow in the darkroom through the use of fans / extraction systems / open windows and take fresh air breaks during processing. 

Also avoid leaving solutions uncovered. Part of the magic of B+W processing lies in watching the image emerge in the development tray, whilst rocking the tray or agitating the print with tongs. Actually, the image will appear just as well if left in the bath all by itself - it might just take a minute longer.
To protect your health and your lungs best cover all baths with transparent sheets of plexiglass or make hinged lids for each tray. There is a precedent for this approach: in commercial print processing development machines are used that are also fully enclosed, and that emit very little harmful vapors. 

This method will substantially reduce the exposure to airborne fumes that may otherwise impede your breathing or even damage your lungs. Working with an enclosed chemistry will significantly reduce your exposure to airborne fumes that might otherwise impede your breathing, and in the long run damage your lung capacity. In the following sections we include extensive writings on the topic of photo processing safety from the book 'Making Art Safely' by Merle Spandorfer, (NY 1992), and by Michael McCann, PhD, and the Center for Safety in the Arts.
“The Gum Bichromate Process"
Be cautious in how you handle ammonium or potassium dichromate: It is dangerous and poisonous. This chemical can cause lesions on your tender flesh through contact and can damage your lungs by breathing it in. “

In the platinotype printing process, photographers make fine-art black-and-white prints using platinum or palladium salts. Often used with platinum, palladium provides an alternative to silver.

Photo-Transfer: The safer Alternative

Mary Stieglitz-Witte: Floral Weave, 1989
photo-transfer via color laser copier.

Many artists achieve results similar to 'Alternative Photography' using a variety of printing methods and photo-transfer processes. These include silkscreen printing, 'liquid light' paint-on photo emulsions, heat transfers for inkjet or laser prints, or
paper transfer using acrylic mediums, which currently is the most popular
method. Lithographic and intaglio processes can also be
adapted to work for image transfer an a wide variety of substrates.

"Van Dyke Brown"

is a printing process named
after Anthony van Dyck.

It involves coating a canvas with ferric ammonium citrate, tartaric acid, and silver nitrate, then exposing it to ultraviolet light. The canvas can be washed with water, and hypo to keep the solutions in place. The image created has a Van Dyke brown color when it’s completed, and unlike other printing methods, does not require a darkroom.
The Van Dyke brown process was patented in Germany in 1895 by Arndt and Troost. It was originally called many different names, such as sepia print or brown print. It has even been called kallitype, however that process uses ferric oxalate instead of ferric ammonium citrate.

Silver Nitrate Safety

As an oxidant, silver nitrate should be properly stored away from organic compounds. Despite its common usage in extremely low concentrations to prevent gonorrhea and control nose bleeds, silver nitrate is still very much toxic and corrosive. Brief exposure will not produce any immediate side effects other than the purple, brown or black stains on the skin, but upon constant exposure to high concentrations, side effects will be noticeable, which include burns. Long-term exposure may cause eye damage. Silver nitrate is known to be a skin and eye irritant. Silver nitrate has not been thoroughly investigated for potential carcinogenic effect.
Silver nitrate is currently unregulated in water sources by the United States Environmental Protection Agency. However, if more than 1 gram of silver is accumulated in the body, a condition called argyria may develop. Argyria is a permanent cosmetic condition in which the skin and internal organs turn a blue-gray color.

Palladium and Platinum Printing

Since their introduction in 1879, palladium and platinum prints have been recognized for their permanence, tonal richness, delicacy, noble presence, and, unfortunately, for their potential adverse health effects.

These metals, when inhaled as powders or absorbed through the skin as liquids, have been associated with long-term health effects.

Some palladium salts are suspected carcinogens; platinum salts may cause a severe form of asthma known as platinosis.

Palladium and platinum procedures are similar. For palladium printing, the sensitizing solution is ferric oxalate plus sodium chloropalladite or palladium chloride.

For platinum prints (platinotype), potassium chloroplatinite or platinum chloride are used.


'Oasis', Cyanotype art on stretched cotton shown at a recent art fair in New York

Photochemicals in
               the Darkroom

by Merle Spandorfer
adapted and updated from her book
'Making Art Safely'
NY, 1992

Photography, which has captured
the imagination of amateurs
and professionals for more than 150 years,
can be irresistible.
The seduction lies in the
myriad possibilities inspired
by aiming a lens at a subject, the simplicity of
pressing the shutter release,
and the thrill of watching
the image develop in the darkroom.
As both creators and viewers, our appetite for
representation can be insatiable.

Merle Spandorfer: 'Blue Mist Echo', 1978, gum bichromate on canvas.
'I was not given suffcient information that I was working with a lung carcinogen',
I'm fully recovered, and my art has taken new directions, and working with
nontoxic materials has become a top priority.

Film-based Photography, however, is not a risk-free activity; inappropriate exposure to photochemical confers significant health risks.
Thus, photography offers substantial challenges to working safely.

Some photochemicals, including solvents, acids, and alkalis, are individually (and predictably) hazardous. Photographers using many different kinds of agents also also face the specter of chemical interactions with unpredictable exposures and adverse health effects.

Many photochemicals are potential irritants, sensitizers (incite allergic reactions), or both.
Follow precautionary information on labels and observe all recommendations and substitutions. Especially, observe indicators, such as 'Caution', 'Danger', and 'Warning'.
In poorly ventilated darkrooms, processing trays containing mixtures of developers, toners, bleaches, and fixes may release gases and vapors in concentrations sufficient to cause health effects if inhaled over longer periods.

Hazardous Gases and Vapors

The following gases and vapors may be particularly hazardous:

gas arises from all ammonia solutions, including washing acids, hypo eliminator, photo rinses bleach fixes, and replenishers. Ammonia irritates the eyes and respiratory tract and may cause chronic lung problems or even death.

gas arises from addition of heat or acid to hypochlorite (bleach) or potassium chlorochromate (an intensifier). Chlorine gas is intensely irritating and potentially lethal.

is a preservative and hardener found in stabilizers, wetting agents, final baths, Kodalith developer, prehardeners, replenishers, and retouching dyes.
Its vapors are highly irritating and may sensitize respiratory tissues. Formaldehyde is also a suspected/known carcinogen. (At the time of publishing this newly edited text, formaldehyde has been banned from many widely available products).

Frequently overlooked symptoms include shortness of breath, eye and skin irritation, headaches, dizziness, nausea, and nosebleeds. The remaining photochemical manufacturers are looking into safer replacements; for example the most recent photo-chemistry introduced processes that were/are less reliant on formaldehyde (using an 'aldehyde insensitive' process).

a sepia toner, irritates the eyes, nose, and throat. Low-level exposures can cause nausea, vomiting, diarrhea, metallic taste, odor of garlic on the breath, dizziness, and fatigue.

forms from nitric acid etching and carbon arc lamps. It is highly toxic by inhalation, and symptoms include fever and chills, cough, shortness of breath, headache, vomiting, and rapid heartbeat.
Prolonged high exposure can be fatal. Chronic exposure may cause pulmonary dysfunction and symptoms of emphysema.

which has a sweet odor, is also released from carbon arc lamps and from photocopy machines. Ozone irritates the eyes as well as the upper and lower airways.

(Carbonyl chloride) arises from chlorinated hydrocarbons (solvents), flames, lighted cigarettes, and ultraviolet light. The odor and irritant properties are not strong enough to give warnings of hazardous concentrations. Therefore, we must learn the sources and avoid them, since phosgene severely irritates the eyes and respiratory tract.

When inhaled, phosgene decomposes in the lungs to form carbon monoxide and hydrochloric acid, which may lead to pulmonary edema or 'water on the lungs'. Symptoms include cough, foamy sputum, and shortness of breath. Moderate exposures can cause symptoms of dryness or burning sensations in in the eyes and throat, chest pain, and shortness of breath.

especially sulfur dioxide, arise by heating or by combing acids with any compound containing sulfur, such as ammonium thiosulfate, per sulfates (reducers), sodium sulfite, sodium thiosulfate, sulfuric acid, and sulfuric acid. Sulfur dioxide gas is a powerful lung irritant that can cause chronic lung problems.


is oderless and therefore difficult to detect. It may arise from incomplete combustion in carbon arc lamps or may form in the body following methylene chloride exposure. In sufficient quantities, it can kill by asphyxiation (oxygen deprivation).

HYDROGEN CYANIDE is formed from heating or combining acid with cyanides (reducers), potassium ferricyanide, or thiocyanates. Cyanide poisoning has received wide press attention; its lethal potential is well known.

 poisoning can also be rapidly lethal. Its characteristic rotten-egg odor may not be detected by some. For others, the smell causes olfactory fatigue, which may decrease awareness as exposure increases.
Unfortunately, there is no reliable indicator of the presence of hydrogen sulfide. Photographers should know that H2S arises from sulfide toning solutions, and by combining acids with potassium sulfide or sodium sulfide.

Low-level exposure may cause digestive and nervous system damage , and symptoms include headache, dizziness, excitation, digestive upset, and unstable gait.
Skin absorption and ingestion hazards

The Skin

The skin is also vulnerable to photochemicals, especially of one processes film and develops photographs with unprotected hands. Wear appropriate gloves when handling and mixing chemicals; use tongs to transfer photographs through the developing process.

This greatly reduces skin exposure, absorption, and irritation. Protection is critical in the presence of cuts or breaks in the skin, for even minor scrapes increase the risk of chemical dermatitis and absorption into the body.

Severe cases of dermatitis have ended careers in photography (Tell 1989). Dermatitis (chemically related) and dermatosis (occupationally related), however, can be treated with corticosteroids, but effective treatment may also require avoidance of all routes of exposure to photochemicals during the healing process.

Ingestion of toxic substances in photography should be rare, but stories persist about photographers who identify or check their solutions by taste. This may be true of the dose and duration of exposure to a substance is minimal. However, even small amounts of acid, alkalis, organic solvents, heavy metals, and other agents used in photography can cause airway or gastrointestinal irritation.

To avoid pain or discomfort of the tongue, lips, or mouth, do not identify or check the strength of photographic solutions by tasting!

Adverse health effects may also arise from exposure to the products of chemical decomposition. For example, photographic fixers have no hazardous ingredients listed in a typical materials safety data sheets, but in the small print under 'decomposition' sulfur dioxide, which can cause airway irritation or bronchitis, is listed as a potential hazard.
Similarly, decomposition of sulfide toners may produce hazardous amounts of hydrogen sulfide gas.

Finally, some color developing agents are suspected carcinogens. These include benzotriazole, hydroquinone, p-methylaminophenol, p-phenyl-enediamine, pyrogallol, 6-nitrobenzimidazole, potassium dichromate and ammonium dichromate powders, thiourea, and formaldehyde (Shaw and Rossol 1989).

We recommend minimizing or avoiding exposure to these agents by substituting agents not associated with the development of tumors in animals or humans.
In summary, photographers must evaluate all photochemicals and the total context of the photographic process for potential health and safety hazards.

Darkroom Safety
and Ventilation

Many photographers maintain darkrooms at home, most often in darkrooms and kitchens. In general, hazards in home photography can be avoided with adequate space and effective ventilation.
General dilution ventilation is usually adequate for hobbyists who undertake black-and-white processing. Greater hazards associated toning, intensifying, and color processing, however, require installation of local exhaust systems. In any case, extraction is advisable also for hobbyist use, and is often quite easy to install, for instance through fitting a window with an exhaust fan.

Because the primary route of entry of photochemicals into the body is through inhalation of vapors or gases (as shown above), appropriate and adequate ventilation is the key factor to safety in photography.

Its fundamental importance cannot be overstated.

If small children are present, or if living and working space cannot be separated, the home is not an appropriate site for a darkroom. We suggest photographers share the costs of a safe workplace located elsewhere.

The Safe Studio:

  • Maintains effective ventilation
  • Maintains a source of accessible, running water
  • Observes local regulations governing air pollution and disposal of potentially hazardous waste
  • Maintains workspace sufficient to separate wet and dry areas
  • Provides gloves and tongues as needed
  • Has walls covered with acid-resistant water-base paint or fitted with plexiglass splash backs.


                By Michael McCann, Ph.D., C.I.H.


   A wide variety of chemicals are used in black and white

 photographic processing.  Film developing is usually done in

 closed canisters.  Print processing uses tray processing, with

 successive developing baths, stop baths, fixing baths, and rinse

 steps.  Other treatments include use of hardeners, intensifiers,

 reducers, toners, and hypo eliminators.  Photochemicals can be

 purchased both as ready-to-use brand name products, or they can

 be purchased as individual chemicals which you can mix yourself.


   Photochemicals can be bought in liquid form, which only need

 diluting, or powder form, which need dissolving and diluting.


 1. Developer solutions and powders are often highly alkaline, and

 glacial acetic acid, used in making the stop bath, is also

 corrosive by skin contact, inhalation and ingestion.

 2. Developer powders are highly toxic by inhalation, and

 moderately toxic by skin contact, due to the alkali and

 developers themselves (see Developing Baths below).  The

 developers may cause methemoglobinemia, an acute anemia resulting

 from converting the iron of hemoglobin into a form that cannot

 transport oxygen.  Fatalities and severe poisonings have resulted

 from ingestion of concentrated developer solutions.


 1. Use liquid chemistry whenever possible, rather than mixing

 developing powders.  Pregnant women, in particular, should not be

 exposed to powdered developer.

 2. When mixing powdered developers, use a glove box (a cardboard

 box with glass or plexiglas top, and two

 holes in the sides for hands and arms), local exhaust

 ventilation, or wear a NIOSH-approved toxic dust respirator.  In

 any case, there should be dilution ventilation (e.g. window

 exhaust fan) if no local exhaust ventilation is provided.

 3. Wear gloves, goggles and protective apron when mixing

 concentrated photochemicals.  Always add any acid to water, never

 the reverse.

 4. An eyewash fountain and emergency shower facilities should be

 available where the photochemicals are mixed due to the corrosive

 alkali in developers, and because of the glacial acetic acid.  In

 case of skin contact, rinse with lots of water.  In case of eye

 contact, rinse for at least 15-20 minutes and call a physician.

 5. Store concentrated acids and other corrosive chemicals on low

 shelves so as to reduce the chance of face or eye damage in case

 of breakage and splashing.

 6. Do not store photographic solutions in glass containers.

 7. Label all solutions carefully so as not to ingest solutions

 accidently.  Make sure that children do not have access to the

 developing baths and other photographic chemicals.


   The most commonly used developers are hydroquinone, monomethyl

 para-aminophenol sulfate, and phenidone.  Several other

 developers are used for special purposes.  Other common

 components of developing baths include an accelerator, often

 sodium carbonate or borax, sodium sulfite as a preservative, and

 potassium bromide as a restrainer or antifogging agent.


 1. Developers are skin and eye irritants, and in many cases

 strong sensitizers.  Monomethyl-p-aminophenol sulfate creates

 many skin problems, and allergies to it are frequent (although

 this is thought to be due to the presence of para-phenylene

 diamine as a contaminant).  Hydroquinone can cause depigmentation

 and eye injury after five or more years of repeated exposure, and

 is a mutagen.  Some developers also can be absorbed

 through the skin to cause severe poisoning (e.g., catechol,

 pyrogallic acid).  Phenidone is only sightly toxic by

 skin contact.

 2. Most developers are moderately to highly toxic by ingestion,

 with ingestion of less than one tablespoon of compounds such as

 monomethyl-p-aminophenol sulfate, hydroquinone, or pyrocatechol
 being possibly fatal for adults.  This might pose a particular

 hazard for home photographers with small children.  Symptoms

 include ringing in the ears (tinnitus), nausea, dizziness,

 muscular twitching, increased respiration, headache, cyanosis

 (turning blue from lack of oxygen) due to methemoglobinemia,

 delirium, and coma.  With some developers, convulsions also can


 3. Para-phenylene diamine and some of its derivatives are highly

 toxic by skin contact, inhalation, and ingestion.  They cause

 very severe skin allergies and can be absorbed through the skin.

 4. Sodium hydroxide, sodium carbonate, and other alkalis used as

 accelerators are highly corrosive by skin contact or ingestion.

 This is a particular problem with the pure alkali or with

 concentrated stock solutions.

 5. Potassium bromide is moderately toxic by inhalation or

 ingestion and slightly toxic by skin contact.  Symptoms of

 systemic poisoning include somnolence, depression, lack of

 coordination, mental confusion, hallucinations, and skin rashes.

 It can cause bromide poisoning in fetuses in cases of high

 exposure of the pregnant woman.

 6. Sodium sulfite is moderately toxic by ingestion or inhalation,

 causing gastric upset, colic, diarrhea, circulatory problems, and

 central nervous system depression.  It is not appreciably toxic

 by skin contact.  If heated or allowed to stand for a long time

 in water or acid, it decomposes to produce sulfur dioxide, which

 is highly irritating by inhalation.


 1. See the section on Mixing Photochemicals for mixing


 2. Do not put your bare hands in developer baths.  Use tongs

 instead.  If developer solution splashes on your skin or eyes

 immediately rinse with lots of water.  For eye splashes, continue

 rinsing for 15-20 minutes and call a physician.  Eyewash

 fountains are important for photography darkrooms.

 3. Do not use para-phenylene diamine or its derivatives if at all



   Stop baths are usually weak solutions of acetic acid.  Acetic

 acid is commonly available as pure glacial acetic acid or 28%

 acetic acid.  Some stop baths contain potassium chrome alum as a


   Fixing baths contain sodium thiosulfate ("hypo") as the fixing

 agent, and sodium sulfite and sodium bisulfite as a preservative.

 Fixing baths also may also contain alum (potassium aluminum

 sulfate) as a hardener and boric acid as a buffer.


 1. Acetic acid, in concentrated solutions, is highly toxic by

 inhalation, skin contact, and ingestion.  It can cause dermatitis

 and ulcers, and can strongly irritate the mucous membranes.  The

 final stop bath is only slightly hazardous by skin contact.

 Continual inhalation of acetic acid vapors, even from the stop

 bath, may cause chronic bronchitis.

 2. Potassium chrome alum or chrome alum (potassium chromium

 sulfate) is moderately toxic by skin contact and inhalation,

 causing dermatitis and allergies.

 3. In powder form, sodium thiosulfate is not significantly toxic

 by skin contact.  By ingestion it has a purging effect on the

 bowels.  Upon heating or long standing in solution, it can

 decompose to form highly toxic sulfur dioxide, which can cause

 chronic lung problems.  Many asthmatics are particularly

 sensitive to sulfur dioxide.

 4. Sodium bisulfite decomposes to form sulfur dioxide if the

 fixing bath contains boric acid, or if acetic acid is

 transferred to the fixing bath on the surface of the print.

 5. Alum (potassium aluminum sulfate) is only slightly toxic.  It

 may cause skin allergies or irritation.

 6. Boric acid is moderately toxic by ingestion or inhalation and

 slightly toxic by skin contact (unless the skin is abraded or

 burned, in which case it can be highly toxic).


 1. All darkrooms require good ventilation to control the level of

 acetic acid vapors and sulfur dioxide gas produced in

 photography.  Kodak recommends at least 10 air changes per hour,

 or 170 cfm for darkrooms and automatic processors.  I recommend

 using the larger of the two ventilation rates.  The exhaust duct

 opening should preferably be located behind and just above the

 stop bath and fixer trays.  The exhaust should not be

 recirculated.  For group darkrooms, the amount of dilution

 ventilation should be 170 cfm times the number of fixer trays.

   Make sure that an adequate source of replacement air is

 provided.  This can be achieved without light leakage by use of

 light traps.  Ducting used with local exhaust systems should

 prevent light leakage from the exhaust outlet.

 2. Wear gloves and goggles.

 3. Cover all baths when not in use to prevent evaporation or

 release of toxic vapors and gases.


   A common after-treatment of negatives (and occasionally prints)

 is either intensification or reduction.  Common intensifiers

 include hydrochloric acid and potassium dichromate, or potassium

 chlorochromate.  Mercuric chloride followed by ammonia or sodium

 sulfite, Monckhoven's intensifier consisting of a mercuric

 salt bleach followed by a silver nitrate/potassium cyanide

 solution, mercuric iodide/sodium sulfite, and uranium

 nitrate are older, now discarded, intensifiers.

   Reduction of negatives is usually done with Farmer's reducer,

 consisting of potassium ferricyanide and hypo.  Reduction has

 also be done historically with iodine/potassium cyanide, ammonium

 persulfate, and potassium permanganate/sulfuric acid.


 1. Potassium dichromate and potassium chlorochromate are probable

 human carcinogens, and can cause skin allergies and ulceration.

 Potassium chlorochromate can release highly toxic chlorine gas if

 heated or if acid is added.

 2. Concentrated hydrochloric acid is corrosive; the diluted acid

 is an skin and eye irritant.

 3. Mercury compounds are moderately toxic by skin contact and may

 be absorbed through the skin.  They are also highly toxic by

 inhalation and extremely toxic by ingestion.  Uranium

 intensifiers are radioactive, and are especially hazardous to the


 4. Sodium or potassium cyanide is extremely toxic by inhalation

 and ingestion, and moderately toxic by skin contact.  Adding acid

 to cyanide forms extremely toxic hydrogen cyanide gas which can

 be rapidly fatal.

 5. Potassium ferricyanide, although only slightly toxic by

 itself, will release hydrogen cyanide gas if heated, if hot acid

 is added, or if exposed to strong ultraviolet light (e.g., carbon

 arcs).  Cases of cyanide poisoning have occurred through treating

 Farmer's reducer with acid.

 6. Potassium permanganate and ammonium persulfate are strong

 oxidizers and may cause fires or explosions in contact with

 solvents and other organic materials.


 1. Chromium intensifiers are probably the least toxic

 intensifiers, even though they are probable human carcinogens.

 Gloves and goggles should be worn when preparing and using these

 intensifiers.  Mix the powders in a glove box or wear a

 NIOSH-approved toxic dust respirator.  Do not expose potassium

 chlorochromate to acid or heat.

 2. Do not use mercury, cyanide or uranium intensifiers, or

 cyanide reducers because of their high or extreme toxicity.

 3. The safest reducer to use is Farmer's reducer.  Do not expose

 Farmer's reducer to acid, ultraviolet light, or heat.


   Toning a print usually involves replacement of silver by

 another metal, for example, gold, selenium, uranium, platinum, or

 iron.  In some cases, the toning involves replacement of silver

 metal by brown silver sulfide, for example, in the various types

 of sulfide toners.  A variety of other chemicals are also used in

 the toning solutions.


 1. Sulfides release highly toxic hydrogen sulfide gas during

 toning, or when treated with acid.

 2. Selenium is a skin and eye irritant and can cause kidney

 damage.  Treatment of selenium salts with acid may

 release highly toxic hydrogen selenide gas.  Selenium toners also

 give off large amounts of sulfur dioxide gas.

 3. Gold and platinum salts are strong sensitizers and can produce

 allergic skin reactions and asthma, particularly

 in fair-haired people.

 4. Thiourea is a probable human carcinogen since it causes cancer

 in animals.


 1. Carry out normal precautions for handling toxic chemicals as

 described in previous sections.  In particular, wear gloves and

 goggles.  Mix powders in a glove box or wear at oxic dust

 respirator.  See also the section on mixing photochemicals.

 2. Toning solutions must be used with local exhaust ventilation

 (e.g. slot exhaust hood, or working on a table immediately in

 front of a window with an exhaust fan at work level).

 3. Take precautions to make sure that sulfide or selenium toners

 are not contaminated with acids.  For example, with two bath

 sulfide toners, make sure you rinse the print well after

 bleaching in acid solution before dipping it in the sulfide


 4. Avoid thiourea whenever possible because of its probable

 cancer status.


   Many other chemicals are also used in black and white

 processing, including formaldehyde as a prehardener, a variety of

 oxidizing agents as hypo eliminators (e.g., hydrogen peroxide and

 ammonia, potassium permanganate, bleaches, and potassium

 persulfate), sodium sulfide to test for residual silver, silver

 nitrate to test for residual hypo, solvents such as methyl

 chloroform and freons for film and print cleaning, and

 concentrated acids to clean trays.

   Electrical outlets and equipment can present electrical hazards

 in darkrooms due to the risk of splashing water.


 1. Concentrated sulfuric acid, mixed with potassium permanganate

 or potassium dichromate, produces highly corrosive permanganic

 and chromic acids.

 2. Hypochlorite bleaches can release highly toxic chlorine gas

 when acid is added, or if heated.

 3. Potassium persulfate and other oxidizing agents used as hypo

 eliminators may cause fires when in contact with easily

 oxidizable materials, such as many solvents and other combustible

 materials.  Most are also skin and eye irritants.


 1. See previous sections for precautions in handling photographic


 2. Cleaning acids should be handled with great care.  Wear

 gloves, goggles and acid-proof, protective apron.  Always add

 acid to the water when diluting.

 3. Do not add acid to, or heat, hypochlorite bleaches.

 4. Keep potassium persulfate and other strong oxidizing agents

 separate from flammable and easily oxidizable


 5. Install ground fault interrupters (GFCIs) whenever electrical

 outlets or electrical equipment (e.g. enlargers) are within six

 feet of the risk of water splashes.


   Color processing is much more complicated than black and white

 processing, and there is a wide variation in processes used by

 different companies.  Color processing can be either done in

 trays or in automatic processors.


   The first developer of color transparency processing usually

 contains monomethyl-p-aminophenol sulfate, hydroquinone, and

 other normal black and white developer components.  Color

 developers contain a wide variety of chemicals including color

 coupling agents, penetrating solvents (such as benzyl alcohol,

 ethylene glycol, and ethoxydiglycol), amines, and others.


 1. See the developing section of black and white processing for

 the hazards of standard black and white developers.

 2. In general, color developers are more hazardous than black and

 white developers.  Para-phenylene diamine, and its dimethyl and

 diethyl derivatives, are known to be highly toxic by skin contact

 and absorption, inhalation, and ingestion.  They can cause very

 severe skin irritation, allergies and poisoning.  Color

 developers have also been linked to lichen planus, an

 inflammatory skin disease characterized by reddish pimples which

 can spread to form rough scaly patches.  Recent color developing

 agents such as 4-amino-N-ethyl-N-[P-methane-

 sulfonamidoethyl]-m-toluidine sesquisulfate monohydrate and

 4-amino-3-methyl-N-ethyl-N-[,3-hydroxyethyl]-aniline sulfate are

 supposedly less hazardous, but still can cause skin irritation

 and allergies.

 3. Most amines, including ethylene diamine, tertiary-butylamine

 borane, the various ethanolamines, etc. are strong sensitizers,

 as well as skin and respiratory irritants.

 4. Although many of the solvents are not very volatile at room

 temperature, the elevated temperatures used in color processing

 can increase the amount of solvent vapors in the air.  The

 solvents are usually skin and eye irritants.


 1. Wear gloves and goggles when handling color developers.  Wash

 gloves with an acid-type hand cleaner (e.g.

 pHisoderm (R)), and then water before removing them.  According

 to Kodak, barrier creams are not effective in preventing

 sensitization due to color developers.

 2. Mix powders in a glove box, or wear a NIOSH-approved toxic

 dust respirator.

 3. Color processing needs more ventilation than black and white

 processing due to the use of solvents and other toxic components

 at elevated temperatures.  Preferably, for tray processing, use a

 3-foot slot hood exhausting 1050 cubic feet/minute (cfm).  Some

 automatic processors can be purchased with an exhaust, which

 would need to be ducted to the outside.


   Many of the chemicals used in other steps of color processing

 are essentially the same as those used for black and white

 processing.  Examples include the stop bath and fixing bath.

 Bleaching uses a number of chemicals, including potassium

 ferricyanide, potassium bromide, ammonium thiocyanate, and acids.

 Chemicals found in prehardeners and stabilizers include

 succinaldehyde and formaldehyde; neutralizers can contain

 hydroxylamine sulfate, acetic acid, and other acids.


 1. Formaldehyde is moderately toxic by skin contact, and highly

 toxic by inhalation and ingestion.  It is an skin, eye and

 respiratory irritant, and strong sensitizer, and is a probable

 human carcinogen.  Formaldehyde solutions contain some methanol,

 which is highly toxic by ingestion.

 2. Succinaldehyde is similar in toxicity to formaldehyde, but is

 not a strong sensitizer or carcinogen.

 3. Hydroxylamine sulfate is a suspected teratogen in humans since

 it is a teratogen (causes birth defects) in animals.  It is also

 a skin and eye irritant.

 4. Concentrated acids, such as glacial acetic acid, hydrobromic

 acid, sulfamic acid and p-toluenesulfonic acids are corrosive by

 skin contact, inhalation and ingestion.

 5. Acid solutions, if they contain sulfites or bisulfites (e.g.,

 neutralizing solutions), can release sulfur dioxide upon

 standing.  If acid is carried over on the negative or

 transparency from one step to another step containing sulfites or

 bisulfites, then sulfur dioxide can be formed.

 6. Potassium ferricyanide will release hydrogen cyanide gas if

 heated, if hot acid is added, or if exposed to strong ultraviolet



 1. Local exhaust ventilation is required for mixing of chemicals

 and color processing.  See previous section for discussion of


 2. Use premixed solutions whenever possible.  For powders, use a

 glove box, or wear a NIOSH-approved respirator with toxic dust


 3. Avoid color processes using formaldehyde, if possible.

 4. Wear gloves, goggles and protective apron when mixing and

 handling color processing chemicals.  When diluting solutions

 containing concentrated acids, always add the acid to the water.

 An eyewash and emergency shower should be available.

 5. A water rinse step is recommended between acid bleach steps

 and fixing steps to reduce the production of sulfur dioxide gas.

 6. Do not add acid to solutions containing potassium ferricyanide

 or thiocyanate salts.

 7. Control the temperature carefully according to manufacturer's

 recommendations to reduce emissions of toxic gases and vapors.


   There is considerable concern about the effect of dumping

 photographic chemicals and solutions down the drain.  Besides

 direct concern about toxicity of the effluent, many

 photochemicals use up oxygen in the water when they under

 biological or chemical degradation.  This lowered oxygen content

 can affect aquatic life.

   Most municipal areas have waste treatment plants with secondary

 bacterial treatment systems.  These plants can handle most

 photochemicals solutions if the volumes and concentrations of

 contaminants are not too high.  For these reasons, local sewer

 authorities regulate the concentrations and, often, the volume of

 chemicals released per day (the load) into sewer systems.  The

 total volume of effluent includes the amount of wash water.

   Septic tanks systems are more fragile, although they can handle

 a certain amount of waste photographic effluents, if they are not

 too toxic to the bacteria and if too much is not released into

 the septic system at one time.

   The following recommendations are for disposing small volumes

 of photographic solutions daily.


 1. Old or unused concentrated photographic chemical solutions,

 toning solutions, ferricyanide solutions, chromium solutions,

 color processing solutions containing high concentrations of

 solvents, and non-silver solutions should be treated as hazardous

 waste.  A licensed waste disposal service should be contacted for

 proper disposal.  Unused materials may be recycled by donating to

 arts organizations or, in some cases, schools, as an alternative.

 2. Contact your local sewer authority for information about

 disposing of your photographic solutions.

 3. Most small-scale photographic processing will not exceed

 effluent regulations.  If your total load (volume/day) is within

 regulated amounts, but the concentrations of particular chemicals

 in a bath too high, then you can use a holding tank large enough

 to hold the process wash water and processing solutions.  Then

 the effluent can be slowly released into the sewer system.  The

 holding tank should be kept covered, and some dilution

 ventilation provided.

 4. Alkaline developer solutions should be neutralized first

 before being poured down the drain.  This can be done with the

 stop bath or citric acid, using pH paper to tell when the

 solution has been neutralized (pH 7).  If the developer contains

 sodium sulfite or bisulfite, there is the hazard of producing

 toxic sulfur dioxide gas if the solution becomes acidic.

 Therefore, neutralize slowly using the pH indicator paper to tell

 you when to stop.  The pH should not drop below 7.

 5. Stop bath left over from neutralization of developer can be

 poured down the drain, once mixed with wash water.

 6. Fixing baths should never be treated with acid (e.g mixing

 with stop bath), since they usually contain sulfites and

 bisulfites which will produce sulfur dioxide gas.

 7. Fixing baths contain large concentrations of silver

 thiocyanate, well above the 5 ppm of silver ion allowed by

 the U.S. Clean Water Act.  The regulations includes silver

 thiocyanate, although silver thiocyanate is not as toxic to

 bacteria as free silver ion, and can be handled by bacterial

 waste treatment plants.  If large amounts of fixer waste are

 produced (more than a few gallons per day), then silver recovery

 should be considered.  For small amounts, mixing with wash water,

 and pouring down the drain are possible.  Local authorities

 should be contacted for advice.

 8. There are several silver recovery systems.  The simplest uses

 steel wool or other source of iron.  The iron dissolves and

 silver is precipitated out.  The precipitated silver must be sent

 to a company that can recover the silver.

 9. Replenishment systems, where fresh solutions are added

 regularly to replace solutions carried out by film or

 paper, reduce the daily volume of solution needing disposal.

 Ultimately, you will have to dispose of these replenished

 systems, using the above guidelines.

 10. For septic systems, Kodak used to recommend that photographic

 solutions (including wash water) constitute a maximum of 1/3 of

 the amount of household sanitary waste going into the septic

 system, and not to release more than a few pints at any one time.

 They no longer make this recommendation since, in some areas, you

 need a permit to dump photographic wastes into septic systems.

 11. If you have large amounts of photographic solutions for

 disposal (but less than 200 gallons daily, including wash water),

 Kodak recommends building your own activated-sludge waste

 treatment center from 55-gallon drums (see chapter references).

 This data sheet was adapted from the 2nd edition of Dr. McCann's

  Artist Beware., Lyons and Burford (1992).


 1. Ayers, G., Zaczkowski, J. (1991). Photo Developments - A Guide

 to Handling Photographic Chemicals. Envisin Compliance, Bramalea,


 2. Eastman Kodak Co. (1986).  CHOICES - Choosing the Right

 Silver-Recovery Method for Your Needs.  Publication No. J-21.

 Eastman Kodak, Rochester.

 3. Eastman Kodak Co. (1986).  Disposal and Treatment of

 Photographic Effluent. Publication No. J-55. Eatman Kodak,


 4. Eastman Kodak Co. (1986).  Disposal of Small Volumes of

 Photographic Processing Solutions.  Publication No. J-52.

 Eastman Kodak, Rochester. (discontinued)

 5. Eastman Kodak Co. (1987).  General guidelines for ventilating

 photographic processing areas, CIS-58. Eastman Kodak,


 6. Eastman Kodak Co. (1979).  Safe Handling of Photographic

 Chemicals. Publication No. J-4.. Kodak, Rochester.

 7. Handley, M. (1988). Photography and Your Health.  Hazard

 Evaluation System and Information Service, California

 Department of Health Services, Berkeley.

 8. Hodgson, M., and Parkinson, D. (1986).  Respiratory disease in

 a photographer.  Am. J. Ind. Med.  9(4), 349-54.

 9. Houk C. & Hart C. (1987).  Hazards in a photography lab; a

 cyanide incident case study.  J. Chem. Educ. 64(10), A234-A236.

 10. Kipen, H., and Lerman, Y. (1986).  Respiratory abnormalities

 among photographic developers: a report of three cases.  Am. J.

 Ind. Med.  9(4), 341-347.

 11. Shaw, S. D., and Rossol, M.  (1991).  Overexposure: Health

 Hazards in Photography. 2nd ed. Allworth Press, New York.

 12. Tell, J. (ed). (1988). Making Darkrooms Saferooms.  National

 Press Photographers Association, Durham.

 For Further Information

   Written and telephoned inquiries about hazards in the arts will

 be answered by the Art Hazards Information Center of the Center

 for Safety in the Arts.  Send a stamped, self-addressed envelope

 for a list of our many publications.

   Permission to reprint this data sheet may be requested in

 writing from CSA.  Write: Center for Safety in the Arts, 5

 Beekman Street, Suite 820, New York, NY 10038.  Telephone (212)


   CSA is partially supported with public funds from the National

 Endowment for the Arts, the New York State Council on the Arts,

 the New York City Department of Cultural Affairs, and the NYS

 Department of Labor Occupational Safety and Health Training and

 Education Program.

 (c) Copyright Center for Safety in the Arts 1994


   On April 6, 1994, the Occupational Safety and Health

 Administration (OSHA) published revisions and additions to

 portions of the general industry safety standard  concerning

 personal protective equipment (PPE).  The standard is effective

 July 5, 1994.  Relevant personal protective equipment include

 eye, face, foot, head and hand protection.  Revisions and

 additions include:

 1. General Requirements (1910.132) - A certified hazard

 assessment must be conducted by the employer to

 determine and select needed PPE.  The PPE must be selected,

 fitted, and the worker provided with training.

 The worker must demonstrate an understanding of need, usage,

 maintenance, and limitations of PPE.  This

 training must be certified.

 2. Eye and Face Protection (1910.133) - The new criteria for

 protective eye and face devices will comply with ANSI Z87.1-1989.

 Eye and face protection must be provided for flying particles,

 molten metal, chemicals vapors, radiation and more.   Corrective

 eye  prescriptions  shall be either worn under the PPE, or

 incorporated in PPE design.  A chart detailing the minimum filter

 shade protection numbers for various processes is provided.

 3. Head Protection (1910.135) - Head protection must be in

 compliance or as effective as the ANSI Safety Requirements for

 Industrial Head Protection Z89.1-1969.

 4. Foot Protection (1910.136) - Protective footwear must comply

 with ANSI Protective Footwear Standard Z41-1991.

 5. Hand Protection (1910.136) - This section is new, and requires

 hand protection for potential absorption of hazards chemicals,

 abrasion, punctures, burns and more.  Employers will base

 selection of hand protection on evaluation of task performance,

 condition, duration of task, and hazard identified.

 6. Appendix A and B are non-mandatory, but give further

 information on selection of PPE.

   While these revisions are already in effect from July 5, OSHA

 has additionally given employers until October 5 for compliance

 with the hazard assessment and training requirements.  Telephone

 Mr. James Foster at OSHA: (202) 219-8151 for further information.

Art Hazards News is published by the Center for Safety in the Arts,

5 Beekman Street, Suite 820, New York, NY 10038. (212) 227-6220.

  0 Discussion responses

Photographic Processing Hazards in Schools

By Michael McCann, Ph.D., C.I.H.

     Photography and photographic processing are increasingly

popular in secondary schools.  This article discusses the hazards

of classroom darkrooms and how to work safely.


     Many of the chemicals used in photographic processing can

cause severe skin problems, and, in some cases, lung problems

through inhalation of dusts and vapors.  The greatest hazard

usually occurs during the preparation and handling of

concentrated stock solutions of the chemicals.

Simple Black and White Processing

     Simple black-and-white processing includes mixing of

chemicals, developing, stop bath, fixing and rinsing steps.  The

developer usually contains hydroquinone and Metol (monomethyl p-

aminophenol sulfate), both of which can cause skin irritation and

allergic reactions.  Hydroquinone may also cause eye problems and

is a mutagen, and therefore might be a cancer risk.  Many other

developers are even more toxic.  Developers are also toxic by

inhalation of the powders and by ingestion, causing

methemoglobinemia and cyanosis (blue lips and fingernails due to

oxygen deficiency).  The developers are dissolved in a strongly

alkaline solution, often containing sodium hydroxide, which can

cause skin irritation and burns.    

     The stop bath consists of a weak solution of acetic acid.

Glacial acetic acid used to make up the stop bath can cause

severe skin burns, and inhalation of even the dilute vapors can

irritate the respiratory system.  Potassium chrome alum,

sometimes used as a stop hardener, contains chromium and can

cause skin and nasal ulceration, and allergies.

     The fixer often contains sodium sulfite, sodium bisulfite,

sodium thiosulfate (hypo), boric acid and potassium alum.  Hypo

and the mixture of sodium sulfite and acids produce sulfur

dioxide gas, especially if acetic acid is carried over from the

stop bath.  Sulfur dioxide is highly irritating to the eyes and

respiratory system, and asthmatics are often very sensitive to

it.  Potassium alum, a hardener, is a weak sensitizer and may

cause some skin irritation or dermatitis.

Advanced Black and White Processing

     Intensification or bleaching, reduction, and toning are

advanced processes in black and white processing.

     Many intensifiers (bleaches) can be very dangerous.  The

common two-component chrome intensifiers contain potassium

dichromate and hydrochloric acid.  The separate components can

cause burns, and the mixture produces chromic acid.  Its vapors

are very corrosive and may cause lung cancer.  One common bleach,

potassium chlorochromate also produces chlorine gas if heated or

treated with  acid.  Handling of the powder of another

intensifier, mercuric chloride, is very hazardous because of

possible mercury poisoning.  Mercuric chloride is also a skin

irritant and can be absorbed through the skin and should not be


     The most common reducer, Farmer's Reducer, contains

potassium ferricyanide.  Under normal conditions it is only

slightly toxic.  However, if it comes into contact with heat,

acids or ultraviolet radiation, the extremely poisonous hydrogen

cyanide gas can be released.  

     Many toners contain highly toxic chemicals.  These include

selenium, uranium, sulfide or liver of sulfur (irritating to skin

and breathing passages), gold and platinum (allergies),  and

oxalic acid (corrosive).  Sulfide or brown toners also produce

highly toxic hydrogen sulfide gas, and selenium toners produce

large amounts of sulfur dioxide gas.

     Hardeners and stabilizers often contain formaldehyde which

is poisonous, very irritating to the eyes, throat and breathing

passages, and can cause dermatitis.  It also causes nasal cancer

in animals.  Some of the solutions used to clean negatives

contain harmful chlorinated hydrocarbons.

Color Processing

     There are many different types of color processes using a

wide variety of chemicals.  In general, color processing is much

more hazardous than simple black and white processing.  In

addition to involving many of the same chemicals that are used in

black-and-white processing, color processing commonly uses many

other hazardous chemicals, including dye couplers - which can

cause severe skin problems, toxic organic solvents, formaldehyde,

and others.  In addition many color processes give off a lot more

sulfur dioxide than does black and white processing.


Choosing Materials and Processes

1. Material Safety Data Sheets should be obtained on all

photographic chemicals.  It is particularly important to check

for hazardous decomposition products in the Reactivity Section

since decomposition of fixers, toners, and other chemicals are

major hazards in photography.

2. Because of the hazards of photochemicals, photographic

processing should be only taught at the secondary school level,

and not in elementary schools.

3. During pregnancy, only simple black and white processing and

use of Farmer's Reducer is recommended; dry chemicals should not

be mixed due to the risk of inhalation of the hazardous powdered

developing agents.  Do not do toning, intensification, or color

processing because of higher risks.

4. Toning, intensification and color processing should not be

taught, except with a few advanced students, and only if there is

proper ventilation (see Ventilation section).  The only reducer

allowed should be potassium ferricyanide and care should be taken

to avoid heating it, mixing with acid or exposing it to

ultraviolet radiation.


1. Kodak recommends at least 10 room air changes per hour of

dilution ventilation for simple black and white processing, or

170 cfm of exhaust per work station or processor. *  I would

recommend the larger of these two exhaust rates. (Fan exhaust

rate in cubic feet/minute (cfm) is calculated by multiplying the

room volume in cubic feet by the number of air changers/hour, and

then dividing by sixty.)  The exhaust opening should be located

at the rear of the sink and as close to sink level as possible.

The air should be completely exhausted to the outside and not

recirculated.  Replacement or makeup air should enter the room

behind the person working at the sink.

2. Mixing of large amounts of photochemicals, toning, and color

processing should have local exhaust ventilation, for example a

slot exhaust hood, but not an overhead canopy hood which would

draw the contaminants past the user's face.  This slot hood would

have to be designed by a industrial ventilation engineer.

Without this type of ventilation, these processes should not be


* "General Guidelines for Ventilating Photographic Processing

Areas,"  CIS-58, Eastman Kodak Company (1987).

Storage and Handling

1. Photographic solutions should be stored safely in clearly

marked containers that are restrained so they will not fall over.

Concentrates should be stored on low shelves.  Do not store

incompatible chemicals such as acids and Farmer's reducer in

close proximity.

2. Gloves, chemical splash goggles approved by the American

National Standards Institute (ANSI), and a protective apron

should be worn when mixing concentrated photochemical solutions

to protect against skin contact.

3. Preferably use liquid chemistry rather than mixing powdered

developers.  If the powders are used, small amounts can be mixed

into a concentrated solution inside a glove box or the teacher

can do it while wearing a toxic dust respirator.  A glove box

consists of an ordinary cardboard box, varnished on the inside

for easy cleaning, with a glass or plexiglass top and two holes

in the sides for insertion of arms.  If respirators are worn, all

OSHA regulations concerning a respirator program should be


4. When diluting glacial acetic acid (or other concentrated

acids), always add the acid to the water, never the reverse. 5.

Tongs should be used to handle photographic prints during

printing operations so that hands are never put into the

developer or other baths.  If skin contact does occur, the skin

should be washed copiously with water and then with an acid-type

skin cleanser.  In case of eye contact rinse for at least 15-20

minutes and contact a physician.

6. Cover trays when not in use or pour chemicals to be reused

into containers, using a funnel.

7. Dispose of small amounts of photographic solutions by pouring

down the sink.  Mixing the stop bath and developer will partially

neutralize them.  Do not mix the stop bath and fixer and flush

with water for at least 5 minutes after pouring the stop bath

before pouring the fixer.  If large enough quantities are

involved, silver recovery might be desirable.

Safety Devices

1. All darkrooms should have eyewash fountains that connect to

the water supply and do not need hands to operate.  In the area

where concentrated developing solutions and glacial acetic acid

are mixed, there should also be an emergency shower.  There

should be no electric switches or electrical outlets within

splash range of the shower.

2. All electrical outlets and electrical equipment within 6 feet

of possible water splashes should be equipped with ground fault

circuit interrupters.

Reprinted from Art Hazards News Vol. 13 No. 9, 1990.

(c) copyright Center for Safety in the Arts 1990