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.

MSDS Film

MSDS Fix

MSDS Print

MSDS Remover

MSDS Stop

MSDS Wetting

• Use liquid chemistry whenever possible, rather than mixing developing powders.  Pregnant women, in particular, should not be exposed to powdered developer.
• 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.
• Wear gloves, goggles and protective apron when mixing concentrated photochemicals.  Always add any acid to water, never the reverse.
• In case of skin contact, rinse with lots of water.  In case of eye contact, rinse for at least 15-20 minutes, preferably using an eyewash station, seek medical attention.
• 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.
• Do not store photographic solutions in glass containers.
• 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 seek medical attention.
• Do not use para-phenylene diamine or its derivatives if at all possible.
• All darkrooms require good ventilation to control the level of  acetic acid vapors and sulfur dioxide gas produced in photography.
• Wear gloves and goggles.
• Cover all baths when not in use to prevent evaporation or release of toxic vapors and gases.
• 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.
• Do not use mercury, cyanide or uranium intensifiers, or cyanide reducers because of their high or extreme toxicity.
• The safest reducer to use is Farmer's reducer.  Do not expose Farmer's reducer to acid, ultraviolet light, or heat.
• 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
• 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).
• Stop bath left over from neutralization of developer can be poured down the drain, once mixed with wash water.
• 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.
• Fixing baths contain large concentrations of silver thiocyanate, well above the 5 ppm of silver ion allowed by the U.S. Clean Water Act.  Collect fixers and either pour into the silver recovery unit or dispose as hazardous waste.

• 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.
• Developer powders are highly toxic by inhalation, and  moderately toxic by skin contact, due to the alkali and developers themselves
• 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 slightly toxic by skin contact.
• 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.  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 occur.
• 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.
• 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.
• 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.
• 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.
• 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.
• Potassium chrome alum or chrome alum (potassium chromium sulfate) is moderately toxic by skin contact and inhalation, causing dermatitis and allergies.
• 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.
• 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.
• Alum (potassium aluminum sulfate) is only slightly toxic.  It may cause skin allergies or irritation.
• 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).
• 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.
• Concentrated hydrochloric acid is corrosive; the diluted acid is a skin and eye irritant.
• 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 kidneys.
• 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.
• 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.
• Potassium permanganate and ammonium persulfate are strong oxidizers and may cause fires or explosions in contact with solvents and other organic materials.
• Sulfides release highly toxic hydrogen sulfide gas during toning, or when treated with acid.
• 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.
• Gold and platinum salts are strong sensitizers and can produce allergic skin reactions and asthma, particularly in fair-haired people.
• Thiourea is a probable human carcinogen since it causes cancer in animals.