4-Nitrophenol (also called p-nitrophenol or 4-hydroxynitrobenzene) is a phenolic compound with the molecular formula C₆H₅NO₃. It is a colourless to light yellow solid with very little odour and is not found naturally in the environment.
What is 4-Nitrophenol used for?
4-Nitrophenol is used to manufacture
Drugs (e.g., acetaminophen)
Fungicides
Methyl and ethyl parathion insecticides
Dyes
To darken leather
4-Nitrophenol is used to manufacture drugs.
In the Environment
Most 4-nitrophenol enters the environment during manufacturing and processing.
It can also be formed in the air as a result of the breakdown of other manufactured chemicals.
Most goes to water and soil, with very little entering the air
It readily breaks down in surface water
It takes a long time to break down in deep soil and groundwater
4-Nitrophenol has not been found in foods
It is a breakdown product of pesticides such as parathion and fluoridifen
It is also formed in auto exhaust
Sources and Routes of Exposure
Sources of Exposure
Exposure to 4-nitrophenol can occur via:
Air, water, and soil contaminated with the chemical
Breathing contaminated workplace air (especially during spills)
Breathing contaminated air or drinking contaminated water near farming areas where certain fungicides are used
Breathing contaminated air or drinking contaminated water near waste sites and landfills
Routes of Exposure
4-nitrophenol can enter the body through:
Lungs (breathing contaminated air)
Stomach (swallowing the chemical)
Skin (some may pass through the skin, but how much is unknown)
Once inside the body, 4-nitrophenol metabolises into other chemicals that are quickly (in hours) excreted in urine.
Health Effects
Acute Effects
In humans, acute inhalation or ingestion of 4-nitrophenol causes:
Headaches
Drowsiness
Nausea
Cyanosis
Eye contact causes irritation.
Animal studies reported:
Increased methemoglobin
Corneal opacity (eye damage)
High toxicity from oral and dermal exposure in rats and mice
Chronic Effects
No information is available on the chronic effects in humans or animals from inhalation or oral exposure
One animal study found no major system effects from chronic dermal exposure
The only observed effects were dermal irritation, including
Erythema
Scaling
Scabbing
Cracking of the skin
The EPA has not established a Reference Concentration (RfC) or a Reference Dose (RfD) for 4-nitrophenol
Reproductive/Developmental Effects
No information available for humans
Animal studies reported:
No histological alterations in the testes and epididymides in mice exposed by inhalation
No changes in reproductive index in pregnant mice given the chemical by gavage (feeding tube)
Cancer Risk
No information available on carcinogenic effects in humans
No evidence of carcinogenic activity in mice exposed dermally for 18 months (NTP study)
EPA has not classified 4-nitrophenol for carcinogenicity
Safety
First Aid Measures
Eye Contact
Remove contact lenses (if any)
Flush eyes with running water for at least 15 minutes (cold water may be used)
Do not use eye ointment
Seek medical attention
Skin Contact
Wash skin immediately with plenty of water
Use non-abrasive soap; cold water may be used
Cover irritated skin with emollient
If irritation persists, seek medical attention
Wash contaminated clothing before reuse
Serious Skin Contact
Wash with disinfectant soap
Cover contaminated skin with anti-bacterial cream
Seek immediate medical attention
Inhalation
Let the victim rest in a well-ventilated area
Seek immediate medical attention
Serious Inhalation
Evacuate the victim to a safe area
Loosen tight clothing (e.g., collar, tie, belt)
Administer oxygen if breathing is difficult
If not breathing, perform mouth-to-mouth resuscitation
Seek medical attention
Ingestion
Do not induce vomiting
Check mouth and lips for signs of damage
Loosen tight clothing
If not breathing, perform mouth-to-mouth resuscitation
Seek immediate medical attention
Exposure Control & Personal Protection
Engineering Controls
Use process enclosures, local exhaust ventilation, or other controls to keep airborne levels below recommended exposure limits
If operations generate dust, fumes, or mist, use ventilation to reduce exposure
Personal Protective Equipment (PPE)
When handling 4-nitrophenol, wear:
Splash goggles
Lab coat
Dust respirator (approved/certified)
Gloves
In case of large spills, wear:
Splash goggles
Full suit
Dust respirator
Boots
Gloves
Use a self-contained breathing apparatus to avoid inhalation
Suggested protective clothing may not be sufficient—consult a specialist before handling.
Regulation
United States
No occupational exposure limits have been established for 4-Nitrophenol. This does not mean that this substance is not harmful. Safe work practices should always be followed.
It should be recognised that 4-Nitrophenol can be absorbed through your skin, thereby increasing your exposure.
Environmental Protection Agency (EPA) says that industry must tell the National Response Centre when 100 pounds or more of 4-nitrophenol have been disposed of.
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