Cresols are organic compounds with the chemical formula C₇H₈O. They belong to a group of chemicals called phenols (or phenolics). Cresols can be either solid or liquid depending on the temperature because their melting points are close to room temperature.
Over time, cresols slowly react with air, which can change their colour from yellow to reddish-brown. Cresols also have a strong smell, often described as similar to coal tar. The name "cresol" comes from their chemical structure (phenols) and their traditional source (creosote).
There are three types of cresols, based on their chemical structure:
Ortho-cresol (o-cresol)
Meta-cresol (m-cresol)
Para-cresol (p-cresol)
These forms can occur separately or as a mixture.
What are Cresols used for?
Cresols are used in a variety of industries for different purposes:
Mixed Cresols
Disinfectants
Preservatives
Wood preservatives
o-Cresol
Solvent
Disinfectant
Chemical intermediate
m-Cresol
Production of herbicides
Precursor to pyrethroid insecticides
Used to make antioxidants
Manufacture of the explosive 2,4,6-nitro-m-cresol
p-Cresol
Used in antioxidants
Fragrance industry
Dye industry
Cresols can also be formed naturally in the body and are found in:
Certain foods
Wood and tobacco smoke
Crude oil
Coal tar
Wood preservatives
Cresols are used for disinfectants.
In the Environment
In the air, cresols break down quickly into other chemicals. They evaporate slowly from soil and water, but bacteria can break them down faster. Since cresols do not attach strongly to soil, they can move into groundwater.
In soil, half of the cresols break down in about a week. Cresols do not build up in fish or other animals.
Sources and Routes of Exposure
Sources of Exposure
Air — Primary Source
Most exposure happens by breathing air containing cresols. They are released into the air from:
Industries using or producing cresols
Car exhaust
Cigarette smoke
Burning wood or trash
Water
Cresols have been found in surface water and groundwater, usually at very low levels. Higher levels are possible near:
Petroleum spills
Hazardous waste sites
Industrial waste
Workplace
Workers may be exposed to cresols during:
Manufacturing
Chemical laboratory work
Coal gasification
Painting or varnishing
Applying insulation to copper wires
Wood-preserving processes
Exposure can occur through breathing in vapours or skin contact.
Food
Low levels of cresols are found in foods like
Tomatoes
Ketchup
Asparagus
Cheese
Butter
Bacon
Smoked foods
Beverages like coffee, tea, wine, whisky, brandy, and rum
Consumer Products
Exposure may occur through skin contact or accidental ingestion of disinfectants and cleaners containing cresols.
Routes of Exposure
Cresols can enter the body through:
Inhalation (breathing)
Ingestion (swallowing)
Eye contact
Skin contact
Health Effects
Acute Effects
Breathing in cresols can cause:
Dryness in the nose and throat
Nasal constriction
Throat irritation
Cresols are strong skin irritants and can cause damage if ingested in large amounts. High exposure may affect the
Respiratory system
Digestive system
Blood
Liver
Kidneys
Central nervous system (CNS)
Animal studies show moderate to high acute toxicity from cresol exposure.
Chronic Effects
There is no information on long-term effects in humans. However, animal studies show that long-term exposure can affect:
Blood
Liver
Kidneys
Central nervous system
Body weight
Regulatory guidelines include:
California EPA chronic exposure limit: 0.004 mg/m³ (based on bone marrow effects in rats)
Oral exposure limits:
o-Cresol and m-Cresol — 0.05 mg/kg/day
p-Cresol — 0.005 mg/kg/day (provisional value)
Reproductive/Developmental Effects
There is no human data available. Animal studies show developmental effects only at high (maternally toxic) doses. No reproductive effects have been reported from oral exposure.
Cancer Risk
There is limited information on the cancer-causing potential of cresols in humans. Animal studies suggest
p-Cresol may promote tumour growth in the forestomach
o-Cresol, m-Cresol, and p-Cresol may promote tumour formation in animal skin studies
Safety Measures
First Aid Measures
Eye Contact
Remove contact lenses if present.
Rinse eyes with running water for at least 15 minutes, keeping eyelids open. Cold water may be used.
Do not use eye ointments.
Seek medical attention immediately.
Skin Contact
If the chemical contacts clothing, remove contaminated clothes carefully.
Use a safety shower to rinse affected areas.
Wash exposed skin with running water and non-abrasive soap, paying attention to folds, creases, and the groin. Cold water may be used.
If irritation persists, seek medical attention.
Wash contaminated clothing before reuse.
Serious Skin Contact
Wash with disinfectant soap.
Apply antibacterial cream.
Seek immediate medical attention.
Inhalation
Move the affected person to a well-ventilated area.
Allow them to rest and seek medical attention immediately.
ACGIH: The American Conference of Governmental Industrial Hygienists has set a Threshold Limit Value (TLV) FOR CRESOLS OF 5 ppm, 22 mg/m3 TWA; Skin
NIOSH: The National Institute for Occupational Safety and Health (NIOSH) has set a Recommended Exposure Limit (REL)for cresols of 2.3 ppm, 10 mg/m3 TWA
Australia
Safe Work Australia: Safe Work Australia has established a Time Weighted Average (TWA) concentration for cresol of 5ppm and 22mg/m3 for an 8-hour workday.
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