Cresols

2022-08-19

Cresols are organic compounds with the molecular formula C7H8O. They are a widely occurring natural and manufactured group of aromatic organic compounds, which are categorised as phenols (sometimes called phenolics). Depending on the temperature, cresols can be solid or liquid because they have melting points not far from room temperature. Like other types of phenols, they are slowly oxidised by long exposure to air and the impurities often give cresols a yellowish to brownish red tint. Cresols have an odour characteristic to that of other simple phenols, reminiscent to some of a “coal tar” smell. The name creosol reflects their structure, being phenols, and their traditional source, creosote. [1] There are three forms of cresols that differ slightly in their chemical structure: ortho-cresol (o-cresol), meta-cresol (m-cresol, and para-cresol (p-cresol). These forms occur separately or as a mixture. [2]

Uses [2,3]

Mixed cresols are used as disinfectants, preservatives, and wood preservatives. o-Cresol is used as a solvent, disinfectant, and chemical intermediate. m-Cresol is used to produce certain herbicides, as a precursor to the pyrethroid insecticides, to produce antioxidants, and to manufacture the explosive, 2,4,6-nitro-m-cresol. p-Cresol is used largely in the formulation of antioxidants and in the fragrance and dye industries. Cresols may be formed normally in the body from other compounds. Cresols are found in many foods and in wood and tobacco smoke, crude oil, coal tar, and in chemical mixtures used as wood preservatives.

In the Environment [2]

In air, cresols quickly break down into other chemicals. They evaporate slowly from soil and water surfaces, but can be quickly degraded by bacteria. Cresols does not attach strongly to soils; therefore, they may move into groundwater below the soil surface. ‘ They may last longer in deep groundwater or water that does not have bacteria. In soil, half the total amount of cresols will break down in about a week. Cresols do not seem to accumulate in fish or other organisms.

Sources & Routes of Exposure

Sources of Exposure [4]

Air-primary source of exposure The primary way you can be exposed to cresols is by breathing air containing them. Releases of cresols into the air occur from:

  • industries using or manufacturing cresols
  • automobile exhaust
  • cigarette smoke
  • wood and trash burning
Water Cresols have been detected in surface waters and groundwater, but generally at low levels (approximately 1 microgram per litre [ug/L] or less).

Higher levels have been detected:

  • where petroleum spills have occurred
  • near hazardous waste sites
  • in industrial effluents

 

Workplace A large number of workers are potentially exposed to cresols. Potential exposures occur in:

  • manufacture of cresols
  • chemical laboratories
  • coal gasification facilities
  • paint and varnish application
  • application of insulation lacquers to copper wires
  • wood-preserving facilities

Exposure may occur through breathing and dermal contact with contaminated air and/or liquid cresols or products containing cresols.

Food Low levels of cresols have been found in some foods such as tomatoes, tomato ketchup, asparagus, cheeses, butter, bacon, and smoked foods.

Some drinks also contain cresols (coffee, black tea, wine, Scotch whisky, brandy, and rum).

Consumer products Exposure may occur through accidental or intentional ingestion or contact of the skin with cleaners or disinfectants containing cresols.

Routes of Exposure [5]

Cresols may cause adverse health effects following exposure via:

  • Inhalation
  • Ingestion
  • Eye Contact
  • Dermal Contact

Health Effects [3]

Acute Effects

Acute inhalation exposure by humans to mixed cresols results in respiratory tract irritation, with symptoms such as dryness, nasal constriction, and throat irritation. Mixed cresols are also strong dermal irritants. Ingestion of high levels of mixed cresols by humans has resulted in effects on the respiratory system, gastrointestinal system, blood, liver, kidney, and CNS. Animal studies have reported respiratory tract and eye irritation, and effects on the liver, kidney, and CNS from acute inhalation exposure to mixed cresols. Acute animal tests in rats have shown mixed cresols to have moderate acute toxicity, while o-cresol, m-cresol, and p-cresol have been shown to have high acute toxicity from oral exposure.

Chronic Effects

No information is available on the chronic effects of mixed cresols in humans. Animal studies have reported effects on the blood, liver, kidney, and CNS, as well as reduced body weight, from oral and inhalation exposure to mixed cresols. EPA has not established a Reference Concentration (RfC) or a Reference Dose (RfD) for mixed cresols. The California Environmental Protection Agency (CalEPA) has established a chronic reference exposure level of 0.004 milligrams per cubic metre (mg/m3) for mixed cresols based on bone marrow effects in rats. EPA has not established an RfC for o-, m-, or p-cresol. The RfD for o-cresol and m-cresol is 0.05 milligrams per kilogram body weight per day (mg/kg/d) based on decreased body weights and neurotoxicity in rats. The provisional RfD for p-cresol is 0.005 mg/kg/d based on neurological and respiratory effects in rabbits. The provisional RfD is a value that has had some form of Agency review, but it does not appear on IRIS.

Reproductive/Developmental Effects

No information is available on the reproductive or developmental effects of mixed cresols in humans. Animal studies have reported developmental effects, but only at maternally toxic doses, and no reproductive effects from oral exposure to mixed cresols.

Cancer Risk

Only anecdotal information is available on the carcinogenic effects of mixed cresols in humans. The only available oral animal study is a 13-week study that suggested that p-cresol may act as a promoter for tumours of the forestomach. Several dermal animal studies have suggested that o-cresol, m-cresol, and p-cresol may act as tumour promoters. EPA has classified o-cresol, m-cresol, and p-cresol as Group C, possible human carcinogens.

Safety [6]

First Aid Measures

  • Eye Contact: Check for and remove any contact lenses. Immediately flush eyes with running water for at least 15 minutes, keeping eyelids open. Cold water may be used. Do not use an eye ointment. Seek medical attention.
  • Skin Contact: If the chemical got onto the clothed portion of the body, remove the contaminated clothes as quickly as possible, protecting your own hands and body. Place the victim under a deluge shower. If the chemical got on the victim’s exposed skin, such as the hands : Gently and thoroughly wash the contaminated skin with running water and non-abrasive soap. Be particularly careful to clean folds, crevices, creases and groin. Cold water may be used. If irritation persists, seek medical attention. Wash contaminated clothing before reusing.
  • Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek immediate medical attention.
  • Inhalation: Allow the victim to rest in a well-ventilated area. Seek immediate medical attention.
  • Serious Inhalation: Evacuate the victim to a safe area as soon as possible. Loosen tight clothing such as a collar, tie, belt or waistband. If breathing is difficult, administer oxygen. If the victim is not breathing, perform mouth-to-mouth resuscitation. WARNING: It may be hazardous to the person providing aid to give mouth-to-mouth resuscitation when the inhaled material is toxic, infectious or corrosive. Seek immediate medical attention.
  • Ingestion: Do not induce vomiting. Examine the lips and mouth to ascertain whether the tissues are damaged, a possible indication that the toxic material was ingested; the absence of such signs, however, is not conclusive. Loosen tight clothing such as a collar, tie, belt or waistband. If the victim is not breathing, perform mouth-to-mouth resuscitation. Seek immediate medical attention.

Exposure Controls & Personal Protection

Engineering Controls

Provide exhaust ventilation or other engineering controls to keep the airborne concentrations of vapours below their respective threshold limit value. Ensure that eyewash stations and safety showers are proximal to the workstation location.

Personal Protective Equipment

The following personal protective equipment is recommended when handling cresols:

  • Splash goggles;
  • Lab coat;
  • Vapour respirator (be sure to use an approved/certified respirator or equivalent);
  • Gloves

Personal Protection in Case of a Large Spill:

  • Splash goggles;
  • Full suit;
  • Vapour respirator;
  • Boots;
  • Gloves;
  • A self-contained breathing apparatus should be used to avoid inhalation of the product.
  • Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.

Regulation

United States [7]

OSHA: The Occupational Safety & Health Administration has set the following Permissible Exposure Limit (PEL) for cresols:

  • General Industry: 29 CFR 1910.1000 Table Z-1 – 5 ppm, 22 mg/m3 TWA; Skin
  • Construction Industry: 29 CFR 1926.55 Appendix A – 5 ppm, 22 mg/m3 TWA; Skin
  • Maritime: 29 CFR 1915.1000 Table Z-Shipyards – 5 ppm, 22 mg/m3 TWA; Skin

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 [8]

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.

References

http://en.wikipedia.org/wiki/Cresol

http://www.atsdr.cdc.gov/tfacts34.pdf

http://www.epa.gov/ttn/atw/hlthef/cresols.html

http://www.atsdr.cdc.gov/phs/phs.asp?id=944&tid=196

http://www.cdc.gov/niosh/docs/81-123/pdfs/0154.pdf

http://www.sciencelab.com/msds.php?msdsId=9923569

https://www.osha.gov/dts/chemicalsampling/data/CH_229800.html

http://www.safeworkaustralia.gov.au/sites/swa/about/Publications/Documents/772/Workplace-exposure-standards-for-airborne-contaminants.docx