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Ethylbenzene
Ethylbenzene Toxic Tips INTRODUCTION
Mechanism of Action
Chemical Description
Ethylbenzene, C8H10, also known as ethylbenzol or phenylethane, is a flammable, colorless liquid with an aromatic odor.1 It is miscible with alcohol and ether and slightly soluble in water. The CAS registry number is 100-41-4. Its molecular weight is 106.16.2
In rat liver mitochondrial preparations, ethylbenzene inhibited glutamate oxidation by acting as a mitochondrial uncoupling agent.4 In rabbit brain tissue, ethylbenzene depleted dopamine during in vitro studies. Depletion of dopamine in the brain may account for changes in neurobehavioral test results in workers with ethylbenzene exposure.6
Uses and Typical Exposure Situations
Ethylbenzene is primarily used as an intermediate in the production of styrene and synthetic polymers in the plastic and rubber industries. It is also used as a solvent and component of automotive and aviation fuels. Exposure in the workplace is rare because ethylbenzene is usually present in complex mixtures such as gasoline or it is handled in closed systems in conversion to styrene. Worker exposures can occur during the manufacture and transportation of ethylbenzene, styrene monomer, cellulose acetate, and synthetic rubber. Ethylbenzene is also involved in the manufacture of paints, varnishes, and other surface coatings.3
CLINICAL PRESENTATION Effects Following Skin Exposure
This compound is a known skin irritant. Prolonged exposure to the skin can cause drying, scaling and blistering.3 Chronic exposure can cause dermatitis.1 Effects Following Inhalation
Ethylbenzene is a known respiratory and mucous membrane irritant. Prolonged high exposure can cause dizziness, light headedness, or loss of consciousness. High exposure can also cause liver damage. Very high levels can cause trouble breathing and even death.3 Chronic exposures to concentrations above 100 ppm cause fatigue and headache.1
METABOLISM AND PHARMACOKINETICS Eye Effects
Ethylbenzene is absorbed through the lungs and can penetrate the skin. Most ethylbenzene is metabolized by hepatic P450 enzymes into mandelic and phenylglyoxylic acids. These metabolites can be monitored in the urine to estimate exposure.4 Initial elimination halftime is 3–4 hours. Later, ethylbenzene is released slowly from the fat where the halftime is 24 hours. Metabolites are excreted in the urine and traces of unchanged ethylbenzene are excreted in the expired air.5
PATHOPHYSIOLOGY Determinants of Toxicity
The airborne concentration of ethylbenzene, the respiratory rate of the individual, and the time of exposure to the contaminated air will determine the amount of toxicant absorbed. The area of the skin exposed, concentration of the ethylbenzene, and length of time on skin contact will determine the amount absorbed through the skin.
1871-5532/$36.00 doi:10.1016/j.jchas.2010.11.005
Ethylbenzene is an irritant of the eyes and mucous membranes. At an airborne concentration of 200 ppm, it causes transient irritation of these structures. At 1,000 ppm, tearing and irritation occur; at 2,000 ppm, severe tearing and severe eye irritation occur; at 5,000 ppm, eye irritation is intolerable.1 Carcinogenicity
There is evidence that ethylbenzene is carcinogenic in animals. A chronic study in rats resulted in adenomas and carcinomas of the renal tubules.7 The International Agency for Research on Cancer (IARC) reports that ethylbenzene is possibly carcinogenic to humans (Group 2B).8 The American Conference of Governmental Industrial Hygienists (ACGIH) has given the A3 designation (confirmed animal carcinogen with unknown relevance to humans) to ethylbenzene.2 Reproductive Effects
There is limited evidence that ethylbenzene causes reproductive effects in animals. In a
ß Division of Chemical Health and Safety of the American Chemical Society Elsevier Inc. All rights reserved.
41
study of rats exposed during gestation, there was an increased number of dead or reabsorbed fetuses, as well as an increase in extra rib formation in pups.9
method 1501 for aromatic hydrocarbons recommends sampling using a solid sorbent tube with coconut shell charcoal, desorption with carbon disulfide, and analysis by gas chromatography with a flame ionization detector.11
2.
FIRST AID Exposure Guidelines
If skin contact occurs, immediately wash or shower with soap and water.3 Contaminated clothing should be removed immediately.1 If contact with the eyes occurs, irrigate them immediately with large amounts of water for at least fifteen minutes.10 If inhalation occurs, remove the individual from exposure. If breathing stops, begin rescue breathing and transfer the person to a medical facility.3
HANDLING AND STORAGE Accidental Release Measures
If a spill or leak occurs, evacuate all persons not wearing protective equipment from the area of the spill or leak; remove all ignition sources; cover the ethylbenzene with activated charcoal adsorbent and place it in a covered container for disposal. Avoid allowing any ethylbenzene from entering a confined space, such as a sewer, because of the possibility of explosive concentrations.3 Storage Guidelines
This compound must be stored in a flammable liquids storage room or cabinet separate from oxidizing materials.4 It should be in a tightly closed container that is grounded and placed in a cool, well-ventilated area. Only non-sparking tools should be used when opening and closing containers of ethylbenzene.3 Reactivities and Incompatibilities
Ethylbenzene is incompatible with oxidizers.4
EXPOSURE CONTROLS Sampling and Analysis
The National Institute for Occupational Safety and Health (NIOSH)
42
The Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for ethylbenzene is 100 ppm as an 8-hour time-weighted average (TWA) concentration. The NIOSH recommended exposure limits (RELs) are 100 ppm as a TWA for up to a 10-hour workday and a 40-hour workweek and 125 ppm as a shortterm exposure limit. The ACGIH threshold limit value (TLV) is 100 ppm as a TWA for a normal 8-hour workday and a 40-hour workweek and a short-term exposure limit (STEL) of 125 ppm for periods not to exceed 15 minutes.1 NIOSH recommends a level of 800 ppm as the Immediately Dangerous to Life or Health (IDLH) level.10
3.
4.
5.
6.
7. PERSONAL PROTECTION
Wearing solvent-resistant gloves and clothing will provide skin protection. Materials made of Barricade1, Viton1, or Teflon1 will provide greater than four hours of resistance to breakthrough.1,3 Indirect-vent, impact and splash resistant goggles will provide eye protection. Contact lenses must not be worn when working with ethylbenzene. When airborne exposures are expected to be over 100 ppm, a NIOSH approved full facepiece respirator with an organic vapor cartridge should be used. At higher exposures, increased protection is obtained by wearing the appropriate full facepiece powered air purifying respirator or supplied-air respirator or self-contained breathing apparatus.3 REFERENCES 1. Occupational Safety and Health Administration (OSHA). Occupational Safety and Health Guideline for Ethyl Benzene, accessed from http://
8.
9.
10.
11.
www.osha.gov/SLTC/healthguide lines/ethylbenzene/recognition.html on October 20, 2010. American Conference of Governmental Industrial Hygienists (ACGIH). 2010 TLVs and BEIs Based on Documentation of the Threshold Limit Values for Chemical Substances and Physical Agents & Biological Exposure Indices. ACGIH, Cincinnati, OH, 2010. New Jersey Department of Health and Senior Services. Hazardous Substance Fact Sheet for Ethylbenzene, accessed from http://nj.gov/health/eoh/rtkweb/ documents/fs/0851.pdf on October 20, 2010. National Library of Medicine. Hazardous Substances Data Bank (HSDB). Fact Sheet for Ethylbenzene, accessed from http://toxnet.nlm.nih.gov/cgi-bin/ sis/search/f?./temp/FLpnlj:1 on November 9, 2010. Zenz, C., Dickerson, O. B., & Horvath, E. P. (Eds.). Occupational Medicine. (3rd ed.). Mosby: St. Louis, MO, 1994. Triebig, G.; Claus, D.; Csuzda, I.; et al. Cross-sectional epidemiological study on neurotoxicity of solvents in paints and lacquers. Int. Arch. Occup. Environ. Health, 1988, 60, 233–241. National Toxicology Program (NTP). NTP Toxicology and Carcinogenesis Studies of Ethylbenzene (CAS No. 100-41-4) in F-344/N Rats and B6C3F1 Mice (Inhalation Studies). TR 466, 1-231. Natl. Toxicol. Program Tech. Rep. Ser. Research Triangle Park, NC, 1999. International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Some Industrial Chemicals, Volume 77, IARC, Lyon, France, 2000. Ungvary, G.; Tatrai, E. On the embryonic effects of benzene and its alkyl derivatives in mice, rats and rabbits. Arch. Toxicol. Suppl. 1985, 8, 425– 430. National Institute for Occupational Safety and Health (NIOSH). NIOSH Pocket Guide to Chemical Hazards. Ethyl benzene, accessed from http:// www.cdc.gov/niosh/npg/ npgd0264.html on November 7, 2010. National Institute for Occupational Safety and Health (NIOSH). Manual of Analytical Methods (NMAM)— Method 1501 for Hydrocarbons, Aromatic, accessed from http:// www.cdc.gov/niosh/docs/2003%2D 154/pdfs/1501.pdf on November 9, 2010.
Journal of Chemical Health & Safety, January/February 2011
Mechanism of Action
Chemical Description
Ethylbenzene, C8H10, also known as ethylbenzol or phenylethane, is a flammable, colorless liquid with an aromatic odor.1 It is miscible with alcohol and ether and slightly soluble in water. The CAS registry number is 100-41-4. Its molecular weight is 106.16.2
In rat liver mitochondrial preparations, ethylbenzene inhibited glutamate oxidation by acting as a mitochondrial uncoupling agent.4 In rabbit brain tissue, ethylbenzene depleted dopamine during in vitro studies. Depletion of dopamine in the brain may account for changes in neurobehavioral test results in workers with ethylbenzene exposure.6
Uses and Typical Exposure Situations
Ethylbenzene is primarily used as an intermediate in the production of styrene and synthetic polymers in the plastic and rubber industries. It is also used as a solvent and component of automotive and aviation fuels. Exposure in the workplace is rare because ethylbenzene is usually present in complex mixtures such as gasoline or it is handled in closed systems in conversion to styrene. Worker exposures can occur during the manufacture and transportation of ethylbenzene, styrene monomer, cellulose acetate, and synthetic rubber. Ethylbenzene is also involved in the manufacture of paints, varnishes, and other surface coatings.3
CLINICAL PRESENTATION Effects Following Skin Exposure
This compound is a known skin irritant. Prolonged exposure to the skin can cause drying, scaling and blistering.3 Chronic exposure can cause dermatitis.1 Effects Following Inhalation
Ethylbenzene is a known respiratory and mucous membrane irritant. Prolonged high exposure can cause dizziness, light headedness, or loss of consciousness. High exposure can also cause liver damage. Very high levels can cause trouble breathing and even death.3 Chronic exposures to concentrations above 100 ppm cause fatigue and headache.1
METABOLISM AND PHARMACOKINETICS Eye Effects
Ethylbenzene is absorbed through the lungs and can penetrate the skin. Most ethylbenzene is metabolized by hepatic P450 enzymes into mandelic and phenylglyoxylic acids. These metabolites can be monitored in the urine to estimate exposure.4 Initial elimination halftime is 3–4 hours. Later, ethylbenzene is released slowly from the fat where the halftime is 24 hours. Metabolites are excreted in the urine and traces of unchanged ethylbenzene are excreted in the expired air.5
PATHOPHYSIOLOGY Determinants of Toxicity
The airborne concentration of ethylbenzene, the respiratory rate of the individual, and the time of exposure to the contaminated air will determine the amount of toxicant absorbed. The area of the skin exposed, concentration of the ethylbenzene, and length of time on skin contact will determine the amount absorbed through the skin.
1871-5532/$36.00 doi:10.1016/j.jchas.2010.11.005
Ethylbenzene is an irritant of the eyes and mucous membranes. At an airborne concentration of 200 ppm, it causes transient irritation of these structures. At 1,000 ppm, tearing and irritation occur; at 2,000 ppm, severe tearing and severe eye irritation occur; at 5,000 ppm, eye irritation is intolerable.1 Carcinogenicity
There is evidence that ethylbenzene is carcinogenic in animals. A chronic study in rats resulted in adenomas and carcinomas of the renal tubules.7 The International Agency for Research on Cancer (IARC) reports that ethylbenzene is possibly carcinogenic to humans (Group 2B).8 The American Conference of Governmental Industrial Hygienists (ACGIH) has given the A3 designation (confirmed animal carcinogen with unknown relevance to humans) to ethylbenzene.2 Reproductive Effects
There is limited evidence that ethylbenzene causes reproductive effects in animals. In a
ß Division of Chemical Health and Safety of the American Chemical Society Elsevier Inc. All rights reserved.
41
study of rats exposed during gestation, there was an increased number of dead or reabsorbed fetuses, as well as an increase in extra rib formation in pups.9
method 1501 for aromatic hydrocarbons recommends sampling using a solid sorbent tube with coconut shell charcoal, desorption with carbon disulfide, and analysis by gas chromatography with a flame ionization detector.11
2.
FIRST AID Exposure Guidelines
If skin contact occurs, immediately wash or shower with soap and water.3 Contaminated clothing should be removed immediately.1 If contact with the eyes occurs, irrigate them immediately with large amounts of water for at least fifteen minutes.10 If inhalation occurs, remove the individual from exposure. If breathing stops, begin rescue breathing and transfer the person to a medical facility.3
HANDLING AND STORAGE Accidental Release Measures
If a spill or leak occurs, evacuate all persons not wearing protective equipment from the area of the spill or leak; remove all ignition sources; cover the ethylbenzene with activated charcoal adsorbent and place it in a covered container for disposal. Avoid allowing any ethylbenzene from entering a confined space, such as a sewer, because of the possibility of explosive concentrations.3 Storage Guidelines
This compound must be stored in a flammable liquids storage room or cabinet separate from oxidizing materials.4 It should be in a tightly closed container that is grounded and placed in a cool, well-ventilated area. Only non-sparking tools should be used when opening and closing containers of ethylbenzene.3 Reactivities and Incompatibilities
Ethylbenzene is incompatible with oxidizers.4
EXPOSURE CONTROLS Sampling and Analysis
The National Institute for Occupational Safety and Health (NIOSH)
42
The Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for ethylbenzene is 100 ppm as an 8-hour time-weighted average (TWA) concentration. The NIOSH recommended exposure limits (RELs) are 100 ppm as a TWA for up to a 10-hour workday and a 40-hour workweek and 125 ppm as a shortterm exposure limit. The ACGIH threshold limit value (TLV) is 100 ppm as a TWA for a normal 8-hour workday and a 40-hour workweek and a short-term exposure limit (STEL) of 125 ppm for periods not to exceed 15 minutes.1 NIOSH recommends a level of 800 ppm as the Immediately Dangerous to Life or Health (IDLH) level.10
3.
4.
5.
6.
7. PERSONAL PROTECTION
Wearing solvent-resistant gloves and clothing will provide skin protection. Materials made of Barricade1, Viton1, or Teflon1 will provide greater than four hours of resistance to breakthrough.1,3 Indirect-vent, impact and splash resistant goggles will provide eye protection. Contact lenses must not be worn when working with ethylbenzene. When airborne exposures are expected to be over 100 ppm, a NIOSH approved full facepiece respirator with an organic vapor cartridge should be used. At higher exposures, increased protection is obtained by wearing the appropriate full facepiece powered air purifying respirator or supplied-air respirator or self-contained breathing apparatus.3 REFERENCES 1. Occupational Safety and Health Administration (OSHA). Occupational Safety and Health Guideline for Ethyl Benzene, accessed from http://
8.
9.
10.
11.
www.osha.gov/SLTC/healthguide lines/ethylbenzene/recognition.html on October 20, 2010. American Conference of Governmental Industrial Hygienists (ACGIH). 2010 TLVs and BEIs Based on Documentation of the Threshold Limit Values for Chemical Substances and Physical Agents & Biological Exposure Indices. ACGIH, Cincinnati, OH, 2010. New Jersey Department of Health and Senior Services. Hazardous Substance Fact Sheet for Ethylbenzene, accessed from http://nj.gov/health/eoh/rtkweb/ documents/fs/0851.pdf on October 20, 2010. National Library of Medicine. Hazardous Substances Data Bank (HSDB). Fact Sheet for Ethylbenzene, accessed from http://toxnet.nlm.nih.gov/cgi-bin/ sis/search/f?./temp/FLpnlj:1 on November 9, 2010. Zenz, C., Dickerson, O. B., & Horvath, E. P. (Eds.). Occupational Medicine. (3rd ed.). Mosby: St. Louis, MO, 1994. Triebig, G.; Claus, D.; Csuzda, I.; et al. Cross-sectional epidemiological study on neurotoxicity of solvents in paints and lacquers. Int. Arch. Occup. Environ. Health, 1988, 60, 233–241. National Toxicology Program (NTP). NTP Toxicology and Carcinogenesis Studies of Ethylbenzene (CAS No. 100-41-4) in F-344/N Rats and B6C3F1 Mice (Inhalation Studies). TR 466, 1-231. Natl. Toxicol. Program Tech. Rep. Ser. Research Triangle Park, NC, 1999. International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Some Industrial Chemicals, Volume 77, IARC, Lyon, France, 2000. Ungvary, G.; Tatrai, E. On the embryonic effects of benzene and its alkyl derivatives in mice, rats and rabbits. Arch. Toxicol. Suppl. 1985, 8, 425– 430. National Institute for Occupational Safety and Health (NIOSH). NIOSH Pocket Guide to Chemical Hazards. Ethyl benzene, accessed from http:// www.cdc.gov/niosh/npg/ npgd0264.html on November 7, 2010. National Institute for Occupational Safety and Health (NIOSH). Manual of Analytical Methods (NMAM)— Method 1501 for Hydrocarbons, Aromatic, accessed from http:// www.cdc.gov/niosh/docs/2003%2D 154/pdfs/1501.pdf on November 9, 2010.
Journal of Chemical Health & Safety, January/February 2011