CHEMICAL INFORMATION SHEETS > BENZENE

ENVIRONMENTAL HEALTH DATA SEARCH
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CAS REGISTRY NUMBER: 71-43-2

CHEMICAL FAMILY: Aromatic hydrocarbon

MOLECULAR FORMULA: C6-H6

DESCRIPTION: Clear, colourless liquid with an aromatic odour.

Agricultural - Solvent for pesticides

Industrial - Predominantly industrial Solvent

Domestic -

USAGE: Used in the manufacture of medicinal chemicals, dyes, plastics, textiles, detergents, artificial leather, varnishes, paints, lacquers, waxes and many other materials. Solvent for inks, paints, rubber, adhesives, coatings, detergent and pesticides. Benzene is found in coal tar distillates, petroleum naphtha and gasoline.

TOLERANCE & EXPOSURE LEVELS: Odour Threshold 5 ppm (Canada)

ROUTES OF EXPOSURE: The primary routes of exposure are inhalation of contaminated air (areas of high traffic, filling stations, industry, cigarette smoke) and consumption of contaminated drinking water (leaking underground petrol tanks). Benzene is detected in various foods. (5)

HEALTH EFFECTS:

SHORT-TERM: Benzene is a fat solvent that causes CNS dysfunction and the destruction of other tissues.(2) Short term exposure can cause drowsiness, dizziness, headache, lightheadedness, nausea, and decreased coordination. Benzene vapour can cause mild irritation of the respiratory tract. Absorbed slightly through the skin. (1) Other acute effects include anorexia, bone marrow depression, eye irritation, hallucinations and muscle twitching. (2)

LONG-TERM: Benzene can impair the formation of red and white blood cells and platelets. Prolonged low level exposure can damage the nervous system and may also cause lesions resembling first or second degree burns. (1) Other chronic effects are cardiac sensitisation, CNS injury, hepatic damage, internal hemorrhage, disturbed iron metabolism, spleno-adrenomegaly and myocardial changes.(2)

CARCINOGENICITY: Can cause cancers of the white blood cells (leukemias). Carcinogen A2 (1) IARC Classification: Group 1

MUTAGENICITY: Benzene can cause chromosomal aberrations in heavily- exposed workers. (1)

REPRODUCTIVE EFFECTS: Benzene can cross the placental barrier and can be present in the fetal blood. It can also cause menstrual disorders. (1)

BIO-ACCUMULATION: Benzene can be stored temporarily in fat. Elimination may take more than five days after exposure has stopped.(1) Detected in 8 samples of mothers milk in U.S urban areas. Using whole blood, 250 subjects ranged from not detected to 5.9ppb, 0.8ppb average. In U.S. National Human Adipose Tissue Survey, 46 specimens had 96% had >4ppb with a maximum of 97ppb.(5) Detected in breath of person without specific exposure at 8-20ppb. (5) Detected in blood samples from children on the North Coast,NSW. (3)
Suspected Effects:Bronchiogenic carcinoma, Hodgkins disease, lymphosarcoma malignant lymphoma, multiple myeloma, mutagenisis, myeloid metaplasia, myocardial sensitisation to epinephrine, paroxysmal nocturnal hemoglobinuria, prenatal damage, postnatal damage and reproductive system damage.(2)

ANIMAL TOXICITY DATA: LD50 (oral, rat): 4894 mg/kg LD50 (oral, rat): 5.6 g/kg LC50 (rat): 16000 ppm/4 hr LC50 (rat): 10000 ppm/7 hr Rats exposed to 20ppm, 8hours per day, 5 days per week for 90 days developed a severe decrease in the number of white blood cells. (1)

REPRODUCTIVE EFFECTS: May cause reduced fetal weight and growth. There is some indication of fetotoxicity with doses which are not necessarily toxic to the dam. (1)

MUTAGENICITY: Wildlife Data: Benzene is not expected to bioconcentrate in aquatic organisms. (5)

ENVIRONMENTAL EFFECTS: Environmental Fate: When released into the atmosphere, gas phase benzene will react with photochemically produced hydroxyl radicals and have a half life of 13.4 days. In polluted atmospheres reaction time is accelerated and half life is 4-6 hours. Products of photooxidation include phenols, nitrophenols, nitrobenzenes, formic acid and peroxyacetyl nitrate. (5) U.S. atmospheric concentrations:Rural: 1.4ppb avg. ('77-80,100sample) Urban: 2.8ppb avg. ('77-80,2292sample) Benzene is fairly soluble in water and is removed from air by rain. In a marine environment, half lives varied from 3.1 days in summer to 23 days in spring. Little degradation occurring in winter. (5) When spilt on soil benzene will rapidly volatilise near the surface. What isn't evaporated will be highly to very highly mobile in soil and will leach to groundwater. (5)

EPA DATA GAPS:

NOTES: Restricted usage in 6 countries. (4)

** Disclaimer: These sheets are designed as summary information and as such are a guide only. The information is compiled from publicly available references which can be supplied on request.

References:

1.Canadian Centre of Occupational Health Database - CCINFO

2.Pesticides and Human Health, W.H.Hallenbeck&K.M.Cunningham-Burns School of Public Health, Uni. of Illinois Chicago, Springer-Verlag

3.Coffs Harbour Chemical Data Base 1991

4.Consolidated List of Products whose Consumption &/or Sale have been Banned, Withdrawn, Severely restricted or not approved by Governments.

5.Handbook of Environmental Fate and Exposure Data for Organic Chemicals, Vol1 Large Production and Priority Pollutants., Philip H. Howard 1989 Lewis Publishers Inc. USA