Xylene Fact Sheet

Source of Exposure

Xylene is used in a variety of solvent applications for gums, synthetic resins, rubbers, paints, and inks. It is also used photographic processes and in the manufacture of insecticides and plastics. Xylene can be found in degreasing agents, cleaners, and petroleum products. Exposures occur through inhalation of vapors and directly through the skin.

Symptoms

Xylene will cause depression of the central nervous system. This narcotic effect will impair performance and affect cerebral function. Other symptoms are erythema, defatting dermatitis, conjunctivitis, renal damage, and paresthesias of the extremities. Xylene has been shown to cause mild hematopoietic system toxicity in experimental animals.

Blood Concentrations

Data shows that the general population background in whole blood for xylene is approximately 3.0 PPB. (EHS data) The Threshold Limit Value for xylene has currently been set at 100,000 PPB for ambient air. Workers exposed to the TLV for 8 hours had blood levels of xylene of 1100 PPB (Egstrom et al).

Toxic Levels

Blood levels of xylene of 2100 PPB have caused irritation of membranes, dizziness, nausea, vomiting, and incoordination (Savolainen et al. 1979). Air concentrations approaching 10,000,000 PPB have caused unconsciousness and even death due to depression of the central nervous system. Individuals who have been sensitized may manifest negative health effects at concentration well within the ranges considered safe for the average population. (See Chemically Hypersensitive Patients.)

Metabolism

Xylene is metabolized at a half-life rate of 20 to 30 hours. Only about 5% of xylene is exhaled unchanged. The balance of the exposure is metabolized by the oxidation of a methyl group to toluic acid. The toluic acid is converted to methylhippuric acid and excreted in the urine.

Summary

Classification: Aromatic Solvents
Population Average: 3.0 PPB (whole blood)
Threshold Limit Value: 1,100 PPB (whole blood) 100,000 PPB (air)
Onset of Symptoms: 2,100 PPB (whole blood) 200,000 PPB (air)
Death: Data not available
LD 50: (oral-rat) 5,000 mg/kg

References

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