Urinary mandelic acid as an exposure test for ethylbenzene

Area of Science:

• Occupational Health
• Toxicology
• Environmental Health

Background:

• Ethylbenzene is an industrial solvent with potential health risks.
• Understanding ethylbenzene absorption and metabolism is crucial for occupational safety.
• Mandelic acid is a primary metabolite used to assess exposure.

Purpose of the Study:

• To quantify ethylbenzene absorption and mandelic acid excretion in humans.
• To determine the kinetics of mandelic acid elimination.
• To develop a reliable biological exposure index for ethylbenzene.

Main Methods:

• Controlled inhalation exposure of six volunteers to varying ethylbenzene concentrations (18-200 mg/m³).
• Measurement of lung retention of ethylbenzene vapor.
• Analysis of urinary mandelic acid for excretion and half-life determination.
• Dermal exposure tests to assess skin absorption.

Main Results:

• Lung retention of ethylbenzene was 49 ± 5%.
• Mandelic acid excretion followed a biphasic elimination pattern with half-lives of 3.1 and 24.5 hours.
• Excreted mandelic acid represented 55 ± 2% of retained ethylbenzene.
• Dermal exposure did not significantly contribute to ethylbenzene uptake.

Conclusions:

• The study established key pharmacokinetic parameters for ethylbenzene exposure.
• A validated biological exposure test for precise low-level ethylbenzene vapor assessment was developed.
• The skin is not a significant route for ethylbenzene vapor absorption.