Benzene Testing

Our Benzene Exposure Biomonitoring service analyses urine samples as part of routine or post incident testing, to help assess the protection measures in place for occupational benzene exposure, to ensure they are working or are being used correctly.

Benzene is a highly flammable liquid that occurs naturally in crude oil and natural gas. You may be exposed to benzene if you work in certain environments, such as oil refineries, chemical and petrochemical plants or the storage, distribution and use of petrol or benzene.

Our service uses liquid chromatography tandem mass spectrometry (LC-MS/MS) to test for levels of S-phenyl mercapturic acid (S-PMA). S-PMA is a metabolite of benzene and indicates total benzene exposure from all sources, whether by vapour inhalation, ingestion or absorption through the skin. S-PMA is therefore recognised as the best biomarker of occupational benzene exposure.


  • Effective risk prevention measure and risk assessment tool
  • Simple non-invasive urine sample collection provides minimal disruption to workflow
  • S-PMA is recognised as the most sensitive biomarker of occupational benzene exposure

Benzene, also known as benzol, is a colourless, flammable liquid with a sweet odour. Benzene is among the 20 most widely used chemicals in the United States as it is used as a starting material in making other chemicals, including plastics, lubricants, rubbers, dyes, detergents, drugs, and pesticides. Benzene is also a natural part of crude oil and gasoline (and therefore motor vehicle exhaust), as well as cigarette smoke.

Individuals that are employed in industries that make or use benzene are at most risk of exposure to high levels of benzene. These industries include petrochemicals, petroleum refining, storage or transport of benzene and petroleum, rubber manufacturing, printers, shoe makers, laboratory technicians, firefighters, and petrol station employees.

Benzene Exposure

As benzene evaporates so quickly, the most common method of exposure is by breathing air containing benzene. When exposed to high levels of benzene in air, about half of the benzene breathed in passes through the lining of the lungs and enters the bloodstream. Benzene can also be absorbed through the skin during contact with a source such as gasoline.

Measuring benzene exposure

When the body absorbs benzene, it will naturally produce; S-phenyl mercapturic acid (S-PMA) as part of the metabolic process, so a positive test for S-PMA will indicate benzene exposure only. The S-PMA test is sufficiently sensitive to meet occupational exposure limits of 1 ppm (parts per million) and lower.

Once in the bloodstream, benzene travels throughout the body and can be temporarily stored in the bone marrow and fat. The metabolites of benzene damage the bone marrow and immune system leading to the loss of both white and red blood cells (aplastic anaemia).

Brief exposure (5–10 minutes) to very high levels of benzene in air (10,000–20,000 ppm) can result in death. Lower levels (700–3,000 ppm) can cause drowsiness, dizziness, rapid heart rate, headaches, tremors, confusion, and unconsciousness.

Benzene is a known carcinogen and long-term exposure can cause leukaemia and other diseases affecting the bone marrow. The seriousness of poisoning caused by benzene depends on the amount, route, and length of time of exposure, as well as the age and pre-existing medical condition of the exposed person.

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