• Confirmed Human Carcinogen, International Agency for Research on Cancer (IARC)
• Non-threshold Toxicant, Canadian Environmental Protection Act (CEPA)
• Listed as a substance requiring a code of practice (Alberta OH&S Code, Schedule 1, Table 1)
• 8-Hour Occupational Exposure Limit: 1 ppm (Alberta OH&S Code, Schedule 1, Table 2)
• Substance Interaction: Substance may be readily absorbed through intact skin (Alberta OH&S Code, Schedule 1, Table 2)

Benzene is a natural component of petroleum and coal. Once widely used as a commercial solvent, benzene has largely been replaced with less toxic alternatives. However, it is still used as a chemical intermediate in the production of many organic chemicals. In the upstream oil and gas industry benzene may be present in emissions from stacks, flares, glycol dehydrators, tank vents, sumps and leaks. Benzene is present in ambient air from vehicle exhaust and other fuel burning processes, and in indoor air from cigarette smoke and building materials.

Exposure to benzene could result in minor health effects, debilitating illness, or death. Acute exposure can produce headaches at low concentrations (50 to 150 ppm), dizziness and rapid heart rate at higher concentrations, and can be fatal at 20,000 ppm. Chronic exposure can bring about severe physical damage or disease:

• reduced number of red and white blood cells or clotting cells;
• damage to bone marrow;
• Leukemia (ANLL – acute non-lymphocytic leukemia);
• cancers of the lymph system, lung, or bladder; and
• possibly, immune system changes as a result of damage to the blood system.
  

In the ambient (general) environment benzene may be inhaled by humans and animals, or it can react with other airborne pollutants to produce toxins such as phenol, nitrobenzene and formic acid. Benzene is not known to be present at levels of concern in food and drinking water, unless those sources have been directly contaminated. Non-occupational exposures are normally very low (ppb range). However, Environment Canada has classified benzene as a "non-threshold toxicant" – which means there is a chance of some adverse effects at any concentration.

In the workplace it’s important to identify whether benzene may be present. If so, an occupational health professional should assess potential routes of benzene exposure, as well as control measures in use. Exposure monitoring may also provide valuable information.

Benzene exposures must be taken seriously. Eliminate exposure where possible. Otherwise, ensure that effective measures to control benzene exposure are used in your workplace.