Workers Exposure to Sewage Safety

This safety Flash serves as a guide to assist employers, supervisors, contractors, sub-contractors and workers in understanding the risks of exposure to sewage and minimizing exposure to it.

People who may be at risk of exposure are:

• workers involved with sewer inspection and maintenance work
• workers working with portable toilet systems
• workers at sewage treatment plants
• agricultural and forestry workers who may be exposed to sewage sludge
• sludge tank drivers/operators
• plumbers

Hazards:

Biological
The potential for illnesses from contact with viruses, bacteria and other microorganisms in sewage is valid, but limited in possibility. The most serious viral risk is hepatitis and the most serious bacterial risk is tetanus. The main route of exposure is hand-to-mouth contact. Breathing in a suspension of particles (aerosols) is a less common means of exposure but may occur whenever sewage is agitated, such as near incoming wastewater inlets and sludge treatment areas.

Chemical
Sanitary sewers and similar confined spaces containing sewage can sometimes be deficient in oxygen due to organic oxidation and displacement by carbon dioxide. They can also contain flammable gases such as methane and toxic gases such as carbon monoxide and hydrogen sulphide. Carbon monoxide, carbon dioxide, and other exhaust gases may sometimes be present due to a poorly located gasoline engine or generator exhausting into the confined space.