Bacteria may put sewage treatment workers at risk

By Amy Norton

NEW YORK (Reuters Health) – Exposure to bacterial toxins
may cause flu-like symptoms, breathing problems and skin
reactions in some workers at sewage treatment plants, a study
has found.

Researchers in the Netherlands found that workers at 67
sewage treatment plants had heightened risks of daily cough,
shortness of breath, skin rash and flu-like symptoms such as
headache and body aches and pains.

The culprit, say the researchers, seems to be the toxins
that are released from both sewage bacteria and the bacteria
that are used to remove pollutants from the wastewater.

Workers with higher exposure to the bacterial substances,
called endotoxins, tended to have more symptoms, according to
findings published in the American Journal of Industrial
Medicine.

However, symptoms were not limited to maintenance workers
and technicians; office staff, many of whom had cleaning tasks
that could expose them to endotoxins, also reported breathing
problems and other symptoms.

The findings indicate that workers at these plants should
be better informed about the potential risks of exposure to
biological agents, according to lead study author Lidwien A. M.
Smit, a researcher at the Institute for Risk Assessment
Sciences at Utrecht University.

Measures such as covering certain machines and other
sources of endotoxin exposure could help, she told Reuters
Health. There should also be mechanical ventilation in areas
where airborne particles from sewage or sludge may be present,
Smit added.

Though workers at the plants in this study wore masks
during certain, specialized jobs, she noted, they did not do so
for standard cleaning tasks around the plant.

The study included 468 employees at Dutch sewage treatment
plants who completed questionnaires on whether and how often
they suffered certain symptoms in the past year. At different
points over one year, some of the workers wore portable air
samplers that monitored their endotoxin exposure.

Smit and her colleagues found that workers had rates of
daily cough, shortness of breath and asthma that were roughly
50 percent higher than those in the general Dutch population.

In addition, flu-like symptoms, breathing problems and skin
irritation grew more common as workers’ endotoxin exposure
increased.

Respiratory and skin problems were also more common among
employees who had worked at the plants for more than 20 years,
suggesting that long-term exposure to bacterial toxins may be
especially likely to trigger those symptoms.

SOURCE: American Journal of Industrial Medicine, July 2005.