BRITAIN鈥橲 largest power station could spread legionnaire鈥檚 disease over
a wide area 鈥榩resenting a potential health hazard to local residents鈥�, an
environmental health officer told the annual meeting of the National Society
for Clean Air this week.
Researchers at the department of microbiology in the University of Leeds
last year reported finding Legionella bacteria in water samples taken from
the cooling towers at Drax power station in Yorkshire. Some samples contained
more than a million bacteria per litre of water. The Drax cooling towers
use water drawn from the River Trent, which receives treated sewage from
nearby towns.
The warning came from Nevil Parkinson, chief environmental health officer
for Selby district, which includes Drax. He complained that the former owner
of the power station, the Central Electricity Generating Board, carried
out several studies of the growth of Legionella in cooling water systems
but never published the results.
Advertisement
There was, he said, very little published data on the water droplets
that emerge from the top of cooling towers or on any bacterial, viral or
chemical pollutants that they might harbour. A single independent study,
carried out over 10 days downwind of Drax four years ago, failed to find
any Legionella.
No outbreak of legionnaire鈥檚 disease has ever been traced to emissions
from cooling towers. But Parkinson argued that a number of cases of similar
diseases such as condenser cleaners鈥� disease and Pontiac fever diagnosed
before 1976 when Legionella was first identified and named, 鈥榳ere associated
with power station cooling water鈥�. American cleaners have contracted legionnaire鈥檚
disease after working in cooling towers. Research in the US indicated that
viable Legionella organisms may be carried for distances of up to 3 kilometres.
During dry weather last autumn the discharge of untreated sewage caused
Drax to emit silt with water droplets. The silt fell on local villages for
eight days.
