Do stainless steel sinks raise risk of Legionnaires’?
‘Bacteria like corroded metal’
STAINLESS steel sinks and taps could increase the risk of killer lung disease Legionnaires’, according to a study.
they triple rates of the bacteria that cause the dangerous form of pneumonia.
Scientists have found the stainless steel corrodes within a few years, leaching iron into the water which deadly bugs can use to grow.
Most cases of Legionnaires’ come from cooling towers and large buildings such as hotels and hospitals, but studies have shown approximately one in five homes of patients with Legionnaires’ contain the legionella bacteria that cause it.
the disease can be deadly for the elderly and causes muscle pain, fever and confusion.
there have been 346 cases reported in england and wales so far this year.
Public Health england (PHe) advises that the danger from the bacteria, which multiply in artificial water supply systems, is higher when a household has not turned on the taps for a week – after being away on holiday, for example.
A study, led by Dutch safety engineer wilco van der Lugt and including PHe, compared stainless steel taps with traditional brass ones to examine the risk. It shows legionella germs are better able to survive and multiply in water samples from stainless steel thermostatic mixer taps, commonly used in showers – with 100,000 bacteria cells discovered per litre.
Mr van der Lugt said: ‘ Stainless steel taps were seen to corrode within just four years, producing the iron which we think legionella need to grow.
‘It solves a mystery for me, of why I was always seeing these bacteria in showers with thermostatic taps but less in showers with more traditional taps.’
Hugh Pennington, emeritus professor of bacteriology at Aberdeen university, said: ‘there is a theoretical risk of people getting Legionnaires’ disease if legionella bacteria is found in water from stainless steel taps.
‘the way to control it is to keep the taps properly maintained and make sure the water is nice and hot to kill off the bugs.’
He added: ‘In our homes, there is no Legionnaires’ protocol like there are in hospitals and hotels. but bacteria like corroded metal because they need iron to grow.’
experts say that to infect humans legionella need to be ‘aerosolised’, escaping into the air so we can breathe in the particles and become unwell.
In homes, that means showers, which break water droplets down into smaller particles, are a greater risk than kitchen sinks. Legionella bacteria thrive on rust from water pipes and can get more fuel from corroding taps.
In 2012 almost 100 people in edinburgh were struck down by an outbreak believed to be linked to industrial cooling towers, with four dying as a result.
the study, published in the International Journal of Hygiene and environmental Health and reported by New Scientist magazine, tested stainless steel, brass- ceramic and brass thermostatic mixer taps, monitoring them for more than three years.
when rust was combined with legionella bacteria in the stainless steel tap, half the water samples ended up infected.
that may be because coatings of stainless steel degrade over time if rust particles are present in the water. the brass mixer tap appeared to be safest.