Lake water rife with cancer toxin
ENDA LEAHY
WATER tested in Irish lakes by a recent scientific study was found to have 20 times the World Health Organisation limit for a cancer-causing toxin but no tests for it are carried out in Ireland.
The chemicals, known as microcystins, cause cancer of the liver and are not covered by the Irish Drinking Water Regulations. The standard chlorination by most Irish treatment plants does not eradicate the toxins, and may even worsen contamination.
The PhD project by a student in Cork Institute of Technology (CIT) invented an ultra-sensitive method for rapid detection of the toxins, which form in blue-green 'cyanobacterial' algae blooms in Irish freshwaters in summer.
It was funded by the Environmental Protection Agency (EPA) and was published this month in the prestigious international journal Analytical Chemistry.The research supervisor for the study, Dr Ambrose Furey, says the findings are a warning to the Government that the toxins, which he describes as "potent tumour promoters", should be regulated. Numerous international studies have found that the toxins cause liver cancer.
Very high doses can cause death within hours. The only study of humans drinking water contaminated with microcystins, carried out in China, found levels of liver cancer seven times higher than the norm.
Dr Furey is now planning a national study of tap water later this year. High levels of nitrate and phosphate pollution of Irish waters have worsened the problem, and global warming is expected to make them more common.
The author of the study, Orla Allis, says no current regulations in Ireland cover microcystins and, while chlorine treatments can help, lower levels may paradoxically worsen contamination.
"Chlorine does degrade the cells which contain the toxins, but what happens a lot of the time is that the cell structure breaks and releases the toxins into the water."Very high concentrations of chlorine are required to get rid of these toxins, and I think the general trend around Ireland [in water treatment plants] would be quite low."
While the likelihood of widespread poisoning of tap water may be slim, there is no testing regime in Ireland.
"The health risks are quite serious," says Dr Furey. "A study in China found that if you take water from wells your chance of getting these blooms is very slim, but if you take water from ground and surface water, as we do, it's much higher. They found a seven-times higher chance of getting liver cancer in China by drinking water from surface lakes and reservoirs because of these compounds."
More than 240 people have contracted liver cancer in Ireland since 2000. No studies linking the toll to microcystins have yet been conducted.
