Scientists at Cork Institute of Technology have called for the nationwide testing of Irish freshwater supplies for the presence of a lethal toxin found in algal bloom.
Microcystin toxins produced in blue-green algae which proliferate at this time of year can cause liver damage and even death if ingested in sufficient quantities.
While not all algal blooms are toxic, Dr Ambrose Furey of CIT has found that up to 70 per cent of blooms found in Irish waters are and should be treated as a potential health hazard. He says councils need to test water used for drinking or recreation to establish whether the toxins, which can survive long after the bloom had faded, are present. Dr Furey and another CIT scientist, Dr Kevin James, have developed a new test for microcystins which can establish whether any toxin is present. The test can be carried out within a day using a small sample of water, whereas existing tests take weeks and require a large volume of water.
"In the past, testing for microcystins was lengthy, complicated and not very sensitive. Therefore, profiling of all of the surface waters in Ireland was an insurmountable task," he explained. With the new test, however, regular monitoring of lakes and other water sources is feasible for the first time.
The Environmental Protection Agency said a system has been established to look at the pre-sence of cyanobacteria, which produce microcystins, in lake water. "Algal samples are already being collected by local authorities and are being sent to the EPA. We will have them analysed and will report on them in due course."
Separately, the Marine Institute tests sea waters for algal toxins because they can accumulate within shellfish and pose a health hazard to consumers.
Algal blooms are a growing problem in many parts of the world with eutrophication - the enrichment of waters with plant nutrients, caused by run-offs of fertilisers and detergents - blamed as a major factor. The problem is worst in high summer, when the surfaces of many Irish rivers and lakes can become choked with algae.
Symptoms of severe microcystin poisoning are diarrhoea, vomiting and pallor. The toxins have been found to double the size of the livers of laboratory mice and also promote tumours.
In China, the incidence of liver cancer in populations that drink pond water containing microcystins was found to be eight times that of people drinking spring water. In one incident in Brazil, 50 patients at a dialysis centre died in 1996 from the effects of drinking lake water contaminated with toxins.
The scientists have found levels of microcystins up to 20 times the internationally permitted limited of 1 microgram per litre in some Irish reservoirs, but Dr Furey says there is no evidence that drinking water is affected. Microcystins are killed by the addition of chlorine.
