Around 400,000 people using Irish water supplies are “possibly affected” by toxins that have been linked to cancers.
Correspondence between the Government and the European Commission from last year shows 412,000 people from 79 water supplies on the Environmental Protection Agency action list are “possibly affected”.
Irish Water confirmed that excess levels of trihalomethane had been detected in their supplies but they are refusing to contact those directly affected and instead say they are launching a campaign to raise awareness about the issue.
Trihalomethanes or THMs are a by-product of the water disinfection process. THMs are a chemical parameter for drinking water and are typically formed by the reaction of chlorine, used to disinfect the water, with natural organic matter like algae, twigs or leaves that may be present in the water.
Long-term exposure to THMs can lead to various types of cancers, such as bladder and colon, miscarriages, birth defects, and low birth rates. They may also cause damage to the heart, lungs, liver, kidney, and central nervous system.
Water supplies most affected are around Kerry and Cork, Kilkenny City, Waterford, Wicklow, Meath, Mayo, Roscommon, Donegal, and Galway.
Irish Water says that when ‘safe’ THM levels are exceeded, it passes the data to the HSE and requests a course of action to take. The utility also said it is currently in the process of developing a national THM Plan.
It is upgrading its chlorine dosing systems for all 856 water treatment plants in the country, and aims to reduce the amount of organic matter.
Because chlorinated water that is standing for six to eight hours begins to develop THMs and most Irish schemes hold water for two to five days, Irish Water says it plans to conduct a regular flushing of reservoirs and pipelines.
A joint paper from the Environmental Protection Agency and the HSA submitted to the European Commission said they accepted that international research shows “that there may be associations with human cancer”, it said there was no immediate risk from the excess of THMs that merited informing consumers.