Scientists studying levels of arsenic in the country’s groundwater have traced higher levels to areas rich in sandstone, in a study led by NUI Galway.
Arsenic levels breached World Health Organisation (WHO) limits of 10 parts per billion (ppb) in areas of Co Kerry, which was selected as a sample county.
The team from NUIG Earth and Ocean Sciences, Dublin Institute of Technology and the University of Limerick noted a link with sandstone as a “predictor”.
Arsenic is a chemical element that can occur naturally in many rock types. Its impact on human health through drinking water has only been widely acknowledged in the past 12 years. Research in 2007 estimated 137 million people in over 70 countries could be at risk.
Long-term exposure has been linked to developing lung, skin, and bladder cancer and heart disease, while short-term exposure to higher levels can cause vomiting, abdominal pain and diarrhoea.
Some 25% of drinking water in Ireland draws on groundwater, but this rises to 100% in certain locations.
Public supplies are routinely tested by the Environmental Protection Agency (EPA), but the onus is on private well owners to monitor quality.
There are an estimated 200,000 private domestic and farm boreholes in Ireland. Treatment for arsenic involves a type of filtration which has to be maintained and monitored regularly.
Kerry was selected for this latest research as a previous study in 2016 by the scientists had identified a small number of groundwater sources in the south-west, in south Mayo and in the north-east as “hot spots” for higher arsenic levels.
Kerry has good analytical infrastructure and expertise within the local authority, and is “one of the most intensively monitored regions in Europe for assessing groundwater quality”, lead scientist Dr Liam Morrison of NUIG said. In all cases, the well owners were notified by the researchers and advised on remedial action, he said.
The study, published in the journal, Frontiers in Environmental Science, identifies a relationship between arsenic and groundwater and surrounding sandstones, indicating geology as a “strong predictor”.
The scientists drew on three Co Kerry datasets; drinking water supplies, well water grant applications, and public groundwater sources — with the majority of samples coming from private sources.
The scientists say that more targeted studies in the future will be needed to “confirm this and understand local-scale variations”.
Dr Morrison said the research would help to develop “high quality public and private water supplies”.
The EPA has confirmed that arsenic levels are tested in public supplies, and it says that no arsenic was detected in any of these public supplies in 2017.
“Private well owners are responsible for testing their own wells,” the EPA said.