Updated 2 hours ago
THERE HAS BEEN an explosion of sea swimming in Ireland in recent times, and with that comes a demand for the best, up-to-date and detailed information about water quality.
Some 73% of the 148 beaches and lakes which are formally designated as swimming spots are deemed to be of an excellent standard under EU testing rules. Overall, 96% meet the minimum standards.
But there is a deeper and more detailed way to analyse the level of pollution, which is not only more revealing but also more concerning. We, a group of researchers at NUI Galway Antimicrobial Resistance and Microbial Ecology (ARME) group have done just that.
For several years, our team has been taking 30 litre samples from swimming spots and beaches around Galway, Cork and north Dublin. Our fieldwork and lab analysis found organisms of public health concern in bathing waters – some of which are designated as of excellent quality.
As well as that, in three pieces of research since 2017 we have reported the detection of antibiotic-resistant bacteria in swimming spots that are designated as of good or excellent quality.
This raises the question as to whether the EU sanctioned testing regime is good enough. The sampling and analysis for the Environmental Protection Agency’s Bathing Water Quality Report are based on the EU Water Framework Directive. Those regulations require local authorities to carry out sampling and testing at least once a month between 1 June and 15 September.
The teams gather samples of water, approximately one litre, from the beaches and swimming spots and they analyse 100 millilitres of the water for bacteria that is found in faeces.
They get two outputs – the most probable number of E. coli present and the most probable number of Intestinal Enterococci present. Based on the number of these in the sample, the waters are designated excellent, good, sufficient or poor.
We do not believe those quality standards are high enough. And here’s why. One part of the research carried out by ARME involved 30 litre samples being taken from 50 locations around Galway, Cork and Fingal, Dublin over several years.
We ran the same tests as the local authority, with the same sample volume. But, we also ran the rest of our 30-litre samples through a special filter to catch any bacteria present. We then carried out molecular tests on extracted DNA in the search for a pathogenic form of E. coli called Shiga-toxigenic E.coli (STEC).
We detected this virulent bacteria in 57% of 84 seawater samples we analysed, some of which were from waters deemed to be excellent quality under the EU standards. The bacteria was also found in 78% of 27 lake and river samples we collected since 2016.
The discovery is not a one-off, nor is it isolated. Shiga-toxigenic E.coli (STEC) is carried naturally by cattle and sheep but it is a risk to humans and a very small quantity has the potential to do us serious…