Over a quarter of people who took part in a University of Galway study on exposure to the herbicide glyphosate, were found to have traces of the chemical in their bodies.

Glyphosate is the worlds most common herbicide and is contained in over 750 products, including Roundup®. It is used as a weed killer in home gardens, parks, public spaces, lawns, and along roadsides. It is also extensively used in farming operations.

In what researchers say is the first study in Ireland to investigate background exposure to glyphosate, 226 people in 68 families were tested. 14 of the families lived on farms, with one of those family members spraying glyphosate-based herbicide. The study analysed tests from all 226 people along with a detailed dietary and lifestyle questionnaire.

Glyphosate was detectable in 26% of samples. There was no statistical difference between farm and non-farm families' exposures, though higher concentrations were detected among some fathers living on farms, likely because they sprayed glyphosate-based pesticide products the day before sampling for the study.

Dietary exposure to such pesticides can occur through ingestion of residues on fruit, vegetables, grains and contaminated water or via skin contact or inhalation exposure during home use of glyphosate-based pesticide products.

Glyphosate is the worlds most common herbicide and is contained in over 750 products (stock image)

The glyphosate levels found in positive samples were well below the levels the European Food Safety Authority (EFSA) says are acceptable without presenting an appreciable health risk.

The researchers behind the study say their findings are very important to understanding how people are exposed to such chemicals in their day to day environments. Dr Alison Connolly, exposure scientist at University of Galway, said: "This study produced important results on human exposures to a chemical of public concern and is particularly timely with the European Commission currently re-evaluating glyphosate.

"Though the quantifiable levels were low, it is essential to understand how chemical exposures can occur among different groups, particularly vulnerable people such as children."

Dr Connolly said the information is necessary for conducting robust regulatory risk assessments, managing exposure levels, and fully understanding their effect on human health.

"This study also demonstrated how beneficial human biomonitoring is for evaluating chemical exposures," she added.

Dr Marie Coggins, Senior Lecturer in Exposure Science at University of Galway said: "Although the exposure data reported is low compared to the current acceptable daily intake value set by EFSA, our risk assessment could change following the publication of EFSAs renewal assessment in early 2023."

Dr Coggins also said that the data suggests that occupational users may have a slightly higher exposure than background levels, which could and should be reduced further by substitution with less harmful methods, careful chemical handling practices and the use of exposure controls such as personal protective equipment.

The use of glyphosate in the EU is currently under review by the European Commission while debate continues about the possible adverse health effects from its use, including a risk of cancer.

However, EFSA currently concludes that glyphosate is unlikely to pose a carcinogenic hazard to humans and the results of this study are interpreted using the current EFSA acceptable daily intake.