Safety tests on vegetables from fields where slurry was dumped illegally have been carried out as part of a wider investigation into the illegal practice.

Clive Tonna from the environmental health directorate yesterday said the investigation included a sampling programme that also studied produce from fields unaffected by slurry.

It is a liquid form of manure and it has been illegal since 2011 to dump it on to fields.

Times of Malta has been reporting on the illegal practice for months on end, sparking an investigation by the Ombudsman.

According to Dr Vasilis Valdramidis from the University of Malta’s food studies department, the presence of slurry in fields tends to increase the risk of bacteria in the produce. While washing vegetables can eliminate surface bacteria, this will not remove bacteria that can be internalised. Mr Tonna said the results of the study should be out soon and the report will be passed on to the Ombudsman.

He would not quantify the percentage of fields studied, insisting the department wanted to wait for the results to be published.

However, he said every field that was reported as having slurry dumped on it was investigated.

They were speaking at a forum on food safety organised as part of the science festival in Valletta, Science in the City, co-hosted by the University of Malta and supported by Times of Malta.

Chemist Alfred Vella focused on chemical contamination carried by dust, pointing a finger at a number of causes including traffic and fireworks.

Mario Caruana, a nutritionalist and researcher, said although chemical contaminants were widespread, it did not mean people should stop consuming vegetables because the level of risk depended on how much was ingested and over what period of time.