A number of water sources used for drinking and irrigation contain trace amounts of potentially hazardous medicines, according to an ongoing Tel Aviv University study.

They have determined that antibiotics added to fishponds in the northern coastal plain have been seeping into groundwater sources used for drinking water and are calling for a halt to the use of such antibiotics or the introduction of measures to keep the drug residue from seeping into the water table. If current practices continue, they said, the groundwater should not be used for human consumption.

Open gallery view Dror Avisar in a field near his home on Zoran. Credit: Alon Ron

Another study analyzed samples of treated wastewater from a sewage plant in the Sharon region that is used for crop irrigation for the presence of amoxicillin, a common antibiotic. Byproducts of the drug were found in a number of the samples. Chronic exposure to these materials can result in an allergic reaction to the drug itself, the researchers said.

"It has become clear to us that various substances, including antibiotic drugs, break down in an ordinary environment into various byproducts, molecules that can be no less problematic than the original substance," Dr. Dror Avisar, head of the TAU hydrochemical laboratory, said. "Chemicals don't disappear, so scientists not only have to identify them but also must understand the processes they create in the environment," Avisar added.

Avisar and his team recently began attempting to replicate environmental conditions in the laboratory, in order to study the breakdown of drug compounds. Among the factors they have looked at are the effects of solar radiation, temperature and water acidity. They have identified nine byproducts of amoxicillin, two of which are potentially toxic.

Avisar said methods to remove drugs or hormones - another hazard - from wastewater can be developed. Hormones, even in small concentrations, have been found to cause serious harm to animals, even changing the sex of fish. For this reason, Avisar said, it is especially important that wastewater from hospitals be treated to remove such traces.

In related news, the European Union, which has also been concerned about the hazards of trace drugs and hormones in the public water supply, released a report last week recommended closer monitoring of contaminants in water sources.