Israel is known as a leading innovator in maximizing the use of water and an important developer of water desalination and recycling techniques. But two recent studies show that the technologies are far from perfect and need improvement.
Researchers from the Hebrew University of Jerusalem and Hadassah Medical Center showed that vegetables and fruits grown in soils irrigated with reclaimed wastewater exposes consumers to minute quantities of pharmaceuticals that have not been filtered out of the water.
The study, recently published in the journal Environmental Science and Technology, found traces of carbamazepine — an anti-epileptic drug commonly sold under the brand names Tegretol, Equetro and Epit — in the urine of a test group of 34 men and women. At the initial measurement, most of the participants had very low, or undetectable levels of carbamazepine in their systems, but after a week eating wastewater-irrigated produce, their carbamazepine levels were “markedly higher” than the other group, said the researchers.
“Treated wastewater-irrigated produce exhibited substantially higher carbamazepine levels than fresh water-irrigated produce,” said Prof. Ora Paltiel, director of the Hebrew University-Hadassah Braun School of Public Health and Community Medicine, who led the research. “It is evident that those who consume produce grown in soil irrigated with treated wastewater increase their exposure to the drug. Though the levels detected were much lower than in patients who consume the drug, it is important to assess the exposure in commercially available produce.”
The study does not make recommendations on how to improve matters, but does say that more work is needed on filtration technology. Although the study showed that there was only trace materials of carbamazepine in the study subjects’ systems, it is possible that there are other pharmaceuticals floating around in recycled water that could be more problematic.
In a second study that is currently ongoing, researchers at Bar-Ilan University and Tel Hashomer Hospital have found a clear connection between the lack of magnesium in desalinated water and a higher death rate in cardiac patients. The results were based on 4,700 cases in the Acute Coronary Syndrome Israeli Survey, a long-term study which between 2002 and 2013 gathered detailed data about heart patients in Israeli hospitals.
Numerous studies have shown that magnesium is helpful for heart patients, and that even patients with significant cardiac problems (such as those who suffered heart attacks) benefit from taking magnesium supplements. Desalinated water – in which almost all minerals, including magnesium, are removed – began flowing through Israeli taps in 2006, in limited areas of the country (today, 75% of Israel’s water comes from desalinated sources).
The researchers looked at the death rates among cardiac patients between 2002 and 2006, and the death rates between 2008 and 2013. Among those patients, the researchers checked the rates between those who lived in and/or were treated at hospitals where the water was desalinated, and areas with “natural” water. The results showed that there was a “strong correlation” between higher death rates and desalinated water. A deeper examination of 211 patients in the desalinated areas showed that they had much lower levels of magnesium than patients (many of whom had recovered) in non-desalination areas.
As a correlative study, the Bar-Ilan/Tel Hashomer research did not break any new ground; indeed, even Israel’s Health Ministry is aware of the problem, and in 2010, it predicted that the annual death toll among cardiac patients in desalinated areas due to a lack of magnesium would be about 250 annually.
Since 2010, however, the amount of desalinated water in use in Israel has doubled. The Health Ministry already in 2010 recommended adding magnesium to desalinated water, but the Finance Ministry balked, as the program would have cost the state treasury NIS 350 million ($93 million) annually.
The researchers are hoping that the new study will swing attention back to the problem, and create public pressure on officials to add magnesium and other essential minerals in treated water.
In any event, the two studies show that even with the advances Israel has made in reclaiming water, more work is needed.
“Israel is a pioneer and world leader in reuse of reclaimed wastewater in the agriculture sector, providing an excellent platform to conduct such a unique study,” Prof. Benny Chefetz of the Hebrew University Faculty of Agriculture, Food and Environment, who led the Hebrew University study.
The study, said Chefetz, “demonstrates ‘proof of concept’ that human exposure to pharmaceuticals occurs through ingestion of commercially available produce irrigated with treated wastewater,” which, together with the second study, provides data that could guide policy and risk assessments.”