Vegetables Treated with Irrigated Wastewater Worsen Human Exposure to Prescription Drugs
As water shortages increase globally, reusing water for agriculture and household purposes is on the rise too. A recent study by a multidisciplinary team of researchers from the Hebrew University of Jerusalem and Hadassah Medical Center, discovered that consuming food grown in soils irrigated with reclaimed water increases levels of carbamazepine, an anti-epileptic medication frequently detected in wastewater, reports Eurekalert.
Drugs make their way into the water supply through the urine of people who take them, and from people flushing prescription medications down the toilet. Water disposed of by pharmaceutical companies also contains pharmaceutical residues. Unfortunately, treatment for waste water used in agriculture usually does not remove these compounds
Exposing pharmaceutical contaminant exposure
The recent study, published in the journal Environmental Science and Technology, was the first time researchers examined the impact pharmaceutical contaminant exposure has on human health. “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,” co-author of the study, Prof. Benny Chefetz from the Faculty of Agriculture, Food and Environment at the Hebrew University, said in a press statement.
“In a randomized controlled trial we have demonstrated that healthy individuals consuming reclaimed wastewater-irrigated produce excreted carbamazepine and its metabolites in their urine, while subjects consuming fresh water-irrigated produce excreted undetectable or significantly lower levels of carbamazepine,” added lead researcher of the study, Prof. Ora Paltiel, Director of the Hebrew University-Hadassah Braun School of Public Health and Community Medicine.
The study tracked 34 men and women who were given vegetables to consume relative to their normal dietary habits. The participants were divided into two groups. During the first week, one group received vegetables grown on a farm irrigated with reclaimed wastewater, whereas the other group received vegetables grown on an organic farm with freshwater. During the second week, the groups switched vegetables: The first group ate vegetables from the organic farm and the second group ate vegetables from the irrigated farm. All the participants were given water from the researchers to drink to control their water exposure
Carbamazepine concentrations spike
The researchers tested the participants’ urine levels for carbamazepine with a chromatography and mass spectrometry-based method. At the beginning of the study, the baseline levels of carbamazepine differed significantly. Some participants had measurable concentrations of carbamazepine, while others did not. After consuming vegetables grown in reclaimed waste water for a week, however, all the participants excreted detectable levels of the drug.
“Treated wastewater-irrigated produce exhibited substantially higher carbamazepine levels than fresh water-irrigated produce,” noted Prof. Paltiel.
“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,” she added.
“This study demonstrates ‘proof of concept’ that human exposure to pharmaceuticals occurs through ingestion of commercially available produce irrigated with treated wastewater, providing data which could guide policy and risk assessments,” said Prof. Chefetz.
Exposure levels may be significantly greater in other countries where waste water is not adequately treated before it’s reused as it is in Israel. Alistair Boxall, a professor of environmental sciences at the University of New York who was not involved in the study, told sources, “This fits what we’ve all suspected but have not shown experimentally, ” adding, “We don’t really know much yet about the effects of low-level but very long-term exposure.”
Paltiel’s group plans to determine if children, the elderly, pregnant women and vegetarians are more exposed to carbamazepine, and whether that exposure has long-term side effects. “Reclaimed wastewater can be a partial solution to agricultural problems in semi-arid regions, but we have to be cognizant that there are potential exposures from this,” she said.