Here's a way to fight the ongoing drought in California: use more wastewater for irrigation. The state's water board suggested that strategy a few years ago, but so far, of the trillions of gallons of water used for irrigation, only about six percent is wastewater. But in Israel, also notoriously dry, half the country's irrigation water is reclaimed water. The question is, could pharmaceutical residues, found in trace amounts in wastewater, make it into veggies—and onto your dinner plate?

Israeli scientists focused on an epilepsy drug called carbamazepine, often found in wastewater. They detected trace quantities in lettuce, parsley, peppers and other wastewater-grown veggies. They then fed volunteers either those veggies, or organic ones grown in freshwater. After a week, the wastewater group did indeed have significantly higher levels of the chemical in their urine, compared to the freshwater group. Switching to a freshwater-grown diet quickly reversed the effect. The finding is in the journal Environmental Science & Technology. [Ora Paltiel et al, Human Exposure to Wastewater-Derived Pharmaceuticals in Fresh Produce: A Randomized Controlled Trial Focusing on Carbamazepine]

One huge caveat: the amount of the drug in the volunteers' urine was some 40,000 times lower than would be found after just one therapeutic dose of the drug. And the researchers say it's unlikely that exposure to such tiny quantities poses any risk. But the result does suggest it's at least possible to ingest unwanted pharmaceuticals in your salad. Something for public health officials to investigate, as they weigh green water policy with what's in our greens.

—Christopher Intagliata

[The above text is a transcript of this podcast.]