Study Finds Pharmaceutical Compounds in Treated Wastewater Accumulate in Plant Leaves

Compounds from psychoactive medications that are commonly found in treated municipal wastewater tend to accumulate in plant leaves when the water is used on crop plants, according to research by Johns Hopkins University. Researchers fed tomatoes, carrots, and lettuce a liquid growth solution that contained one of four medicines used to treat depression, bipolar disorder, and seizures. They found that plants absorbed and metabolized the epilepsy drug lamotrigine and its byproducts, but carbamazepine accumulated in higher concentrations across the plant tissues, including the edible carrot roots, tomato fruits, and lettuce leaves. Tomato leaves contained more than 200 times the concentration of pharmaceuticals than their fruits did, while the concentrations in carrot leaves were roughly seven-fold that of the edible roots. Researchers said that those concentrations are not cause for alarm; they only help to create a map of where the chemical compounds go.