The Effect of Soil Moisture Depletion on the Uptake of Pharmaceuticals into Edible Crops.

Reclaimed wastewater has been increasingly used for irrigation throughout the world, but questions remain about potential public health risks. The accumulation of emerging contaminants in crops has been proposed but little data exists regarding the uptake of these compounds by crops consumed fresh by humans. A series of greenhouse experiments were conducted to determine the potential for compounds found in treated effluent to accumulate in crops eaten fresh under different irrigation regimes. Atenolol, ofloxacin, and diclofinac were chosen as model compounds to determine uptake into the edible portion of crops. Crops were irrigated with waters having three concentrations of the drug and irrigation was timed to allow soil moisture depletion levels of 0.15, 0.25, and 0.4 bar corresponding to root zone concentration factors of 1.7, 2.5, and 3.1. Irrigation replenished the soil moisture to saturation and no overall leaching occurred. Compound uptake was related to compound concentration in the irrigation water and the soil moisture depletion level prior to irrigation.