Insights into the Uptake Processes of Wastewater-Borne Pharmaceuticals by Vegetables Myah Goldstein, †,‡ Moshe Shenker, † and Benny Chefetz* ,†,‡ † Department of Soil and Water Sciences, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel ‡ The Hebrew University Center of Excellence in Agriculture and Environmental Health, P.O. Box 12, Rehovot 76100, Israel * S Supporting Information ABSTRACT: An increasing number of reports on plant uptake of pharmaceutical compounds (PCs) have been recently published, raising concerns of human exposure through dietary intake. In this study, PC uptake and translocation were evaluated in cucumber and tomato plants to elucidate the effects of PC physicochemical properties, soil type, and irrigation-water quality. Nonionic PCs were taken up and accumulated at higher levels in plants grown in soils of lower organic matter and clay content. While the concentration of most PCs in cucumber and tomato leaves were of similar order, their concentrations in the tomato fruit were much lower than in the cucumber fruit. This is related to differences in fruit physiology. Our data suggest that irrigation with treated wastewater reduces the bioavailability of acidic PCs for uptake by cucumber plants as compared to fresh water irrigation. This study sheds light on factors affecting the uptake of PCs by crops irrigated with treated wastewater, the governing role of PCs’ physicochemical properties along with the physiological nature of the plant, soil properties and water quality that together determine uptake, translocation, and accumulation within plant organs. Occurrence of metabolites in plant suggests that PC metabolism has to be evaluated to reveal the total uptake. ■ INTRODUCTION The growing demand for water in arid and semiarid regions exceeds the supply of renewable fresh water (FW) resources. Thus, treated wastewater (TWW) is becoming an important source of water for irrigation. For example, in Israel, more than 85% of TWW is used for crop irrigation; in Spain, ∼71% and in California, ∼46% of reclaimed wastewater is utilized in agriculture. 1 Thus, TWW makes up 50% of the total irrigation-water use in Israel, 17% in Spain, and only 6% in California. Organic pollutants, including endocrine-disrupting compounds, active pharmaceutical compounds (PCs), and other synthetic compounds have been detected in streams across the US receiving inputs of TWW. 2 Similar findings have been reported for river water receiving TWW in Europe 3-5 and China. 6 PCs have also been detected in TWW used for irrigation in different countries. 4,7-9 In the past few years, there has been an increase in the number of publications on plant uptake of PCs, showing that once in the agricultural environment, organic pollutants and various PCs have the potential to be taken up by crops. 9-17 Boxall et al. 11 reported uptake at high levels of certain veterinary medicines with a range of lipophilicity in lettuce leaves and carrot roots. Another study reported that bioaccumulation of neutral PCs by cabbage and Wisconsin Fast Plants is higher than that of positively charged PCs under hydroponic conditions. 12 Accumulation of PCs at higher levels in plant roots than in aboveground compartments was reported for barley and carrots grown in soils spiked with PCs. 13 Distribution in the aboveground organs has also been observed, with higher bioaccumulation in leaves than in fruit. 9 The proportion of an organic compound taken up by plant roots and its transportation route within the plant depend largely on its physicochemical properties. 18 Lipophilicity and charge play major roles in transport following root uptake. 19,20 Thus, the octanol-water partition coefficient (K ow ) has been suggested as a reliable predictor of uptake behavior. 19 However, for weak acidic and weak basic compounds which can be ionized based on the pH of the soil solution as well as the pH of the plant compartment, K ow cannot be used as a suitable parameter to predict uptake. Uptake of weak acids increases as the pH of the external solution decreases, due to higher diffusion of the undissociated molecule across the cell membranes. Due to the higher pH inside the apoplast, dissociation occurs, and the anion cannot easily pass back through the lipophilic membrane, thus causing the molecule to accumulate within the cell. This process is known as ion- trapping. 21 Positively charged compounds are likely to bind to the negatively charged cell walls, reducing their translocation in the plant. Lipophilic compounds, due to their ability to Received: February 19, 2014 Revised: April 17, 2014 Accepted: April 21, 2014 Published: April 21, 2014 Article pubs.acs.org/est © 2014 American Chemical Society 5593 dx.doi.org/10.1021/es5008615 | Environ. Sci. Technol. 2014, 48, 5593-5600