Uptake, translocation, and accumulation of pharmaceutical and hormone contaminants in vegetables

The widespread occurrence of pharmaceuticals and personal care products (PPCPs) and natural hormones in watersheds has been recognized as an emerging environmental issue. Potential uptake and internalization of these emerging contaminants by food plants that are irrigated with contaminated water is becoming a food safety issue. In the present study, uptake, translocation, and accumulation of seven PPCPs and three steroid hormones in lettuce and tomato plants grown under hydroponic conditions were investigated. An isotopic dilution method was developed for the analysis of trace levels of PPCPs and hormones in vegetables using liquid chromatography-tandem mass spectrometry (LC-MS/MS), combined with ultrasonication-shaking extraction and solid phase extraction (SPE) cleanup for sample preparation. All target PPCPs and hormones were detected in the lettuce and tomato roots with concentrations ranging from 12.5 μg kg^-1 up to 20.9 mg kg^-1 when the plants were grown in hydroponic solutions containing each compound at 50 μg L^-1. This result indicates that these contaminants can be bound to or taken up by the plant roots. Interestingly, the concentrations of caffeine (CAF) and carbamazepine (CBZ) in lettuce and tomato leaves were much higher than those in roots, suggesting that these two PPCPs can easily translocate from plant roots to leaves via water transpiration and thereby accumulate in plant leaves. For other target PPCPs and hormones, the translocation factor (TF) values were very small in lettuce and tomato plants, implying poor translocation of these chemicals from roots to above-ground plant parts following uptake. The bioaccumulation factors (BAFs) in tomato fruits for all target compounds except CBZ were much less than 1. By contrast, three PPCPs had BAFs >15 in lettuce leaves, indicating there may be potential risk of exposure to these contaminants through consumption of this leafy vegetable.