Knowledge of the concentration of the bioavailable forms of mercury in the soil is necessary, especially, if these soils contain above-limit total mercury concentrations. The bioavailability of mercury in soil samples collected from the vicinity of abandoned cinnabar mines was evaluated using diffusive gradients in the thin films technique (DGT) and mercury phytoaccumulation by vegetables (lettuce, spinach, radish, beetroot, carrot, and green peas). Mercury was accumulated primarily in roots of vegetables. The phytoaccumulation of mercury into edible plant parts was site-specific as well as vegetable species-specific. The mercury concentration in edible parts decreased in the order: spinach leaf ≥ lettuce leaf ≥ carrot storage root ≥ beetroot storage root > radish storage root > pea legume. The translocation index as well as the target hazard quotient indicate the possible usability of soils from the vicinity of abandoned cinnabar mines for planting pod vegetables (peas). A strong positive correlation (r = 0.75 to 0.92, n > 30, p < 0.05) was observed between mercury concentration in secondary roots, the storage roots, leaves of vegetables and the flux of mercury from soil to the DGT units, and the effective concentration of mercury in soil solutions.

Metal concentrations (As, Cd, Pb, Cr, Ba, Co, Ni, Cu, and Zn) in conventional and organic produce were assessed, specifically, five most-consumed vegetables from the US including potato, lettuce, tomato, carrot and onion. They were from four representative supermarkets in a college town in Florida. All vegetables contained detectable metals, while As, Cd, Pb, Cr, and Ba are toxic metals, Co, Ni, Cu, and Zn are nutrients for humans. The mean concentrations of As, Cd, Pb, Cr and Ba in five vegetables were 7.86, 9.17, 12.1, 44.8 and 410 μg/kg for organic produce, slightly lower than conventional produce at 7.29, 15.3, 17.9, 46.3 and 423 μg/kg. The mean concentrations of Co, Ni, Cu, and Zn in five vegetables were 3.86, 58.5, 632, and 2528 μg/kg for organic produce, comparable to conventional produce at 5.94, 68.2, 577, and 2354 μg/kg. For toxic metals, the order followed tomato < lettuce < onion < carrot < potato, with root vegetables being the highest. All metals in vegetables were lower than the allowable concentrations by FAO/WHO. Health risks associated with vegetable consumption based on daily intake and non-carcinogenic risk based on hazard quotient were lower than allowable limits. For the five most-consumed vegetables in the US, metal contents in conventional produce were slightly greater than organic produce, especially for Cd and Pb.

With the increasing use of treated wastewater and biosolids in agriculture, residues of pharmaceutical and personal care products (PPCPs) in these reused resources may contaminate food produce via plant uptake, constituting a route for human exposure. Although various PPCPs have been reported to be taken up by plants in laboratories or under field conditions, at present little information is available on their metabolism in plants. In this study, we applied carrot cell cultures to investigate the plant metabolism of PPCPs. Five phase I metabolites of carbamazepine were identified and the potential metabolism pathways of carbamazepine were proposed. We also used the carrot cell cultures as a rapid screening tool to initially assess the metabolism potentials of 18 PPCPs. Eleven PPCPs, including acetaminophen, caffeine, meprobamate, primidone, atenolol, trimethoprim, DEET, carbamazepine, dilantin, diazepam, and triclocarban, were found to be recalcitrant to metabolism. The other 7 PPCPs, including triclosan, naproxen, diclofenac, ibuprofen, gemfibrozil, sulfamethoxazole, and atorvastatin, displayed rapid metabolism, with 0.4–47.3% remaining in the culture at the end of the experiment. Further investigation using glycosidase hydrolysis showed that 1.3–20.6% of initially spiked naproxen, diclofenac, ibuprofen, and gemfibrozil were transformed into glycoside conjugates. Results from this study showed that plant cell cultures may be a useful tool for initially exploring the potential metabolites of PPCPs in plants as well as for rapidly screening the metabolism potentials of a variety of PPCPs or other emerging contaminants, and therefore may be used for prioritizing compounds for further comprehensive evaluations.

Root crops, carrot and celeriac, were exposed to atmospheric deposition in a polluted versus reference area. An effect was observed on the As, Cd and Pb concentrations of the leaves and the storage organs. The concentrations in the whole storage organs correlated well with atmospheric deposition, which shows that they even could be used for biomonitoring. Nevertheless, leaves remain much more appropriate. The results revealed also a significant increase of the As and Cd concentration in the consumable part of the storage organs as a function of their atmospheric deposition. As such the experiments allowed deriving regression equations, useful for modeling the atmospheric impact of trace elements on the edible parts of root crops. For Pb, however, there was hardly any significant impact on the inner parts of the storage organs and as such the transfer of Pb in the food chain through root crops can be considered to be negligible.

Nonylphenol (NP), an environmental estrogen, is actually a complicated mixture of isomers, although it is commonly considered to be a single compound. There are many routes for crops to come into contact with NP; however, little is known about the plant uptake and metabolism of NP, especially at the isomer level. This study comparatively evaluated the uptake and in-planta metabolism of 4-n-NP and its 10 isomers using both carrot cells and intact plants. The rapid metabolism of 4-n-NP was observed in the callus tissues and intact plants with half-lives of 2 h and 4.72 d, respectively. Six conjugates of 4-n-NP were identified in the cell extracts using high resolution mass spectrometry. The primary transformation pathway was found to be the direct conjugation (Phase II metabolism) with the parent compound at the hydroxyl. Furthermore, 4-NP isomers with short side chains and/or bulky α-substituents were more resistant to plant metabolism and showed a greater tendency for accumulation. The influence of the side chains to the isomer selectivity was verified by the molecular docking between glycosyltransferase and 4-NP isomers. This study highlighted the necessity to consider isomer-specificity in the plant accumulation of NP and the environmental and human health implications of NP conjugates.

The reuse of treated wastewater for agricultural irrigation in arid and hot climates where plant transpiration is high may affect plant accumulation of pharmaceutical and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs). In this study, carrot, lettuce, and tomato plants were grown in solution containing 16 PPCP/EDCs in either a cool-humid or a warm-dry environment. Leaf bioconcentration factors (BCF) were positively correlated with transpiration for chemical groups of different ionized states (p < 0.05). However, root BCFs were correlated with transpiration only for neutral PPCP/EDCs (p < 0.05). Neutral and cationic PPCP/EDCs showed similar accumulation, while anionic PPCP/EDCs had significantly higher accumulation in roots and significantly lower accumulation in leaves (p < 0.05). Results show that plant transpiration may play a significant role in the uptake and translocation of PPCP/EDCs, which may have a pronounced effect in arid and hot climates where irrigation with treated wastewater is common.

Carbamazepine (CBZ) is an antiepileptic drug that is frequently detected in wastewater treatment plants, soil and plants after irrigation with treated wastewater or application of biosolids. However, little information is available on the fate and uptake of CBZ in edible vegetables. In this study, radioautographic visualization of the ¹⁴C distribution revealed that ¹⁴C-CBZ can be taken up by all three ready-to-eat vegetables. Furthermore, a mass-balance study was conducted to evaluate the dynamic processes of the uptake and translocation of CBZ by ¹⁴C labeling. ¹⁴C-CBZ was gradually taken up with the growth of vegetables, with maximum uptake ratios of 2.19 ± 0.15, 2.86 ± 0.24 and 0.25 ± 0.05% of applied ¹⁴C in celery, carrot and pak choi, respectively. The bioconcentration factors (BCFs) based on ¹⁴C measurements ranged from 7.6 to 26.1 for celery, 3.6–12.9 for carrot, and 4.4–44 for pak choi. ¹⁴C-CBZ was easily translocated from the roots to the leaves and/or stems. The amendment of biosolids had a significant inhibitory effect on the uptake and translocation of ¹⁴C-CBZ from soil.