Grantee Research Project Results
2016 Progress Report: Reclaimed Water Irrigation: Plant Accumulation and Risks of Contaminants of Emerging Concern (CECs)
EPA Grant Number: R835829Title: Reclaimed Water Irrigation: Plant Accumulation and Risks of Contaminants of Emerging Concern (CECs)
Investigators: Gan, Jay , Trumble, John T.
Current Investigators: Gan, Jay , Trumble, John T. , Dudley, Stacia , Pennington, Marcus , sun, Chengliang
Institution: University of California - Riverside
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2015 through August 31, 2018 (Extended to February 28, 2020)
Project Period Covered by this Report: September 1, 2015 through August 31,2016
Project Amount: $749,631
RFA: Human and Ecological Health Impacts Associated with Water Reuse and Conservation Practices (2014) RFA Text | Recipients Lists
Research Category: Water , Human Health
Objective:
The proposal has four objectives: (1) controlled experiments to evaluate plant uptake and metabolism of emerging contaminants; (2) field studies to evaluate plant accumulation of emerging contaminants under realistic conditions; (3) controlled experiments to evaluate effects of emerging contaminants on terrestrial insects and risk assessment to predict human exposure and risks; and (4) carry out educational and outreach activities. We have completed experiments to address objectives (1) and (3), and have surveyed potential field sites for carrying objective (2). We have yet to carry out any activity under objective (4). The project objectives have not changed from the original application. We have not encountered any difficulties and are confident that we will be able to carry out this project as planned.
Progress Summary:
Plant uptake and metabolism of CECs: We have carried out experiments to explore metabolism of a number of pharmaceuticals in plants using Arabidopsis thaliana cells and commonly consumed vegetables (i.e., radish, cucumber, lettuce and carrots) as model plants. To date, we have completed cell culture experiments for diclofenac, sulfamethoxazole, gemfibrizol, diazepam, ibuprofen, and naproxen. Hydroponic experiments are ongoing for some of the CECs using radish and cucumber.
For most CECs considered so far, we have observed active metabolism, including rapid and extensive conjugation with amino acids, sulfates, and glucose. These findings suggest that conjugation is a common pathway for plants to transform pharmaceuticals and such conjugation may have preserved the bioactivity of these compounds if they are deconjugated through enzymatic reactions in, for example, human gut. The biological activity of these conjugates should be better determined to better understand their potential risks to non-target organisms, including humans.
Stress-Related Symptoms Induced by CECs and Detoxification Mechanisms Introduction of CECs into soil through water reuse may also cause stresses to plants and phytotoxicity. Using cucumber as a model plant, we have evaluated the phytotoxicity of mixed pharmaceuticals and personal care products (PPCPs). Results show that PPCPs caused oxidative damage to the plasma membrane and lipid in plant seedlings, and the damage was less pronounced in the leaves. The damage was also proportional to the exposure concentration of CECs. The levels of chlorophyll a and chlorophyll b decreased with increasing PPCP concentrations. The results together demonstrate that contact with PPCPs can cause a range of reactions in higher plants, and that at high concentrations, physiological and biochemical processes may be altered and compromised.
The Effects of Pharmaceuticals on fly (detritivore Megaselia scalaris): We have continued our work to investigate toxicity acute and developmental toxicity effects of CECs on agriculturally and economically important insects. An important detritivore (organism which feeds on dead/ decaying mater), Megaselia scalaris (the coffin fly) was treated with environmentally relevant concentrations of select PPCPs. Caffeine was found to increase the mortality in the flies. Of the individuals that reached adulthood, those that were treated with antibiotics or hormones were delayed in development when compared to the control. Interestingly, PPCP treatment had an impact on sex differences and on when the sexes emerged. There was an increase in time in the larval stage in the antibiotic and hormone-treated insects, and females took significantly longer to become pupa in hormone-treated groups when compared to the control. Therefore, exposure to CECs at environmentally relevant concentrations may cause a range of effects on ecologically or agriculturally important insects. We will next consider the effects of PPCPs on cabbage looper (Trichoplusia ni) and green-peach aphids (Myzus persicae).
Future Activities:
For next year, we plan to continue controlled experiments to address Objectives (1) and (3) by expanding the list of test compounds and organisms, and to prepare and start field experiments at one or two locations in California. We also plan to actively pursue opportunities for stakeholder outreach and education to disseminate our research findings.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 23 publications | 16 publications in selected types | All 16 journal articles |
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Type | Citation | ||
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Fu Q, Wu X, Ye Q, Ernst F, Gan J. Biosolids inhibit bioavailability and plant uptake of triclosan and triclocarban. Water Research 2016;102:117-124. |
R835829 (2016) R835829 (2017) R835829 (2019) |
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Supplemental Keywords:
Soil, chemical transport, exposure, metabolism, toxics, organics, environmental chemistry, analytical, monitoring, water irrigation, contaminants;Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.