Insight into the distribution of pharmaceuticals in soil-water-plant systems

Pharmaceuticals in agricultural soils originating from irrigation with treated wastewater and land-applied biosolids can enter field crops. However, little is known about the role of pore water in plant uptake of pharmaceuticals from soils. In this study, the fate, uptake and distribution of fifteen commonly used pharmaceuticals in soil-water-radish systems were investigated to examine the relationship between the accumulation and their physicochemical processes in soils. The results indicate that the distribution of pharmaceuticals between soil and pore water, as well as their biodegradation, combined to govern the bioavailability of pharmaceuticals to plant uptake. Fourteen out of 15 pharmaceuticals could enter radish tissues in which the accumulation ranged from 2.1 to 14080 ng/g. Comparison of bioconcentration factors (BCFs) on the basis of pharmaceutical concentration in bulk soil vs. in pore water implies that pharmaceuticals present in soil pore water are the major bioavailable fractions to plant uptake. The pore water-based BCFs exhibited a positive linear relationship with log Dow for the pharmaceuticals with >90% as neutral species in soil pore water, while such relationship was not observed between bulk soil-based BCFs and log Dow mainly due to sorption by soil. Other than hydrophobicity, the dissociation of ionizable pharmaceuticals in the soil pore water and (or) root cells may lead to the “ion-trap” effects and thus influence the uptake and translocation process. The large molecular-size pharmaceuticals (e.g., tylosin) manifested a minimum uptake due plausibly to the limited permeability of cell membranes

Investigating the exposure and impacts of chemical UV-filters in coral reef ecosystems : Review and research gap prioritisation

Coral reefs are amongst the world's most productive and biologically diverse ecosystems and in recent decades have experienced an unparalleled decline due to various anthropogenically induced stressors. Ultraviolet (UV) filters found within personal care products such as sunscreen are an emerging chemical pollutant with a growing concern of toxicity to reef organisms. In this study a systematic literature review was conducted to [1] determine the current understanding of spatial distribution and occurrence of UV-filters exposed to the marine environment, [2] synthesise current ecotoxicological thresholds of relevant reef organisms under various UV filter exposures, [3] identify research gaps related to both exposure and toxicity of UV-filters in coral reef ecosystems. With gaps identified, a survey was developed and distributed to experts in the field representing academic, governmental, not-for-profit, and industry researchers in order to prioritise research gaps and inform future research efforts. The survey identified the need for better understanding of the impacts of co-stressors, long-term exposure, mixture and degradation product exposure and realistic environmental conditions. Ultimately, this review, will help guide priority research efforts to understand the risks of UV-filter exposure to coral reef ecosystems. This article is protected by copyright. All rights reserved

Nontargeted Screening of Contaminants of Emerging Concern in the Glen Valley Wastewater Treatment Plant, Botswana

There is growing concern about the prevalence and impact of contaminants of emerging concern (CECs). The environmental monitoring of CECs has, however, been limited in low- and middle-income countries due to the lack of advanced analytical instrumentation locally. In the present study we employed a nontargeted and suspect screening workflow via liquid chromatography coupled with high-resolution mass spectrometry (HRMS) to identify known and unknown pollutants in the Glen Valley wastewater treatment plant, Botswana, complemented by analysis of groundwater samples. The present study represents the first HRMS analysis of CECs in water samples obtained in Botswana. Suspect screening of 5942 compounds qualitatively identified 28 compounds, including 26 pharmaceuticals and two illicit drugs (2-ethylmethcathinone and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol). Nontargeted analysis tentatively identified the presence of 34 more compounds including (5ξ)-12,13-dihydroxypodocarpa-8,11,13-trien-7-one, 12-aminododecanoic acid, atenolol acid, brilliant blue, cyclo leucylprolyl, decanophenone, DL-carnitine, N,N′-dicyclohexylurea, N4-acetylsulfamethoxazole, NP-003672, and 24 polyethylene glycol polymers. The highest number of detections were in influent wastewater (26 CECs) followed by effluent wastewater (10 CECs) and, lastly, groundwater (4 CECs). Seventeen CECs detected in the influent water were not detected in the effluent waters, suggesting reduced emissions due to wastewater treatment. Two antiretroviral compounds (abacavir and tenofovir) were detected in the influent and effluent sources. This suggests that wastewater treatment plants are a major pathway of chemical pollution to the environment in Botswana and will help inform prioritization efforts for monitoring and remediation that is protective of these key ecosystems. Environ Toxicol Chem 2024;43:52–61

The emerging threat of human-use antifungals in sustainable and circular agriculture schemes

Rapidly growing global populations mandate greater crop productivity despite increasingly scarce natural resources, including freshwater. The adoption of sustainable agricultural practices seek to address such issues, but an unintended consequence is the exposure of agricultural soils and associated biota to emerging contaminants including azole pharmaceutical antifungals. We show that environmentally relevant exposure to three commonly prescribed azole antifungals can reduce mycorrhizal 33P transfer from the soil into the host plant. This suggests that exposure to azoles may have a significant impact on mycorrhizal-mediated transfer of nutrients in soil-plant systems. Understanding the unintended consequences of sustainable agricultural practices is needed to ensure the security and safety of future food production systems. Summary: Sustainable farming practices are increasingly necessary to meet the demands of a growing population under constraints imposed by climate change. These practices, in particular the reuse of wastewater and amending soil with wastewater derived biosolids, provide a pathway for man-made chemicals to enter the agricultural environment. Among the chemicals commonly detected in wastewater and biosolids are pharmaceutical azole antifungals. Fungi, in particular mycorrhiza-forming fungal symbionts of plant roots, are key drivers of nutrient cycling in the soil–plant system. As such, greater understanding of the impacts of azole antifungal exposure in agricultural systems is urgently needed. We exposed wheat (Triticum aestivum L. cv. ‘Skyfall’) and arbuscular mycorrhizal fungi to environmentally relevant concentrations of three azole antifungals (clotrimazole, miconazole nitrate and fluconazole). We traced the mycorrhizal-acquired 33P from the soil into the host plant in contaminated versus non-contaminated soils and found 33P transfer from mycorrhizal fungi to host plants was reduced in soils containing antifungals. This represents a potentially major disruption to soil nutrient flows as a result of soil contamination. Our work raises the major issue of exposure of soil biota to pharmaceuticals such as azole antifungals, introduced via sustainable agricultural practices, as a potentially globally important disruptive influence on soil nutrient cycles. The impacts of these compounds on non-target organisms, beneficial mycorrhizal fungi in particular, could have major implications on security and sustainability of future food systems

Detection, Occurrence and Fate of Emerging Contaminants in Agricultural Environments

A total of 43 papers published in 2014 were reviewed ranging from detailed descriptions of analytical methods, to fate and occurrence studies, to measuring and predicting biological effects for a wide variety of emerging contaminants likely to occur in agricultural environments. New methods and studies on veterinary pharmaceuticals, natural and synthetics steroids, and antibiotic resistance genes in agricultural environments continue to expand our knowledge base on the occurrence and potential impacts of these compounds. This review is divided into the following sections: Introduction, Analytical Methods, Occurrence and Fate, Antibiotic Resistance Genes, and Risk Assessment

Emerging contaminant exposure to aquatic systems in the Southern African Development Community

The growing production and use of chemicals and the resultant increase in environmental exposure is of particular concern in developing countries where there is rapid industrialization and population growth but limited information on the occurrence of emerging contaminants. Advances in analytical techniques now allow for the monitoring of emerging contaminants at very low concentrations with the potential to cause harmful ecotoxicological effects. Therefore, we provide the first critical assessment of the current state of knowledge about chemical exposure in waters of the Southern African Developmental Community (SADC). We achieved this through a comprehensive literature review and the creation of a database of chemical monitoring data. Of the 59 articles reviewed, most (n = 36; 61.0%) were from South Africa, and the rest were from Botswana (n = 6; 10.2%), Zimbabwe (n = 6; 10.2%), Malawi (n = 3; 5.1%), Mozambique (n = 3; 5.1%), Zambia (n = 2; 3.4%), Angola (n = 1; 1.7%), Madagascar (n = 1; 1.7%), and Tanzania (n = 1; 1.7%). No publications were found from the remaining seven SADC countries. Emerging contaminants have only been studied in South Africa and Botswana. The antiretroviral drug ritonavir (64.52 µg/L) was detected at the highest average concentration, and ibuprofen (17 times) was detected most frequently. Despite being the primary water source in the region, groundwater was understudied (only 13 studies). High emerging contaminant concentrations in surface waters indicate the presence of secondary sources of pollution such as sewage leakage. We identify research gaps and propose actions to assess and reduce chemical pollution to enable the SADC to address the Sustainable Development Goals, particularly Goal 3.9, to reduce the deaths and illnesses from hazardous chemicals and contamination. Environ Toxicol Chem 2022;41:382–395

Legacy and current pesticide residues in Syr Darya, Kazakhstan: Contamination status, seasonal variation and preliminary ecological risk assessment

The Syr Darya is one of two major rivers in Central Asia supplying critical fresh water to the Aral Sea. In spite of the river’s importance and agriculturally-intensive history, few studies have provided a modern evaluation of and the occurrence of pesticide residues potential effects to aquatic life. The primary goal of this investigation was to determine seasonal variations in ambient concentrations of modern and legacy pesticides in bottom sediment and water of the Syr Darya in Kazakhstan (KZ) downstream from an agriculturally-intensive watershed in Uzbekistan. Grab samples and passive samplers were used at five remote sampling stations during June 2015 to provide a baseline for ecotoxicological evaluation. Results were compared with samples collected during and after the agricultural growing season. Polar organic chemical integrative samplers (POCIS) were used in June and calibrated for time-weighted average concentrations of current use pesticides. Among legacy chlorinated pesticides measured in grab samples from the river, lindane (γ-HCH) was detected most frequently with the highest concentrations occurring during June. For all the sampling events, residues of lindane (γ-HCH) ranged from 0.014 to 0.24 μg/L detected in water samples, are among the highest concentrations reported for rivers globally. Concentrations of γ-HCH, p,p’-DDE and dieldrin were highest in October when dieldrin concentrations approached 0.4 μg/L. Sources of legacy pesticides may be either illicit upstream use or evidence of previous atmospheric contamination of glacial meltwater. Chronic exposure to these residues may lead to ecological risk to lower order organisms in both the sediment and water column. Includes Supplementary Material

Activated carbons of varying pore structure eliminate the bioavailability of 2,3,7,8-tetrachlorodibenzo-p-dioxin to a mammalian (mouse) model

The use of activated carbon (AC) as an in situ sorbent amendment to sequester polychlorinated-dibenzo-p-dioxins and furans (PCDD/Fs) present in contaminated soils and sediments has recently gained attention as a novel remedial approach. This remedy could be implemented at much lower cost while minimizing habitat destruction as compared to traditional remediation technologies that rely on dredging/excavation and landfilling. Several prior studies have demonstrated the ability of AC amendments to reduce pore water concentrations and hence bioaccumulation of PCDD/Fs in invertebrate species. However, our recent study was the first to show that AC had the ability to sequester 2,3,7,8‑tetrachlorodibenzo‑p‑dioxin (TCDD) in a form that eliminated bioavailability to a mammalian (mouse) model. Here we show that three commercially available ACs, representing a wide range of pore size distributions, were equally effective in eliminating the bioavailability of TCDD based upon two sensitive bioassays, hepatic induction of cyp1A1 mRNA and immunoglobulin M antibody-forming cell response. These results provide direct evidence that a wide range of structurally diverse commercially available ACs may be suitable for use as in situ sorbent amendments to provide a cost-effective remedy for PCDD/F contaminated soils and sediments. Potentially, adaption of this technology would minimize habitat destruction and be protective of ecosystem and human health

Suspect and non-targeted screening of chemical pollutants in Botswana's aquatic environments

Chemical pollution in the aquatic systems of Botswana has been sparsely studied despite its potential ecological importance. Here, we perform a study of water samples collected from 13 locations distributed across Botswana to obtain the first overview of the nature and distribution of chemical contaminants across the country's aquatic environment. High resolution mass spectrometry was applied using non-targeted and suspect screening methods to qualitatively analyse samples. A total of 114 contaminants of emerging concern (CECs) were identified including 68 (59.6 %) pharmaceuticals and pharmaceutical metabolites; 16 (14.2 %) pesticides; 13 (11.4 %) psychoactive compounds and metabolites; 11 (9.7 %) industrial chemicals and intermediates and lastly, 5 (4.4 %) personal care products. Allopurinol, 3,4-dimethylmethcathinone, and diazolidinyl urea represented the most commonly detected pharmaceutical, psychoactive drug and personal care product, respectively. The pesticide dodemorph and three industrial chemicals (stearamide, pthalic acid and bis(2-ethylhexyl) phthalate) were detected in all samples obtained. 90 CECs were detected in receiving water (from 7 sample locations), 75 in wastewater (from 3 sample locations) and 60 in surface water (from 9 sample locations). Of the compounds detected, only 8 had been identified in environmental samples acquired in Botswana previously. We discuss the variations in the nature and frequency of chemical pollutants detected in this work in a geographical context. The results indicate that Botswana's aquatic systems are subject to pollution, despite wastewater treatment and that in order to mitigate potentially harmful effects on both human and aquatic ecosystems, more investigations are required to correctly identify, track and tackle the sources of pollution

Mechanistic study on uptake and transport of pharmaceuticals in lettuce from water

The dissemination of pharmaceuticals in agroecosystems originating from land application of animal manure/sewage sludge and irrigation with treated wastewater in agricultural production has raised concern about the accumulation of pharmaceuticals in food products. The pathways of pharmaceutical entries via plant roots, transport to upper fractions, and the factors influencing these processes have yet been systematically elucidated, thus impeding the development of effective measures to mitigate pharmaceutical contamination in food crops. In this study, lettuce uptake of thirteen commonly used pharmaceuticals was investigated using a hydroponic experimental setting. Pharmaceutical sorption by lettuce roots was measured in order to evaluate the influence on pharmaceutical transport from roots to shoots. Small-sized pharmaceuticals e.g., caffeine and carbamazepine with molecular weight (MW) 12.0 L g−1) and demonstrated a reduced transport to shoots. Large-sized pharmaceuticals (e.g. MW >400 g mol−1) including lincomycin, monensin sodium, and tylosin could be excluded from cell membranes, resulting in the predominant accumulation in lettuce roots. Large-sized oxytetracycline existed as zwitterionic species that could slowly enter lettuce roots; however, the relatively strong interaction with lettuce roots limits its transport to shoots. The mass balance analysis revealed that acetaminophen, β-estradiol, carbadox, estrone and triclosan were readily metabolized in lettuce with >90% loss during 144-h exposure period. A scheme was proposed to describe pharmaceutical uptake and transport in plant, which could reasonably elucidate many literature-reported results. Molecular size, reactivity and ionic speciation of pharmaceuticals, as well as plant physiology, collectively determine their uptake, transport and accumulation in plants