Qualitative Risk Analysis for Contents of Dry Toilets Used to Produce Novel Recycling Fertilizers

Human excreta are a sustainable, economical source of nutrients, and can be used to produce recycling fertilizer for horticulture by collecting and processing the contents of dry toilets. Herein, we discuss the key categories of risk associated with the main groups of materials commonly found in dry toilets. The study was part of the development of a German product standard for marketable and quality-assured recycling fertilizers from human excreta for use in horticulture. Particular attention is paid to ensuring that the fertilizer is epidemiologically and environmentally harmless and that the quality of the recycling fertilizer is adequate in terms of low pollution and nutrient availability. In sum, the risk of transmissible human pathogens lies within the human excreta, particularly feces; plant materials added during composting are of particular phytosanitary relevance; pharmaceutical residues in excrements and chemical additives are potential sources of pollutants; non-biodegradable contaminants can cause pollution and injury; and the horticultural risks involve mainly the ammonia emission potential and in some cases the salinity effects of urine. These risks can be reduced significantly (i) with education of users around proper operation of dry toilets and the consequences of adding inappropriate waste, (ii) with facilitation of proper use with general waste bins and clear instructions, and importantly (iii) by using modern sanitization and cleaning processes and testing for harmful substances under the guidance of local laws and regulations, ensuring safe and high-quality fertilizers. In conclusion, the benefits of using dry toilet contents to produce fertilizers for use in horticulture are unquestionable. Our analysis highlights the need to support recycling optimization and awareness for the purpose of a sustainable circular economy and to minimize the risk of harm to humans and the environment overall.

Added value recyclability of glass fiber waste as photo-oxidation catalyst for toxic cytostatic micropollutants

There is an increased interest in recycling valuable waste materials for usage in procedures with high added values. Silica microparticles are involved in the processes of catalysis, separation, immobilization of complexants, biologically active compounds, and different nanospecies, responding to restrictive requirements for selectivity of various chemical and biochemical processes. This paper presents the surface modification of accessible and dimensionally controlled recycled silica microfiber with titanium dioxide. Strong base species in organic solvents: methoxide, ethoxide, propoxide, and potassium butoxide in corresponding alcohol, activated the glass microfibres with 12-13 µm diameter. In the photo-oxidation process of a toxic micro-pollutant, cyclophosphamide, the new composite material successfully proved photocatalytic effectiveness. The present work fulfills simultaneously two specific objectives related to the efforts directed towards a sustainable environment and circular economy: recycling of optical glass microfibers resulted as waste from the industry, and their usage for the photo-oxidation of highly toxic emerging micro-pollutants.

Mass spectrometry based in vitro assay investigations on the transformation of pharmaceutical compounds by oxidative enzymes

The ubiquitous presence of trace organic chemicals in wastewater and surface water leads to a growing demand for novel removal technologies. The use of isolated enzymes has been shown to possess the capability for a targeted application but requires a clearer mechanistic understanding. In this study, the potential of peroxidase from horseradish (HRP) and laccase from Pleurotus ostreatus (LccPO) to transform selected trace organic chemicals was studied using mass spectrometry (MS)-based in vitro enzyme assays. Conversion by HRP appeared to be more efficient compared to LccPO. Diclofenac (DCF) and sotalol (STL) were completely transformed by HRP after 4 h and immediate conversion was observed for acetaminophen (APAP). During treatment with LccPO, 60% of DCF was still detectable after 24 h and no conversion was found for STL. APAP was completely transformed after 20 min. Sulfamethoxazole (SMX), carbamazepine (CBZ), ibuprofen (IBP) and naproxen (NAP) were insusceptible to enzymatic conversion. In pharmaceutical mixtures, HRP exhibited a preference for DCF and APAP and the generally less efficient conversion of STL was enhanced in presence of APAP. Transformation product pattern after treatment with HRP revealed polymerization products for DCF while STL showed cleavage reactions. DCF product formation shifted towards a proposed dimeric iminoquinone product in presence of APAP whereas a generally less pronounced product formation in mixtures was observed for STL. In conclusion, the enzymatic treatment approach worked selectively and efficiently for a few pharmaceuticals. However, for application the investigation and possibly immobilization of multiplex enzymes being able to transform diverse chemical structures is recommended.

Sources and processes affecting the spatio-temporal distribution of pharmaceuticals and X-ray contrast media in the water resources of the Lower Jordan Valley, Jordan

The closed basin of the Lower Jordan Valley with the Dead Sea as final sink features high evapotranspiration rates and almost complete reuse of treated wastewater for irrigation farming. This study focuses on the water transfer schemes and the presence, spreading, and potential accumulation of pharmaceutical residues in the local water resources based on findings of a five-year monitoring program. Overall 16 pharmaceuticals and 9 iodinated X-ray contrast media were monitored in groundwater, surface water, and treated wastewater. A total of 95 samples were taken to cover all geographical settings and flow paths from origin (wastewater) to target (groundwater). Nine substances were detected in groundwater, with concentrations ranging between 11 ng/L and 33,000 ng/L. Sometimes, detection rates were higher than in comparable studies: Diatrizoic acid 75%, iopamidol 42%, iopromide 19%, iomeprol 11%, carbamazepine and iohexol 8%, ibuprofen 6%, and fenofibrate and iothalamic acid 3%. Concentrations in groundwater generally increase from north to south depending on the application of treated wastewater for irrigation. Almost all substances occurred most frequently and with highest concentrations in treated wastewater, followed by surface water and groundwater. As exception, diatrizoic acid was found more frequently in groundwater than in treated wastewater, with concentrations being similar. This indicates the persistence of diatrizoic acid with long residence times in local groundwater systems, but may also reflect changing prescription patterns, which would be in accordance with increasing iopamidol findings and surveys at local hospitals. Trend analyses confirm this finding and indicate a high probability of increasing iopamidol concentrations, while other substances did not reveal any trends. However, no proof of evaporative enrichment could be found. The high spatial and temporal variability of the concentrations measured calls for further systematic studies to assess the long-term evolution of organic trace substances in this reuse setting.

Biodegradability and ecotoxicitiy of tramadol, ranitidine, and their photoderivatives in the aquatic environment

PURPOSE

This study was designed to assess the fate and the overall potential impacts of the widely prescribed drugs ranitidine and tramadol after their introduction into the aquatic environment.

METHODS

The probability to detect these two drugs in the aquatic environment was studied by analyzing their abiotic and biotic degradation properties. For this purpose, samples were irradiated with different light sources, and three widely used biodegradability tests from the OECD series, the closed bottle test (OECD 301 D), the manometric respirometry test (OECD 301 F) and the Zahn-Wellens test (OECD 302 B), were conducted. The ecotoxicity of the photolytically formed transformation products was assessed by performing the bacterial growth inhibition test (EN ISO 10712). Furthermore, quantitative structure-activity relationship analysis and a risk analysis based on the calculation of the predicted environmental concentrations have also been conducted to assess the environmental risk potential of the transformation products. The possible formation of stable products by microbial or photolytical transformation has been investigated with DOC and LC-MS analytics.

RESULTS

In the present study, neither ranitidine, nor tramadol, nor their photoderivatives were found to be readily or inherently biodegradable according to test guidelines. The photolytic transformation was faster under a UV lamp compared to the reaction under an Xe lamp with a spectrum that mimics sunlight. No chronic toxicity against bacteria was found for ranitidine or its photolytic decomposition products, but a low toxicity was detected for the resulting mixture of the photolytic transformation products of tramadol.

CONCLUSIONS

The study demonstrates that transformation products may have a higher environmental risk potential than the respective parent compounds.

Multi-biomarker approach for the evaluation of the cyto-genotoxicity of paracetamol on the zebra mussel (Dreissena polymorpha)

Paracetamol (PCM; N-(4-hydroxyphenyl)acetamide) is a widely used analgesic and antipyretic agent that is utilized in human medicine. Its use is so widespread that it is constantly being introduced into global water bodies where it reaches concentrations up to several microgL(-1). A battery of eight biomarkers was applied in the freshwater bivalve Dreissena polymorpha in order to evaluate its potential sub-lethal effect. Mussels were exposed for 96h to increasing environmental concentrations (1, 5, 10nM) of PCM. Cyto-genotoxicity was determined in mussel hemocytes by the lysosomal membrane stability (Neutral Red Retention Assay), the single cell gel electrophoresis (SCGE) assay, the micronucleus test (MN test) and assessments of the apoptotic frequency (DNA diffusion assay). Moreover, in order to evaluate the probable alterations to the mussels' oxidative status, measurements of the activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and the detoxifying enzyme glutathione S-transferase (GST) were performed using the cytosolic fraction extracted from a pool of entire mussels. The biomarker battery demonstrated moderate cyto-genotoxicity in zebra mussel hemocytes since no primary DNA fragmentation was measured by the SCGE assay and only a slight increase in fixed DNA damage was registered by apoptotic and MN frequencies. Significant destabilization of the lysosomal membrane from baseline levels was evident at 5 and 10nM at the end of the exposures, as was a high induction capacity of the activities of CAT and GST.

The presence of pharmaceuticals in the environment due to human use--present knowledge and future challenges

Intensive research on pharmaceuticals in the environment started about 15 years ago. Since then a vast amount of literature has been published. The input and presence of active pharmaceutical ingredients (APIs) and their fate in the environment were and is still of high interest. As it has been extensively demonstrated that the active compounds are present in the environment some of the research interest has moved from analysis of the compounds, which is still undertaken, to effect studies in the lab and in field trials. It has been found that environmental concentrations can cause effects in wildlife if proper tools are applied for effect assessment. The question of mixture toxicity has gained more and more attention. It has been learned that classical tests may underestimate effects and risks. Work has been done in the field of risk assessment and risk management. As for risk management strategies to eliminate pharmaceuticals from wastewater or from the effluent of sewage treatment plants have been proposed and investigated. A tremendous amount of literature can now be found describing technical management measures such as oxidative or photolytic effluent treatment, filtering techniques, and application of charcoal. It has been learned however, that each of these approaches has its specific shortcomings. Therefore, additional approaches such as including people handling and using the compounds, and focusing on the properties of the compounds ("green pharmacy") came into focus. Accordingly, this review gives an overview of the present state of knowledge presenting typical results and lines of discussion. This review makes no claim to give a complete overview including the full detailed body of knowledge of pharmaceuticals in the environment. Rather, it addresses important and typical topics to stimulate discussion.

Metabolism of acetaminophen (paracetamol) in plants--two independent pathways result in the formation of a glutathione and a glucose conjugate

BACKGROUND, AIM, AND SCOPE

Pharmaceuticals and their metabolites are detected in the aquatic environment and our drinking water supplies. The need for high quality drinking water is one of the most challenging problems of our times, but still only little knowledge exists on the impact of these compounds on ecosystems, animals, and man. Biological waste water treatment in constructed wetlands is an effective and low-cost alternative, especially for the treatment of non-industrial, municipal waste water. In this situation, plants get in contact with pharmaceutical compounds and have to tackle their detoxification. The mechanisms for the detoxification of xenobiotics in plants are closely related to the mammalian system. An activation reaction (phase I) is followed by a conjugation (phase II) with hydrophilic molecules like glutathione or glucose. Phase III reactions can be summarized as storage, degradation, and transport of the xenobiotic conjugate. Until now, there is no information available on the fate of pharmaceuticals in plants. In this study, we want to investigate the fate and metabolism of N-acetyl-4-aminophenol (paracetamol) in plant tissues using the cell culture of Armoracia rusticana L. as a model system.

MATERIALS AND METHODS

A hairy root culture of A. rusticana was treated with acetaminophen in a liquid culture. The formation and identification of metabolites over time were analyzed using HPLC-DAD and LC-MSn techniques.

RESULTS

With LC-MS technique, we were able to detect paracetamol and identify three of its metabolites in root cells of A. rusticana. Six hours after incubation with 1 mM of acetaminophen, the distribution of acetaminophen and related metabolites in the cells resulted in 18% paracetamol, 64% paracetamol-glucoside, 17% paracetamol glutathione, and 1% of the corresponding cysteine conjugate.

DISCUSSION

The formation of two independently formed metabolites in plant root cells again revealed strong similarities between plant and mammalian detoxification systems. The detoxification mechanism of glucuronization in mammals is mirrored by glucosidation of xenobiotics in plants. Furthermore, in both systems, a glutathione conjugate is formed. Due to the existence of P450 enzymes in plants, the formation of the highly reactive NAPQI intermediate is possible.

CONCLUSIONS

In this study, we introduce the hairy root cell culture of A. rusticana L. as a suitable model system to study the fate of acetaminophen in plant tissues. Our first results point to the direction of plants being able to take up and detoxify the model substrate paracetamol. These first findings underline the great potential of using plants for waste water treatments in constructed wetlands.

RECOMMENDATIONS AND PERSPECTIVES

This very first study on the detoxification of a widely used antipyretic agent in plant tissues again shows the flexibility of plant detoxification systems and their potential in waste water treatment facilities. This study covers only the very first steps of acetaminophen detoxification in plants; still, there is no data on long-term exposure as well as the possible impact of pharmaceuticals on the plant health and stress defense. Long-term experiments need to be performed to follow the fate of acetaminophen in root and leaf cells in a whole plant system, and to evaluate possible usage of plants for the remediation of acetaminophen from waste water.