Biochemical and life cycle effects of triclosan chronic toxicity to earthworm Eisenia fetida

Advancing Soil Risk Assessment: A Novel Earthworm Cocoon Test with a Complementary Toxicokinetic-Toxicodynamic Modeling Approach

In the current European Union pesticide risk assessment for soil organisms, effect endpoints from laboratory studies (Tier 1) and field studies (higher-tier risk assessment) are compared with predicted environmental concentrations in soil, derived from the proposed use pattern. The simple but conservative initial Tier 1 risk assessment considers a range of worst-case assumptions. In contrast, the higher-tier assessment focuses on specific conditions tested in the corresponding field study. Effect modeling, such as toxicokinetic-toxicodynamic (TKTD) modeling, is considered a promising future tool to address uncertainties in soil risk assessment, such as extrapolation to different ecological, pedo-climatical, or agronomical situations, or to serve as an intermediate tier for potential refinement of the risk assessment. For the implementation of TKTD modeling in soil organism risk assessment, data on earthworm growth and reproduction over time are required, which are not provided by the standard Organisation for Economic Co-operation and Development (OECD) 222 laboratory test. The underlying study with carbendazim presents a new earthworm cocoon test design, based on the OECD 222 test, to provide the necessary data as input for TKTD modeling. This proposed test design involves destructive samplings at days 7, 14, 21, and 28, enabling the determination of growth, cocoon number, and the number of juveniles hatched per cocoon in 7-day intervals. The new cocoon test allowed the disentanglement of the toxic effect of carbendazim in earthworms: At the highest concentration prominent effects on growth and reproductive output were observed, and the number of cocoons was significantly reduced compared to control. The results highlighted different physiological modes of action: effect on growth via higher maintenance costs as a primary mode of action as well as a reduced number of cocoons (effect on reproduction) and a lower number of juveniles hatching from each cocoon (hazard during oogenesis) as a secondary mode of action. We provide an example of how this new test's data can be used to feed a dynamic energy budget theory-TKTD model of Eisenia fetida. We also validate it against the original OECD 222 test design, outlining its potential future use in soil risk assessment. Environ Toxicol Chem 2024;43:2377-2386. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Development Features on the Selection of Animal Models for Teratogenic Testing

Today, the use of animal models from different species continues to represent a fundamental step in teratogenic testing, despite the increase in alternative solutions that provide an important screening to the enormous quantity of new substances that aim to enter the market every year. The maintenance of these models is due to the sharing of similar development processes with humans, and in this way they represent an important contribution to the safety in the use of the compounds tested. Furthermore, the application of advances in embryology to teratology, although hampered by the complexity of reproductive processes, continues to prove the importance of sensitivity during embryonic and fetal development to detect potential toxicity, inducing mortality/abortion and malformations.In this chapter, essential periods of development in different models are outlined, highlighting the similarities and differences between species, the advantages and disadvantages of each group, and specific sensitivities for teratogenic testing. Models can be divided into invertebrate species such as earthworms of the species Eisenia fetida/Eisenia andrei, Caenorhabditis elegans, and Drosophila melanogaster, allowing for rapid results and minor ethical concerns. Vertebrate nonmammalian species Xenopus laevis and Danio rerio are important models to assess teratogenic potential later in development with fewer ethical requirements. Finally, the mammalian species Mus musculus, Rattus norvegicus, and Oryctolagus cuniculus, phylogenetically closer to humans, are essential for the assessment of complex specialized processes, occurring later in development.Regulations for the development of toxicology tests require the use of mammalian species. Although ethical concerns and costs limit their use in large-scale screening. On the other hand, invertebrate and vertebrate nonmammalian species are increasing as alternative animal models, as these organisms combine low cost, less ethical requirements, and culture conditions compatible with large-scale screening. Their main advantage is to allow high-throughput screening in a whole-animal context, in contrast to the in vitro techniques, not dependent on the prior identification of a target. Better knowledge of the development pathways of animal models will allow to maximize human translation and reduce the number of animals used, leading to a selection of compounds with an improved safety profile and reduced time to market for new drugs.

Effects of elevated temperature and decreased soil moisture content on triclosan ecotoxicity to earthworm E. fetida

Emerging pollutants and climate change are two main challenges affecting soil organisms today. Changes in temperature and soil moisture with climate change are key factors determining activity and fitness of soil dwelling organisms. The occurrence and toxicity of antimicrobial agent triclosan (TCS) in terrestrial environment is of high concern, while no data are available on TCS toxicity changes to terrestrial organisms under global climate change. The study's aim was to assess the impact of elevated temperature, decreased soil moisture content, and their complex interaction on triclosan-induced changes in Eisenia fetida life cycle parameters (growth, reproduction, and survival). Eight-week TCS-contaminated soil (10-750 mg TCS kg^-1) experiments with E. fetida were performed at four different treatments: C (21 °C + 60% water holding capacity (WHC)); D (21 °C and 30% WHC); T (25 °C + 60% WHC); and T + D (25 °C + 30% WHC). TCS had negative impact on the earthworm mortality, growth, and reproduction. Changing climate conditions have altered TCS toxicity to E. fetida. Drought and drought in combination with elevated temperature enhanced the adverse effects of TCS on earthworm survival, growth rate, and reproduction, while single elevated temperature slightly reduced TCS lethal toxicity as well as toxicity to growth rate and reproduction.

Earthworm Eisenia fetida potential for sewage sludge amended soil valorization by heavy metal remediation and soil quality improvement

Sewage sludge reuse in agriculture is increasing, however it can be an important route for contaminants to enter the environment. The aim of this study was to evaluate earthworm Eisenia fetida capability to reduce heavy metal content in the sewage sludge (SS) amended soil and increase soil fertility in terms of soil nutrients content. Adult earthworms were introduced into aged SS amended soil (0-200 Mg ha^-1) and left for 65 days. Earthworms have stabilized soil pH and accelerated organic matter mineralization. The concentrations of most heavy metals during the vermiremediation sharply decreased, K and Mg decreased to a moderate extent, whereas Ca content has increased. The highest removal efficiency was detected for Ni, Co and Mn (> 80%), bioconcentration factors were as follows Zn > Co > Cu > Ni > Mn > Cr. The content of major nutrients (S, P) was substantially higher compared to the initial values. The most efficient remediation and soil quality improvement was achieved under the doses of 25-50 Mg ha^-1. Higher (≥ 100 Mg ha^-1) doses might restrict this technique application because of earthworm mortality and retarded growth. Overall, the study shows that vermiremediation might be a sustainable technique for ecological stabilization of SS amended soil and converting to usable for agricultural needs.

Ecotoxicity of triclosan in soil: an approach using different species

Triclosan is an antimicrobial agent widely used in personal care products and an emerging contaminant with potential to have harmful effects to edaphic organisms. This study aimed to evaluate the impacts of exposure to triclosan on the microbiota, plants, and edaphic animals using isolated bioassays and a microcosm scale representation (multispecies system). Among the isolated bioassays, the phytotoxicity test with Lactuca sativa, avoidance test with Eisenia andrei, and acute toxicity with E. andrei and Armadillidium vulgare were used. The multispecies system used seeds of L. sativa and Sinapis alba, together with earthworms and terrestrial isopods. This system also evaluated microbial activity through alkaline phosphatase and the metabolic profile using Ecoplate™, BIOLOG microplates. Exposure to triclosan impacted seedling growth in the isolated bioassay and germination and root growth in the microcosm scale assay; it also caused mortality in terrestrial isopods, earthworm avoidance and alteration of alkaline phosphatase, and the consumption profile of carbohydrates and carboxylic acids in the microbiota. The ecotoxicological effects evaluated in the multispecies system were perceived even in low concentrations of triclosan, indicating that the interaction of this xenobiotic with the environment and organisms in a more realistic scenario can compromise ecosystem services.

Toxicity of soil antimony to earthworm Eisenia fetida (Savingy) before and after the aging process

Information on soil antimony (Sb) toxicity to earthworm Eisenia fetida (Savingy) is limited. This ecotoxicology study was designed to quantify the soil Sb toxicity to earthworm E. fetida before and after aging process, establishing dose-effect relationship between Sb content and mortality. Results of the avoidance test and acute test showed that the values of net avoidance response, escape rate and mortality were generally decreased in aged treatment compared to that in fresh treatment, respectively from 93.33% to 66.67%, 36.67% to 13.33% and 100% to 53.33% (15 d) taking TL800 (treatment level of 800 mg/kg) for example, meanwhile the values of median lethal content (LC₅₀) at 72 h, 7 d and 15 d were respectively increased from 355.27 mg/kg to 2324.55 mg/kg, 322.19 mg/kg and 1743.19 mg/kg and 282.74 mg/kg to 745.94 mg/kg, indicating that aging process could reduce the Sb acute toxicity to earthworm. According to a three-step sequential extraction procedure, the bioavailable Sb ranged from 24.45% to 43.24% and 16.97% to 27.70% in fresh treatment and aged treatment, respectively, and the mortality of earthworm for 24 h decreased with the decrease of the content of mild acid-soluble antimony (which decreased averagely from 23.09% to 14.00%), which was more suited to assess Sb toxicity. This is the first report that confirms the toxicity of soil Sb to earthworm E. fetida as well as the considering of aging process and speciation.

Triclocarban affects earthworms during long-term exposure: Behavior, cytotoxicity, oxidative stress and genotoxicity assessments

Triclocarban (TCC) is a contaminant of emerging concern widely applied as an antimicrobial in personal care products and introduced into the terrestrial environment through the application of biosolids (i.e., treated sewage sludge) in agriculture. Displaying the potential to bioaccumulate in the food chain and a high half-life in the soil, the presence of this compound in the environment may lead to potential ecological risks. In this context, TCC toxicity assessments in Eisenia andrei earthworms were carried out through acute, avoidance and chronic tests following cytotoxicity, antioxidant system, i.e. acatalase (CAT), glutathione-S-transferase (GST), glutathione (GSH), lipid peroxidation (LPO), and DNA damage (comet assay) evaluations. An LC₅₀ of 3.3 ± 1.6 mg cm^-2 in the acute contact test and an EC₅₀ of 1.92 ± 0.31 mg kg^-1 in the avoidance test during 72 h and 48 h, respectively, were obtained. The behavioral test indicates earthworm avoidance from 15.0 mg kg^-1 of TCC. During chronic soil exposure, a 44% reduction in earthworm cell viability was observed after 14 days of exposure to 10 mg kg^-1 TCC, while an increase in the percentage of amoebocyte cells also ocurred. Chronic exposure to TCC led to reduced CAT and GST activities, decreased GSH levels and increased LPO in exposed organisms. DNA damage was observed after 45 days from a 1 mg kg^-1 dose of TCC. Therefore, TCC exhibits toxicological potential to Eisenia andrei earthworms, mainly during long-term exposures. This study provides mechanistic earthworm information towards understanding the environmental and human health implications of TCC exposure and draws attention to correct biosolid management.

Wheat and ryegrass biomass ashes as effective sorbents for metallic and organic pollutants from contaminated water in lab-engineered cartridge filtration system

Three plant biomasses (miscanthus, ryegrass and wheat) have been considered for the preparation of five different sorbents evaluated for their potential to sorb cadmium and lead and four emergent organic compounds (diclofenac, sulfamethoxazole, 17α-ethynylestradiol and triclosan) from artificially contaminated water. Lab-created cartridges were filled with each sorbent and all experiments were systematically compared to activated charcoal Norit®. Results from activated charcoal, wheat straw and acidified wheat straw were supported by the Langmuir and Freundlich models. Wheat straw ashes were an excellent metal extractor that exceeded the potential of well-known activated charcoal. Acidified sorbents (wheat and ryegrass) were very effective in eliminating the selected emerging organic contaminants displaying equipotent or superior activity compared to activated charcoal. These results open the way for further in natura studies by proposing new biosource materials as new effective tools in the fight against water pollution.

In-vivo and in-vitro tests to assess toxic mechanisms of nano ZnO to earthworms

Increasing applications of engineered nanomaterials lead to the release of nanoparticles into various environmental media, especially soil. However, the environmental behavior of nano ZnO in soil and the toxic mechanism to terrestrial invertebrates were not fully understood. In this study, the concentrations of nano ZnO in earthworms (Eisenia fetida) were measured to assess its bioaccumulation. The ratio of nano ZnO in earthworms to soil in 250 mg/kg treatment group was lower than that in 10 mg/kg treatment group as the earthworms would not take up too much nano ZnO to protect themselves from the damage. Combination of in-vivo and in-vitro tests was adapted to investigate the toxic mechanism of nano ZnO to earthworms. In in-vivo test, biomarkers including ROS, SOD, and MDA suggested that the toxic effects of nano ZnO to earthworms were caused by the oxidative stress. To further elucidate its toxic mechanism, in-vitro toxicity test was carried out by employing earthworm coelomocytes. The biomarkers, intracellular ROS, extracellular LDH, and cell viability showed concentration-dependent manner with nano ZnO in the culture media, demonstrating that in-vitro toxicity test could be utilized to reveal the toxic mechanism of nano ZnO to earthworms or other organisms.

Research Progress on Toxic Effects and Water Quality Criteria of Triclosan

Triclosan (TCS) is an effective broad-spectrum antimicrobial agent that is widely used in personal care products. It has been detected in different environmental media, and poses high potential ecological risk. In this article, we carried out a literature review of recent studies on the toxic effects of TCS from different aspects at the molecular, cell, tissue, organ, and individual level. TCS can exhibit acute toxicity to aquatic organisms, affect the normal expression and physiological function of enzymes and genes, and produce cytotoxicity. Many studies have demonstrated that TCS exerts significant endocrine-disrupting effects on organisms, interfering the normal physiological functions of the reproductive, thyroid, and nervous systems via related signaling pathways. Moreover, we reported current research on the water quality criteria of TCS and discuss possible future research directions.

Bioconcentration, behavioral, and biochemical effects of the non-steroidal anti-inflammatory drug diclofenac in Daphnia magna

The non-steroidal anti-inflammatory drug (NSAID) diclofenac is one of the most frequently studied as well as controversially discussed pharmaceutically active drug on the subject of its relevance to the environment. This study was conducted to assess the bioconcentration potential of diclofenac and its behavioral and biochemical effects in Daphnia magna. The bioconcentration factors of diclofenac determined after 48 h of aqueous exposure in Daphnia magna were 70.94 and 8.02 for the nominal exposure concentrations of 5 and 100 μg/L, respectively. Diclofenac exposure obviously decreased the filtration and ingestion rates of the daphnids. A significant increase of the acetylcholinesterase activity that was observed in this study indicates that diclofenac might not have neurobehavioral toxicity in Daphnia magna. Significant induction of malondialdehyde content is an indication of overproduction of reactive oxygen species leading to oxidative damage in daphnids after diclofenac exposure. Moreover, significant inhibition of the superoxide dismutase, catalase, and glutathione reductase activities implies that the antioxidant defense system of Daphnia magna was overwhelmed. Also, significant inhibition of glutathione s-transferase activity might point to the fact that the enzyme was not capable to detoxify diclofenac in Daphnia magna. These findings indicate that diclofenac can accumulate and consequently stimulate behavioral and biochemical disturbances in Daphnia magna.