Toxicological Risk Assessment Research Articles

The analytical evaluation threshold for inorganic metal extractables and leachables analysis of medical devices

Chemical characterization of medical devices uses the analytical evaluation threshold (AET) to determine reportable organic extractables, as these chemicals may be of toxicological concern and should be addressed via toxicological risk assessment. The AET is not applicable to metal extractables due to the exclusion of toxicity data on inorganics from the dataset used to derive dose-based threshold (DBT) values. This results in minimal guidance for reporting metal extractables. Herein, an AET for metals, or mAET, is proposed as a reporting threshold for individual metal extractables. The mAET can ensure metals are reported that are at quantities that may present a patient safety risk. This may reduce the number of metals reported in a chemical characterization report, improving the efficiency of the overall biocompatibility evaluation by removing unneeded effort and resource time. Conversely, an analytical method’s ability to report all metals at toxicologically relevant levels can be confirmed by comparing method sensitivity to mAET values. DBTs were developed for 70 metals, permitting mAET values to be determined. These mAET values were then compared to metal reporting limits from 13 previously conducted chemical characterization studies, which used varying extraction designs and analytical methods, to determine the impact of the mAET.

Toxicological risk assessment of triadimenol for human exposure, broiler health, and food safety

Triadimenol, a widely used triazole fungicide, leaves residues that pose risks to broiler health, food safety, and human health. Current studies focus on lab animals, leaving limited data regarding its impact on non-target organisms in agricultural ecosystems. Moreover, the doses in current studies often exceed typical agricultural pollution levels of triadimenol. Therefore, this study evaluates the toxic effects of triadimenol by exposing broilers to different concentrations (0.05-20 mg/kg) in their feed for 42 days, assessing growth performance, organ index, hematological parameters, histopathology, jejunum morphology, and tissue residues. The results show that triadimenol contamination at 0.05-20 mg/kg in feed does not significantly affect broiler growth performance. However, the significant changes in hematological parameters suggest the potential hematological toxicity of triadimenol in broilers. Triadimenol at 1 mg/kg or higher induces hepatotoxic and nephrotoxic effects, and significantly alters kidney organ index and histopathology in broilers. Additionally, when the triadimenol contamination level in feed exceeds 1 mg/kg, the residues in edible tissues of broilers exceed the limits set by the EU and China. Overall, our study indicates that even low-dose exposure to triadimenol poses potential risks, highlighting the need for strict regulation of its use in agriculture to protect food safety and human health.

Benchmark dose modeling for epidemiological dose-response assessment using case-control studies.

Following a previous article that focused on integrating epidemiological data from prospective cohort studies into toxicological risk assessment, this paper shifts the focus to case-control studies. Specifically, it utilizes the odds ratio (OR) as the main epidemiological measure, aligning it with the benchmark dose (BMD) methodology as the standard dose-response modeling approach to determine chemical toxicity values for regulatory risk assessment. A standardized BMD analysis framework has been established for toxicological data, including input data requirements, dose-response models, definitions of benchmark response, and consideration of model uncertainty. This framework has been enhanced by recent methods capable of handling both cohort and case-control studies using summary data that have been adjusted for confounders. The present study aims to investigate and compare the "effective count" based BMD modeling approach, merged with an algorithm used for converting odds ratio to relative risk in cohort studies with partial data information (i.e., the Wang algorithm), with the adjusted OR-based BMD analysis approach. The goal is to develop an adequate BMD modeling framework that can be generalized for analyzing published case-control study data. As in the previous study, these methods were applied to a database examining the association between bladder and lung cancer and inorganic arsenic exposure. The results indicate that estimated BMDs and BMDLs are relatively consistent across both methods. However, modeling adjusted OR values as continuous data for BMD estimation aligns better with established practices in toxicological BMD analysis, making it a more generalizable approach.

Monitoring and Assessment of Toxicological Risks of Poultry Meat Contaminated with Heavy Metals.

This study aimed to investigate the heavy metal contamination in poultry meat of Kotli Sattian, Rawalpindi. The meat samples from ten sites were analyzed for lead, cadmium, chromium, copper, arsenic, nickel, zinc, iron, sodium, and calcium. The possible health risks of these metals were also observed. Mean lead, cadmium, chromium, arsenic, and nickel concentrations were higher than the permissible limits of the World Health Organization (WHO). Metals in meat samples showed the trend of Fe > Na > Zn > Ni > Ca > As > Cr > Pb > Cu > Cd. All the studied metals except lead were statistically significant (P ≤ 0.05). The hazard quotient (HQ) values of all the metals were below one, except iron. Iron showed chronic health risks in both adults (1.63) and children (3.64). Moreover, the cumulative hazard index (HI) of the metals indicated that meat consumption can pose a significant chronic toxic risk in both adults and children as the HI value was 2.06 for adults and 4.61 for children, which is greater than one. The carcinogenic risk (CR) of arsenic in meat for adults and children exceeded the acceptable range, making it a metal of concern. This means that the consumption of small concentrations of metal through meat may be the source of severe toxicological consequences. It can be concluded that meat is contaminated with metals; therefore, appropriate precautions should be taken to minimize this contamination.

Modelling hemodynamics regulation in rats and dogs to facilitate drugs safety risk assessment.

Pharmaceutical companies routinely screen compounds for hemodynamics related safety risk. In vitro secondary pharmacology is initially used to prioritize compounds while in vivo studies are later used to quantify and translate risk to humans. This strategy has shown limitations but could be improved via the incorporation of molecular findings in the animal-based toxicological risk assessment. The aim of this study is to develop a mathematical model for rat and dog species that can integrate secondary pharmacology modulation and therefore facilitate the overall pre-clinical safety translation assessment. Following an extensive literature review, we built two separate models recapitulating known regulation processes in dogs and rats. We describe the resulting models and show that they can reproduce a variety of interventions in both species. We also show that the models can incorporate the mechanisms of action of a pre-defined list of 50 pharmacological mechanisms whose modulation predict results consistent with known pharmacology. In conclusion, a mechanistic model of hemodynamics regulations in rat and dog species has been developed to support mechanism-based safety translation in drug discovery and development.

Health consequences of harmful chemicals in foods: insights from the WHO Global Burden of Foodborne Disease Study

Abstract Foods can be an important source of human exposure to harmful chemicals. Contamination can occur at any stage of the food chain; with chemicals that occur naturally or by anthropogenic pollution in the environment and during production processes from farm level to the kitchen of the consumer. The variety of chemicals in foods is broad and associated with a wide range of adverse health effects. Where toxicological risk assessment of chemicals in foods serves the purpose of protecting populations from exposure levels constituting a health concern, burden of disease methodology provides a quantitative snapshot of the current impact of chemicals on disease occurrence and population health. This allows for the comparison across hazards, health effects and foods and eventually prioritized allocation of resources to maximize health benefits. Following the advice by the World Health Organization Foodborne Disease Burden Epidemiology Reference group (WHO/FERG), WHO published in 2015 the first estimates of the global burden of foodborne disease. More than 400,000 deaths and 33 million disability-adjusted life years were estimated due to unsafe foods in 2010; the largest proportion due to foodborne pathogens, as the contribution of only 3 chemical hazards (dioxins, aflatoxin B1 and cassava cyanide) was included. WHO, once more under the advice by the re-established WHO/FERG (2021-2025), is currently working to update the 2010 estimates. Besides applying updated data and methodological improvements in managing data gaps and time series analysis, WHO’s ambition is to consider a wider range of chemicals and associated health effects for the year of 2020. In this presentation, we will share insights on the WHO estimates of the global burden of foodborne chemicals, and explore the methodological opportunities and challenges that estimating the burden of foodborne chemicals provides for informing policies.

Evaluating the performance of multi-omics integration: a thyroid toxicity case study.

Multi-omics data integration has been repeatedly discussed as the way forward to more comprehensively cover the molecular responses of cells or organisms to chemical exposure in systems toxicology and regulatory risk assessment. In Canzler etal. (Arch Toxicol 94(2):371-388. https://doi.org/10.1007/s00204-020-02656-y ), we reviewed the state of the art in applying multi-omics approaches in toxicological research and chemical risk assessment. We developed best practices for the experimental design of multi-omics studies, omics data acquisition, and subsequent omics data integration. We found that multi-omics data sets for toxicological research questions were generally rare, with no datasets comprising more than two omics layers adhering to these best practices. Due to these limitations, we could not fully assess the benefits of different data integration approaches or quantitatively evaluate the contribution of various omics layers for toxicological research questions. Here, we report on a multi-omics study on thyroid toxicity that we conducted in compliance with these best practices. We induced direct and indirect thyroid toxicity through Propylthiouracil (PTU) and Phenytoin, respectively, in a 28-day plus 14-day recovery oral rat toxicity study. We collected clinical and histopathological data and six omics layers, including the long and short transcriptome, proteome, phosphoproteome, and metabolome from plasma, thyroid, and liver. We demonstrate that the multi-omics approach is superior to single-omics in detecting responses at the regulatory pathway level. We also show how combining omics data with clinical and histopathological parameters facilitates the interpretation of the data. Furthermore, we illustrate how multi-omics integration can hint at the involvement of non-coding RNAs in post-transcriptional regulation. Also, we show that multi-omics facilitates grouping, and we assess how much information individual and combinations of omics layers contribute to this approach.

Predictive, integrative, and regulatory aspects of AI-driven computational toxicology – Highlights of the German Pharm-Tox Summit (GPTS) 2024

The 9th German Pharm-Tox Summit (GPTS) and the 90th Annual Meeting of the German Society for Experimental and Clinical Pharmacology and Toxicology (DGPT) took place in Munich from March 13–15, 2024. The event brought together over 700 participants from around the world to discuss cutting-edge developments in the fields of pharmacology and toxicology as well as scientific innovations and novel insights. A key focus of the conference was on the rapidly increasing role of computational toxicology, artificial intelligence (AI), and machine learning (ML) into the field, marking a shift away from traditional methods and allowing the reduction of animal testing as primary tool for toxicological risk assessment. Tools such as Toxometris.ai showcased the potential of AI-based risk assessments for predicting carcinogenicity, offering more ethical and efficient alternatives. Additionally, computer-driven models like computer-aided pattern analysis (C@PA) for drug toxicity prediction were presented, emphasizing the growing role of chem- and bioinformatic applications in computational sciences. Throughout the summit, there was a strong focus on the need for regulatory innovation to support the adoption of these advanced technologies and ensure the safety and sustainability of chemical substances and drugs.

Computational Strategies for Assessing Adverse Outcome Pathways: Hepatic Steatosis as a Case Study.

The evolving landscape of chemical risk assessment is increasingly focused on developing tiered, mechanistically driven approaches that avoid the use of animal experiments. In this context, adverse outcome pathways have gained importance for evaluating various types of chemical-induced toxicity. Using hepatic steatosis as a case study, this review explores the use of diverse computational techniques, such as structure-activity relationship models, quantitative structure-activity relationship models, read-across methods, omics data analysis, and structure-based approaches to fill data gaps within adverse outcome pathway networks. Emphasizing the regulatory acceptance of each technique, we examine how these methodologies can be integrated to provide a comprehensive understanding of chemical toxicity. This review highlights the transformative impact of in silico techniques in toxicology, proposing guidelines for their application in evidence gathering for developing and filling data gaps in adverse outcome pathway networks. These guidelines can be applied to other cases, advancing the field of toxicological risk assessment.

Building knowledge of NAMs through risk science

The 12th World Congress on Alternatives and Animal Use in the Life Sciences provided a platform for mobilizing and exchanging knowledge on the advancements in science and technology. It also provided an opportunity for experts to discuss how to accelerate the adoption of new strategies and tools. One of these recommendations advocated the need to bridge the gap between the next generation of scientists who have yet to learn about ‘New Approach Methodologies’ (NAMs) and the current generation of thought leaders who have pioneered the development and validation of these non-animal approaches to toxicological risk assessment. Consequently, a mini-course, held at Canada's University of Ottawa, was developed for students, aged 13–16 years, interested in learning about risk science and how NAMs can be used to inform human health risk assessment. This course also served as a platform for creating a virtual training roadmap, provided in this paper, thereby bringing this knowledge to a broader audience of learners who are establishing their careers in the field of risk science.

Heavy Metal Concentrations in Selected Herbal Drinks Sold in Abeokuta, Ogun State, and Their Toxicological Risk Assessment

Heavy Metal Concentrations in Selected Herbal Drinks Sold in Abeokuta, Ogun State, and Their Toxicological Risk Assessment

CEC02-04 The virtual human approach to animal-free chemical hazard and risk assessment in developmental toxicology

CEC02-04 The virtual human approach to animal-free chemical hazard and risk assessment in developmental toxicology

Toxicological effects of di(2-ethylhexyl)phthalate on dandelions: Insights into physiological, metabolic, and molecular docking perspectives

Di(2-ethylhexyl)phthalate (DEHP) is one of the most widely used plasticizers in plastic manufacturing. However, the toxicological effects of DEHP on dandelions remain poorly understood. This study comprehensively analyzed and explored the response mechanisms of dandelions to 1, 10, 50, and 100 mg L−1 DEHP influencing the morphophysiological growth, metabolomics, and molecular docking. DEHP reduced chlorophyll synthesis, inhibited plant growth, and induced oxidative-state-associated stress, which was manifested by the excessive production of reactive oxygen species, an increase in antioxidant enzyme activities, and enhanced synthesis of some osmoregulatory compounds, including proline and soluble protein. An analysis of the integrated biological response index showed that the toxicity was dose-dependent. Molecular docking demonstrated that DEHP could bind stably to three enzymes, and the binding energy was peroxidase (POD) > catalase (CAT) > superoxide dismutase (SOD). Metabolomics revealed that metabolite abundance and metabolic pathways were altered by DEHP, with 88 and 72 primary metabolites identified in shoots and roots, respectively. Amino acid, sugar, and organic acid metabolism were severely disturbed, with the most significant effects being on carbohydrate metabolism, valine, leucine, and isoleucine biosynthesis. Our study elucidated the influence of DEHP exposure on dandelions, providing new insights into the toxicity mechanisms and toxicological risk assessment.

A potential toxicological risk assessment of heavy metals and pesticides in irrigated rice cultivars near industrial areas of Dhaka, Bangladesh.

Rice intake represents a significant pathway through which humans accumulate heavy metals. This study presents a comprehensive analysis of heavy metal and pesticide contamination in rice cultivars irrigated with industrial wastewater near Dhaka, Bangladesh, a region heavily influenced by industrial activities. This study employed a unique methodology that not only quantified the concentrations of heavy metals and pesticide residues in rice grains but also extended to evaluating the physicochemical properties of rice stems, husks, soil, and irrigation water. The findings revealed alarmingly high levels of heavy metals such as lead, cadmium, chromium, nickel, and mercury in the soil and irrigation water, with concentrations in some cases exceeding the World Health Organization safety thresholds by 2 to 15 times. Notably, the rice grains also exhibited significant contamination, including substantial amounts of diazinon and fenitrothion pesticides, exceeding the established safety limits. The study employed hazard quotients (HQs) and cancer risk (CR) assessments to evaluate the potential health risks associated with the consumption of contaminated rice. The results indicated HQ values were greater than 1 for rice grains across the sampled fields, suggesting a considerable non-carcinogenic health risk, particularly from lead exposure, which was found at levels twice the standard limit in all the sampling fields. Moreover, the CR values for As, Pb, Cd, Co, and Mn highlighted a significant carcinogenic risk in several instances.

Tissue Distribution and Toxicological Risk Assessment of Mercury and Other Elements in Northern Populations of Wolverine (Gulo gulo)

Wolverines are facultative scavengers that feed near the top of terrestrial food chains. We characterized concentrations of mercury and other trace elements in tissues of wolverine from a broad geographic area, representing much of their contemporary distribution in northwestern North America. We obtained tissues from 504 wolverines, from which mercury was measured on muscle (n = 448), kidney (n = 222), liver (n = 148), hair (n = 130), and brain (n = 52). In addition, methylmercury, seven trace elements (arsenic, cadmium, chromium, cobalt, lead, nickel, selenium), and arsenic compounds were measured on a subset of samples. Concentrations of mercury and other trace elements varied between tissues and were generally highest in kidney compared to brain, liver and muscle. Mercury was predominately as methylmercury in brain and muscle, but largely as inorganic mercury in liver and kidney. Mercury concentrations of hair were moderately correlated with those of internal tissues (Pearson r = 0.51–0.75, p ≤ 0.004), making hair a good non-lethal indicator of broad spatial or temporal differences in mercury exposure to wolverine. Arsenobetaine was the dominant arsenic compound identified in tissues, and arsenite, arsenocholine and dimethylarsinic acid were also detected. A preliminary risk assessment suggested the cadmium, lead, mercury, and selenium concentrations in our sample of wolverines were not likely to pose a risk of overt toxicological effects. This study generated a comprehensive dataset on mercury and other trace elements in wolverine, which will support future contaminants study of this northern terrestrial carnivore.

Development and structure of the discipline “Applied chemistry in medicine” (elective course) at the school of medicine

Along with teaching the natural science and medical principles, it is the author's proposal to create a new subject for electives, “How Applied Chemistry Helps in Medication” to see education level of medical application in higher education students within the Faculty of Medicine. This elective tries to amalgamate two different topics involving both chemistry and medicine. Besides this, it places serious emphasis on the importance of public health within the context of medical practice, of the significant role chemical principles may play in the modern health care system. Students have an opportunity to investigate subjects like environmental toxicology, pharmaceutical chemistry, and chemical risk assessment in which they can perceive the chemistry’s face with the public health field. The knowledge about disease prevention strategies, health promotion and community wellness obtained as a result can enhance the skillset students need to work towards evidence-based approaches in disease prevention. The course is designed as a 3.0 credits ECTS specified by the regulatory requirements. Thematic subjects get covered and include chemical principles, toxicology, pharmaceutical chemistry, environmental toxicology, and chemical risk assessment. Sessions are designed to provide a complete picture of the domain and the methodological toolkit, while at the same time they are interactive and practical by applying theoretical concepts to real-life situations. Introduce the development of problem-solving and critical thinking as one of the learning objectives.

New metabolites of 2-ethylhexyl salicylate in human urine after simulated real-life dermal sunscreen application

2-Ethylhexyl salicylate (EHS) is an organic UV filter which is used in sunscreen and other personal care products. The dermal uptake of EHS was studied in several dermal-exposure experiments. This paper aims to coherently assess urine samples after dermal exposure for the biomarkers EHS, 5OH-EHS, 5oxo-EHS, and 5cx-EPS as well as further biomarkers of interest, specifically 4OH-EHS, 4oxo-EHS, 2OH-EHS, and 6OH-EHS, for the first time. Samples from 18 participants of a pre-existing dermal exposure study under real-life conditions were reassessed using a comprehensive LC-MS/MS method. EHS accounts for 34 % of the cumulative excretion of all analytes within 24 h after exposure, followed by 5OH-EHS (19 %), 5cx-EPS (18 %), 4OH-EHS (15 %) and 5oxo-EHS (11 %). Further metabolites were only quantified in minor amounts. EHS as the most prominent excretion parameter in this study demonstrates the missing first-pass effect after dermal absorption. Furthermore, the applied novel comprehensive analytical procedure revealed oxidation at the ω (5cx-EPS, 6OH-EHS), ω-1 (5OH-EHS, 5oxo-EHS), and ω-2 positions (4OH-EHS, 4oxo-EHS) in the main chain of the ethylhexyl group as well as oxidation in the side chain (2OH-EHS). The presented data are of high relevance for a reliable toxicological risk assessment of dermal exposure to EHS.

A Comparative Study of Phase I and II Hepatic Microsomal Biotransformation of Phenol in Three Species of Salmonidae: Hydroquinone, Catechol, and Phenylglucuronide Formation.

The in vitro biotransformation of phenol at 11 °C was studied using pre-spawn adult rainbow (Oncorhynchus mykiss) (RBT), brook (Salvelinus fontinalis) (BKT), and lake trout (Salvelinus namaycush) (LKT) hepatic microsomal preparations. The incubations were optimized for time, cofactor concentration, pH, and microsomal protein concentration. Formation of Phase I ring-hydroxylation and Phase II glucuronidation metabolites was quantified using HPLC with dual-channel electrochemical and UV detection. The biotransformation of phenol over a range of substrate concentrations (1 to 180 mM) was quantified, and the Michaelis-Menten kinetics constants, Km and Vmax, for the formation of hydroquinone (HQ), catechol (CAT), and phenylglucuronide (PG) were calculated. Species differences were noted in the Km values for Phase I enzyme production of HQ and CAT, with the following rank order of apparent enzyme affinity for substrate: RBT > BKT = LKT. However, no apparent differences in the Km for Phase II metabolism of phenol to PG were detected. Conversely, while there were no apparent differences in Vmax between species for HQ or CAT formation, the apparent maximum capacity for PG formation was significantly less in LKT than that observed for RBT and BKT. These experiments provide a means to quantify metabolic activation and deactivation of xenobiotics in fish, to compare activation and deactivation reactions across species, and to act as a guide for future predictions of new chemical biotransformation pathways and rates in fish. These experiments provided the necessary rate and capacity (Km and Vmax) inputs that are required to parameterize a fish physiologically based toxicokinetic (PB-TK) model for a reactive chemical that is readily biotransformed, such as phenol. In the future, an extensive database of these rate and capacity parameters on important fish species for selected chemical structures will be needed to allow the effective use of predictive models for reactive, biotransformation chemicals in aquatic toxicology and environmental risk assessment.

Bridging the Gap Between Human Toxicology and Ecotoxicology Under One Health Perspective by a Cross-Species Adverse Outcome Pathway Network for Reproductive Toxicity.

Although ecotoxicological and toxicological risk assessments are performed separately from each other, recent efforts have been made in both disciplines to reduce animal testing and develop predictive approaches instead, for example, via conserved molecular markers, and in vitro and in silico approaches. Among them, adverse outcome pathways (AOPs) have been proposed to facilitate the prediction of molecular toxic effects at larger biological scales. Thus, more toxicological data are used to inform on ecotoxicological risks and vice versa. An AOP has been previously developed to predict reproductive toxicity of silver nanoparticles via oxidative stress on the nematode Caenorhabditis elegans (AOPwiki ID 207). Following this previous study, our present study aims to extend the biologically plausible taxonomic domain of applicability (tDOA) of AOP 207. Various types of data, including in vitro human cells, in vivo, and molecular to individual, from previous studies have been collected and structured into a cross-species AOP network that can inform both human toxicology and ecotoxicology risk assessments. The first step was the collection and analysis of literature data to fit the AOP criteria and build a first AOP network. Then, key event relationships were assessed using a Bayesian network modeling approach, which gave more confidence in our overall AOP network. Finally, the biologically plausible tDOA was extended using in silico approaches (Genes-to-Pathways Species Conservation Analysis and Sequence Alignment to Predict Across Species Susceptibility), which led to the extrapolation of our AOP network across over 100 taxonomic groups. Our approach shows that various types of data can be integrated into an AOP framework, and thus facilitates access to knowledge and prediction of toxic mechanisms without the need for further animal testing. Environ Toxicol Chem 2024;00:1-14. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Toxicological risk assessment using spring water quality indices in plateaus of Giresun Province/Türkiye: a holistic hydrogeochemical data analysis

Water scarcity is a growing concern due to rapid urbanization and population growth. This study assesses spring water quality at 20 stations in Giresun province, Türkiye, focusing on potentially toxic elements and physicochemical parameters. The Water Quality Index rated most samples as "excellent" during the rainy season and "good" during the dry season, except at stations 4 (40° 35′ 12″ North/38° 26′ 34″ East) and 19 (40° 44′ 28″ North/38° 06′ 53″ West), indicating "poor" quality. Mean macro-element concentrations (mg/L) were: Ca (34.27), Na (10.36), Mg (8.26), and K (1.48). Mean trace element values (μg/L) were: Al (1093), Zn (110.54), Fe (67.45), Mn (23.03), Cu (9.79), As (3.75), Ni (3.00), Cr (2.84), Pb (2.70), Co (1.93), and Cd (0.76). Health risk assessments showed minimal non-carcinogenic risks, while carcinogenic risk from arsenic slightly exceeded safe limits (CR = 1.75E−04). Higher arsenic concentrations during the rainy season were due to increased recharge, arsenic-laden surface runoff, and human activities. Statistical analyses (PCA, PCC, HCA) suggested that metals and physico-chemical parameters originated from lithogenic, anthropogenic, or mixed sources. Regular monitoring of spring water is recommended to mitigate potential public health risks from waterborne contaminants.