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Archives of Toxicology Oct 2023After the detection of high environmental and occupational exposure to polychlorinated biphenyls (PCBs) in a German recycling company for transformers and capacitors in... (Review)
Review
After the detection of high environmental and occupational exposure to polychlorinated biphenyls (PCBs) in a German recycling company for transformers and capacitors in 2010, the multidisciplinary medical surveillance program "HELPcB" (Health Effects in High-Level Exposure to PCB) was established for former PCB-exposed workers of the company, their family members, employees of surrounding companies, and area residents to investigate potential adverse health effects by PCB exposure in a longitudinal study approach with up to seven examination time points between 2010 and 2019. More than 300 individuals were enrolled into the program. Assessments particularly included plasma and urine concentrations of PCB congeners and their metabolites, clinical laboratory parameters, Comet assay, analysis of telomere length, neuropsychological examinations, psychological screening, abdominal and thyroid ultrasound examination. This review summarizes the main results of the studies conducted in the HELPcB program yielding relevant new data on potential adverse effects of PCB exposure in humans and potential mechanisms that underlie these effects. Even larger studies in PCB-exposed individuals are warranted to confirm the results of this program and to further establish causality between PCB exposure and clinical effects in humans.
Topics: Humans; Polychlorinated Biphenyls; Longitudinal Studies; Comet Assay; Drug-Related Side Effects and Adverse Reactions; Electric Power Supplies
PubMed: 37594590
DOI: 10.1007/s00204-023-03578-1 -
Chemical Research in Toxicology Feb 2021As a field, computational toxicology is concerned with using models to predict and understand the origins of toxicity. It is fast, relatively inexpensive, and avoids... (Review)
Review
As a field, computational toxicology is concerned with using models to predict and understand the origins of toxicity. It is fast, relatively inexpensive, and avoids the ethical conundrum of using animals in scientific experimentation. In this perspective, we discuss the importance of computational models in toxicology, with a specific focus on the different model types that can be used in predictive toxicological approaches toward mutagenicity (SARs and QSARs). We then focus on how quantum chemical methods, such as density functional theory (DFT), have previously been used in the prediction of mutagenicity. It is then discussed how DFT allows for the development of new chemical descriptors that focus on capturing the steric and energetic effects that influence toxicological reactions. We hope to demonstrate the role that DFT plays in understanding the fundamental, intrinsic chemistry of toxicological reactions in predictive toxicology.
Topics: Animals; Density Functional Theory; Mutagenicity Tests; Quantitative Structure-Activity Relationship; Toxicity Tests
PubMed: 32643924
DOI: 10.1021/acs.chemrestox.0c00113 -
Environmental Science and Pollution... Sep 2022
Topics: Animals; Environment; Humans; Mutagenesis; Mutagenicity Tests; Mutagens
PubMed: 35917065
DOI: 10.1007/s11356-022-22247-x -
Biomolecules Jul 2020Bisphenol A (BPA) is an oestrogenic endocrine disruptor widely used in the production of certain plastics, e.g., polycarbonate, hard and clear plastics, and epoxy resins... (Review)
Review
Bisphenol A (BPA) is an oestrogenic endocrine disruptor widely used in the production of certain plastics, e.g., polycarbonate, hard and clear plastics, and epoxy resins that act as protective coating for food and beverage cans. Human exposure to this chemical is thought to be ubiquitous. BPA alters endocrine function, thereby causing many diseases in human and animals. In the last few decades, studies exploring the mechanism of BPA activity revealed a direct link between BPA-induced oxidative stress and disease pathogenesis. Antioxidants, reducing agents that prevent cellular oxidation reactions, can protect BPA toxicity. Although the important role of antioxidants in minimizing BPA stress has been demonstrated in many studies, a clear consensus on the associated mechanisms is needed, as well as the directives on their efficacy and safety. Herein, considering the distinct biochemical properties of BPA and antioxidants, we provide a framework for understanding how antioxidants alleviate BPA-associated stress. We summarize the current knowledge on the biological function of enzymatic and non-enzymatic antioxidants, and discuss their practical potential as BPA-detoxifying agents.
Topics: Animals; Antioxidants; Benzhydryl Compounds; DNA Breaks; Endocrine Disruptors; Humans; Lipid Peroxidation; Models, Animal; Mutagenicity Tests; Phenols; Poisoning
PubMed: 32722388
DOI: 10.3390/biom10081105 -
International Journal of Environmental... Jul 2021Pesticide adjuvants (PAs) denote the general term for auxiliaries in pesticide preparations except for the active components. Toluene, chloroform, and trichloroethylene...
Pesticide adjuvants (PAs) denote the general term for auxiliaries in pesticide preparations except for the active components. Toluene, chloroform, and trichloroethylene are the three most commonly used PAs as organic solvents. The residues of the three chemicals in the process of production and application of pesticides may endanger the ecosystem. In the present study, the mutagenicity of toluene, chloroform, and trichloroethylene as well the mixture of the three chemicals was tested by the reverse mutation test (Ames test) with TA97, TA98, TA100, and TA102 strains in the system with and without rat liver microsomal preparations (S9). The four tester strains have been used for more than 40 years to detect mutagenic compounds in chemicals, cosmetics, and environmental samples. The mutagenicity was detected on tester strains in the separated experiment from the three chemicals. The addition of S9 decreased the mutation ratios of toluene to four strains, except for the TA100 strain, but increased the mutation ratios of chloroform to four strains except for the TA98 strain. Trichloroethylene caused positive mutagenicity to become negative on the TA102 strain. In the mixed experiment, positive effects were detected only on the TA102 strain in the absence of S9. The addition of S9 increased the mutagenicity except for the TA102 strain. The mixture of toluene, chloroform, and trichloroethylene showed antagonism in mutagenicity to tester strains, except for the TA102 strain without S9. However, the mixture showed a synergistic effect to tester strains after adding S9 except for the TA98 strain.
Topics: Animals; Chloroform; Ecosystem; Mutagenicity Tests; Mutagens; Pesticides; Rats; Toluene; Trichloroethylene
PubMed: 34360388
DOI: 10.3390/ijerph18158095 -
Toxicology Reports 2021Ovatodiolide is a bioactive cembrane-type diterpenoid isolated from (L.) Kuntze. It has been proven that ovatodiolide is anti-inflammatory, anti-tumorigenic,...
Ovatodiolide is a bioactive cembrane-type diterpenoid isolated from (L.) Kuntze. It has been proven that ovatodiolide is anti-inflammatory, anti-tumorigenic, anti-melanogenic and attenuates asthma by regulating signaling pathways. The aim of this study was to evaluate the safety of ovatodiolide by conducting genotoxicity tests and 28-day oral toxicity tests in rats. Genotoxicity assays were conducted by using a bacterial reverse mutation test and mammalian chromosomal aberration test to assess whether ovatodiolide causes reverse mutations and mutagenicity with or without metabolism activation. For the mammalian erythrocyte micronucleus test, mice were administered a single dose of 0, 250, 500 or 1000 mg/kg b.w. ovatodiolide by single gavage. In the acute oral toxicity test, rats were given a single dose of ovatodiolide 1000 mg/kg b.w. by single gavage. In the 28-day oral toxicity test, groups were divided into a control, ovatodiolide 10, 25 and 50 mg/kg b.w. The results showed that there was no mutagenicity in the bacterial reverse mutation test or the mammalian chromosomal aberration test with or without S9 fraction. Ovatodiolide did not produce an increase in micronucleated reticulocytes in the micronucleus test. The results revealed that the acute oral toxicity of ovatodiolide is over 1000 mg/kg b.w. in rats. Moreover, 10, 25 and 50 mg/kg b.w. of ovatodiolide did not cause a significant effect in rats. According to the results of the genotoxicity and oral toxicity studies in rats, ovatodiolide did not produce any adverse effects, and the tested doses can serve as clinical references.
PubMed: 34722163
DOI: 10.1016/j.toxrep.2021.10.010 -
Scientific Reports Aug 2020The Quilombola communities are mostly isolated and deprived of sources of treated water, garbage collection and sewage, consuming fresh water from wells, streams, lakes,...
The Quilombola communities are mostly isolated and deprived of sources of treated water, garbage collection and sewage, consuming fresh water from wells, streams, lakes, among others. This lack of basic infrastructure can be a relevant factor in exposing residents to substances and factors that are harmful to the integrity of their genetic material that can lead to carcinogenesis. Based on this, the objective of this study was to evaluate the genomic and mutagenic/cytotoxic damage in the adult population of two Quilombola communities (one urban and another rural region), in the state of Goiás, Brazil. For this purpose, the leukocyte of peripheral blood Comet Assay in 68 individuals and Micronucleus Test from exfoliated buccal cells of oral mucosa in 21 volunteers were performed. The results evidenced genomic damage, especially for the community of Aparecida de Goiânia city, which detected significant values (p < 0.05), for the length of the comet's tail and for of the Olive Tail Moment. In the micronucleus test, significant differences were only detected (p < 0.05), when it came to the distribution of nuclear changes among the groups. Therefore, it is essential to perform constant population biomonitoring studies to help guarantee health and, consequently, the quality of life.
Topics: Brazil; Comet Assay; Environmental Exposure; Humans; Micronucleus Tests; Residence Characteristics
PubMed: 32848182
DOI: 10.1038/s41598-020-71195-4 -
Regulatory Toxicology and Pharmacology... Aug 2021Lithium orotate, the salt of lithium and orotic acid, has been marketed for decades as a supplemental source of lithium with few recorded adverse events. Nonetheless,...
Lithium orotate, the salt of lithium and orotic acid, has been marketed for decades as a supplemental source of lithium with few recorded adverse events. Nonetheless, there have been some concerns in the scientific literature regarding orotic acid, and pharmaceutical lithium salts are known to have a narrow therapeutic window, albeit, at lithium equivalent therapeutic doses 5.5-67 times greater than typically recommended for supplemental lithium orotate. To our knowledge, the potential toxicity of lithium orotate has not been investigated in preclinical studies; thus, we conducted a battery of genetic toxicity tests and an oral repeated-dose toxicity test in order to further explore its safety. Lithium orotate was not mutagenic or clastogenic in bacterial reverse mutation and in vitro mammalian chromosomal aberration tests, respectively, and did not exhibit in vivo genotoxicity in a micronucleus test in mice. In a 28-day, repeated-dose oral toxicity study, rats were administered 0, 100, 200, or 400 mg/kg body weight/day of lithium orotate by gavage. No toxicity or target organs were identified; therefore, a no observed adverse effect level was determined as 400 mg/kg body weight/day. These results are supportive of the lack of a postmarket safety signal from several decades of human consumption.
Topics: Administration, Oral; Animals; Cell Line; Chromosome Aberrations; Cricetulus; DNA Damage; Dietary Supplements; Dose-Response Relationship, Drug; Mice; Micronucleus Tests; No-Observed-Adverse-Effect Level; Organometallic Compounds; Rats; Toxicity Tests, Subacute
PubMed: 34146638
DOI: 10.1016/j.yrtph.2021.104973 -
Archives of Toxicology Jun 2020The risk assessment of chemical carcinogens is one major task in toxicology. Even though exposure has been mitigated effectively during the last decades, low levels of... (Review)
Review
The risk assessment of chemical carcinogens is one major task in toxicology. Even though exposure has been mitigated effectively during the last decades, low levels of carcinogenic substances in food and at the workplace are still present and often not completely avoidable. The distinction between genotoxic and non-genotoxic carcinogens has traditionally been regarded as particularly relevant for risk assessment, with the assumption of the existence of no-effect concentrations (threshold levels) in case of the latter group. In contrast, genotoxic carcinogens, their metabolic precursors and DNA reactive metabolites are considered to represent risk factors at all concentrations since even one or a few DNA lesions may in principle result in mutations and, thus, increase tumour risk. Within the current document, an updated risk evaluation for genotoxic carcinogens is proposed, based on mechanistic knowledge regarding the substance (group) under investigation, and taking into account recent improvements in analytical techniques used to quantify DNA lesions and mutations as well as "omics" approaches. Furthermore, wherever possible and appropriate, special attention is given to the integration of background levels of the same or comparable DNA lesions. Within part A, fundamental considerations highlight the terms hazard and risk with respect to DNA reactivity of genotoxic agents, as compared to non-genotoxic agents. Also, current methodologies used in genetic toxicology as well as in dosimetry of exposure are described. Special focus is given on the elucidation of modes of action (MOA) and on the relation between DNA damage and cancer risk. Part B addresses specific examples of genotoxic carcinogens, including those humans are exposed to exogenously and endogenously, such as formaldehyde, acetaldehyde and the corresponding alcohols as well as some alkylating agents, ethylene oxide, and acrylamide, but also examples resulting from exogenous sources like aflatoxin B, allylalkoxybenzenes, 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx), benzo[a]pyrene and pyrrolizidine alkaloids. Additionally, special attention is given to some carcinogenic metal compounds, which are considered indirect genotoxins, by accelerating mutagenicity via interactions with the cellular response to DNA damage even at low exposure conditions. Part C finally encompasses conclusions and perspectives, suggesting a refined strategy for the assessment of the carcinogenic risk associated with an exposure to genotoxic compounds and addressing research needs.
Topics: Animals; Carcinogenicity Tests; Carcinogens; DNA Damage; Humans; Mutagenicity Tests; Mutagens; Risk Assessment; Toxicogenetics
PubMed: 32542409
DOI: 10.1007/s00204-020-02733-2 -
Environmental and Molecular Mutagenesis Dec 2022The OECD Test Guideline 488 (TG 488) for the Transgenic Rodent Gene Mutation Assay has undergone several revisions to update the recommended design for studying... (Review)
Review
The OECD Test Guideline 488 (TG 488) for the Transgenic Rodent Gene Mutation Assay has undergone several revisions to update the recommended design for studying mutations in somatic tissues and male germ cells. The recently revised TG recommends a single sampling time of 28 days following 28 days of exposure (i.e., 28 + 28 days) for all tissues, irrespective of proliferation rates. An alternative design (i.e., 28 + 3 days) is appropriate when germ cell data is not required, nor considered. While the 28 + 28 days design is clearly preferable for slowly proliferating somatic tissues and germ cells, there is still uncertainty about the impact of extending the sampling time to 28 days for rapidly somatic tissues. Here, we searched the available literature for evidence supporting the applicability and utility of the 28 + 28 days design for rapidly proliferating tissues. A total of 79 tests were identified. When directly comparing results from both designs in the same study, there was no evidence that the 28 + 28 days regimen resulted in a qualitatively different outcome from the 28 + 3 days design. Studies with a diverse range of agents that employed only a 28 + 28 days protocol provide further evidence that this design is appropriate for rapidly proliferating tissues. Benchmark dose analyses demonstrate high quantitative concordance between the 28 + 3 and 28 + 28 days designs for rapidly proliferating tissues. Accordingly, our review confirms that the 28 + 28 days design is appropriate to assess mutagenicity in both slowly and rapidly proliferating somatic tissues, and germ cells, and provides further support for the recommended design in the recently adopted TG 488.
Topics: Animals; Male; Rodentia; Animals, Genetically Modified; Mutation; Mutagens; Germ Cells; Mutagenicity Tests
PubMed: 36271823
DOI: 10.1002/em.22514