RESUMO
Although the United States Food & Drug Administration (FDA) has provided guidance on the control of drug degradants for prescription drugs, there is less guidance on how to set degradant specifications for FDA OTC monograph drugs. Given that extensive impurity testing was not part of the safety paradigm in original OTC monographs, a weight of evidence (WOE) approach to qualify OTC degradants is proposed. This approach relies on in silico tools and read-across approaches alongside standard toxicity testing to determine safety. Using several drugs marketed under 21 CFR 341 as case studies, this research demonstrates the utility of a WOE approach across data-rich and data-poor degradants. Based on degradant levels ranging from 1 to 4% of the maximum daily doses of each case study drug and 10th percentile body weight data for each patient group, children were recognized as having the highest potential exposure relative to adults per body mass. Depending on data availability and relationship to the parent API, margins of safety (MOS) or exposure margins were calculated for each degradant. The findings supported safe use, and indicated that this contemporary WOE approach could be utilized to assess OTC degradants. This approach is valuable to establish specifications for degradants in OTCs.
Assuntos
Antitussígenos , Medicamentos sem Prescrição , United States Food and Drug Administration , Medicamentos sem Prescrição/efeitos adversos , Humanos , Estados Unidos , Antitussígenos/efeitos adversos , Tosse/tratamento farmacológico , Medição de Risco , Criança , Contaminação de Medicamentos , Adulto , Testes de Toxicidade/métodos , Resfriado Comum/tratamento farmacológicoRESUMO
In October 2022, the World Health Organization (WHO) convened an expert panel in Lisbon, Portugal in which the 2005 WHO TEFs for chlorinated dioxin-like compounds were reevaluated. In contrast to earlier panels that employed expert judgement and consensus-based assignment of TEF values, the present effort employed an update to the 2006 REP database, a consensus-based weighting scheme, a Bayesian dose response modeling and meta-analysis to derive "Best-Estimate" TEFs. The updated database contains almost double the number of datasets from the earlier version and includes metadata that informs the weighting scheme. The Bayesian analysis of this dataset results in an unbiased quantitative assessment of the congener-specific potencies with uncertainty estimates. The "Best-Estimate" TEF derived from the model was used to assign 2022 WHO-TEFs for almost all congeners and these values were not rounded to half-logs as was done previously. The exception was for the mono-ortho PCBs, for which the panel agreed to retain their 2005 WHO-TEFs due to limited and heterogenous data available for these compounds. Applying these new TEFs to a limited set of dioxin-like chemical concentrations measured in human milk and seafood indicates that the total toxic equivalents will tend to be lower than when using the 2005 TEFs.
Assuntos
Dioxinas , Bifenilos Policlorados , Dibenzodioxinas Policloradas , Animais , Humanos , Teorema de Bayes , Dibenzofuranos/toxicidade , Dibenzofuranos Policlorados/toxicidade , Dioxinas/toxicidade , Mamíferos , Bifenilos Policlorados/toxicidade , Dibenzodioxinas Policloradas/toxicidade , Organização Mundial da SaúdeRESUMO
The toxic equivalency factors (TEFs) approach for dioxin-like chemicals (DLCs) is currently based on a qualitative assessment of a heterogeneous data set of relative estimates of potency (REPs) spanning several orders of magnitude with highly variable study quality and relevance. An effort was undertaken to develop a weighting framework to systematically evaluate and quantitatively integrate the quality and relevance for development of more robust TEFs. Six main-study characteristics were identified as most important in characterizing the quality and relevance of an individual REP for human health risk assessment: study type, study model, pharmacokinetics, REP derivation method, REP derivation quality, and endpoint. Subsequently, a computational approach for quantitatively integrating the weighting framework parameters was developed and applied to the REP2004 database. This was accomplished using a machine learning approach which infers a weighted TEF distribution for each congener. The resulting database, weighted for quality and relevance, provides REP distributions from >600 data sets (including in vivo and in vitro studies, a range of endpoints, etc.). This weighted database provides a flexible platform for systematically and objectively characterizing TEFs for use in risk assessment, as well as providing information to characterize uncertainty and variability. Collectively, this information provides risk managers with information for decision making.
Assuntos
Dioxinas , Bifenilos Policlorados , Dibenzodioxinas Policloradas , Humanos , Dioxinas/toxicidade , Medição de Risco , Incerteza , Bases de Dados FactuaisRESUMO
In 2005, the World Health Organization (WHO) re-evaluated Toxic Equivalency factors (TEFs) developed for dioxin-like compounds believed to act through the Ah receptor based on an updated database of relative estimated potency (REP)(REP2004 database). This re-evalution identified the need to develop a consistent approach for dose-response modeling. Further, the WHO Panel discussed the significant heterogeneity of experimental datasets and dataset quality underlying the REPs in the database. There is a critical need to develop a quantitative, and quality weighted approach to characterize the TEF for each congener. To address this, a multi-tiered approach that combines Bayesian dose-response fitting and meta-regression with a machine learning model to predict REPS' quality categorizations was developed to predict the most likely relationship between each congener and its reference and derive model-predicted TEF uncertainty distributions. As a proof of concept, this 'Best-Estimate TEF workflow' was applied to the REP2004 database to derive TEF point-estimates and characterizations of uncertainty for all congeners. Model-TEFs were similar to the 2005 WHO TEFs, with the data-poor congeners having larger levels of uncertainty. This transparent and reproducible computational workflow incorporates WHO expert panel recommendations and represents a substantial improvement in the TEF methodology.
Assuntos
Dioxinas , Bifenilos Policlorados , Dioxinas/toxicidade , Teorema de Bayes , Medição de Risco , Incerteza , Receptores de Hidrocarboneto ArílicoRESUMO
BACKGROUND: It is well-recognized that consumers face many challenges in understanding and applying nutritional guidance for low-calorie sweeteners (LCS). Thus, this research aims to (1) assess how benchmarks for safe levels of consumption of LCS are utilized by researchers, and (2) understand how varying use of such benchmarks may contribute to challenges in understanding and applying nutritional guidance for LCS consumption. METHODS: A systematic mapping exercise was employed to characterize when and how acceptable daily intake (ADI) values are used as health-based benchmarks in nutrition research studies that consider the safety of LCS. RESULTS: Based on results from charting 121 studies, our findings demonstrate that comparisons of LCS intake to an ADI derived by an authoritative body have been made in a diverse set of published literature, varying widely in their objectives, approaches, and populations of interest. The majority of studies compared the ADI to intake in a population under study; these represent the type of comparison that is most consistent with the intent of the ADI. Other applications of the ADI included use as a benchmark in experimental studies, risk-benefit analyses, and metabolism studies. CONCLUSION: Although most instances of ADI use were reasonable within the context of the individual studies' objectives, the diversity in use by original-study authors amplifies the continued need for development of "best practices" regarding the use and interpretation of the ADIs in current research. Using comparisons to the ADI can be a helpful way to provide context to research findings. However, in doing so, it is important that researchers utilize the value in a manner specific with its intent, as the ADI is a metric that represents an estimate of the amount of a substance that can be consumed daily over a lifetime without presenting an appreciable risk to health.
Assuntos
Benchmarking , Edulcorantes , Ingestão de Energia , Humanos , Nível de Efeito Adverso não Observado , Estado NutricionalRESUMO
In 2019 California's Office of Environmental Health Hazard Assessment (OEHHA) initiated a review of the carcinogenic hazard potential of acetaminophen. In parallel with this review, herein we evaluated the mechanistic data related to the steps and timing of cellular events following therapeutic recommended (≤4 g/day) and higher doses of acetaminophen that may cause hepatotoxicity to evaluate whether these changes indicate that acetaminophen is a carcinogenic hazard. At therapeutic recommended doses, acetaminophen forms limited amounts of N-acetyl-p-benzoquinone-imine (NAPQI) without adverse cellular effects. Following overdoses of acetaminophen, there is potential for more extensive formation of NAPQI and depletion of glutathione, which may result in mitochondrial dysfunction and DNA damage, but only at doses that result in cell death - thus making it implausible for acetaminophen to induce the kind of stable, genetic damage in the nucleus indicative of a genotoxic or carcinogenic hazard in humans. The collective data demonstrate a lack of a plausible mechanism related to carcinogenicity and are consistent with rodent cancer bioassays, epidemiological results reviewed in companion manuscripts in this issue, as well as conclusions of multiple international health authorities.
Assuntos
Acetaminofen/toxicidade , Fenômenos Bioquímicos/efeitos dos fármacos , Carcinógenos/toxicidade , Doença Hepática Induzida por Substâncias e Drogas , Fígado/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Animais , Fenômenos Bioquímicos/fisiologia , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/patologia , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/fisiologia , Humanos , Fígado/metabolismo , Fígado/patologia , Transdução de Sinais/fisiologiaRESUMO
Systematic review tools and approaches developed for clinical medicine are often difficult to apply "off the shelf" in order to meet the needs of chemical risk assessments. To address such, we propose an approach that can be used by practitioners for using evidence-based methods to facilitate the risk assessment process. The framework builds on and combines efforts conducted to date by a number of agencies and researchers; the novelty is in combining these efforts with a practical understanding of risk assessment, and translating such into a 'step-by-step' guide. The approach relies on three key components: problem formulation, systematic evidence mapping, and systematic review, applied using a stepwise approach. Unique to this framework is the consideration of exposure in selecting, prioritizing, and evaluating data (e.g., dose-relevance, routes of exposure, etc.). Using the proposed step-by-step process, critical appraisal of individual studies (e.g., formal and structured assessment of both relevance and reliability) and integration efforts are considered in context of specified risk assessment objectives (e.g., mode of action, dose-response) as well as chemical-specific considerations. The resulting framework provides a logical approach of how evidence-based methods can be used to facilitate risk assessment, and elevates the use of systematic methods beyond hazard identification to directly facilitating transparent and objective selection of candidate studies and/or datasets used to quantitatively characterize risk, and to better use the underlying process to inform the approaches used to develop toxicity values.
Assuntos
Medicina Baseada em Evidências , Projetos de Pesquisa , Testes de Toxicidade/estatística & dados numéricos , Animais , Interpretação Estatística de Dados , Humanos , Modelos Estatísticos , Medição de Risco , Revisões Sistemáticas como Assunto , IncertezaRESUMO
In 2019, the California Office of Environmental Health Hazard Assessment (OEHHA) initiated a review of the carcinogenic hazard potential of acetaminophen. The objective of the analysis herein was to inform this review by assessing whether variability in patient baseline characteristics (e.g. baseline glutathione (GSH) levels, pharmacokinetics, and capacity of hepatic antioxidants) leads to potential differences in carcinogenic hazard potential at different dosing schemes: maximum labeled doses of 4 g/day, repeated doses above the maximum labeled dose (>4-12 g/day), and acute overdoses of acetaminophen (>15 g). This was achieved by performing simulations of acetaminophen exposure in thousands of diverse virtual patients scenarios using the DILIsym® Quantitative Systems Toxicology (QST) model. Simulations included assessments of the dose and exposure response for toxicity and mode of cell death based on evaluations of the kinetics of changes of: GSH, N-acetyl-p-benzoquinone-imine (NAPQI), protein adducts, mitochondrial dysfunction, and hepatic cell death. Results support that, at therapeutic doses, cellular GSH binds to NAPQI providing sufficient buffering capacity to limit protein adduct formation and subsequent oxidative stress. Simulations evaluating repeated high-level supratherapeutic exposures or acute overdoses indicate that cell death precedes DNA damage that could result in carcinogenicity and thus acetaminophen does not present a carcinogenicity hazard to humans at any dose.
Assuntos
Acetaminofen/efeitos adversos , Analgésicos não Narcóticos/administração & dosagem , Testes de Carcinogenicidade , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Simulação por Computador , Neoplasias Hepáticas/induzido quimicamente , Fígado/efeitos dos fármacos , Acetaminofen/farmacocinética , Analgésicos não Narcóticos/farmacocinética , Antioxidantes/metabolismo , Morte Celular/efeitos dos fármacos , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/patologia , Dano ao DNA , Relação Dose-Resposta a Droga , Glutationa/metabolismo , Humanos , Fígado/metabolismo , Fígado/patologia , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Mitocôndrias Hepáticas/efeitos dos fármacos , Mitocôndrias Hepáticas/metabolismo , Mitocôndrias Hepáticas/patologia , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Medição de RiscoRESUMO
Hexavalent chromium [Cr(VI)] is known to cause lung cancer in workers of certain industries, but an association with stomach cancer is uncertain and widely debated. Systematic review and meta-analyses were conducted to assess the risk of stomach cancer mortality/morbidity in humans and experimental animals exposed to Cr(VI). In accordance with the protocol (PROSPERO #CRD4201605162), searches in PubMed and Embase®, and reviews of secondary literature bibliographies, were used to identify eligible studies. Critical appraisal of internal validity and qualitative integration were carried out using the National Toxicology Program's Office of Health Assessment and Translation (OHAT) approach; meta-analyses were conducted based on the occupational data (the only data suitable for quantitative assessment). Forty-seven publications (3 animal, 44 occupational, 0 non-occupational) met the eligibility criteria. Stomach cancer was only observed in one high risk of bias animal study, and in the low risk of bias studies no stomach cancer was observed. Thus, confidence in this evidence base is high. Environmental epidemiology studies did not meet eligibility criteria because exposure and outcome were not measured at the individual level. Meta-analyses of human data resulted in overall meta relative risks of 1.08 (95% CI: 0.96-1.21) including all studies and 1.03 (95%CI: 0.84-1.26) excluding studies associated with the highest risk of bias. Because most occupational studies have high risk of bias for confounding and exposure domains, the overall confidence in this evidence base is low to moderate. Combining the streams of evidence per the OHAT approach, Cr(VI) does not pose a stomach cancer hazard in humans.
Assuntos
Cromo/toxicidade , Exposição Ambiental/estatística & dados numéricos , Poluentes Ambientais/toxicidade , Neoplasias Gástricas/epidemiologia , Neoplasias Gástricas/induzido quimicamenteRESUMO
Increasing interest in characterizing risk assessment uncertainty is highlighted by recent recommendations from the National Academy of Sciences. In this paper we demonstrate the utility of applying qualitative and quantitative methods for assessing uncertainty to enhance risk-based decision-making for 2,3,7,8-tetrachlorodibenzo-p-dioxin. The approach involved deconstructing the reference dose (RfD) via evaluation of the different assumptions, options, models and methods associated with derivation of the value, culminating in the development of a plausible range of potential values based on such areas of uncertainty. The results demonstrate that overall RfD uncertainty was high based on limitations in the process for selection (e.g., compliance with inclusion criteria related to internal validity of the co-critical studies, consistency with other studies), external validity (e.g., generalizing findings of acute, high-dose exposure scenarios to the general population), and selection and classification of the point of departure using data from the individual studies (e.g., lack of statistical and clinical significance). Building on sensitivity analyses conducted by the US Environmental Protection Agency in 2012, the resulting estimates of RfD values that account for the uncertainties ranged from ~1.5 to 179 pg/kg/day. It is anticipated that the range of RfDs presented herein, along with the characterization of uncertainties, will improve risk assessments of dioxins and provide important information to risk managers, because reliance on a single toxicity value limits the information needed for making decisions and gives a false sense of precision and accuracy.
Assuntos
Benchmarking/normas , Relação Dose-Resposta a Droga , Poluentes Ambientais/normas , Nível de Efeito Adverso não Observado , Dibenzodioxinas Policloradas/normas , Dibenzodioxinas Policloradas/toxicidade , Medição de Risco/métodos , Humanos , Valores de Referência , Estados UnidosRESUMO
The National Academy of Science has recommended that a risk of bias (RoB; credibility of the link between exposure and outcome) assessment be conducted on studies that are used as primary data sources for hazard identification and dose-response assessment. Few applications of such have been conducted. Using trichloroethylene and congenital heart defects (CHDs) as a case study, we explore the role of RoB in chemical risk assessment using the National Toxicology Program's Office of Health Assessment and Translation RoB tool. Selected questions were tailored to evaluation of CHD and then applied to 12 experimental animal studies and 9 epidemiological studies. Results demonstrated that the inconsistent findings of a single animal study were likely explained by the limitations in study design assessed via RoB (eg, lack of concurrent controls, unvalidated method for assessing outcome, unreliable statistical methods, etc). Such limitations considered in the context of the body of evidence render the study not sufficiently reliable for the development of toxicity reference values. The case study highlights the utility of RoB as part of a robust risk assessment process and specifically demonstrates the role RoB can play in objectively selecting candidate data sets to develop toxicity values.
Assuntos
Cardiopatias Congênitas , Revisões Sistemáticas como Assunto , Tricloroetileno , Animais , Feminino , Humanos , Gravidez , Viés , Cardiopatias Congênitas/induzido quimicamente , Cardiopatias Congênitas/epidemiologia , Troca Materno-Fetal , Medição de Risco/métodos , Solventes/toxicidade , Tricloroetileno/toxicidadeRESUMO
Systematic reviews, pioneered in the clinical field, provide a transparent, methodologically rigorous and reproducible means of summarizing the available evidence on a precisely framed research question. Having matured to a well-established approach in many research fields, systematic reviews are receiving increasing attention as a potential tool for answering toxicological questions. In the larger framework of evidence-based toxicology, the advantages and obstacles of, as well as the approaches for, adapting and adopting systematic reviews to toxicology are still being explored. To provide the toxicology community with a starting point for conducting or understanding systematic reviews, we herein summarized available guidance documents from various fields of application. We have elaborated on the systematic review process by breaking it down into ten steps, starting with planning the project, framing the question, and writing and publishing the protocol, and concluding with interpretation and reporting. In addition, we have identified the specific methodological challenges of toxicological questions and have summarized how these can be addressed. Ultimately, this primer is intended to stimulate scientific discussions of the identified issues to fuel the development of toxicology-specific methodology and to encourage the application of systematic review methodology to toxicological issues.
Assuntos
Metanálise como Assunto , Toxicologia/métodosRESUMO
Titanium dioxide (TiO2) has been characterized as a poorly soluble particulate (PSP) with low toxicity. It is well accepted that low toxicity PSPs such as TiO2 induce lung tumors in rats when deposition overwhelms particle clearance mechanisms. Despite the sensitivity of rats to PSPs and questionable relevance of PSP-induced tumors to humans, TiO2 is listed as a possible human carcinogen by some agencies and regulators. Thus, environmental toxicity criteria for TiO2 are needed for stakeholders to evaluate potential risks from environmental exposure and regulatory compliance. A systematic review of the literature was conducted to characterize the available data and identify candidate datasets upon which toxicity values could be derived. Key to this assessment, a survey of mechanistic data relevant for lung cancer was used to support quantitative inhalation risk assessment approaches. A total of 473 human studies were identified, 7 of which were epidemiological studies that met inclusion criteria to quantitatively characterize carcinogenic endpoints in humans. None of these studies supported derivation of toxicity criteria; therefore, animal data were used to derived safety values for TiO2 using different dose-metrics (regional deposited dose ratios, TiO2 particle surface area lung burden, and volumetric overload of alveolar macrophages), benchmark dose modeling, and different low-dose extrapolation approaches. Based on empirical evidence and mechanistic support for nonlinear mode of action involving particle overload, chronic inflammation and cell proliferation, a no significant risk level (NSRL) of 300 µg/day was derived. By comparison, low-dose linear extrapolation from tumor incidence in the rat lung resulted in an NSRL value of 44 µg/day. These toxicity values should be useful for stakeholders interested in assessing risks from environmental exposure to respirable TiO2.
Assuntos
Testes de Carcinogenicidade/métodos , Poluentes Ambientais/toxicidade , Exposição por Inalação/efeitos adversos , Neoplasias Pulmonares/induzido quimicamente , Titânio/toxicidade , Animais , Relação Dose-Resposta a Droga , Feminino , Humanos , Modelos Lineares , Neoplasias Pulmonares/epidemiologia , Masculino , Nível de Efeito Adverso não Observado , Dinâmica não Linear , Exposição Ocupacional/efeitos adversos , Ratos , Medição de RiscoRESUMO
Tetrabromobisphenol A (TBBPA) is used in a diverse array of products to improve fire safety. The National Toxicology Program (NTP) recently completed a 2-year bioassay for TBBPA. The objective of the present study was to develop a cancer-based and a non-cancer based toxicity value and to compare such to appropriate estimates of human exposure. Data from the NTP 2-year and 13-week studies were selected to develop candidate toxicity values. Benchmark dose modeling and subsequent evaluation of candidate values resulted in selection of an oral reference dose (RfD) of 0.6 mg kg(-1) day(-1) based on uterine hyperplasia in rats and an oral cancer slope factor (OSF) of 0.00315 per mg kg(-1) day(-1) based on an increased incidence of uterine tumors in rats. Lifetime average daily dose (LADD) estimates ranged from 2.2 E(-7) to 3.9 E(-6) mg kg(-1) day(-1) based on age-adjusted exposures to TBBPA via breast milk consumption, dietary intake, soil/dust ingestion and drinking water ingestion in infants, young children, older children and adults. Average daily dose (ADD) estimates ranged from 3.2 E (-7) to 8.4 E(-5) mg kg(-1) day(-1). Resulting margin of exposure (MOE) values were > 800 000 for non-cancer endpoints and > 32,000,000 for cancer-based endpoints. These data collectively indicate a low level of health concern associated with exposures to TBBPA based on current data. It is anticipated that the exposure estimates, along with the toxicity values described within, should be informative for understanding human health hazards associated with TBBPA.
Assuntos
Exposição Ambiental/efeitos adversos , Bifenil Polibromatos/toxicidade , Administração Oral , Adolescente , Adulto , Animais , Criança , Pré-Escolar , Relação Dose-Resposta a Droga , Água Potável/análise , Poeira/análise , Determinação de Ponto Final , Feminino , Humanos , Hiperplasia/induzido quimicamente , Hiperplasia/patologia , Lactente , Masculino , Camundongos , Leite Humano/química , Ratos , Testes de Toxicidade , Neoplasias Uterinas/induzido quimicamente , Neoplasias Uterinas/patologiaRESUMO
Formaldehyde is recognized as carcinogenic for the portal of entry sites, though conclusions are mixed regarding lymphohematopoietic (LHP) cancers. This systematic review assesses the likelihood of a causal relationship between formaldehyde and LHP cancers by integrating components recommended by NASEM. Four experimental rodent bioassays and 16 observational studies in humans were included following the implementation of the a priori protocol. All studies were assessed for risk of bias (RoB), and meta-analyses were conducted on epidemiological studies, followed by a structured assessment of causation based on GRADE and Bradford Hill. RoB analysis identified systemic limitations precluding confidence in the epidemiological evidence due to inadequate characterization of formaldehyde exposure and a failure to adequately adjust for confounders or effect modifiers, thus suggesting that effect estimates are likely to be impacted by systemic bias. Mixed findings were reported in individual studies; meta-analyses did not identify significant associations between formaldehyde inhalation (when measured as ever/never exposure) and LHP outcomes, with meta-SMRs ranging from 0.50 to 1.51, depending on LHP subtype. No associations with LHP-related lesions were reported in reliable animal bioassays. No biologically plausible explanation linking the inhalation of FA and LHP was identified, supported primarily by the lack of systemic distribution and in vivo genotoxicity. In conclusion, the inconsistent associations reported in a subset of the evidence were not considered causal when integrated with the totality of the epidemiological evidence, toxicological data, and considerations of biological plausibility. The impact of systemic biases identified herein could be quantitatively assessed to better inform causality and use in risk assessment.
Assuntos
Formaldeído , Exposição por Inalação , Formaldeído/toxicidade , Humanos , Animais , Exposição por Inalação/efeitos adversos , Neoplasias Hematológicas/induzido quimicamente , Neoplasias Hematológicas/epidemiologia , Medição de Risco , Carcinógenos/toxicidadeRESUMO
Polybrominated diphenyl ethers (PBDEs) have been used in a wide variety of consumer applications as additive flame retardants. In North America, scientists have noted continuing increases in the levels of PBDE congeners measured in human serum. Some recent studies have found that PBDEs are associated with adverse health effects in humans, in experimental animals, and wildlife. This laboratory previously demonstrated that urinary elimination of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) is saturable at high doses in mice; however, this dose-dependent urinary elimination has not been observed in adult rats or immature mice. Thus, the primary objective of this study was to examine the mechanism of urinary elimination of BDE-47 in adult mice using a physiologically based pharmacokinetic (PBPK) model. To support this objective, additional laboratory data were collected to evaluate the predictions of the PBPK model using novel information from adult multi-drug resistance 1a/b knockout mice. Using the PBPK model, the roles of mouse major urinary protein (a blood protein carrier) and P-glycoprotein (an apical membrane transporter in proximal tubule cells in the kidneys, brain, intestines, and liver) were investigated in BDE-47 elimination. The resulting model and new data supported the major role of m-MUP in excretion of BDE-47 in the urine of adult mice, and a lesser role of P-gp as a transporter of BDE-47 in mice. This work expands the knowledge of BDE-47 kinetics between species and provides information for determining the relevancy of these data for human risk assessment purposes.
Assuntos
Éteres Difenil Halogenados/farmacocinética , Éteres Difenil Halogenados/urina , Modelos Biológicos , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/fisiologia , Animais , Relação Dose-Resposta a Droga , Humanos , Camundongos , Camundongos Knockout , Proteína 2 Associada à Farmacorresistência Múltipla , Proteínas Associadas à Resistência a Múltiplos Medicamentos/deficiência , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/fisiologia , Ratos , Distribuição Tecidual/efeitos dos fármacos , Distribuição Tecidual/genéticaRESUMO
A series of recent and proposed workshops address the interface between key characteristics and mechanistic pathway descriptions (adverse outcome pathways and mode of action) to identify commonalities and potential for complementary application. Informed by different communities, these constructs have collective potential to increase confidence to support the application of mechanistic data in hazard assessment. This forum article summarizes concepts, introduces evolving understanding, and invites future collaboration to contribute to better common understanding and development of good practice in the use of mechanistic data in hazard assessment.
Assuntos
Rotas de Resultados Adversos , Medição de RiscoRESUMO
Aspartame has been studied extensively and evaluated for its safety in foods and beverages yet concerns for its potential carcinogenicity have persisted, driven primarily by animal studies conducted at the Ramazzini Institute (RI). To address this controversy, an updated systematic review of available human, animal, and mechanistic data was conducted leveraging critical assessment tools to consider the quality and reliability of data. The evidence base includes 12 animal studies and >40 epidemiological studies reviewed by the World Health Organization which collectively demonstrate a lack of carcinogenic effect. Assessment of >1360 mechanistic endpoints, including many guideline-based genotoxicity studies, demonstrate a lack of activity associated with endpoints grouped to key characteristics of carcinogens. Other non-specific mechanistic data (e.g., mixed findings of oxidative stress across study models, tissues, and species) do not provide evidence of a biologically plausible carcinogenic pathway associated with aspartame. Taken together, available evidence supports that aspartame consumption is not carcinogenic in humans and that the inconsistent findings of the RI studies may be explained by flaws in study design and conduct (despite additional analyses to address study limitations), as acknowledged by authoritative bodies.
Assuntos
Aspartame , Edulcorantes , Animais , Humanos , Aspartame/toxicidade , Carcinogênese , Testes de Carcinogenicidade , Carcinógenos/toxicidade , Reprodutibilidade dos Testes , Edulcorantes/toxicidadeRESUMO
BACKGROUND: Recommendations and guidance from scientific bodies do not provide clear messages about potential health risks or benefits of coffee consumption. Numerous studies have demonstrated inverse (beneficial) effects of coffee consumption for many adverse outcomes such as cancer and cardiovascular disease; fewer studies demonstrate risks. However, the risk-benefit relationship has not yet been fully assessed using quantitative metrics preferred by policy makers (disability-adjusted life years [DALYs]). OBJECTIVE: Conduct a quantitative analysis of the risk-benefit for coffee consumption and all-cause mortality using the Benefit-Risk Analysis for Foods (BRAFO) framework and the DALY as a quantitative metric. METHOD: A systematic search and appraisal of meta-analyses investigating coffee consumption and all-cause mortality was conducted. Using the BRAFO framework, evidence was assessed in context of potential risks or benefits associated with the reference scenario - coffee consumption (assessed by varying the consumption level in three analyses) in adults aged 15+ versus the alternative scenario of no coffee consumption. DALYs were used to quantify risks and benefits based on risk ratios from meta-analyses with populations from the United States. RESULTS: Meta-analyses consistently report an inverse (beneficial) relationship between coffee consumption and all-cause mortality; subsequently, even while varying consumption amounts and prevalence of coffee consumption, DALYs calculated consistently demonstrated findings in the direction of prevention of healthy years of life lost with variable magnitude. More than 3.5 million DALYs, or â¼3.35% of estimated years of healthy life lost could be prevented by consuming one cup of coffee per day, up to 4.7% of estimated years of healthy life lost could be prevented at current consumption rates ranging from 1 to 8 cups/day, and even more benefit could be seen (prevention of an estimated 6% of years of healthy life lost) if consumers all drank 3 cups of coffee per day. IMPACT: Policy that directs consumers to avoid drinking coffee may be a detriment to the overall health of the population given the substantial potential benefits of coffee consumption on all-cause mortality for adults.