33 results on '"Tritscher, Angelika"'
Search Results
2. The Melamine Incident: Implications for International Food and Feed Safety
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Gossner, Céline Marie-Elise, Schlundt, Jørgen, Embarek, Peter Ben, Hird, Susan, Lo-Fo-Wong, Danilo, Beltran, Jose Javier Ocampo, and Tritscher, Angelika
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- 2009
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3. Role of Metabolic Activation in the Carcinogenicity of Estrogens: Studies in an Animal Liver Tumor Model
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Metzler, Manfred, Blaich, Günter, and Tritscher, Angelika M.
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- 1990
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4. Integrated Approach for Evaluating Species and Interindividual Differences in Responsiveness to Dioxins and Structural Analogs
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Clark, George, Tritscher, Angelika, Bell, Douglas, and Lucier, George
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- 1992
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5. Polybrominated Dibenzo-p-Dioxins, Dibenzofurans, and Biphenyls: Inclusion in the Toxicity Equivalency Factor Concept for Dioxin-Like Compounds
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van den Berg, Martin, Denison, Michael S., Birnbaum, Linda S., DeVito, Michael J., Fiedler, Heidelore, Falandysz, Jerzy, Rose, Martin, Schrenk, Dieter, Safe, Stephen, Tohyama, Chiharu, Tritscher, Angelika, Tysklind, Mats, and Peterson, Richard E.
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- 2013
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6. Guidance on setting of acute reference dose (ARfD) for pesticides
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Solecki, Roland, Davies, Les, Dellarco, Vicki, Dewhurst, Ian, Raaij, Marcel van, and Tritscher, Angelika
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- 2005
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7. The 2005 World Health Organization Reevaluation of Human and Mammalian Toxic Equivalency Factors for Dioxins and Dioxin-Like Compounds
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Van den Berg, Martin, Birnbaum, Linda S., Denison, Michael, De Vito, Mike, Farland, William, Feeley, Mark, Fiedler, Heidelore, Hakansson, Helen, Hanberg, Annika, Haws, Laurie, Rose, Martin, Safe, Stephen, Schrenk, Dieter, Tohyama, Chiharu, Tritscher, Angelika, Tuomisto, Jouko, Tysklind, Mats, Walker, Nigel, and Peterson, Richard E.
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- 2006
8. The risk assessment paradigm and its application for trichothecenes
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Tritscher, Angelika M. and Page, Samuel W.
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- 2004
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9. Human health risk assessment of processing-related compounds in food
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Tritscher, Angelika M
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- 2004
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10. Induction of Lung Lesions in Female Rats Following Chronic Exposure to 2,3,7,8-Tetrachlorodibenzo-p-dioxin
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Tritscher, Angelika M., Mahler, Joel, Portier, Christopher J., Lucier, George W., and Walker, Nigel J.
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- 2000
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11. Harmonized methodology to assess chronic dietary exposure to residues from compounds used as pesticide and veterinary drug.
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Arcella, Davide, Boobis, Alan, Cressey, Peter, Erdely, Holly, Fattori, Vittorio, Leblanc, Jean-Charles, Lipp, Markus, Reuss, Rainer, Scheid, Stefan, Tritscher, Angelika, Van der Velde-Koerts, Trijntje, and Verger, Philippe
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VETERINARY drugs ,VETERINARY drug residues ,CHILDREN ,PESTICIDES ,FOOD additives ,PESTICIDE residues in food ,RISK managers ,HEALTH risk assessment - Abstract
Risk assessments for pesticide and veterinary drug residues in food are performed respectively by the Joint FAO/WHO Expert Meeting on Pesticide Residues (JMPR) and the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The models used by the two Committees to assess chronic dietary exposure are based on different data and assumptions which may be confusing, particularly for risk managers, when the same compound is used to treat plants and animals. This publication details the results of combined chronic dietary exposure assessments for eight compounds used both as pesticide and veterinary drugs. It compares the results from models in use by JMPR and JECFA with those from national estimates performed by 17 countries. Results show that the JECFA model is better reflecting less than lifetime dietary exposure by considering consumption of children and high consumers. The JMPR model is a suitable model for estimating average chronic (lifetime) exposure to residues present in widely and regularly consumed staple commodities. However, it is suitable neither for estimating children's exposure nor more generally for assessing less than lifetime dietary exposure. In order to select the appropriate exposure model related to the occurrence of adverse effects i.e. effects occurring over less-than-lifetime or effects occurring only over lifetime, this paper proposes criteria to match the toxicological profile of the compound and the appropriate exposure scenarios. These approaches will continue to be harmonized to ensure the most scientifically sound basis for the risk assessment for pesticides and veterinary drug residues and consequently for other chemicals in food. [ABSTRACT FROM AUTHOR]
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- 2019
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12. Mycotoxin contamination of sorghum and its contribution to human dietary exposure in four sub-Saharan countries.
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Ssepuuya, Geoffrey, Van Poucke, Christof, Ediage, Emmanuel Njumbe, Mulholland, Catherine, Tritscher, Angelika, Verger, Philippe, Kenny, Mary, Bessy, Catherine, and De Saeger, Sarah
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MYCOTOXINS ,FOOD safety ,SORGHUM ,FOOD contamination ,FUMONISINS - Abstract
This research aimed at evaluating the safety, and the type, level and prevalence of mycotoxins in grain sorghum of four sub-Saharan African (SSA) countries (Burkina Faso, Ethiopia, Mali and Sudan). A multi-analyte LC-MS/MS method for quantification of 23 mycotoxins (nivalenol, deoxynivalenol, fusarenon X, neosolaniol, 3-acetyl deoxynivalenol, 15-acetyl deoxynivalenol, diacetoxyscirpenol, roquefortine C, HT-2 toxin, alternariol, T-2 toxin, FB1, FB2, FB3, zearalenone, aflatoxin G
1 , aflatoxin G2 , aflatoxin B1 , aflatoxin B2 , sterigmatocystin, OTA, altenuene, alternariol monomethylether) was applied to different sorghum matrices. Of the 1533 analysed samples, 33% were contaminated with at least one of the following mycotoxins: aflatoxins, fumonisins, sterigmatocystin, Alternaria toxins, OTA and zearalenone. Country of origin, colour, source and collection period of sorghum samples significantly influenced the type, level and prevalence of mycotoxins. Sterigmatocystin (15%), fumonisins (17%) and aflatoxins (13%) were the most prevalent. FB1 (274 ± 585 µg/kg) had the highest mean concentration followed by FB2 (214 ± 308 µg/kg) while diacetoxyscirpenol (8.12 ± 19.2 µg/kg) and HT-2 (11.9 ± 0.00 µg/kg) had the lowest concentrations. Neosolaniol, fusarenon-X, 3-acetyl deoxynivalenol, 15-acetyl deoxynivalenol, T-2 toxin, nivalenol and roquefortine C were not detected in any of the samples. Sudan had the lowest prevalence and mean concentration of all mycotoxins. Pink sorghum had the highest concentrations of fumonisins and aflatoxins. Mycotoxins from Aspergillus spp. and Alternaria spp. are the mycotoxins of concern in SSA grain sorghum with regard to prevalence, concentration and possible health risk from exposure. Based on the performed risk characterisation, daily consumption of sorghum containing aflatoxins, alternariol, alternariol monomethyl ether, sterigmatocystin and OTA could result in exceeding the established health-based guidance values for these toxins. [ABSTRACT FROM AUTHOR]- Published
- 2018
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13. Characterizing chronic and acute health risks of residues of veterinary drugs in food: latest methodological developments by the joint FAO/WHO expert committee on food additives.
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Boobis, Alan, Cerniglia, Carl, Chicoine, Alan, Fattori, Vittorio, Lipp, Markus, Reuss, Rainer, Verger, Philippe, and Tritscher, Angelika
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VETERINARY drugs ,FOOD additives ,DRUG residues ,HEALTH risk assessment ,ANTI-infective agents - Abstract
The risk assessment of residues of veterinary drugs in food is a field that continues to evolve. The toxicological end-points to be considered are becoming more nuanced and in light of growing concern about the development of antimicrobial resistance, detailed analysis of the antimicrobial activity of the residues of veterinary drugs in food is increasingly incorporated in the assessment. In recent years, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) has refined its approaches to provide a more comprehensive and fit-for-purpose risk assessment. This publication describes in detail the consideration of acute and chronic effects, the estimation of acute and chronic dietary exposure, current approaches for including microbiological endpoints in the risk assessment, and JECFA’s considerations for the potential effects of food processing on residues from veterinary drugs. JECFA now applies these approaches in the development of health-based guidance values (i.e. safe exposure levels) for residues of veterinary drugs. JECFA, thus, comprehensively addresses acute and chronic risks by using corresponding estimates for acute and chronic exposure and suitable correction for the limited bioavailability of bound residues by the Gallo-Torres model. On a case-by-case basis, JECFA also considers degradation products that occur from normal food processing of food containing veterinary drug residues. These approaches will continue to be refined to ensure the most scientifically sound basis for the establishment of health-based guidance values for veterinary drug residues. [ABSTRACT FROM PUBLISHER]
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- 2017
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14. WHO/UNEP global surveys of PCDDs, PCDFs, PCBs and DDTs in human milk and benefit-risk evaluation of breastfeeding.
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Berg, Martin, Kypke, Karin, Kotz, Alexander, Tritscher, Angelika, Lee, Seoung, Magulova, Katarina, Fiedler, Heidelore, and Malisch, Rainer
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CONTAMINATION of human milk ,POLYCHLORINATED dibenzofurans ,POLYCHLORINATED dibenzodioxins ,DDT (Insecticide) ,POLYCHLORINATED biphenyls ,BREASTFEEDING - Abstract
Since 1987, the World Health Organization (WHO) carried out global surveys on polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in human milk. This study presents a review of the three most recent surveys from 2000 to 2010, including DDT. The objective was to identify global quantitative differences and provide baseline information for 52 countries or provide time-trends for countries with previous data. Individual human milk samples were collected following a WHO-designed procedure and combined to form a national pooled sample. Here, we report global levels for PCDDs, PCDFs, PCBs and the sum of o, p′-DDT, p, p′-DDT, o, p′-DDE, p, p′-DDE, o, p′-DDD and p, p′-DDD ( ΣDDTs). A concise risk-benefit evaluation related to human milk contamination with these persistent organic pollutants (POPs) was also done. Large global and regional differences were observed. Levels of PCDDs and PCDFs were highest in India and some European and African countries. PCB levels were highest in East and West Europe. The highest levels of ΣDDTs were found in less industrialized countries. A temporal downward trend for PCDDs, PCDFs and PCBs is indicated. A risk-benefit assessment indicates that human milk levels of PCDDs, PCDFs and PCBs are still significantly above those considered toxicologically safe, while ΣDDTs are below or around those considered safe. With respect to potential adverse health effects, a more dominant role of in utero exposure versus lactational exposure is indicated. If potential adverse effects are balanced against positive health aspects for (breastfed) infants, the advantages of breastfeeding far outweigh the possible disadvantages. Our observations provide a strong argument to plea for further global source-directed measures to reduce human exposure further to dioxin-like compounds. [ABSTRACT FROM AUTHOR]
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- 2017
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15. Ensuring food safety and nutrition security to protect consumer health: 50 years of the Codex Alimentarius Commission
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Tritscher, Angelika, Miyagishima, Kazuaki, Nishida, Chizuru, and Branca, Francesco
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Consumer protection -- Analysis ,Food -- Safety and security measures ,Health - Abstract
The globalization of trade, which has contributed to food availability and diversification throughout the world, has also increased the chances that the food produced in one place will affect the [...]
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- 2013
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16. Open risk assessment: data.
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Gilsenan, Mary B., Abbinante, Fabrizio, O'Dea, Eileen, Canals, Ana, and Tritscher, Angelika
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ACQUISITION of data ,RISK assessment ,FOOD consumption ,DIGITAL technology ,INTERNETWORKING - Abstract
Since its foundation, EFSA and the Member States have made significant progress in the area of data collection for risk assessment and monitoring. In partnership with competent authorities and research organisations in the Member States, EFSA has become a central hub of the European data on food consumption, chemical occurrence and foodborne outbreaks. Beyond EFSA's use of these data and sharing of contaminants and food consumption data with the World Health Organization and the Food and Agriculture Organization to support international risk assessment, they remain largely unexploited. In addition, for some of its risk assessments, EFSA also relies on published information, as well as on scientific studies sponsored and submitted by industry. The environment in which the Authority operates has significantly evolved since its foundation. The growth of digital technology has granted scientists and consumers alike faster and more efficient access to data and information. The open data movement, which has entered the sphere of the European Union institutions, is unleashing the potential for reuse of data. In parallel, the work of EFSA is increasingly subject to demands for more openness and transparency across its spectrum of stakeholders. EFSA aims to enhance the quality and transparency of its outputs by giving access to data and promoting the development of collaborative platforms in Europe and internationally. EFSA also plans to work with data providers and organisations funding research to adopt open data concepts and standards; gaining better access to, and making better use of, data from a wider evidence base. During the breakout session on 'Open Risk Assessment: Data' at the EFSA 2nd Scientific Conference 'Shaping the Future of Food Safety, Together' (Milan, Italy, 14-16 October 2015) opportunities and challenges associated with open data, data interoperability and data quality were discussed by sharing experiences from various sectors within and outside EFSA's remit. This paper provides an overview of the presentations and discussions during the breakout session. [ABSTRACT FROM AUTHOR]
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- 2016
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17. Integration of epidemiological and toxicological information into risk assessment—the melamine example
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Tritscher, Angelika
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- 2013
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18. A proposed framework for assessing risk from less-than-lifetime exposures to carcinogens.
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Felter, Susan P., Conolly, Rory B., Bercu, Joel P., Bolger, P. Michael, Boobis, Alan R., Bos, Peter M. J., Carthew, Philip, Doerrer, Nancy G., Goodman, Jay I., Harrouk, Wafa A., Kirkland, David J., Lau, Serrine S., Llewellyn, G. Craig, Preston, R. Julian, Schoeny, Rita, Schnatter, A. Robert, Tritscher, Angelika, van Velsen, Frans, and Williams, Gary M.
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QUANTITATIVE research ,CANCER risk factors ,HEALTH risk assessment ,BIOLOGICAL assay ,ADULT education workshops - Abstract
Quantitative methods for estimation of cancer risk have been developed for daily, lifetime human exposures. There are a variety of studies or methodologies available to address less-than-lifetime exposures. However, a common framework for evaluating risk from less-than-lifetime exposures (including short-term and/or intermittent exposures) does not exist, which could result in inconsistencies in risk assessment practice. To address this risk assessment need, a committee of the International Life Sciences Institute (ILSI) Health and Environmental Sciences Institute conducted a multisector workshop in late 2009 to discuss available literature, different methodologies, and a proposed framework. The proposed framework provides a decision tree and guidance for cancer risk assessments for less-than-lifetime exposures based on current knowledge of mode of action and dose-response. Available data from rodent studies and epidemiological studies involving less-than-lifetime exposures are considered, in addition to statistical approaches described in the literature for evaluating the impact of changing the dose rate and exposure duration for exposure to carcinogens. The decision tree also provides for scenarios in which an assumption of potential carcinogenicity is appropriate (e.g., based on structural alerts or genotoxicity data), but bioassay or other data are lacking from which a chemical-specific cancer potency can be determined. This paper presents an overview of the rationale for the workshop, reviews historical background, describes the proposed framework for assessing less-than-lifetime exposures to potential human carcinogens, and suggests next steps. [ABSTRACT FROM AUTHOR]
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- 2011
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19. Overall weight of evidence approaches in chemical risk assessment
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Tritscher, Angelika
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- 2012
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20. The 2005 World Health Organization Reevaluation of Human and Mammalian Toxic Equivalency Factors for Dioxins and Dioxin-Like Compounds.
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Berg, Martin Van den, Birnbaum, Linda S., Denison, Michael, De Vito, Mike, Farland, William, Feeley, Mark, Fiedler, Heidelore, Hakansson, Helen, Hanberg, Annika, Haws, Laurie, Rose, Martin, Safe, Stephen, Schrenk, Dieter, Tohyama, Chiharu, Tritscher, Angelika, Tuomisto, Jouko, Tysklind, Mats, Walker, Nigel, and Peterson, Richard E.
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DIOXINS ,POLYCHLORINATED biphenyls ,DIBENZOFURANS ,TOXICITY testing - Abstract
In June 2005, a World Health Organization (WHO)-International Programme on Chemical Safety expert meeting was held in Geneva during which the toxic equivalency factors (TEFs) for dioxin-like compounds, including some polychlorinated biphenyls (PCBs), were reevaluated. For this reevaluation process, the refined TEF database recently published by Haws et al. (2006, Toxicol. Sci. 89, 4–30) was used as a starting point. Decisions about a TEF value were made based on a combination of unweighted relative effect potency (REP) distributions from this database, expert judgment, and point estimates. Previous TEFs were assigned in increments of 0.01, 0.05, 0.1, etc., but for this reevaluation, it was decided to use half order of magnitude increments on a logarithmic scale of 0.03, 0.1, 0.3, etc. Changes were decided by the expert panel for 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) (TEF = 0.3), 1,2,3,7,8-pentachlorodibenzofuran (PeCDF) (TEF = 0.03), octachlorodibenzo-p-dioxin and octachlorodibenzofuran (TEFs = 0.0003), 3,4,4′,5-tetrachlorbiphenyl (PCB 81) (TEF = 0.0003), 3,3′,4,4′,5,5′-hexachlorobiphenyl (PCB 169) (TEF = 0.03), and a single TEF value (0.00003) for all relevant mono-ortho–substituted PCBs. Additivity, an important prerequisite of the TEF concept was again confirmed by results from recent in vivo mixture studies. Some experimental evidence shows that non-dioxin–like aryl hydrocarbon receptor agonists/antagonists are able to impact the overall toxic potency of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds, and this needs to be investigated further. Certain individual and groups of compounds were identified for possible future inclusion in the TEF concept, including 3,4,4′-TCB (PCB 37), polybrominated dibenzo-p-dioxins and dibenzofurans, mixed polyhalogenated dibenzo-p-dioxins and dibenzofurans, polyhalogenated naphthalenes, and polybrominated biphenyls. Concern was expressed about direct application of the TEF/total toxic equivalency (TEQ) approach to abiotic matrices, such as soil, sediment, etc., for direct application in human risk assessment. This is problematic as the present TEF scheme and TEQ methodology are primarily intended for estimating exposure and risks via oral ingestion (e.g., by dietary intake). A number of future approaches to determine alternative or additional TEFs were also identified. These included the use of a probabilistic methodology to determine TEFs that better describe the associated levels of uncertainty and “systemic” TEFs for blood and adipose tissue and TEQ for body burden. [ABSTRACT FROM PUBLISHER]
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- 2006
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21. Carcinogenicity. Hepatocarcinogenesis in Female Sprague-Dawley Rats following Discontinuous Treatment with 2,3,7,8-Tetrachlorodibenzo-p-dioxin.
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Walker, Nigel J., Tritscher, Angelika M., Sills, Robert C., Lucier, George W., and Portier, Christopher J.
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TETRACHLORODIBENZODIOXIN ,DIOXINS ,CARCINOGENESIS ,HEPATOTOXICOLOGY ,LIVER tumors ,PLACENTA ,GLUTATHIONE transferase - Abstract
In this study, we investigated the time course of promotion of tumors and putatively preneoplastic altered hepatic foci in the livers of diethylnitrosamine (DEN)-initiated female Sprague-Dawley rats. These rats had been treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) under different dosing regimens, but we used the same administered biweekly dose of 1.75 μg/kg of body weight. Animals were treated continuously for up to 60 weeks, or continuously for 30 weeks, followed by cessation of treatment for up to 30 weeks. In addition, TCDD treatment in these groups was begun either 2 or 18 weeks after initiation with DEN. Liver tumors were only observed in animals after 60 weeks on the study and were increased by continuous TCDD treatment, relative to controls. The incidence of hepatocellular adenoma and carcinoma combined, in animals treated with TCDD for 30 weeks followed by no TCDD treatment for 30 weeks (17%), was lower than in animals receiving either TCDD (79%) or vehicle control (corn oil) alone (55%) for 60 weeks. The lower liver-tumor incidence after cessation of TCDD treatment paralleled time-dependent decreases in the volume fraction occupied by placental glutathione S-transferase-positive altered hepatic foci and the number of foci per unit volume, but not the mean focus volume that exhibited a time-dependent increase after cessation of TCDD treatment. Cessation of TCDD treatment led to reductions in liver TCDD levels, and these changes were reflected in a cessation of reduced body weight because of TCDD treatment. These data indicate that liver-tumor promotion by TCDD in female rats is dependent upon continuous exposure to TCDD, and that alterations in patterns of TCDD exposure can have significant effects on tumor incidence not reflected by standard measures of dioxin exposure. [ABSTRACT FROM PUBLISHER]
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- 2000
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22. Accumulation of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Liver of Control Laboratory Rats.
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HEUVEL, JOHN P. VANDEN, CLARK, GEORGE C., TRITSCHER, ANGELIKA M., and LUCIER, GEORGE W.
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Polychlorinated dibenzo--dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls belong to a class of compounds, the polyhalogenated aromatic hydrocarbons (PHAHs), which are ubiquitous environmental contaminants. Due to the existence of a common mechanism of action, i.e., binding to the Ah receptor, the activity of members of this class of compounds is generally expressed relative to the prototypical 2,3,7,8-tetrachlorodibenzo--dioxin (TCDD) as toxic equivalency factors (TEFs). In the present studies we examined the presence of PCDDs and PCDFs in standard laboratory feed and in the liver of untreated rats at three different ages (60, 140, and 200 days) in terms of concentration and in toxic equivalents (TEQs, TEF × concentration). Feed was shown to contain trace amounts of PCDDs and PCDFs and control rat liver was shown to contain several PCDD and PCDF congeners in terms of concentration of congener and concentration of TEQs contributed by that congener. The total concentration of TEQs increased with increasing age in rat liver, going from 20 ppt TEQ at 60 days to 78 ppt TEQ at 200 days of age. This accumulation in dioxin-like activity was due primarily to PCDFs. In particular the congener 2,3,4,7,8-pentachlorodibenzofuran accrued in untreated rat liver accounting for approximately 80% of the total TEQ at 200 days of age. These studies affirm the pervasive presence of PHAHs and suggest prudence in evaluating chronic rat studies in which interference from background levels of PCDDs and PCDFs may be a factor. [ABSTRACT FROM PUBLISHER]
- Published
- 1994
23. Isolation and characterization of a novel gene induced by 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin in rat liver.
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Selmin, Ornella, Lucier, George W., Clark, George C., Tritscher, Angelika M., Heuvel, John P.Vanden, Gastel, Jonathan A., Walker, Nigel J., R-Sutter, Thomas, and Bell, Douglas A.
- Abstract
The differential display technique was used to identify genes whose expression was regulated by 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). Expression of a novel sequence was up-regulated in a dose-dependent fashion in liver of Sprague-Dawley male rats exposed to both chronic and acute treatment with TCDD, as measured by densito-metry of Northern blot analyses (P < 0.01). A rapid amplification of cDNA ends (RACE) procedure was used to isolate a 1.8 kb cDNA from a rat liver cDNA preparation. This cloned cDNA, called 25-Dx, was sequenced and found to encode a peptide of 223 amino acids. In control rats, the 25-Dx gene was expressed at high levels in lung and liver. A hydrophobic domain of 14 residues followed by a proline-rich domain, both located in the N-terminal region, showed 71% homology with the transmembrane domain of the precursor for the interleukin-6 receptor and a conserved consensus sequence found in the cytokine/growth factor/prolactin receptor superfamily respectively. [ABSTRACT FROM PUBLISHER]
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- 1996
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24. Persistence of TCDD-induced hepatic cell proliferation and growth of enzyme altered foci after chronic exposure followed by cessation of treatment in DEN initiated female rats.
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Tritscher, Angelika M., Clark, George C., Sewall, Charles, Sills, Robert C., Maronpot, Robert, and Lucier, George W.
- Abstract
2,3,7,8-Tetrachlorodibenzo--dioxin (TCDD) is a potent tumor promoter in two-stage models of hepatocarcinogenesis. This study focuses on the persistence or reversibility of TCDD-mediated changes in livers after 30 weeks of treatment and cessation of treatment. Diethylnitrosamine (DEN) initiated animals (175 mg/kg) were promoted bl-weekly with TCDD at a dose equivalent to 125 ng/kg/day for 30 weeks without or with a following waiting period of 32 weeks before necropsy. 2,3,7,8-Tetrachlorodibenzo--dioxin liver concentration decreased 300-fold in the 32 week waiting period but was still five-fold above background. Induction of CYP1A1 dependent enzyme activity decreased according to TCDD tissue levels. In contrast, cell proliferation, as measured by BrdU-labeling index, was still 2.8-fold increased over controls in the TCDD group with waiting period compared to a 4-fold increase over controls at the end of the 30 week dosing period. Enzyme altered hepatic foci expressing the placental form of glutathione S-transferase decreased in number but the remaining foci were significantly increased in size and the percent of liver occupied by foci was higher at the end of the waiting period as compared to livers at the end of the dosing period. Liver tumor incidence at the end of the waiting period was 71% (5 of 7 animals) and the livers showed an increase in bile duct lesions with only mild toxicity. There was pronounced bile duct proliferation in DEN/TCDD treated animals after the waiting period with intense expression of TGFα in bile duct epithelial cells as detected by immunohistochemical methods. In comparison, at the end of the 30 week dosing period the livers showed more severe toxicity and only mild bile duct proliferation. Also, one small hepatocellular adenoma was observed. It is concluded that as opposed to CYP1A1 induction the more complex biological responses, cell proliferation and selective growth of certain preneoplastic foci, are persistent after prolonged TCDD treatment within the experimental framework of our study. [ABSTRACT FROM PUBLISHER]
- Published
- 1995
25. TCDD-mediated changes in hepatic epidermal growth factor receptor may be a critical event in the hepatocarcinogenic action of TCDD.
- Author
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Sewall, Charles H., Lucier, George W., Tritscher, Angelika M., and Clark, George C.
- Abstract
2,3,7,8-Tetrachlorodibenzo--dioxin (TCDD) is a potent liver tumor promoter in rats, with females being more sensitive than males. The epidermal growth factor receptor (EGFR) pathway has been implicated in altered cell growth patterns induced by tumor promoters. We investigated hepatic EGFR levels in a two-stage initiation promotion model. The TCDD doses were chosen to encompass the dose range administered in a previous chronic bioassay currently used to determine the cancer potency commonly used for human health risk assessments. TCDD was administered biweekly by oral gavage to female Sprague-Dawley rats for 30 weeks following initiation by a single dose of diethylnitrosamine (DEN). TCDD-mediated decreased EGF receptor levels were demonstrated in intact but not ovariectomized animals, consistent with previous tumor data. Likewise, previous studies have shown that TCDD induces cell proliferation in intact rats but not ovariectomized rats. We report a significant dose-dependent decrease in plasma membrane EGF receptor maximum binding capacity in both initiated and non-initiated intact rats at TCDD doses equivalent to 3.5, 10.7, 35.7 and 125 ng/kg/day. There was a significant correlation between EGF receptor effects and liver TCDD concentration. The decrease in plasma membrane EGFR determined by equilibrium binding was confirmed quantitatively by EGF stimulation of EGFR autophosphorylation as well as qualitatively by immunohistochemical detection in control and treated rats. These results demonstrate that the observed down modulation of the EGFR by TCDD is ovarian-dependent and is a sensitive effect induced at dose levels associated with TCDD hepatocarcinogenicity in rodent bioassays. [ABSTRACT FROM PUBLISHER]
- Published
- 1993
26. WHO’s public health agenda in response to the Fukushima Daiichi nuclear accident.
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van Deventer, Emilie, del Rosario Perez, Maria, Tritscher, Angelika, Fukushima, Kazuko, and Carr, Zhanat
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PUBLIC health ,FUKUSHIMA Nuclear Accident, Fukushima, Japan, 2011 ,TSUNAMIS ,FOOD safety ,DRINKING water ,SAFETY - Abstract
The World Health Organization (WHO) has responded to the 2011 East-Japan earthquake and tsunami through the three levels of its decentralised structure. It has provided public health advice regarding a number of issues relating to protective measures, potassium iodide use, as well as safety of food and drinking water, mental health, travel, tourism, and trade. WHO is currently developing an initial health risk assessment linked to a preliminary evaluation of radiation exposure around the world from the Fukushima Daiichi nuclear accident. Lessons learned from this disaster are likely to help future emergency response to multi-faceted disasters. [ABSTRACT FROM AUTHOR]
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- 2012
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27. Risk-based classification and evaluation of carcinogens: An international perspective
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Tritscher, Angelika and Vickers, Carolyn
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- 2007
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28. Derivation of toxicity equivalency factors for marine biotoxins associated with Bivalve Molluscs.
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Botana, Luis M., Hess, Philip, Munday, Rex, Nathalie, Arnich, DeGrasse, Stacey L., Feeley, Mark, Suzuki, Toshiyuki, van den Berg, Martin, Fattori, Vittorio, Garrido Gamarro, Esther, Tritscher, Angelika, Nakagawa, Rei, and Karunasagar, Iddya
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SEAFOOD contamination , *BIVALVES , *TOXINS , *PUBLIC health , *BIOLOGICAL assay ,RISK factors - Abstract
Background Seafood toxins pose an important risk to human health, and maximum levels were imposed by regulatory authorities throughout the world. Several toxin groups are known, each one with many analogues of the major toxin. Regulatory limits are set to ensure that commercially available seafood is not contaminated with unsafe levels. Scope and approach The mouse bioassay was used to measure the toxicity in seafood extracts to determine if a sample exceeded regulatory limits. The advantage of this approach was to provide an estimation of the total toxicity in the sample. As instrumental methods of analysis advance and serve as replacements to the mouse bioassay, the challenge is translating individual toxin concentrations into toxicity to determine whether regulatory limits have been exceeded. Such analyses provide accurate quantitation of the toxin analogues, by they have widely dissimilar potencies. Thus, knowledge of the relative toxicities is required for risk assessment and determining overall toxicity. The ratios between the toxicity of the analogues and that of a reference compound within the same toxin group are termed “Toxicity Equivalency Factors” (TEFs). Key findings and conclusions In this document, the requirements for determining TEFs of toxin analogues are described, and recommendations for research to further refine TEFs are identified. The proposed TEFs herein, when applied to toxin analogue concentrations determined using analytical methods, will provide a base to determine overall toxicity, thereby protecting human health. [ABSTRACT FROM AUTHOR]
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- 2017
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29. Accumulation of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Liver of Control Laboratory Rats
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Vanden Heuvel, John P., Clark, George C., Tritscher, Angelika M., and Lucier, George W.
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- 1994
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30. Dioxins (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-furans) in traditional clay products used during pregnancy
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Reeuwijk, Noortje M., Talidda, Antonia, Malisch, Rainer, Kotz, Alexander, Tritscher, Angelika, Fiedler, Heidelore, Zeilmaker, Marco J., Kooijman, Martin, Wienk, Koen J.H., Traag, Wim A., and Hoogenboom, Ron L.A.P.
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POLYCHLORINATED dibenzodioxins , *POLYCHLORINATED dibenzofurans , *CLAY products , *GEOPHAGY , *PREGNANCY , *MILK analysis , *SOIL pollution , *BIOLOGICAL assay , *COMPARATIVE studies - Abstract
Abstract: Geophagy, the practice of consuming clay or soil, is encountered among pregnant women in Africa, Eastern Asia and Latin America, but also in Western societies. However, certain types of clay are known to contain high concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The aim of this study was to determine the PCDD/F contents of orally consumed clays purchased from Dutch and African markets. Congener patterns were compared with those of pooled human milk samples collected in eight African countries, to investigate a possible relationship with clay consumption. From the Dutch market thirteen clay products were examined, seven of African and six of Suriname origin. From seven African countries, twenty clay products were collected. All 33 clay products were screened with a cell-based bioassay and those showing a high response were analyzed by GC/HRMS. High PCDD/F concentrations were measured in three clay products from the Dutch market, ranging from 66 to 103 pg TEQ g-1, whereas clay products from African countries were from 24 to 75 pg TEQ g-1. Patterns and relatively high concentrations of PCDD/Fs in human milk samples from the Democratic Republic of the Congo and Côte d’Ivoire suggest a relationship with the consumption of contaminated clay. Frequent use of PCDD/F contaminated clay products during pregnancy may result in increased exposure of the mother and subsequently the developing fetus and new-born child. The use of these contaminated clays during pregnancy should be carefully considered or even discouraged. [Copyright &y& Elsevier]
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- 2013
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31. Advancing human health risk assessment.
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Lanzoni A, Castoldi AF, Kass GE, Terron A, De Seze G, Bal-Price A, Bois FY, Delclos KB, Doerge DR, Fritsche E, Halldorsson T, Kolossa-Gehring M, Hougaard Bennekou S, Koning F, Lampen A, Leist M, Mantus E, Rousselle C, Siegrist M, Steinberg P, Tritscher A, Van de Water B, Vineis P, Walker N, Wallace H, Whelan M, and Younes M
- Abstract
The current/traditional human health risk assessment paradigm is challenged by recent scientific and technical advances, and ethical demands. The current approach is considered too resource intensive, is not always reliable, can raise issues of reproducibility, is mostly animal based and does not necessarily provide an understanding of the underlying mechanisms of toxicity. From an ethical and scientific viewpoint, a paradigm shift is required to deliver testing strategies that enable reliable, animal-free hazard and risk assessments, which are based on a mechanistic understanding of chemical toxicity and make use of exposure science and epidemiological data. This shift will require a new philosophy, new data, multidisciplinary expertise and more flexible regulations. Re-engineering of available data is also deemed necessary as data should be accessible, readable, interpretable and usable. Dedicated training to build the capacity in terms of expertise is necessary, together with practical resources allocated to education. The dialogue between risk assessors, risk managers, academia and stakeholders should be promoted further to understand scientific and societal needs. Genuine interest in taking risk assessment forward should drive the change and should be supported by flexible funding. This publication builds upon presentations made and discussions held during the break-out session 'Advancing risk assessment science - Human health' at EFSA's third Scientific Conference 'Science, Food and Society' (Parma, Italy, 18-21 September 2018)., (© 2019 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.)
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- 2019
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32. Guidance on the risk assessment of substances present in food intended for infants below 16 weeks of age.
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Hardy A, Benford D, Halldorsson T, Jeger MJ, Knutsen HK, More S, Naegeli H, Noteborn H, Ockleford C, Ricci A, Rychen G, Schlatter JR, Silano V, Solecki R, Turck D, Bresson JL, Dusemund B, Gundert-Remy U, Kersting M, Lambré C, Penninks A, Tritscher A, Waalkens-Berendsen I, Woutersen R, Arcella D, Court Marques D, Dorne JL, Kass GE, and Mortensen A
- Abstract
Following a request from the European Commission to EFSA, the EFSA Scientific Committee (SC) prepared a guidance for the risk assessment of substances present in food intended for infants below 16 weeks of age. In its approach to develop this guidance, the EFSA SC took into account, among others, (i) an exposure assessment based on infant formula as the only source of nutrition; (ii) knowledge of organ development in human infants, including the development of the gut, metabolic and excretory capacities, the brain and brain barriers, the immune system, the endocrine and reproductive systems; (iii) the overall toxicological profile of the substance identified through the standard toxicological tests, including critical effects; (iv) the relevance for the human infant of the neonatal experimental animal models used. The EFSA SC notes that during the period from birth up to 16 weeks, infants are expected to be exclusively fed on breast milk and/or infant formula. The EFSA SC views this period as the time where health-based guidance values for the general population do not apply without further considerations. High infant formula consumption per body weight is derived from 95th percentile consumption. The first weeks of life is the time of the highest relative consumption on a body weight basis. Therefore, when performing an exposure assessment, the EFSA SC proposes to use the high consumption value of 260 mL/kg bw per day. A decision tree approach is proposed that enables a risk assessment of substances present in food intended for infants below 16 weeks of age. The additional information needed when testing substances present in food for infants below 16 weeks of age and the approach to be taken for the risk assessment are on a case-by-case basis, depending on whether the substance is added intentionally to food and is systemically available., (© 2017 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.)
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- 2017
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33. Food safety surveillance and response.
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Bishop J and Tritscher A
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- 2012
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