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Bowden AM, Escher SE, Rose J, Sadekar N, Patlewicz G, O'Keeffe L, Bury D, Hewitt NJ, Giusti A, Rothe H. Workshop report: Challenges faced in developing inhalation thresholds of Toxicological Concern (TTC) - State of the science and next steps. Regul Toxicol Pharmacol 2023; 142:105434. [PMID: 37302561 PMCID: PMC10494708 DOI: 10.1016/j.yrtph.2023.105434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/30/2023] [Accepted: 06/08/2023] [Indexed: 06/13/2023]
Abstract
A challenging step in human risk assessment of chemicals is the derivation of safe thresholds. The Threshold of Toxicological Concern (TTC) concept is one option which can be used for the safety evaluation of substances with a limited toxicity dataset, but for which exposure is sufficiently low. The application of the TTC is generally accepted for orally or dermally exposed cosmetic ingredients; however, these values cannot directly be applied to the inhalation route because of differences in exposure route versus oral and dermal. Various approaches of an inhalation TTC concept have been developed over recent years to address this. A virtual workshop organized by Cosmetics Europe, held in November 2020, shared the current state of the science regarding the applicability of existing inhalation TTC approaches to cosmetic ingredients. Key discussion points included the need for an inhalation TTC for local respiratory tract effects in addition to a systemic inhalation TTC, dose metrics, database building and quality of studies, definition of the chemical space and applicability domain, and classification of chemicals with different potencies. The progress made to date in deriving inhalation TTCs was highlighted, as well as the next steps envisaged to develop them further for regulatory acceptance and use.
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Affiliation(s)
- Anthony M Bowden
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, UK.
| | | | | | - Nikaeta Sadekar
- Research Institute for Fragrance Materials, Inc., Mahwah, NJ, USA
| | - Grace Patlewicz
- Center for Computational and Exposure, US Environmental Protection Agency, RTP, NC, 27711, USA
| | | | - Dagmar Bury
- L'Oréal Research & Innovation, Clichy, France
| | | | | | - Helga Rothe
- SciConT (formerly at Coty), Darmstadt, Germany
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2
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Liu F, Hutchinson RW. Semiquantitative sensitization safety assessment of extractable and leachables associated with parenteral pharmaceutical products. Regul Toxicol Pharmacol 2023; 138:105335. [PMID: 36608924 DOI: 10.1016/j.yrtph.2023.105335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 11/11/2022] [Accepted: 01/03/2023] [Indexed: 01/07/2023]
Abstract
Extractable and leachables (E&Ls) associated with parenteral pharmaceutical products should be assessed for patient safety. One essential safety endpoint is local or systemic sensitization. However, there are no regulatory guidelines for quantitative sensitization safety assessment of E&Ls. A semiquantitative sensitization safety assessment workflow is developed to refine the sensitization safety assessment of E&Ls associated with parenteral pharmaceutical products. The workflow is composed of two sequential steps: local skin sensitization and systemic sensitization safety assessment. The local skin sensitization step has four tiers. The output from this step is the acceptable exposure level for local sensitization (AELls) and this safety threshold can be used for local sensitization safety assessment. From the derived AELls, the systemic sensitization safety assessment at step 2 proceeds in 2 tiers. The output from this workflow is the derivation of acceptable exposure level for systemic sensitization (AELss). When the estimated human daily exposure (HDE) is compared with the AELss, the margin of exposure is calculated to determine the sensitization safety of E&Ls following parenteral administration. The current work represents an initial effort to develop a scientifically robust process for sensitization safety assessment of E&Ls associated with parenteral pharmaceutical products.
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Affiliation(s)
- Frank Liu
- The Estée Lauder Companies, 155 Pinelawn Rd, Melville, NY, USA.
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Staal YCM, Bil W, Bokkers BGH, Soeteman-Hernández LG, Stephens WE, Talhout R. Challenges in Predicting the Change in the Cumulative Exposure of New Tobacco and Related Products Based on Emissions and Toxicity Dose-Response Data. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:10528. [PMID: 36078242 PMCID: PMC9518537 DOI: 10.3390/ijerph191710528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/17/2022] [Accepted: 08/18/2022] [Indexed: 06/15/2023]
Abstract
Many novel tobacco products have been developed in recent years. Although many may emit lower levels of several toxicants, their risk in the long term remains unclear. We previously published a method for the exposure assessment of mixtures that can be used to compare the changes in cumulative exposure to carcinogens among tobacco products. While further developing this method by including more carcinogens or to explore its application to non-cancer endpoints, we encountered a lack of data that are required for better-substantiated conclusions regarding differences in exposure between products. In this special communication, we argue the case for more data on adverse health effects, as well as more data on the composition of the emissions from tobacco products. Such information can be used to identify significant changes in relevance to health using the cumulative exposure method with different products and to substantiate regulatory decisions.
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Affiliation(s)
- Yvonne C. M. Staal
- National Institute for Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, The Netherlands
| | - Wieneke Bil
- National Institute for Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, The Netherlands
| | - Bas G. H. Bokkers
- National Institute for Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, The Netherlands
| | - Lya G. Soeteman-Hernández
- National Institute for Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, The Netherlands
| | - W. Edryd Stephens
- School of Earth & Environmental Sciences, University of St Andrews, St Andrews KY16 9AJ, UK
| | - Reinskje Talhout
- National Institute for Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, The Netherlands
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Staal YCM, Bos PMJ, Talhout R. Methodological Approaches for Risk Assessment of Tobacco and Related Products. TOXICS 2022; 10:491. [PMID: 36136456 PMCID: PMC9505557 DOI: 10.3390/toxics10090491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/17/2022] [Accepted: 08/18/2022] [Indexed: 06/16/2023]
Abstract
Health risk assessment of tobacco and related products (TRPs) is highly challenging due to the variety in products, even within the product class, the complex mixture of components in the emission and the variety of user behaviour. In this paper, we summarize methods that can be used to assess the health risks associated with the use of TRPs. The choice of methods to be used and the data needed are dependent on the aim. Risk assessment can be used to identify the emission components of highest health concern. Alternatively, risk assessment methods can be used to determine the absolute risk of a TRP, which is the health risk of a product, not related to other products, or to determine the relative risk of a TRP, which is the health risk of a TRP compared to, for example, a cigarette. Generally, health risk assessment can be based on the effects of the complete mixture (whole smoke) or based on the (added) effects of individual components. Data requirements are dependent on the method used, but most methods require substantial data on identity and quantity of components in emissions and on the hazards of these components. Especially for hazards, only limited data are available. Currently, due to a lack of suitable data, quantitative risk assessment methods cannot be used to inform regulation.
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Barron MG, Otter RR, Connors KA, Kienzler A, Embry MR. Ecological Thresholds of Toxicological Concern: A Review. FRONTIERS IN TOXICOLOGY 2022; 3:640183. [PMID: 35295098 PMCID: PMC8915905 DOI: 10.3389/ftox.2021.640183] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 02/10/2021] [Indexed: 12/22/2022] Open
Abstract
The ecological threshold of toxicological concern (ecoTTC) is analogous to traditional human health-based TTCs but with derivation and application to ecological species. An ecoTTC is computed from the probability distribution of predicted no effect concentrations (PNECs) derived from either chronic or extrapolated acute toxicity data for toxicologically or chemically similar groups of chemicals. There has been increasing interest in using ecoTTCs in screening level environmental risk assessments and a computational platform has been developed for derivation with aquatic species toxicity data (https://envirotoxdatabase.org/). Current research and development areas include assessing mode of action-based chemical groupings, conservatism in estimated PNECs and ecoTTCs compared to existing regulatory values, and the influence of taxa (e.g., algae, invertebrates, and fish) composition in the distribution of PNEC values. The ecoTTC continues to develop as a valuable alternative strategy within the toolbox of traditional and new approach methods for ecological chemical assessment. This brief review article describes the ecoTTC concept and potential applications in ecological risk assessment, provides an overview of the ecoTTC workflow and how the values can be derived, and highlights recent developments and ongoing research. Future applications of ecoTTC concept in different disciplines are discussed along with opportunities for its use.
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Affiliation(s)
- Mace G Barron
- U.S. EPA, Office of Research & Development, Gulf Breeze, FL, United States
| | - Ryan R Otter
- The Data Science Institute, Middle Tennessee State University, Murfreesboro, TN, United States
| | | | - Aude Kienzler
- European Commission, Joint Research Centre (JRC), Ispra, Italy
| | - Michelle R Embry
- Health and Environmental Sciences Institute, Washington, DC, United States
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Kovarich S, Cappelli CI. Use of In Silico Methods for Regulatory Toxicological Assessment of Pharmaceutical Impurities. Methods Mol Biol 2022; 2425:537-560. [PMID: 35188646 DOI: 10.1007/978-1-0716-1960-5_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The use of novel non-testing methodologies to support the toxicological assessment of drug impurities is having a growing impact in the regulatory framework for pharmaceutical development and marketed products. For DNA reactive (mutagenic) impurities specific recommendations for the use of in silico structure-based approaches (namely (Q)SAR methodologies) are provided in the ICH M7 guideline. In 2018 a draft reflection paper has been published by EMA addressing open issues in the qualification approach of non-genotoxic impurities (NGI) according to the ICH Q3A/Q3B guidelines, and proposing the use of alternative testing strategies, including TTC, (Q)SAR, read-across, and in vitro approaches, to gather impurity-specific safety information.In the present chapter we describe a workflow to perform the safety assessment of drug impurities based on non-testing in silico methodologies. The proposed approach consists of a stepwise decision scheme including three key phases: PHASE 1: assessment of bacterial mutagenicity and consequent classification of impurities according to ICH M7; PHASE 2: risk characterization of mutagenic impurities (Classes 1, 2 or 3); PHASE 3: qualification of non-mutagenic impurities (Classes 4 or 5). The proposed decision scheme offers the possibility to acquire impurity-specific data, also if testing is not feasible, and to decide on further in vitro testing, besides meeting 3R's principle.
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Wang Z, Wang YYL, Scott WC, Williams ES, Ciarlo M, DeLeo P, Brooks BW. Comparative influences of dermal and inhalational routes of exposure on hazards of cleaning product ingredients among mammalian model organisms. ENVIRONMENT INTERNATIONAL 2021; 157:106777. [PMID: 34314977 DOI: 10.1016/j.envint.2021.106777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 07/06/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Health risks resulting from dermal or inhalational exposures are frequently assessed based on rodent oral toxicity information due to a lack of species- or route-specific toxicity data. Default uncertainty factors (UFs; e.g., 10-fold) are also applied during risk assessments to account for variability such as inter-species, intra-species, exposure duration, dose-response, and route-to-route extrapolations. However, whether rodent oral data and a default UF approach can provide adequate protection for other mammalian species under dermal or inhalational exposure scenarios remains understudied, particularly for cleaning product ingredients. Therefore, we collated and examined publicly available median lethal dose (LD50), no-observed-adverse-effect level (NOAEL) and lowest-observed-adverse-effect level (LOAEL) values from different types of standard mammalian toxicity studies for rats (dermal and inhalational), mice, rabbits, guinea pigs, and dogs (oral, dermal and inhalational) using the Cleaning Product Ingredient Safety Initiative (CPISI) database. Probabilistic hazard assessments using chemical toxicity distributions (CTDs) were subsequently conducted, and threshold concentrations (TCs) and 95% confidence intervals (95% CIs) were derived to identify thresholds of toxicological concern (TTCs). Relative sensitivities among or between mammalian species, exposure routes, and chemical classes were also compared based on calculated TC5s and 95% CIs to support future toxicology studies and hazard and risk assessments. We then identified uncertainty factors (UFs) using both CTD comparisons and individual UF probability distributional approaches. Based on available rodent inhalational data, chemical category-specific UFs were derived for ethers. Additionally, we also determined whether default UFs of 10 or 100 would be protective for various distributions of cleaning product ingredients. Our novel observations among these routes of exposure and common mammalian model organisms appear particularly useful for read across and screening-level health hazard and risk assessments when limited data exists for specific chemicals.
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Affiliation(s)
- Zhen Wang
- Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou 515063, China.
| | - Yolina Yu Lin Wang
- Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou 515063, China
| | - W Casan Scott
- Department of Environmental Science, Baylor University, Waco, TX, USA
| | | | - Michael Ciarlo
- EA Engineering, Science & Technology, Inc., Baltimore, MD, USA
| | - Paul DeLeo
- American Cleaning Institute, Washington, DC, USA
| | - Bryan W Brooks
- Department of Environmental Science, Baylor University, Waco, TX, USA; School of Environment, Jinan University, Guangzhou 510632, China; Institute of Biomedical Studies, Baylor University, Waco, TX, USA.
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Zaleski R, Embry M, McKee R, Teuschler LK. Exploring the utility of the Threshold of Toxicological Concern (TTC) as a screening approach for complex substances. Regul Toxicol Pharmacol 2021; 127:105051. [PMID: 34614434 DOI: 10.1016/j.yrtph.2021.105051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/10/2021] [Accepted: 09/29/2021] [Indexed: 11/28/2022]
Abstract
The Threshold of Toxicological Concern (TTC) has been applied to assess chemical safety for use, particularly in the food safety area. Although the TTC was developed for application to an individual chemical structure, more recently this concept has been suggested for the assessment of combined exposures to multiple chemicals. This study evaluated the potential for applying the TTC to a specific type of co-exposure, that of a complex substance of variable composition which contains multiple constituents, following the World Health Organization/International Programme on Chemical Safety framework for risk assessment of combined exposure to multiple chemicals. The results indicated that the TTC threshold was lower (i.e., more conservative) than regulatory thresholds derived for the same substance or even its most toxic constituent, providing assurance that the TTC could meet the requirements for a conservative screening process. This case study indicates that the TTC concept can be a useful tool to screen for potential risks from complex substances, with the consideration of additional aspects such as variability in chemical constituents and their relative proportions within the substance.
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Affiliation(s)
- R Zaleski
- ExxonMobil Biomedical Sciences Inc, 1545 Route 22 East, Annandale, NJ, 08801, USA.
| | - M Embry
- Health and Environmental Sciences Institute, 740 15th Street NW, Suite 600, Washington, DC, 20005, USA.
| | - R McKee
- ExxonMobil Biomedical Sciences Inc, 1545 Route 22 East, Annandale, NJ, 08801, USA; Hillsborough, NJ, USA.
| | - L K Teuschler
- LK Teuschler & Associates, 6634 Tenth Avenue Terr So, St. Petersburg, FL, 33707, USA.
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Batke M, Afrapoli FM, Kellner R, Rathman JF, Yang C, Cronin MTD, Escher SE. Threshold of Toxicological Concern—An Update for Non-Genotoxic Carcinogens. FRONTIERS IN TOXICOLOGY 2021; 3:688321. [PMID: 35295144 PMCID: PMC8915827 DOI: 10.3389/ftox.2021.688321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 05/25/2021] [Indexed: 11/22/2022] Open
Abstract
The Threshold of Toxicological Concern (TTC) concept can be applied to organic compounds with the known chemical structure to derive a threshold for exposure, below which a toxic effect on human health by the compound is not expected. The TTC concept distinguishes between carcinogens that may act as genotoxic and non-genotoxic compounds. A positive prediction of a genotoxic mode of action, either by structural alerts or experimental data, leads to the application of the threshold value for genotoxic compounds. Non-genotoxic substances are assigned to the TTC value of their respective Cramer class, even though it is recognized that they could test positive in a rodent cancer bioassay. This study investigated the applicability of the Cramer classes specifically to provide adequate protection for non-genotoxic carcinogens. For this purpose, benchmark dose levels based on tumor incidence were compared with no observed effect levels (NOELs) derived from non-, pre- or neoplastic lesions. One key aspect was the categorization of compounds as non-genotoxic carcinogens. The recently finished CEFIC LRI project B18 classified the carcinogens of the Carcinogenicity Potency DataBase (CPDB) as either non-genotoxic or genotoxic compounds based on experimental or in silico data. A detailed consistency check resulted in a dataset of 137 non-genotoxic organic compounds. For these 137 compounds, NOEL values were derived from high quality animal studies with oral exposure and chronic duration using well-known repositories, such as RepDose, ToxRef, and COSMOS DB. Further, an effective tumor dose (ETD10) was calculated and compared with the lower confidence limit on benchmark dose levels (BMDL10) derived by model averaging. Comparative analysis of NOEL/EDT10/BMDL10 values showed that potentially bioaccumulative compounds in humans, as well as steroids, which both belong to the exclusion categories, occur predominantly in the region of the fifth percentiles of the distributions. Excluding these 25 compounds resulted in significantly higher but comparable fifth percentile chronic NOEL and BMDL10 values, while the fifth percentile EDT10 value was slightly higher but not statistically significant. The comparison of the obtained distributions of NOELs with the existing Cramer classes and their derived TTC values supports the application of Cramer class thresholds to all non-genotoxic compounds, such as non-genotoxic carcinogens.
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Affiliation(s)
- Monika Batke
- Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM), Hannover, Germany
| | | | - Rupert Kellner
- Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM), Hannover, Germany
| | - James F. Rathman
- Altamira, LLC, Columbus, OH, United States
- Molecular Networks GmbH, Nuremberg, Germany
| | - Chihae Yang
- Altamira, LLC, Columbus, OH, United States
- Molecular Networks GmbH, Nuremberg, Germany
| | - Mark T. D. Cronin
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Sylvia E. Escher
- Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM), Hannover, Germany
- *Correspondence: Sylvia E. Escher
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Serafimova R, Coja T, Kass GEN. Application of the Threshold of Toxicological Concern (TTC) in Food Safety: Challenges and Opportunities. FRONTIERS IN TOXICOLOGY 2021; 3:655951. [PMID: 35295160 PMCID: PMC8915901 DOI: 10.3389/ftox.2021.655951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 02/26/2021] [Indexed: 01/04/2023] Open
Abstract
The safety assessment of chemicals added or found in food has traditionally made use of data from in vivo studies performed on experimental animals. The nature and amount of data required to carry out a risk assessment is generally stipulated either in the different food legislations or in sectoral guidance documents. However, there are still cases where no or only limited experimental data are available or not specified by law, for example for contaminants or for some minor metabolites from active substances in plant protection products. For such cases, the Threshold of Toxicological Concern (TTC) can be applied. This review explores the use of the TTC approach in food safety in the European Union, in relation to the different food sectors, legal requirements and future opportunities.
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Affiliation(s)
| | - Tamara Coja
- Austrian Agency for Health and Food Safety, Vienna, Austria
| | - George E. N. Kass
- European Food Safety Authority, Parma, Italy
- *Correspondence: George E. N. Kass
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Mahony C, Bowtell P, Huber M, Kosemund K, Pfuhler S, Zhu T, Barlow S, McMillan DA. Threshold of toxicological concern (TTC) for botanicals - Concentration data analysis of potentially genotoxic constituents to substantiate and extend the TTC approach to botanicals. Food Chem Toxicol 2020; 138:111182. [DOI: 10.1016/j.fct.2020.111182] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 02/03/2020] [Accepted: 02/05/2020] [Indexed: 12/21/2022]
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More SJ, Bampidis V, Benford D, Bragard C, Halldorsson TI, Hernández-Jerez AF, Hougaard Bennekou S, Koutsoumanis KP, Machera K, Naegeli H, Nielsen SS, Schlatter JR, Schrenk D, Silano V, Turck D, Younes M, Gundert-Remy U, Kass GEN, Kleiner J, Rossi AM, Serafimova R, Reilly L, Wallace HM. Guidance on the use of the Threshold of Toxicological Concern approach in food safety assessment. EFSA J 2019; 17:e05708. [PMID: 32626331 PMCID: PMC7009090 DOI: 10.2903/j.efsa.2019.5708] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The Scientific Committee confirms that the Threshold of Toxicological Concern (TTC) is a pragmatic screening and prioritisation tool for use in food safety assessment. This Guidance provides clear step‐by‐step instructions for use of the TTC approach. The inclusion and exclusion criteria are defined and the use of the TTC decision tree is explained. The approach can be used when the chemical structure of the substance is known, there are limited chemical‐specific toxicity data and the exposure can be estimated. The TTC approach should not be used for substances for which EU food/feed legislation requires the submission of toxicity data or when sufficient data are available for a risk assessment or if the substance under consideration falls into one of the exclusion categories. For substances that have the potential to be DNA‐reactive mutagens and/or carcinogens based on the weight of evidence, the relevant TTC value is 0.0025 μg/kg body weight (bw) per day. For organophosphates or carbamates, the relevant TTC value is 0.3 μg/kg bw per day. All other substances are grouped according to the Cramer classification. The TTC values for Cramer Classes I, II and III are 30 μg/kg bw per day, 9 μg/kg bw per day and 1.5 μg/kg bw per day, respectively. For substances with exposures below the TTC values, the probability that they would cause adverse health effects is low. If the estimated exposure to a substance is higher than the relevant TTC value, a non‐TTC approach is required to reach a conclusion on potential adverse health effects. This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2019.EN-1661/full
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Rusyn I, Greene N. The Impact of Novel Assessment Methodologies in Toxicology on Green Chemistry and Chemical Alternatives. Toxicol Sci 2019; 161:276-284. [PMID: 29378069 DOI: 10.1093/toxsci/kfx196] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The field of experimental toxicology is rapidly advancing by incorporating novel techniques and methods that provide a much more granular view into the mechanisms of potential adverse effects of chemical exposures on human health. The data from various in vitro assays and computational models are useful not only for increasing confidence in hazard and risk decisions, but also are enabling better, faster and cheaper assessment of a greater number of compounds, mixtures, and complex products. This is of special value to the field of green chemistry where design of new materials or alternative uses of existing ones is driven, at least in part, by considerations of safety. This article reviews the state of the science and decision-making in scenarios when little to no data may be available to draw conclusions about which choice in green chemistry is "safer." It is clear that there is no "one size fits all" solution and multiple data streams need to be weighed in making a decision. Moreover, the overall level of familiarity of the decision-makers and scientists alike with new assessment methodologies, their validity, value and limitations is evolving. Thus, while the "impact" of the new developments in toxicology on the field of green chemistry is great already, it is premature to conclude that the data from new assessment methodologies have been widely accepted yet.
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Affiliation(s)
- Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Nigel Greene
- Predictive Compound Safety and ADME, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts 02451
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Chebekoue SF, Krishnan K. Derivation of Occupational Thresholds of Toxicological Concern for Systemically Acting Noncarcinogenic Organic Chemicals. Toxicol Sci 2018; 160:47-56. [PMID: 29036659 DOI: 10.1093/toxsci/kfx155] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Many substances in workplace do not have occupational exposure limits. The threshold of toxicological concern (TTC) principle is part of the hierarchy of approaches useful in occupational health risk assessment. The aim of this study was to derive occupational TTCs (OTTCs) reflecting the airborne concentrations below which no significant risk to workers would be anticipated. A reference dataset consisting of the 8-h threshold limit values-Time-Weighted Average for 280 organic substances was compiled. Each substance was classified into low (class I), intermediate (class II), or high (class III) hazard categories as per Cramer rules. For each chemical, n-octanol:water partition coefficient and vapor pressure along with the molecular weight were used to predict the blood:air partition coefficient. The blood:air partition coefficient along with data on water solubility and ventilation rate allowed the prediction of pulmonary retention factor and absorbed dose in workers. For each Cramer class, the distribution of the predicted doses was analyzed to identify the various percentile values corresponding to the OTTC. Accordingly, for Cramer classes I-III, the OTTCs derived in this study correspond to 0.15, 0.0085, and 0.006 mmol/d, respectively, at the 10th percentile level, while these values were 1.5, 0.09 and 0.03 mmol/d at the 25th percentile level. The proposed OTTCs are not meant to replace the traditional occupational exposure limits, but can be used in data-poor situations along with exposure estimates to support screening level risk assessment and prioritization.
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Affiliation(s)
- Sandrine F Chebekoue
- Département de Santé Environnementale et Santé au Travail, École de Santé Publique de l'Université de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Kannan Krishnan
- Département de Santé Environnementale et Santé au Travail, École de Santé Publique de l'Université de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada
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Hoersch J, Hoffmann-Doerr S, Keller D. Derivation of an inhalation TTC for the workplace based on DNEL values reported under REACH. Toxicol Lett 2018; 290:110-115. [PMID: 29596887 DOI: 10.1016/j.toxlet.2018.03.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/01/2018] [Accepted: 03/26/2018] [Indexed: 10/17/2022]
Abstract
The Threshold of Toxicological Concern (TTC) concept defines a generic tolerable exposure for chemicals of unknown toxicity below which the risk of adverse health effects is considered very small. The original concept was refined and extended over the years, based either on differentiated structural classes or on additional information on certain toxicological endpoints. Initially, the focus of the TTC application was only on systemic toxic effects after repeated oral intake and consisted of one value. However, under well-defined boundary conditions, a long-term systemic inhalation TTC could also serve as a cut-off criterion for occupational exposure in those cases where workers are exposed to very low levels of chemicals by inhalation contact and could therefore reduce the need to perform animal tests. Within the scope of the European REACH legislation, several thousand systemic long-term inhalation Derived No Effect Levels (DNELs) for workers have been published. By statistical evaluation of the DNEL distribution of 1876 chemicals and the resulting 99th percentiles, we propose an inhalation workplace TTC for systemic effects in the region of 50 μg/m3 (7 μg/kg body weight/day). Specific exclusion criteria apply for the discussed concept.
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Affiliation(s)
- Johanna Hoersch
- Henkel AG & Co. KGaA, Henkelstr. 67, 40589 Düsseldorf, Germany.
| | | | - Detlef Keller
- Henkel AG & Co. KGaA, Henkelstr. 67, 40589 Düsseldorf, Germany
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16
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Geraets L, Zeilmaker MJ, Bos PM. The importance of inclusion of kinetic information in the extrapolation of high-to-low concentrations for human limit setting. Toxicol Lett 2018; 282:81-92. [DOI: 10.1016/j.toxlet.2017.10.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 10/06/2017] [Accepted: 10/07/2017] [Indexed: 10/18/2022]
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17
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Zheng C, Wang Q, Ning Y, Fan Y, Feng S, He C, Zhang TC, Shen Z. Isolation of a 2-picolinic acid-assimilating bacterium and its proposed degradation pathway. BIORESOURCE TECHNOLOGY 2017; 245:681-688. [PMID: 28917103 DOI: 10.1016/j.biortech.2017.09.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/03/2017] [Accepted: 09/04/2017] [Indexed: 06/07/2023]
Abstract
Burkholderia sp. ZD1, aerobically utilizes 2-picolinic acid as a source of carbon, nitrogen and energy, was isolated. ZD1 completely degraded 2-picolinic acid when the initial concentrations ranged from 25 to 300mg/L. Specific growth rate (μ) and specific consumption rate (q) increased continually in the concentration range of 25-100mg/L, and then declined. Based on the Haldane model and Andrew's model, μmax and qmax were calculated as 3.9 and 16.5h-1, respectively. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was used to determine the main intermediates in the degradation pathway. Moreover, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was innovatively used to deduce the ring cleavage mechanism of N-heterocycle of 2-picolinic acid. To our knowledge, this is the first report on not only the utilization of 2-picolinic acid by a Burkholderia sp., but also applying FT-ICR-MS and ATR-FTIR for exploring the biodegradation pathway of organic compounds.
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Affiliation(s)
- Chunli Zheng
- Department of Environmental Science and Engineering, State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, PR China
| | - Qiaorui Wang
- Department of Environmental Science and Engineering, State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, PR China
| | - Yanli Ning
- Xi'an Modern Chemistry Research Institute, Xi'an 710065, PR China
| | - Yurui Fan
- Department of Environmental Science and Engineering, State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, PR China
| | - Shanshan Feng
- Department of Environmental Science and Engineering, State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, PR China
| | - Chi He
- Department of Environmental Science and Engineering, State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, PR China; School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
| | - Tian C Zhang
- 205D, PKI, Civil Engineering Department, University of Nebraska-Lincoln at Omaha campus, Omaha, NE 68182-0178, USA
| | - Zhenxing Shen
- Department of Environmental Science and Engineering, State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, PR China
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18
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Landsiedel R, Ma-Hock L, Wiench K, Wohlleben W, Sauer UG. Safety assessment of nanomaterials using an advanced decision-making framework, the DF4nanoGrouping. JOURNAL OF NANOPARTICLE RESEARCH : AN INTERDISCIPLINARY FORUM FOR NANOSCALE SCIENCE AND TECHNOLOGY 2017; 19:171. [PMID: 28553159 PMCID: PMC5423989 DOI: 10.1007/s11051-017-3850-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 04/10/2017] [Indexed: 05/14/2023]
Abstract
As presented at the 2016 TechConnect World Innovation Conference on 22-25 May 2016 in Washington DC, USA, the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) 'Nano Task Force' proposes a Decision-making framework for the grouping and testing of nanomaterials (DF4nanoGrouping) consisting of three tiers to assign nanomaterials to four main groups with possible further subgrouping to refine specific information needs. The DF4nanoGrouping covers all relevant aspects of a nanomaterial's life cycle and biological pathways: intrinsic material properties and system-dependent properties (that depend upon the nanomaterial's respective surroundings), biopersistence, uptake and biodistribution, and cellular and apical toxic effects. Use, release, and exposure route may be applied as 'qualifiers' to determine if, e.g., nanomaterials cannot be released from products, which may justify waiving of testing. The four main groups encompass (1) soluble, (2) biopersistent high aspect ratio, (3) passive, and (4) active nanomaterials. The DF4nanoGrouping foresees a stepwise evaluation of nanomaterial properties and effects with increasing biological complexity. In case studies covering carbonaceous nanomaterials, metal oxide, and metal sulfate nanomaterials, amorphous silica and organic pigments (all nanomaterials having primary particle sizes below 100 nm), the usefulness of the DF4nanoGrouping for nanomaterial hazard assessment was confirmed. The DF4nanoGrouping facilitates grouping and targeted testing of nanomaterials. It ensures that sufficient data for the risk assessment of a nanomaterial are available, and it fosters the use of non-animal methods. No studies are performed that do not provide crucial data. Thereby, the DF4nanoGrouping serves to save both animals and resources.
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Affiliation(s)
- Robert Landsiedel
- Experimental Toxicology and Ecology, BASF SE, Carl-Bosch-Strasse 38, D-67056 Ludwigshafen, Germany
| | - Lan Ma-Hock
- Experimental Toxicology and Ecology, BASF SE, Carl-Bosch-Strasse 38, D-67056 Ludwigshafen, Germany
| | - Karin Wiench
- Regulatory Toxicology, BASF SE, 67056 Ludwigshafen, Germany
| | - Wendel Wohlleben
- Experimental Toxicology and Ecology, BASF SE, Carl-Bosch-Strasse 38, D-67056 Ludwigshafen, Germany
- Advanced Materials Research, BASF SE, 67056 Ludwigshafen, Germany
| | - Ursula G. Sauer
- Scientific Consultancy—Animal Welfare, Hallstattfeld 16, 85579 Neubiberg, Germany
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19
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Indoor air guide values for glycol ethers and glycol esters—A category approach. Int J Hyg Environ Health 2016; 219:419-36. [DOI: 10.1016/j.ijheh.2016.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 04/13/2016] [Accepted: 04/13/2016] [Indexed: 11/22/2022]
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