In vitro and in vivo genotoxicity assessment of HI-6 dimethanesulfonate/oxime.

Organophosphate compounds, which induce organophosphate poisoning, were originally used as pesticides. But this type of product has also been used as warfare nerve agent like sarin, soman, Russian VX, or tabun. HI-6-dimethanesulfonate is a salt of the oxime HI-6 used in the treatment of nerve-agent poisoning. It is known to be the best re-activator component of inactivated acetyl cholinesterase. HI-6-dimethanesulfonate has shown a higher level of solubility with similar potency to reactivate acetyl cholinesterase and a similar pharmacokinetics profile compared with HI-6 dichloride. HI-6 dimethanesulfonate was tested for its mutagenic and genotoxic potential by use of the standard ICH S2R (1) battery for the evaluation of pharmaceuticals. HI-6-dimethanesulfonate was mutagenic in the Ames test only in the presence of metabolic activation. In the mutation assay at the Tk locus in L5178Y mouse-lymphoma cells, HI-6-dimethanesulfonate showed mutagenic activity both with and without metabolic activation, with a significant increase in small colonies. The effects were in favour of a clastogenic activity. It was concluded that the compound was mutagenic and possibly clastogenic in vitro. In contrast, the in vivo micronucleus test in rat bone-marrow did not demonstrate any genotoxic activity and the Comet assay performed in rat liver did not show any statistically or biologically significant increases in DNA strand-breaks. The results of both in vivo studies performed on two different organs with two endpoints are sufficient to conclude the absence of a genotoxic hazard in vivo and to consider that there is no genotoxic concern in humans for HI-6-dimethanesulfonate.

Nuclear tau, a key player in neuronal DNA protection.

Tau, a neuronal protein involved in neurodegenerative disorders such as Alzheimer disease, which is primarily described as a microtubule-associated protein, has also been observed in the nuclei of neuronal and non-neuronal cells. However, the function of the nuclear form of Tau in neurons has not yet been elucidated. In this work, we demonstrate that acute oxidative stress and mild heat stress (HS) induce the accumulation of dephosphorylated Tau in neuronal nuclei. Using chromatin immunoprecipitation assays, we demonstrate that the capacity of endogenous Tau to interact with neuronal DNA increased following HS. Comet assays performed on both wild-type and Tau-deficient neuronal cultures showed that Tau fully protected neuronal genomic DNA against HS-induced damage. Interestingly, HS-induced DNA damage observed in Tau-deficient cells was completely rescued after the overexpression of human Tau targeted to the nucleus. These results highlight a novel role for nuclear Tau as a key player in early stress response.

Scientific Opinion on Flavouring Group Evaluation 63, Revision 4 (FGE.63Rev4): consideration of aliphatic secondary saturated and unsaturated alcohols, ketones and related esters evaluated by JECFA (59th and 69th meetings) structurally related to flavouring substances evaluated by EFSA in FGE.07Rev6.

The EFSA Panel on Food Additives and Flavourings was requested to evaluate 43 flavouring substances assigned to the Flavouring Group Evaluation 63 (FGE.63), using the Procedure as outlined in the Commission Regulation (EC) No 1565/2000. Twenty-nine substances have already been considered in FGE.63 and its revisions ([FL-no: 02.023, 02.099, 02.104, 02.136, 02.155, 02.252, 07.015, 07.069, 07.081, 07.099, 07.100, 07.101, 07.102, 07.114, 07.123, 07.151, 07.190, 07.240, 07.247, 07.249, 07.256, 09.281, 09.282, 09.657, 09.658, 09.923, 09.924, 09.925 and 09.936]). The remaining 14 flavouring substances have been cleared with respect to genotoxicity in FGE.204Rev1 ([FL-no: 02.102, 02.193, 07.044, 07.048, 07.082, 07.104, 07.105, 07.106, 07.107, 07.121, 07.139, 07.177, 07.188 and 07.244]) and they are considered in this revision 4 of FGE.63. The substances were evaluated through a stepwise approach that integrates information on the structure-activity relationships, intake from current uses, toxicological threshold of concern (TTC) and available data on metabolism and toxicity. The Panel concluded that none of these 43 substances gives rise to safety concerns at their levels of dietary intake, when estimated on the basis of the 'Maximised Survey-derived Daily Intake' (MSDI) approach. Besides the safety assessment of the flavouring substances, the specifications for the materials of commerce have also been considered and found adequate for 43 flavouring substances. However, for 14 of these flavouring substances in the present revision and for 10 of the substances in the previous revision (FGE.63Rev3), the 'modified Theoretical Added Maximum Daily Intakes' (mTAMDIs) values are equal to or above the TTCs for their structural classes (I and II). For 15 substances previously evaluated in FGE.63Rev3, use levels are still needed to calculate the mTAMDI estimates. Therefore, in total for 39 flavouring substances, more data on uses and use levels should be provided to finalise their safety evaluations.

Scientific Opinion on Flavouring Group Evaluation 7, Revision 6 (FGE.07Rev6): saturated and unsaturated aliphatic secondary alcohols, ketones and esters of secondary alcohols and saturated linear or branched-chain carboxylic acids from chemical group 5.

The EFSA Panel on Food Additives and Flavourings was requested to evaluate 55 flavouring substances assigned to the Flavouring Group Evaluation 07 (FGE.07), using the Procedure as outlined in the Commission Regulation (EC) No 1565/2000. Fifty-three substances have already been considered in FGE.07 and its revisions. This revision 6 includes two additional substances which have been cleared with respect to genotoxicity in FGE.201Rev2 (4-methyl-3-hepten-5-one [FL-no: 07.261]) and FGE.204Rev1 (non-2-en-4-one, [FL-no: 07.187]). The substances were evaluated through a stepwise approach that integrates information on the structure-activity relationships, intake from current uses, toxicological threshold of concern (TTC) and available data on metabolism and toxicity. The Panel concluded that none of the 55 substances gives rise to safety concerns at their levels of dietary intake, when estimated on the basis of the 'Maximised Survey-derived Daily Intake' (MSDI) approach. Besides the safety assessment of the flavouring substances, the specifications for the materials of commerce have also been considered and found adequate. Normal and maximum use levels were available for all flavouring substances. For 52 substances, including the newly included substances [FL-no: 07.187 and 07.261], their 'modified Theoretical Added Maximum Daily Intakes' (mTAMDIs) estimates were above the TTC for their structural classes (I and II). Therefore, for these 52 flavouring substances, more detailed data on uses and use levels should be provided to finalise their safety evaluations.

Study of oxidative DNA damage in TK6 human lymphoblastoid cells by use of the thymidine kinase gene-mutation assay and the in vitro modified comet assay: determination of No-Observed-Genotoxic-Effect-Levels.

Nowadays, there is clear progress in using the threshold concept in genetic toxicology, but its demonstration and acceptance in risk assessment is still under debate. Although it has been accepted for some non-DNA-reactive agents for which mechanisms of action were demonstrated, there is a growing weight of evidence to also support the existence of thresholded dose-responses for DNA-reactive agents. In this context, we have recently shown in human TK6 lymphoblastoid cells, that DNA-oxidizing agents [potassium bromate, bleomycin and hydrogen peroxide (via glucose oxidase)] produced non-linear dose-responses in the in vitro micronucleus test, thus allowing the determination of No-Observed-Genotoxic-Effect-Levels (NOGELs). Therefore, the aim of the present study was to focus on the analysis of thresholded dose-response curves in order to further investigate the existence of NOGELs for these same directly DNA-damaging agents, by use of other genotoxicity endpoints. Mutation frequency was determined after a 1-h treatment in the thymidine kinase (TK) gene-mutation assay. Primary DNA damage, especially oxidative DNA damage, was also assessed after 1h of treatment, followed - or not - by a 23-h recovery period, with the modified version of the comet assay (i.e. with the glycosylases Fpg and hOgg1). Overall, our analysis demonstrates that there is convincing evidence to support the existence of thresholded dose-responses for DNA-oxidizing agents. The determination of NOGELs depends on the genotoxic endpoint studied and consequently requires different genotoxicity assays performed concurrently. NOGELs could only be defined for the induction of chromosomal aberrations and gene mutations, i.e. for an effect-endpoint but not for primary DNA damage, i.e. for an exposure-endpoint. Further statistical analyses of these data are now required in order to draw conclusions on the exact level of the thresholds.

Workshop summary: Top concentration for in vitro mammalian cell genotoxicity assays; and report from working group on toxicity measures and top concentration for in vitro cytogenetics assays (chromosome aberrations and micronucleus).

The selection of maximum concentrations for in vitro mammalian cell genotoxicity assays was reviewed at the 5th International Workshop on Genotoxicity Testing (IWGT), 2009. Currently, the top concentration recommended when toxicity is not limiting is 10mM or 5mg/ml, whichever is lower. The discussion was whether to reduce the limit, and if so whether the 1mM limit proposed for human pharmaceuticals was appropriate for testing other chemicals. The consensus was that there was reason to consider reducing the 10mM limit, and many, but not all, attendees favored a reduction to 1mM. Several proposals are described here for the concentration limit. The in vitro cytogenetics expert working group also discussed appropriate measures and level of cytotoxicity. Data were reviewed from a multi-laboratory trial of the in vitro micronucleus (MN) assay with multiple cell types and several types of toxicity measurements. The group agreed on a preference for toxicity measures that take cell proliferation after the beginning of treatment into account (relative increase in cell counts, relative population doubling, cytokinesis block proliferation index or replicative index), and that this applies both to in vitro MN assays and to in vitro chromosome aberration assays. Since relative cell counts (RCC) underestimate toxicity, many group members favored making a recommendation against the use of RCC as a toxicity measure for concentration selection. All 14 chemicals assayed for MN induction in the multi-laboratory trial were detected without exceeding 50% toxicity by any measure, but some were positive only at concentrations with toxicity quite close to 50%. The expert working group agreed to accept the cytotoxicity range recommended by OECD guideline 487 (55±5% toxicity at the top concentration scored). This also reinforces the original intent of the guidance for the in vitro chromosome aberration assay, where ">50%" was intended to target the range close to 50% toxicity.

Strategies in case of positive in vivo results in genotoxicity testing.

At the 2009 International Workshop on Genotoxicity Testing in Basel, an expert group gathered to provide guidance on suitable follow-up tests to describe risk when basic in vivo genotoxicity tests have yielded positive results. The working group agreed that non-linear dose-response curves occur in vivo with at least some DNA-reactive agents. Quantitative risk assessment in such cases requires the use of (1) adequate data, i.e., the use of all available data for the selection of reliable in vivo models to be used for quantitative risk assessment, (2) appropriate mathematical models and statistical analysis for characterizing the dose-response relationships and allowing the use of quantitative and dose-response information in the interpretation of results, (3) mode of action (MOA) information for the evaluation and analysis of risk, and (4) reliable assessments of the internal dose across species for deriving acceptable margins of exposure and risk levels. Hence, the elucidation of MOA and understanding of the mechanism underlying the dose-response curve are important components of risk assessment. The group agreed on the need for (i) the development of in vivo assays, especially multi-endpoint, multi-species assays, with emphasis on those applicable to humans, and (ii) consensus about the most appropriate mathematical models and statistical analyses for defining non-linear dose-responses and exposure levels associated with acceptable risk.

Scientific Opinion on Flavouring Group Evaluation 67, Revision 3 (FGE.67Rev3): consideration of 23 furan-substituted compounds evaluated by JECFA at the 55th, 65th, 69th and 86th meetings.

The Panel on Food Additives and Flavourings (FAF) was requested to consider the JECFA evaluations of 25 flavouring substances assigned to the Flavouring Group Evaluation 67 (FGE.67Rev3), using the Procedure as outlined in the Commission Regulation (EC) No 1565/2000. Eleven substances have already been considered in FGE.67 and its revisions (FGE.67Rev1 and FGE.67Rev2). During the current assessment, two substances were no longer supported by industry, therefore 12 candidate substances are evaluated in FGE.67Rev3. New genotoxicity and toxicity data are available for 2-pentylfuran [FL-no: 13.059] and 2-acetylfuran [FL-no: 13.054], which are representative substances of subgroup IV [FL-no: 13.069, 13.106, 13.148] and VI-B [FL-no: 13.045, 13.070, 13.083, 13.101, 13.105, 13.138, 13.163], respectively. Based on these data, the Panel concluded that the concern for genotoxicity is ruled out for both [FL-no: 13.054] and [FL-no: 13.059] and consequently for the substances that they represent. Since the candidate substances cannot be anticipated to be metabolised to innocuous products only, they were evaluated along the B-side of the Procedure. The Panel derived a NOAEL of 22.6 mg/kg bw per day and a BMDL of 8.51 mg/kg bw per day, for 2-acetylfuran and 2-pentylfuran, respectively. For all 12 substances sufficient margins of safety were calculated when based on the MSDI approach. Adequate specifications for the materials of commerce are available for all 23 flavouring substances. The Panel agrees with JECFA conclusions, for all 23 substances, 'No safety concern at estimated levels of intake as flavouring substances' based on the MSDI approach. For 18 substances [FL-no: 13.021, 13.022, 13.023, 13.024, 13.031, 13.045, 13.047, 13.054, 13.059, 13.074, 13.083, 13.101, 13.105, 13.106, 13.138, 13.148, 13.163 and 13.190], the mTAMDI intake estimates are above the threshold of toxicological concern (TTC) for their structural classes and more reliable data on uses and use levels are required to finalise their evaluation.

Scientific Opinion on Flavouring Group Evaluation 13 Revision 3 (FGE.13Rev3): furfuryl and furan derivatives with and without additional side-chain substituents and heteroatoms from chemical group 14.

The Panel on Food additives and Flavourings of the EFSA was requested to update Flavouring Group Evaluation 13 using the Procedure as outlined in Commission Regulation (EC) No 1565/2000, to include an evaluation of the flavouring substances 2-ethyl-5-methylfuran [FL-no: 13.125] and 2-octylfuran [FL-no: 13.162]. FGE.13 revision 3 (FGE.13Rev3) deals with 26 flavourings substances of which 24 have been already evaluated to be of no safety concern. For [FL-no: 13.125] and [FL-no: 13.162], a concern for genotoxicity was raised in FGE.13Rev1. This concern could be ruled out based on new genotoxicity data on supporting substances in FGE.67Rev3. Subsequently, [FL-no: 13.125 and 13.162] were evaluated, through a stepwise approach that integrates intake from current uses, toxicological threshold of concern (TTC), and available data on metabolism and toxicity, along the B-side of the Procedure, making use of a BMDL of 8.51 mg/kg body weight (bw) per day. The Panel derived this BMDL from an oral subchronic toxicity study with the supporting substance 2-pentylfuran [FL-no: 13.059]. Using this BMDL, for [FL-no: 13.125 and 13.162], adequate margins of safety were calculated based on the MSDI approach. The Panel concluded that the 26 candidate substances in FGE.13Rev3 do not give rise to safety concerns at their levels of dietary intake, when estimated on the basis of the MSDI approach. Adequate specifications for the materials of commerce have been provided for all 26 substances. Data on uses and use levels are needed for [FL-no: 13.130]. For 21 flavouring substances [FL-no: 13.011, 13.102, 13.108, 13.113, 13.114, 13.122, 13.125, 13.127, 13.129, 13.132, 13.133, 13.135, 13.136, 13.139, 13.141, 13.143, 13.146, 13.149, 13.162, 13.178 and 13.185], the mTAMDI intake estimates are above the TTC for their structural class and more reliable data on uses and use levels are required to finalise their evaluation.

Cytosine arabinoside, vinblastine, diethylstilboestrol and 2-aminoanthracene tested in the in vitro human TK6 cell line micronucleus test (MNvit) at Institut Pasteur de Lille in support of OECD draft test guideline 487.

The reference genotoxic agents Cytosine arabinoside, Vinblastine, Diethylstilboestrol and 2-Aminoanthracene were tested in the in vitro micronucleus assay, in human lymphoblastoid TK6 cells, without cytokinesis block, at the laboratories of Institut Pasteur de Lille, France. This was done in support of the toxicity measures recommended in the late 2007 version of the draft OECD Test Guideline 487 for the testing of chemicals. All four reference agents were positive in the assay at concentrations giving approximately 50% toxicity or less as assessed by draft Test Guideline 487 recommended measures, relative population doublings and relative increase in cell counts. Accordingly, this work supports the premise that relative population doublings and relative increase in cell counts are appropriate measures of toxicity for the non-cytokinesis blocked in vitro micronucleus assay.

Risk assessment of consumption of methylchavicol and tarragon: the genotoxic potential in vivo and in vitro.

Methylchavicol (or estragole), a natural flavouring substance present in tarragon, was confirmed as a genotoxic chemical in the in vitro UDS test in cultured rat hepatocytes and in the in vivo UDS test in hepatocytes of exposed rats. Deep-frozen tarragon was clearly less genotoxic than methylchavicol at equivalent dose levels, and desiccated tarragon was negative. Both forms of tarragon tested in vitro have the ability to decrease significantly the genotoxicity of methylchavicol added to the culture medium at concentrations

Study of gene expression profiles in TK6 human cells exposed to DNA-oxidizing agents.

During the last decade, there has been clear progress in using threshold in risk assessment but its acceptance by scientists is still under debate. Contrary to indirect DNA-damaging agents, DNA-reactive agents have been assumed to have a non-threshold mode of action, as they directly induce DNA lesions that potentially can be converted into mutations. However, in recent years there is a growing number of data establishing threshold doses even for these DNA-reactive compounds. Indeed, there are several defence and repair mechanisms that provide protection and that may be responsible for genotoxic thresholds. In this context, we recently showed that DNA-oxidizing agents exhibit a thresholded dose-response in vitro with respect to chromosomal alterations. We have hypothesized the involvement of different cellular responses whose nature and efficiency depend on the stress level. The aim of this study was to develop a more complete understanding of these underlying mechanisms. We investigated global gene expression profiles of human lymphoblastoid TK6 cells after exposure to potassium bromate and hydrogen peroxide (via glucose oxidase). Cells were treated for 1h and mRNAs were isolated either immediately at the end of the treatment or after a 23-h recovery period. Our results showed that cells have developed elaborate cellular responses to oxidative stress in order to maintain genomic integrity. Many of altered genes were redox-sensitive transcription factors such as p53, NF-kappaB, AP-1 and Nrf2. Their downstream target genes and signalling pathways were subsequently activated leading mainly to the induction of antioxidant defenses, inflammation, cell cycle arrest, DNA repair and cell death. Overall, our study allowed the identification of key events involved in the thresholded response observed after DNA-oxidizing agents exposure and shows the usefulness of the combination of standard in vitro genotoxicity assays with gene expression profiling technology to determine modes of action, particularly for critical risk assessment.

Scientific Opinion on Flavouring Group Evaluation 72, Revision 2 (FGE.72Rev2): consideration of aliphatic, branched-chain saturated and unsaturated alcohols, aldehydes, acids and related esters evaluated by JECFA (61st, 68th and 69th meetings) and structurally related to flavouring substances in FGE.05Rev3.

The EFSA Panel on Food Additives and Flavourings was requested to evaluate 31 flavouring substances assigned to the Flavouring Group Evaluation 72 (FGE.72), using the Procedure as outlined in the Commission Regulation (EC) No 1565/2000. Twenty-three substances have already been considered in FGE.72 and FGE.72Rev1 ([FL-no: 02.011, 02.012, 02.027, 02.029, 02.058, 02.076, 02.109, 05.020, 05.021, 05.124, 05.148, 05.169, 08.036, 08.044, 08.047, 08.055, 08.064, 08.070, 08.079, 09.273, 09.408, 09.931 and 16.001]). The remaining eight flavouring substances have been cleared with respect to genotoxicity in FGE.200Rev1 ([FL-no: 05.114]) and FGE.201Rev2 ([FL-no: 02.174, 05.033, 05.090, 05.095, 05.105, 05.107 and 05.126]) and they are considered in this revision 2 of FGE.72. The substances were evaluated through a stepwise approach that integrates information on the structure-activity relationships, intake from current uses, toxicological threshold of concern (TTC), and available data on metabolism and toxicity. The Panel concluded that none of these 31 substances gives rise to safety concerns at their levels of dietary intake, estimated on the basis of the 'Maximised Survey-derived Daily Intake' (MSDI) approach. Besides the safety assessment of the flavouring substances, the specifications for the materials of commerce have also been considered and found adequate for all 31 flavouring substances. For 21 substances, evaluated through the Procedure in the previous revision (FGE.72Rev1), no normal and maximum use levels are available. For four substances, the modified Theoretical Added Maximum Daily Intake (mTAMDI) intake estimates are equal to ([FL-no: 05.090]) or above ([FL-no: 05.107, 05.105, 05.033]) the TTC for their structural class. Therefore, for these 25 substances more detailed data on uses and use levels should be provided in order to refine their exposure assessments and to finalise their safety evaluations.

Scientific Opinion on Flavouring Group Evaluation 69, Revision 1 (FGE.69Rev1): consideration of aromatic substituted secondary alcohols, ketones and related esters evaluated by JECFA (57th meeting), structurally related to aromatic ketones from chemical group 21 evaluated by EFSA in FGE.16Rev2.

The EFSA Panel on Food Additives and Flavourings was requested to evaluate 35 flavouring substances attributed to the Flavouring Group Evaluation 69 (FGE.69), using the Procedure as outlined in the Commission Regulation (EC) No 1565/2000. Thirty-two substances have already been considered in FGE.69 [FL-no: 02.033, 02.034, 02.036, 02.064, 02.065, 02.080, 07.004, 07.013, 07.022, 07.023, 07.025, 07.026, 07.028, 07.029, 07.032, 07.038, 07.040, 07.042, 07.070, 07.079, 07.086, 07.087, 09.144, 09.178, 09.179, 09.189, 09.200, 09.231, 09.249, 09.476, 09.486 and 09.501]. The remaining three substances [FL-no: 02.066, 07.024 and 07.027] have been cleared with respect to genotoxicity in FGE.215Rev1 and are considered in this revision FGE.69Rev1. The substances were evaluated through a stepwise approach, namely the Procedure, that integrates information on the structure-activity relationships, intake from current uses, Threshold of Toxicological Concern (TTC) and available data on metabolism and toxicity. The Panel considered that for 33 flavouring substances evaluated through the Procedure the specifications are adequate and the Panel agrees with JECFA conclusions 'No safety concern at estimated levels of intake as flavouring substances' when based on the MSDI approach. For two flavouring substances [FL-no: 07.038 and 07.042], there is insufficient information on their chemical identity to reach a final conclusion. For six substances [FL-no: 02.066, 07.013, 07.024, 07.028, 07.032 and 07.086], there is no concern when the exposure was estimated based on the 'modified Theoretical Added Maximum Daily Intake' (mTAMDI) approach. For 28 substances, use levels are needed to calculate the mTAMDI estimates in order to identify those flavouring substances that need more refined exposure assessment and to finalise the evaluation accordingly. For one substance [FL-no: 07.027], more reliable data on uses and use levels are required in order to finalise the safety evaluation.

Scientific Opinion on Flavouring Group Evaluation 61 Revision 2 (FGE.61Rev2): consideration of aliphatic acetals evaluated by JECFA (57th, 63rd and 68th meetings) structurally related to acetals evaluated by EFSA in FGE.03Rev2.

The EFSA Panel on Food Additives and Flavourings was requested to evaluate 12 flavouring substances attributed to the Flavouring Group Evaluation 61 (FGE.61), using the Procedure as outlined in the Commission Regulation (EC) No 1565/2000. Nine substances have already been considered in FGE.61 and FGE.61Rev1 [FL-no: 06.001, 06.004, 06.005, 06.008, 06.009, 06.015, 06.028, 06.037, 06.081]. The remaining three substances [FL-no: 06.025, 06.031 and 06.072] have been cleared with respect to genotoxicity in FGE.200Rev1 and are considered in this revision 2 of FGE.61. The substances were evaluated through a stepwise approach that integrates information on the structure-activity relationships, intake from current uses, toxicological threshold of concern (TTC), and available data on metabolism and toxicity. The Panel concluded that none of the 12 substances gives rise to safety concerns at their levels of dietary intake, estimated on the basis of the 'Maximised Survey-derived Daily Intake' (MSDI) approach. Besides the safety assessment of the flavouring substances, the specifications for the materials of commerce have also been considered and found adequate. For nine flavouring substances [FL-no: 06.001, 06.004, 06.005, 06.008, 06.009, 06.015, 06.028, 06.037 and 06.081], use levels are still needed to calculate the modified Theoretical Added Maximum Daily Intake (mTAMDI) values in order to identify those flavouring substances that need more refined exposure assessment and to finalise the evaluation accordingly.

Scientific Opinion on Flavouring Group Evaluation 71 Revision 1 (FGE.71Rev1): consideration of aliphatic, linear, α,ß-unsaturated alcohols, aldehydes, carboxylic acids, and related esters evaluated by JECFA (63rd and 69th meeting) structurally related to flavouring substances evaluated in FGE.05Rev3.

The EFSA Panel on Food Additives and Flavourings was requested to evaluate 39 flavouring substances assigned to the Flavouring Group Evaluation 71 (FGE.71), using the Procedure in Commission Regulation (EC) No 1565/2000. Nine substances have already been considered in FGE.71 [FL-no: 08.054, 08.073, 08.123, 09.037, 09.156, 09.157, 05.158, 09.235, 09.239]. The remaining 30 substances [FL-no: 02.020, 02.050, 02.090, 02.112, 02.137, 02.156, 02.210, 05.037, 05.060, 05.070, 05.073, 05.076, 05.078, 05.102, 05.109, 05.150, 05.171, 05.179, 09.276, 09.277, 09.303, 09.385, 09.394, 09.395, 09.396, 09.397, 09.398, 09.399, 09.678 and 09.841] have been cleared with respect to genotoxicity in FGE.200Rev1 and they are considered in this revision. The substances were evaluated through a stepwise approach that integrates information on the structure-activity relationships, intake from current uses, toxicological threshold of concern (TTC), and available data on metabolism and toxicity. The Panel concluded that none of the 39 substances gives rise to safety concerns at their levels of dietary intake, estimated on the basis of the 'Maximised Survey-derived Daily Intake' (MSDI) approach. Besides the safety assessment of the flavouring substances, the specifications for the materials of commerce have also been considered and found adequate, except for [FL-no: 08.073 and 09.235]. For these two substances, data on the composition of the stereoisomeric mixture should be requested. Normal and maximum use levels should be provided for nine flavouring substances [FL-no: 08.054, 08.073, 08.123, 09.037, 09.156, 09.157, 05.158, 09.235, 09.239]. For two flavouring substances [FL-no: 02.020 and 05.076], the 'modified Theoretical Added Maximum Daily Intake' (mTAMDI) estimates are above the TTC for their structural class I. Therefore, additional information on uses and use levels should be provided for these eleven substances in order to finalise their evaluation.

Scientific Opinion on Flavouring Group Evaluation 91, Revision 3 (FGE.91Rev3): consideration of aliphatic, aromatic and α,ß-unsaturated sulfides and thiols evaluated by JECFA (53rd, 61st, 68th and 76th meetings), structurally related to substances in FGE.08Rev5.

The EFSA Panel on Food Additives and Flavourings was requested to evaluate 49 flavouring substances assigned to the Flavouring Group Evaluation 91 (FGE.91), using the Procedure as outlined in the Commission Regulation (EC) No 1565/2000. Forty-four substances have been considered in FGE.91 and its revisions (FGE.91Rev1 and FEG.91Rev2). With regard to the remaining five flavouring substances considered in this revision 3 of FGE.91: two ([FL-no: 12.065 and 12.079]) have been cleared with respect to genotoxicity in FGE.201Rev2; two ([FL-no: 12.169 and 12.241]) were originally allocated to FGE.74Rev4 and one ([FL-no: 12.304]) to FGE.08Rev5. The Panel considered the flavouring substance [FL-no: 12.169] representative for the tertiary monothiols [FL-no: 12.038, 12.085, 12.137, 12.138, 12.145, 12.252, 12.259, 12.241 and 12.304]. The substances were evaluated through a stepwise approach that integrates information on the structure-activity relationships, intake from current uses, toxicological threshold of concern (TTC), and available data on metabolism and toxicity. The Panel concluded that none of these 49 substances gives rise to safety concerns at their levels of dietary intake, estimated on the basis of the 'Maximised Survey-derived Daily Intake' (MSDI) approach. The specifications for the materials of commerce have also been considered and found adequate for all 49 flavouring substances. For five substances [FL-no: 12.077, 12.162, 12.265, 12.267 and 17.036], evaluated through the Procedure in FGE.91Rev2, no normal and maximum use levels are available. For 10 substances [FL-no: 12.065, 12.038, 12.079, 12.108, 12.139, 12.264, 12.274, 12.252, 12.284 and 12.304], the modified Theoretical Added Maximum Daily Intake (mTAMDI) intake estimates are above the TTC for their structural class. Therefore, for these 15 substances, more detailed data on uses and use levels should be provided in order to refine their exposure assessments and to finalise their safety evaluations.

Study of oxidative DNA damage in TK6 human lymphoblastoid cells by use of the in vitro micronucleus test: Determination of No-Observed-Effect Levels.

The existence of thresholds for indirect DNA-damaging agents has been widely accepted in the last few years. In contrast, DNA-reactive agents have been assumed to have a non-threshold mode of action, as they directly induce DNA lesions that have the potential to be converted into mutations. However, this does not take into account protective factors acting to reduce or repair genotoxic damage. Among the compounds acting through possible threshold-mechanisms, some of them induce DNA damage by oxidative stress. In this context, the aim of our study was to investigate the dose-response relationship of well-known DNA-oxidizing agents acting through different mechanisms of oxidative stress, viz. potassium bromate, bleomycin and hydrogen peroxide (by the action of glucose oxidase) by assessing the induction of chromosomal damage using the in vitro micronucleus test (MNT) on the human lymphoblastoid cell line TK6. In order to provide a first characterization of their genotoxic mechanism, two treatment schedules were applied. Cells received both short-term treatment followed by a recovery time (1 + 23 h, 2 + 22 h, 3 + 21 h or 6 + 18 h) and long-term treatment (24h continually). Our results show interesting non-linear dose-effect relationships starting with a range of non-mutagenic very low doses allowing the determination of a No-Observed-Effect Level (NOEL) and going step-wise up to higher doses. After a short exposure, three different plateaus were observed suggesting complex activations and interactions of different cellular mechanisms whose nature and efficiency were dose-dependent. In contrast, after a long treatment, the dose-response curves were different depending on the test compound investigated. Therefore, the in vitro MNT seems to be an appropriate predictive test to establish the NOEL(s) of DNA-oxidizing agents. In order to confirm and to determine the origin of the different cellular step-wise responses observed, additional mechanistic studies would be required, especially by means of other genotoxicity endpoints and gene-expression profiling.

Aloe-emodin-induced DNA fragmentation in the mouse in vivo comet assay.

Aloe-emodin (AE) and derivatives may be present as undesired components co-extracted during extraction of plants containing anthraquinonic derivatives for preparation of diacetylrhein. AE is a well-known in vitro mutagen, but up to now it failed to induce any clear in vivo genotoxic activity in the chromosome aberration assay in rat bone marrow or the in vivo/in vitro UDS test in liver. However, the two target organs noted during rodent carcinogenicity studies with danthron and emodin, two other well-known anthraquinone derivatives, are the colon and the kidney. Therefore, the choice of the organs for testing the genotoxicity of AE, i.e. bone marrow and liver, may be considered inadequate to demonstrate a possible in vivo genotoxic activity. In this context, the in vivo mouse comet assay was performed on both isolated kidney and colon cells in order to demonstrate a possible organospecific genotoxicity after oral administration of AE. Concurrently, the Ames test and the in vitro micronucleus assay with TK6 human lymphoblastoid cells were performed in their microscale version both with S9 from Aroclor 1254-induced liver or kidney, and without S9. AE induced primary DNA damage in the liver and in the kidney as observed between 3 and 6h after two oral administrations at 500, 1000 and 2000mg/kg bw, underlining an in vivo genotoxic mechanism of action. Furthermore, AE induced a clear genotoxic activity both in the Salmonella typhimurium strains TA1537 and TA98 and in the in vitro micronucleus assay in the absence as well as in the presence of metabolic activation. As no significant variation in the genotoxic activity of AE was noted when using either liver or kidney S9-mix, it seems that no quantitatively and/or qualitatively specific renal metabolism occurs. The kidney may be a target organ of AE as it is the major route of excretion. Under such conditions the separation of AE components should take place and the residual content of undesired AE derivatives should be made as low as reasonably achievable. AE present in plant extracts should be considered as an in vivo genotoxin and this property should be taken into account in the risk assessment for human exposure.

The presence of arginine may be a source of false positive results in the Ames test.

An increase in the number of revertant colonies in the Ames test is generally taken as a strong indication of mutagenic activity of a test compound. However, irrelevant positive findings may constitute a major problem in regulatory drug testing. In this study, mixtures containing only amino acids such as glycine, lysine, arginine and isoleucine, routinely used as peptide preservatives in polypeptide pharmaceutical products, were investigated for mutagenesis in the Ames Salmonella typhimurium test. The results demonstrated that in the presence of metabolic activation, all the solutions containing arginine induced an increase in the number of revertant colonies in strains TA98, TA100 and TA1535 compared with the solvent control. More specifically, for strain TA98, all arginine doses tested, i.e. from 0.4 to 8 mg/plate induced a statistically significant increase in the number of revertants. This increase was biologically significant from 1.2 to 8 mg/plate. For strain TA100, the five highest test doses, i.e., from 1.2 to 8 mg/plate, induced statistically and biologically significant increases in the number of revertants. A statistically significant increase in colony number was also observed in strain TA1535, but only at the maximal test dose of 8 mg/plate arginine. These increases were observed with arginine from two different sources, suggesting that the observed effect would not be due to the presence of potential impurities in the type of arginine used. Our findings show that a functional metabolic activation system was required to induce an increase in the number of colonies. The presence of vitamin C inhibited the arginine-induced increase in the number of revertant colonies in S. typhimurium strain TA98, suggesting a potential involvement of oxidative stress.