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  1. Article ; Online: Integrated skin sensitization assessment based on OECD methods (III): Adding human data to the assessment.

    Natsch, Andreas

    ALTEX

    2023  Volume 40, Issue 4, Page(s) 571–583

    Abstract: Skin sensitizer potency assessment based on new approach methodologies is key to deriving a point of departure (PoD) for risk assessment. Regression models to predict a PoD based on OECD-validated in vitro tests and trained on local lymph node assay ( ... ...

    Abstract Skin sensitizer potency assessment based on new approach methodologies is key to deriving a point of departure (PoD) for risk assessment. Regression models to predict a PoD based on OECD-validated in vitro tests and trained on local lymph node assay (LLNA) data were previously presented, and results from human tests were recently compiled. To integrate both data sources, the Reference Chemical Potency List (RCPL), which provides potency values (PV) for 33 chemicals integrating LLNA and human data in a structured weight-of-evidence approach, was developed. When calculating regression models vs PV or LLNA data, different weights for the input parameters were noted. As the RCPL is based on too few chemicals to train robust statistical models, the list of human data was extended to a larger set of PV (n = 139) with associated in vitro data. This database was used to retrain the regression models and to compare regression models trained vs (i) LLNA, (ii) PV or (iii) human DSA04 values. Using the PV as a target, predictive models of similar predictivity to the LLNA-based models were obtained, which mainly differ in a lesser weight of cytotoxicity and a higher weight of cell activation and reactivity parameters. Analysis of the human DSA04 dataset indicates a similar pattern but also shows that the human dataset is too small and biased to be a key dataset for potency prediction. Hence, an enlarged set of PV values appears to be a complementary tool to train predictive models next to an LLNA-only database.
    MeSH term(s) Humans ; Dermatitis, Allergic Contact ; Organisation for Economic Co-Operation and Development ; Local Lymph Node Assay ; Databases, Factual ; Models, Statistical ; Skin ; Allergens
    Chemical Substances Allergens
    Language English
    Publishing date 2023-04-17
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 165707-0
    ISSN 1868-8551 ; 1018-4562 ; 0946-7785
    ISSN (online) 1868-8551
    ISSN 1018-4562 ; 0946-7785
    DOI 10.14573/altex.2302081
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Book: Special issue Human (mal)-odours

    Natsch, Andreas

    chemistry, biochemistry and perception

    (Flavour and fragrance journal ; 28,4)

    2013  

    Title variant Human (mal)-odours
    Author's details guest ed.: Andreas Natsch
    Series title Flavour and fragrance journal ; 28,4
    Collection
    Language English
    Size S. 199 - 268 : Ill., graph. Darst
    Publisher Wiley
    Publishing place Chichester
    Publishing country Great Britain
    Document type Book
    HBZ-ID HT017703349
    Database Catalogue ZB MED Nutrition, Environment, Agriculture

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  3. Article ; Online: Scientific discrepancies in European regulatory proposals on endocrine disruptors-REACH regulation quo vadis?

    Natsch, Andreas

    Archives of toxicology

    2021  Volume 95, Issue 11, Page(s) 3601–3609

    Abstract: The EU chemical strategy for sustainability places a high focus on endocrine-disrupting chemicals (ED), the importance of their identification with increased testing and a ban in consumer products by a generic approach. It is assumed that for ED no ... ...

    Abstract The EU chemical strategy for sustainability places a high focus on endocrine-disrupting chemicals (ED), the importance of their identification with increased testing and a ban in consumer products by a generic approach. It is assumed that for ED no threshold and hence no safe dose exists, leading to this generic approach. This view appears to be linked to the claim that for ED 'low-dose non-monotonic dose response' (low-dose NMDR) effects are observed. Without this hypothesis, there are no scientific reasons why classical risk assessment cannot be applied to the ED mode-of-action. Thus, whether for ED low-dose NMDR effects are considered a reproducible scientific fact by European authorities is Gretchen's question in this politicized field. Recent documents by the SCCS, EFSA and ECHA reviewed herein illustrate the diverging views within European scientific bodies on this issue. Furthermore, ED researchers never replicated findings on low-dose NMDR in blinded inter-laboratory experiments and the CLARITY-BPA core studies could not find evidence for reproducible NMDR for BPA. ECHA proposes a battery of in vitro tests to test all chemicals for ED properties. However, these tests were never validated for relevance and their high positivity rate could lead to increased follow-up animal testing. Based on (i) lack of reproducibility data for low-dose NMDR, (ii) diverging views within European authorities on NMDR and (iii) lack of fully validated in vitro test methods it might be premature to fast-track the wide-ranging changes in the regulatory landscape proposed by the authorities ultimately leading to drastically increased animal testing.
    MeSH term(s) Animals ; Dose-Response Relationship, Drug ; Endocrine Disruptors/toxicity ; European Union ; Reproducibility of Results ; Risk Assessment
    Chemical Substances Endocrine Disruptors
    Language English
    Publishing date 2021-09-10
    Publishing country Germany
    Document type Letter
    ZDB-ID 124992-7
    ISSN 1432-0738 ; 0340-5761
    ISSN (online) 1432-0738
    ISSN 0340-5761
    DOI 10.1007/s00204-021-03152-7
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: The trilogy of human musk receptors: linking receptor activation, genotype, and sensory perception.

    Emter, Roger / Merillat, Christel / Dossenbach, Sandro / Natsch, Andreas

    Chemical senses

    2024  Volume 49

    Abstract: The scent of musk plays a unique role in the history of perfumery. Musk odorants comprise 6 diverse chemical classes and perception differences in strength and quality among human panelists have long puzzled the field of olfaction research. Three odorant ...

    Abstract The scent of musk plays a unique role in the history of perfumery. Musk odorants comprise 6 diverse chemical classes and perception differences in strength and quality among human panelists have long puzzled the field of olfaction research. Three odorant receptors (OR) had recently been described for musk odorants: OR5AN1, OR1N2, and OR5A2. High functional expression of the difficult-to-express human OR5A2 was achieved by a modification of the C-terminal domain and the link between sensory perception and receptor activation for the trilogy of these receptors and their key genetic variants was investigated: All 3 receptors detect only musky smelling compounds among 440 commercial fragrance compounds. OR5A2 is the key receptor for the classes of polycyclic and linear musks and for most macrocylic lactones. A single P172L substitution reduces the sensitivity of OR5A2 by around 50-fold. In parallel, human panelists homozygous for this mutation have around 40-60-fold higher sensory detection threshold for selective OR5A2 ligands. For macrocyclic lactones, OR5A2 could further be proven as the key OR by a strong correlation between in vitro activation and the sensory detection threshold in vivo. OR5AN1 is the dominant receptor for the perception of macrocyclic ketones such as muscone and some nitromusks, as panelists with a mutant OR5A2 are still equally sensitive to these ligands. Finally, OR1N2 appears to be an additional receptor involved in the perception of the natural (E)-ambrettolide. This study for the first time links OR activation to sensory perception and genetic polymorphisms for this unique class of odorants.
    MeSH term(s) Humans ; Smell/genetics ; Odorants ; Receptors, Odorant/metabolism ; Genotype ; Lactones ; Perception ; Fatty Acids, Monounsaturated
    Chemical Substances musk (095I377U8F) ; Receptors, Odorant ; Lactones ; Fatty Acids, Monounsaturated
    Language English
    Publishing date 2024-04-09
    Publishing country England
    Document type Journal Article
    ZDB-ID 754122-3
    ISSN 1464-3553 ; 0379-864X
    ISSN (online) 1464-3553
    ISSN 0379-864X
    DOI 10.1093/chemse/bjae015
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Integrated skin sensitization assessment based on OECD methods (II): Hazard and potency by combining kinetic peptide reactivity and the "2 out of 3" Defined Approach.

    Natsch, Andreas / Gerberick, George Frank

    ALTEX

    2022  Volume 39, Issue 4, Page(s) 647–655

    Abstract: Depending on regulatory requirements, the skin sensitization risk for new chemicals with potential consumer skin contact must be assessed by experimental testing by (i) binary hazard assessment to identify sensitizers, (ii) subclassification of ... ...

    Abstract Depending on regulatory requirements, the skin sensitization risk for new chemicals with potential consumer skin contact must be assessed by experimental testing by (i) binary hazard assessment to identify sensitizers, (ii) subclassification of sensitizers according to the Global Harmonized System (GHS), and (iii) derivation of a point of departure (PoD) for risk assessment. The Organisation for Economic Co-operation and Development (OECD) recently published a test guideline incorporating the “2 out of 3” defined approach (2o3 DA) for skin sensitization hazard assessment and added the kinetic direct peptide reactivity assay (kDPRA) as a stand-alone test guideline method for GHS subclassification. The 2o3 DA requires that at least two in vitro tests are conducted. The cell-based tests and the kDPRA generate, next to a binary outcome with a fixed threshold, continuous concentration-response data, which can be used in quantitative regression models to derive a PoD. The sequence of testing for the 2o3 DA is flexible. Here we compare different testing sequences and how they can be combined with kDPRA data to provide a PoD in parallel to hazard identification (hazard ID) and GHS subclassification. A set of 188 chemicals with available in vitro data was evaluated for the final PoD using these dif-ferent testing sequences. The results indicate that testing can start with DPRA / kDPRA and either of the cell-based assays, and that testing can stop after two congruent tests without major impact on the final PoD for chemicals within the applica-bility domain of the kDPRA.
    MeSH term(s) Animals ; Animal Testing Alternatives/methods ; Organisation for Economic Co-Operation and Development ; Skin ; Kinetics ; Peptides/toxicity ; Dermatitis, Allergic Contact
    Chemical Substances Peptides
    Language English
    Publishing date 2022-04-11
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 165707-0
    ISSN 1868-8551 ; 1018-4562 ; 0946-7785
    ISSN (online) 1868-8551
    ISSN 1018-4562 ; 0946-7785
    DOI 10.14573/altex.2201142
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Integrated skin sensitization assessment based on OECD methods (I): Deriving a point of departure for risk assessment.

    Natsch, Andreas / Gerberick, George Frank

    ALTEX

    2022  Volume 39, Issue 4, Page(s) 636–646

    Abstract: Three guidelines covering key events in the skin sensitization adverse outcome pathway are endorsed by the Organisation for Economic Co-operation and Development (OECD). A recent guideline covers defined approaches (DA) to combine data from these tests ... ...

    Abstract Three guidelines covering key events in the skin sensitization adverse outcome pathway are endorsed by the Organisation for Economic Co-operation and Development (OECD). A recent guideline covers defined approaches (DA) to combine data from these tests for regulatory (sub)classification. The guideline methods provide continuous data that could charac-terize the sensitization potency on a more granular scale beyond (sub)classifications. We assembled a comprehensive database of in vitro and in vivo results from OECD guideline tests. Building on a previous approach using regression models, we provide quantitative models using input data from the kinetic direct peptide reactivity assay (kDPRA), the KeratinoSens™ (KS) assay, and the human cell line activation test (h-CLAT) to calculate a point of departure (PoD) in the form of a predicted local lymph node assay (LLNA) EC3 value for use in risk assessment. Predictive models include results from either two or all three assays. Detailed analysis versus in vivo data estimates redundancy between different tests and helps guide model selection. All models were tested on a set of case studies selected for their availability of multiple LLNA reference data in the OECD database. The predicted PoDs were within or close to the range of the variation of the historical LLNA data for most of these cases studies, and overall, the models predicted the in vivo value with a median fold-misprediction factor of around 2.5. The robustness of the models was characterized by comparing a comprehensive historical database versus the curated dataset provided by the OECD working group on DA.
    MeSH term(s) Animals ; Humans ; Animal Testing Alternatives/methods ; Organisation for Economic Co-Operation and Development ; Dermatitis, Allergic Contact ; Local Lymph Node Assay ; Skin ; Risk Assessment
    Language English
    Publishing date 2022-04-11
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 165707-0
    ISSN 1868-8551 ; 1018-4562 ; 0946-7785
    ISSN (online) 1868-8551
    ISSN 1018-4562 ; 0946-7785
    DOI 10.14573/altex.2201141
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Reply to Comment on "Reduced specificity for the local lymph node assay for lipophilic chemicals: Implications for the validation of new approach methods for skin sensitization" by Roberts and Basketter.

    Natsch, Andreas / Kleinstreuer, Nicole / Asturiol, David

    Regulatory toxicology and pharmacology : RTP

    2023  Volume 140, Page(s) 105371

    MeSH term(s) Humans ; Local Lymph Node Assay ; Skin ; Dermatitis, Allergic Contact/etiology
    Language English
    Publishing date 2023-03-08
    Publishing country Netherlands
    Document type Letter ; Comment
    ZDB-ID 604672-1
    ISSN 1096-0295 ; 0273-2300
    ISSN (online) 1096-0295
    ISSN 0273-2300
    DOI 10.1016/j.yrtph.2023.105371
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: ECHA ARN documents: chemical grouping without a toxicological rationale.

    Natsch, Andreas / Adamsson, Greg / Rocha, Vanessa

    Archives of toxicology

    2023  Volume 97, Issue 5, Page(s) 1433–1437

    Abstract: The EU chemical strategy for sustainability (CSS) plans to use chemical grouping to "prioritise (…) substances for restrictions for all uses through grouping, instead of regulating them one by one". Thus, toxicological grouping will become a key tool ... ...

    Abstract The EU chemical strategy for sustainability (CSS) plans to use chemical grouping to "prioritise (…) substances for restrictions for all uses through grouping, instead of regulating them one by one". Thus, toxicological grouping will become a key tool used by regulatory authorities in Europe. Over the last 2 years, ECHA has published a high number of documents labelled "Assessment of Regulatory Needs (ARN)" which are based on groups of chemicals based on structural considerations. The ARN documents are legally non-binding, yet they present the public impression of a conclusion about restrictions for groups or sub-groups of chemicals and hence may set a precedent for further binding actions. ECHA has set out definitions on what is considered a group in REACH Annex XI. However, as shown in this commentary based on five examples, the ARN do not follow these principles and propose toxicological groupings without taking into consideration mode of action and the toxicological information on the chemicals. Given the emphasis on grouping projected by the CSS, the groupings in the ARN set an unfortunate precedent on what a toxicological group means and they do not follow clear scientific standards or established toxicological principles. They also lead to a public image of guilt by association for chemicals, without any recourse for registrants to establish the scientific basis for their safe use, as presented within REACH registrations.
    MeSH term(s) Europe ; Risk Assessment
    Language English
    Publishing date 2023-03-22
    Publishing country Germany
    Document type Letter
    ZDB-ID 124992-7
    ISSN 1432-0738 ; 0340-5761
    ISSN (online) 1432-0738
    ISSN 0340-5761
    DOI 10.1007/s00204-023-03479-3
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Reduced specificity for the local lymph node assay for lipophilic chemicals: Implications for the validation of new approach methods for skin sensitization.

    Natsch, Andreas / Kleinstreuer, Nicole / Asturiol, David

    Regulatory toxicology and pharmacology : RTP

    2023  Volume 138, Page(s) 105333

    Abstract: Meaningful and accurate reference data are crucial for the validation of New Approach Methodologies (NAMs) in toxicology. For skin sensitization, multiple reference datasets are available including human patch test data, guinea pig data and data from the ...

    Abstract Meaningful and accurate reference data are crucial for the validation of New Approach Methodologies (NAMs) in toxicology. For skin sensitization, multiple reference datasets are available including human patch test data, guinea pig data and data from the mouse local lymph node assay (LLNA). When assessed against the LLNA, a reduced sensitivity has been reported for in vitro and in chemico assays for lipophilic chemicals with a LogP ≥3.5, resulting in reliability restrictions within the h-CLAT OECD test guideline. Here we address the question of whether LLNA data are an appropriate reference for chemicals in this physicochemical range. Analysis of LLNA vs human reference data indicates that the false-discovery rate of the LLNA is significantly higher for chemicals with LogP ≥3.5. We present a mechanistic hypothesis whereby irritation caused by testing lipophilic chemicals at high test doses leads to unspecific cell proliferation. The accompanying analysis indicates that for lipophilic chemicals with negative calls in in vitro and in chemico assays, resorting to the LLNA is not necessarily a better option. These results indicate that the validation of NAMs in this particular LogP range should be based on a more holistic evaluation of the reference data and not solely upon LLNA data.
    MeSH term(s) Animals ; Mice ; Humans ; Guinea Pigs ; Local Lymph Node Assay ; Dermatitis, Allergic Contact/etiology ; Dermatitis, Allergic Contact/pathology ; Reproducibility of Results ; Skin ; Patch Tests ; Allergens/toxicity ; Lymph Nodes/pathology
    Chemical Substances Allergens
    Language English
    Publishing date 2023-01-03
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 604672-1
    ISSN 1096-0295 ; 0273-2300
    ISSN (online) 1096-0295
    ISSN 0273-2300
    DOI 10.1016/j.yrtph.2023.105333
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: What Makes Us Smell: The Biochemistry of Body Odour and the Design of New Deodorant Ingredients.

    Natsch, Andreas

    Chimia

    2015  Volume 69, Issue 7-8, Page(s) 414–420

    Abstract: Today, axilla odours are socially stigmatized and are targeted with deodorants and antiperspirants representing a multi-billion market. Axilla odours aren't simple byproducts of our metabolism but specifically formed by an intricate interplay between i) ... ...

    Abstract Today, axilla odours are socially stigmatized and are targeted with deodorants and antiperspirants representing a multi-billion market. Axilla odours aren't simple byproducts of our metabolism but specifically formed by an intricate interplay between i) specific glands, ii) secreted amino acid conjugates of highly specific odorants and iii) selective enzymes present in microorganisms colonizing our skin, providing a natural 'controlled-release' mechanism. Within a multidisciplinary research project, we were able to elucidate the structure of key body odorants, isolate and characterize secreted amino acid conjugates and identify the enzymes responsible for odour release. These enzymes then served as targets for the development of specific active compounds in an almost medicinal chemistry approach, an approach rarely used in the cosmetic field so far. Here we review the key new insights into the biochemistry of human body odour formation, with some remarks on the experimental steps undertaken and hurdles encountered. The development of deodorant actives and the difficult path to market for such specifically acting cosmetic actives is discussed. The basic insights into the biochemistry also opened the way to address some questions in population genetics: Why have large proportions of Asians lost the 'ability' to form body odours? Do twins smell the same? Are our typical body odours indeed influenced by the immune system as often claimed? After addressing these questions, I'll conclude with the key remaining challenges in this field on an ecological niche that is 'anatomically very close to our heart'.
    MeSH term(s) Chemistry, Pharmaceutical ; Deodorants/chemistry ; Deodorants/pharmacology ; Drug Design ; Humans ; Odorants/analysis ; Skin/chemistry ; Skin/metabolism ; Skin/microbiology
    Chemical Substances Deodorants
    Language English
    Publishing date 2015
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 1516-7
    ISSN 0009-4293
    ISSN 0009-4293
    DOI 10.2533/chimia.2015.414
    Database MEDical Literature Analysis and Retrieval System OnLINE

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