New Approach Methods (NAMs) in the sciencebased derivation of limit values – current and futureroleStatement of the DFG Permanent Senate Commission for theInvestigation of Health Hazards of Chemical Compounds inthe Work Area
Deutsche Forschungsgemeinschaft

Information Management

January 2023

Dr. Katja Hartig
Life Sciences – Medicine
Tel.: +49 (0)228 885-2359
E-mail: katja.hartig@dfg.de
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In recent years there has been increasing controversy at both national and international level
about the necessity and human relevance of animal experiments, as well as the possibilities
of dispensing with them entirely, also in connection with the derivation of limit values for hazardous substances. In some cases the view is expressed that animal experiments are alreadybeing replaced more or less completely by the use of so-called New Approach Methods(NAMs), or that this will happen in the near future. The MAK Commission cannot share thisassessment at this stage, as a quantitative risk assessment requires in vivo data from human
and/or animal studies that allow the identification of critical target organs, the consideration ofcomplex multiple effects as well as the quantitative identification of the lowest adverse effectconcentration. In fact, also NAMs include in vivo studies, studies on suitable cellular test systems and computer-based models. In all these areas, NAMs are capable of providing valuableadditional insights regarding the mode and mechanism of action and therefore to a sciencebased risk assessment. They can help minimise animal testing, but they cannot replace it entirely. This assessment will be elaborated in the following.
The central task of the MAK Commission is to derive limit values for the workplace. This is aquantitative risk assessment that usually requires epidemiological data, human volunteer studies and/or results from animal experiments. In addition, mechanistic data and information isrequired from short-term tests such as genotoxicity studies based on in vitro tests. In order tobe able to derive limit values, a very good data basis is required. If only insufficient substancespecific information is available, no MAK or BAT values can be established. In recent years,
NAMs have been increasingly developed and discussed that might usefully supplement andpossibly change existing toxicological risk assessments. In particular, promising possibilities
are offered by the joint consideration and use of the various NAMs and conceptual approaches
such as adverse outcome pathways (AOP).
Today, the term “NAMs” covers a broad spectrum of technologies and methods that are notnecessarily limited to in vitro or in silico (see for example US EPA, EFSA, ECHA):•

Computer-based identification of critical structural features, so-called in silico methods (e.g. QSAR and read-across).

•

In chemico methods (e.g. for the non-cell-based identification of reactive substanceswith potentially toxic properties).

•

In vitro tests: Cell-based systems of varying complexity (2D and 3D cultures, including cocultures, organoids and organ-on-chip systems), usually of human origin andavailable for different organs; broadband screening methods (omics, cell painting
methods); targeted high content screening (target molecules: receptors, enzymes).

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In vitro biokinetics: Modelling of the available intracellular concentration derived fromthe nominal concentration, taking into account various factors such as uptake by thecells, binding to proteins and lipids, and also binding to cell culture vessels and loss
through evaporation.

•

IVIVE (in vitro to in vivo extrapolation): Conversion of the available concentration
defined on an in vitro basis at which an adverse effect was observed to the corresponding human-equivalent concentration using physiologically-based kinetics(PBK) models. The human equivalent dose is referred to as the “point of departure”(POD) for the risk assessment.

•

Toxicological studies on “simple” organisms (e.g. zebrafish, fish embryo, C. elegans).

•

Use of in vitro studies and investigations on simple organisms for the validation ofread-across predictions.

•

Computer models: Integration of multiple in silico and in vitro data streams using
available databases (data integration approaches and AI).

It must be taken into account here that the establishment of some test systems such as organoids and organ-on-chip systems is highly complex; despite intensive research activity, standardisation and validation of the systems currently remain very difficult.
What potential is offered by the increased development and establishment of NAMs atpresent and in the future?
One particular potential offered by NAMs is in the area of identifying the toxic properties of a
substance (hazard). For example, different test methods can be used to describe so-calledmolecular initiating (MI) and subsequent key events (KE) in AOPs. Mechanistic knowledge ofthe mode of action of a chemical has always been considered in the derivation of maximum
workplace concentrations, and NAMs can provide a wealth of information and data to supplement this knowledge. Such substance information could be used in connection with the socalled read-across process, for example, in the risk assessment of related chemicals where
insufficient substance-specific data are available for the respective chemicals in question. This
procedure is already used in individual cases and could be significantly expanded in the future
if the data base were broader and this data were made available on a curated basis.
Another aspect that is currently the subject of intense debate, also in connection with the EU’s
new chemicals strategy, is the aspect of Safe and Sustainable by Design. In concrete terms,
this means that toxicological aspects are considered even before new chemicals are placedon the market or new materials are designed, taking into account the entire life cycle of therelevant products. Comparable to the detection of mutagenic effects using the Ames test, particularly critical properties could be identified at an early stage in this way, and the relevant
chemicals or materials replaced with toxicologically less critical substances or components.
Such procedures are already routinely used in the chemical and pharmaceutical industry, forexample to exclude substances with questionable toxicological profiles in the early phase ofactive substance development.
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In recent years, considerable progress has also been made in the field of so-called omics
methods, which are used to assess complex biological reactions of chemicals and which canbe used to establish toxicity profiles and further elucidate mechanisms of action; these are
already successfully applied when it comes to determining the comparative properties of nanomaterials. Omics methods are also valuable tools to provide more in-depth information on
animal experiments, e.g. by means of transcriptome or proteome studies at the single cell andtissue level or using ex vivo tissue sections. A prerequisite for the optimum use of the results
is good accessibility and usability of the relevant data; one example is the ToxCast/Tox21
Dashboard database which is operated by the US Environmental Protection Agency (US EPA).
All in all, the establishment of NAMs is a very dynamic process and it can be expected thatnumerous methods will be refined in future; in addition to hazard considerations, (a) toxicokinetic aspects will be increasingly incorporated, and (b) further approaches for quantifying doseresponse relationships will be generated in the area of in vitro methods. NAMs already makea significant contribution to the so-called 3Rs principle in animal experiments, the objective of
which is to replace such experiments (Replacement), reduce the number of animals (Reduction) and reduce the suffering of the animals (Refinement) to a level that is strictly necessary.
How are these methods already included in the assessments, limit value derivations
and classifications carried out by the MAK Commission?
The general prerequisite and starting point for the derivation of limit values is the identificationof the most sensitive toxicological endpoint in vivo, i.e. in humans or in animal experiments,
providing the results from animal experiments are plausibly transferable to humans. This includes both the toxic properties of a substance (hazard) and the risk, which also takes into
account the reaching of critical concentrations in the target organ. Possible interspecies differences in toxicokinetics and dynamics are likewise considered here. The MAK Commission
already uses additional data from NAMs – where available – in order to assess the relevant
substances as comprehensively as possible. For several years now, data from so-called PBPK(Physiologically-Based Pharmacokinetic) models have been used for individual substances toanalyse internal exposure to the toxic substance, taking into account physiological and biochemical differences between species. For example, for the assignment of the pregnancy
group of acetone, the main metabolite of 2-propanol, a PBPK model has been applied to estimate the internal exposure for foetuses based on comparative analyses between the parent
substance 2-propanol and its metabolite acetone. Conversely, based on internal exposure andthe relevant modelling, an air limit value for lead and its inorganic compounds was recently
derived at which the critical internal exposure for the majority of workers (95th percentile) is
not exceeded.
Another example is the use of ToxCast/Tox21 Dashboard data provided by the US EPA toestablish the hazards and for the use of AOPs of individual substances. These data provide
information on a wide variety of receptor interactions that may indicate an endocrine or livertoxic effect, for example. Furthermore, it is foreseeable that promising NAMs will develop in
the relevant areas/endpoints of “sensory irritation” and neurotoxicity testing. Such data haveso far only been used to clarify or confirm mechanisms of action, however. Exceptions here
are cosmetics, where animal testing is no longer permitted for toxicological assessment of theingredients and the product; animal testing is now also being largely replaced in the identification of sensitising effects. In all other areas, quantitative in vitro to in vivo extrapolation
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(QIVIVE) will gain in importance particularly in connection with future developments towards
animal-free in vitro and in silico methods. These models should make it possible to use in vitro
data to simulate concentrations in plasma or in specific target organs/tissues of an organismand estimate at which dosages effective in vitro concentrations are reached in vivo.
All in all, the MAK Commission engages very closely with the current possibilities offered byusing NAMs and also conceptually with future application possibilities; for this purpose, highranking international researchers have been involved in recent years to report on and discuss
the current status of possibilities and limitations in the use of NAMs. Focus areas here haveincluded the possibilities of omics methods to differentiate between genotoxic and non-genotoxic activities of chemicals, and the usefulness of information from the ToxCast/Tox21 Dashboard to assess the hazard potential of chemicals.
Several members of the MAK Commission are actively involved in the development and establishment of NAMs to address specific questions, for example concerning comparative toxicity profiles for nanomaterials, the establishment of test systems for neurotoxicity, sensory
irritation effects and sensitising effects, as well as for the application of an in vitro test battery
for developmental neurotoxicity in the regulation of plant protection products.
It is highly likely that a sensible combination of these methods will lead to a situation in the
future where, for example, effective read-across limit values can be established for many more
substances. At all levels, however, traditional toxicological data are currently still used as training sets to validate NAMs. One of the greatest difficulties of NAMs at present is the quantitative
extrapolation of in vitro to in vivo. There are also challenges involved in comparing in vivo
rodent studies with in vitro studies that are mainly based on human cell systems. In addition,
there are uncertainties in the assessment of combined test systems and the definition of therelevant and sufficient extent of testing. For this reason, integrated testing strategies have only
been presented for a small number of toxicological endpoints such as skin sensitisation andirritation. In terms of developmental neurotoxicity, too, the in vitro test battery was used by the
EFSA in a case study in the context of IATA (Integrated Approaches for Testing and Assessment). Nonetheless, the objective of a comprehensive assessment of new, toxicologically still
poorly investigated substances, especially for endpoints such as chronic toxicity, reproductive
toxicity and carcinogenicity, is still a long way off.
In summary, from the point of view of the MAK Commission, the establishment of NAMs iscurrently – and probably in the near future, too – not yet far enough advanced to be usedreliably on their own for the purpose of quantitative risk assessment and limit value derivation,
replacing animal testing entirely, for example. There is still a considerable need for research
here, including both the establishment of suitable test systems and their validation. However,NAMs already offer a useful and valuable supplement to the more conventional toxicologicalresearch methods in some areas.

Statements from other organisations:
EPA: USEPA (2021) New Approach Methods Work Plan (v2). U.S. Environmental Protection
Agency, Washington, DC. EPA/600/X-21/209
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ECHA: European Chemicals Agency (2016) New Approach Methodologies in Regulatory Science; Proceedings of a scientific workshop, Helsinki, 19-20 April 2016. ECHA-16-R-21-EN.
https://doi.org/10.2823/543644
EFSA: Escher SE, Partosch F, Konzok S, Jennings P, Luijten M, Kienhuis A, de Leeuw V,
Reuss R, Lindemann K-M, Hougaard Bennekou S (2022) Development of a Roadmap for Action on New Approach Methodologies in Risk Assessment. EFSA Supporting publication 2022:
EN-7341. https://doi.org/10.2903/sp.efsa.2022.EN-7341
IARC: Samet JM, Chiu WA, Cogliano V, Jinot J, Kriebel D, Lunn RM, Beland FA, Bero L,
Browne P, Fritschi L, Kanno J, Lachenmeier DW, Lan Q, Lasfargues G, Le Curieux F, Peters
S, Shubat P, Sone H, White MC, Williamson J, Yakubovskaya M, Siemiatycki J, White PA,
Guyton KZ, Schubauer-Berigan MK, Hall AL, Grosse Y, Bouvard V, Benbrahim-Tallaa L, El
Ghissassi F, Lauby-Secretan B, Armstrong B, Saracci R, Zavadil J, Straif K, Wild CP (2020)
The IARC Monographs: Updated Procedures for Modern and Transparent Evidence Synthesis
inCancerHazardIdentification.
J
NatlCancerInst
112:
30–37.
https://doi.org/10.1093/jnci/djz169

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Commission Membership
Members of the Commission
Professor Dr. Andrea Hartwig (Chair), Karlsruhe Institute of Technology (KIT), Institute of Applied Biosciences, Department of Food Chemistry and Toxicology
Professor Dr. Michael Arand, University of Zurich, Institute of Pharmacology and Toxicology
Professor Dr. Michael Bader, BASF SE, Corporate Health Management, Ludwigshafen
Professor Dr. Brunhilde Blömeke, Trier University, Department of Environmental Toxicology
Professor Dr. Thomas Brüning, Institute for Prevention and Occupational Medicine of the German Social Accident Insurance of the Ruhr University Bochum (IPA)
Professor Dr. Hans Drexler (Vice-Chair), Friedrich-Alexander-Universität Erlangen-Nürnberg,
Institute and Polyclinic for Occupational, Social and Environmental Medicine
Professor Dr. Bernd Epe, Johannes Gutenberg University Mainz, Institute of Pharmacy andBiochemistry
Professor Dr. Manigé Fartasch, Institute for Prevention and Occupational Medicine of the German Social Accident Insurance of the Institute of the Ruhr University Bochum (IPA)
Professor Dr. med. Ellen Fritsche, IUF – Leibniz Research Institute for Environmental Medicine
Research gGmbH
Professor Dr. Thomas Göen, Friedrich-Alexander Universität Erlangen-Nuremberg, Instituteand Polyclinic of Occupational, Social and Environmental Medicine
Private lecturer Dr. rer. nat. Andrea Haase, German Federal Institute for Risk Assessment(BfR), Department 7: Chemical and Product Safety, Division 76: Fibre and Nanotoxicology
Professor Dr. Ernst Hallier, University of Göttingen, Institute of Industrial, Social and Environmental Medicine
Professor Dr. Uwe Heinrich, Fraunhofer Institute for Toxicology and Experimental Medicine(ITEM), Hanover
Professor Dr. med. Susanne Valerie Herold, University of Gießen, Department 11: Medicine
Dr. rer. nat. Heiko Udo Käfferlein, Institute for Prevention and Occupational Medicine of theGerman Social Accident Insurance of the Institute of the Ruhr University Bochum (IPA)
Dr. Edgar Leibold, BASF SE, FEP/P Department, Ludwigshafen
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Professor Dr. Gabriele Leng, Currenta GmbH & Co. OHG, Safety-Health Protection – Instituteof Biomonitoring, Leverkusen
Professor Dr. Bernhard Michalke, Helmholtz Munich, German Research Center for Environmental Health GmbH, Department of Analytical Biogeochemistry, Neuherberg
Private lecturer Dr. Frauke Neff, Städtisches Klinikum München GmbH, Medizet – Medical
Service Centre, Department of Pathology
Professor Dr. Dennis Nowak, University Hospital Munich, Institute and Polyclinic for Occupational, Social and Environmental Medicine
Dr. Dirk Pallapies, Institute for Prevention and Occupational Medicine of the German Social
Accident Insurance of Ruhr University Bochum (IPA)
Professor Dr. rer. nat. Lothar Rink, Uniklinik RWTH Aachen, AöR, Department of Immunology
Private lecturer Dr. rer. nat. Bernd Roßbach, University Medicine of the Johannes Gutenberg
University Mainz, Institute of Occupational, Social and Environmental Medicine
Dr. Roel Schins, Leibniz Research Institute for Environmental Medicine, Düsseldorf
Professor Dr. Simone Schmitz-Spanke, Friedrich-Alexander-Universität Erlangen-Nürnberg,
Institute and Polyclinic for Occupational, Social and Environmental Medicine
Professor Dr. rer. nat. Nicole Schupp, University Hospital of Düsseldorf, Institute of Toxicology
Professor Dr. Michael Schwarz, University of Tübingen, Institute of Experimental and Clinical,
Pharmacology and Toxicology, Tübingen
Professor Dr. med. Andreas Seidler, Dresden University of Technology, Carl Gustav Carus
Medical Faculty, Institute and Polyclinic for Occupational and Social Medicine (IPAS)
Professor Dr. med. Kurt Straif, ISGlobal – Campus Mar, Barcelona Biomedical Research Park,
Doctor Aiguader 88, 08003 Barcelona
Private lecturer Dr. Christoph van Thriel, Leibniz Research Centre for Working Environmentand Human Factors at TU Dortmund
Professor Dr. Wolfgang Uter, Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute ofMedical Informatics, Biometry and Epidemiology
Professor Dr. Dirk Walter, Universitätsklinikum Giessen und Marburg GmbH, Institute and Polyclinic for Occupational and Social Medicine, Gießen
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Permanent guests of the Commission
Dr. med. Maren Beth-Hübner, Berufsgenossenschaft Rohstoffe und chemische Industrie (BG
RCI), Competence Centre Hazardous Substances and Biological Agents, Heidelberg
Professor Dr. Dietmar Breuer, Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA), Department 2: Chemical and Biological Impacts, Sankt Augustin
Dr. Ralph Hebisch, Federal Institute for Occupational Safety and Health (BAuA), Department
4 – Hazardous Substances and Biological Agents, Group 4.4 – Hazardous Substance Measurements, Dortmund
Dr. Agnes Schulte, German Federal Institute for Risk Assessment (BfR), Berlin

The statement was prepared with the support of the Senate Commission’s Scientific
Secretariat.

Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area

Working Group “Quality in Clinical Research”
Members of the Working Group
Professor Dr. Bernd Fleischmann, Bonn (Chair)
Professor Dr. Christopher Baum, Hanover
Professor Dr. Klaus-Michael Debatin, Ulm
Professor Dr. Simone Fulda, Frankfurt
Professor Dr. Wolfgang Herr, Regensburg
Professor Dr. Andreas Meyer-Lindenberg, Mannheim
Professor Dr. Georg Peters, Münster
Professor Dr. Esther von Stebut-Borschitz, Mainz
Dr. Frank Wissing, Berlin
Guests of the Working Group
Professor Julia Fischer, Göttingen
DeutscheForschungsgemeinschaft
Professor
Dr. Michael Sendtner,(DFG)
WürzburgGermanResearch
Foundation
Professor Brunna Tuschen-Caffier, Freiburg
Kennedyallee
53175
Bonn
Professor40,
Onur
Güntürkün,
BochumPostal address: 53170 Bonn, Germany
Professor Roland Lill, Marburg
Tel.: + 49 (0)228 885-1
Fax: + 49 (0)228 885-2777
DFG Head Officepostmaster@dfg.de
Dr. Katja Hartig, Bonnwww.dfg.de/en

Dr. Britta Mädge, Bonn
Dr. Tanja Kollei, Bonn
The SCCR’s Scientific Secretariat
Corina Schnabel M.A., Freiburg

This statement is supported and endorsed by the DFG Senate Commission on Animal Protection and Experimentation.