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XX Word Congress on Safety and Health at Work 2014 Symposium on Threshold Limit Values

XX Word Congress on Safety and Health at Work 2014 Symposium on Threshold Limit Values for Chemical Substances and Nanomaterials An Overview of Methods to Develop Occupational Exposure Limits in Europe Hermann M. Bolt

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XX Word Congress on Safety and Health at Work 2014 Symposium on Threshold Limit Values

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  1. XX Word Congress on Safety and Health at Work 2014 Symposium on Threshold Limit Values for Chemical Substances and Nanomaterials An Overview of Methods to Develop Occupational Exposure Limits in Europe Hermann M. Bolt Leibniz Research Centre for Working Environment and Human Factors, TU Dortmund (IfADo) Chair, Scientific Committee for Occupational Exposure Limits (SCOEL), Luxemburg WHO Collaborating Centrefor Occupational Health Aug. 25, 2014

  2. The Position of Scientific Advisory Bodies • The general discourse and interplay leading to OEL/BLV regulations is similar at national and EU levels: Political authorities Legislation on occupational standards Scientific experts Social partners: employers/industry, trade unions

  3. OELs and BLVs: Development of the SCOEL Mandate 1990: SEG established SCOEL strategy for carcinogens 1988 1989 1990 1995 1997 1980 2004 2007 Revision/extension of „Biological Monitoring“ EUR 19253“Methodology of derivation of OELs“ Commission Decision 95/320/EC  setting up SCOEL Council Directive 90/394/EEC  protection of workers to carcinogens Council Directive 89/391/EEC  introduction of measures/safety and health of workers Council Directive 88/642/EEC  amending the Directive of 1980 Council Directive 80/1107/EEC  protection of workers from the risk related to exposure to chemical, physical and biological agents at work

  4. Commission Decision (95/320/EC) of 12 July 1995, setting up a Scientific Committee for Occupational Exposure Limits to Chemical Agents (SCOEL) Article 2 (1) ... „The Committee shall in particular give advice on the setting of Occupational Exposure Limits (OELs) based on scientific data and, where appropriate, shall propose values which may include: • the eight-hour time-weighted average (TWA), • short-term limits/excursion limits (STEL), • biological limit values. The OELs may be supplemented, as appropriate, by further notations. The Committee shall advise on any absorption of the substance in question via other routes (such as skin and/or mucous membranes) which is likely to occur.“ Review: European aspects of standard setting in occupational hygiene and medicine. Rev.Environ.Health 16:81-86

  5. . „Indicative Values“vs. „Binding Values“ Two ways for the legal implementation of values • D 98/24/CE on chemical agents(indicative and binding values) • D2004/37/CEon carcinogens and mutagens (only binding) - IOELVs : Based on health criteria, derived from the assessment of updated and validated scientific data Below this exposure no adverse effects are expected. - BOELVs : Take also into account practical and socio-economical factors and the risk accepted by society They are considered “political-type” values*. * Political decision: to define “acceptable”versus“non-acceptable” risk

  6. Formal Procedures Development of limit values • Prioritisation of chemicals • Collection of existing data (by SCOEL members, contractor or JRC) • Evaluation of scientific data • Recommendation of limit value(s) • Scientific discussion (including 6 months consultation) and final recommendation (including analytical methods) • Consultation of social partners • Adoption (Commission/EP + Council) • Transposition (national) and use

  7. SCOEL’s Mandate • Scientific assessment to the EC ( D 95/320/CE) , especifically in relation to the legislation ( 98/24/CE + 2004/37/CE) foreseen to set occupational exposure limits (OELs) • Identification of available scientific data • Evaluation of the relationship exposure/effects • Recommendation of "OELs" : 8-h TWA, 15-min STEL, BLVs and “notations” (eg. skin absorption, sensitisation, carcinogen category) based on own methodology • Published recommendations (Aug. 2014) : 172

  8. Procedures Methodology • Evaluations on a “case by case“ basis • Recommendations with clear justifications (published on the EU website) • Critical effects and mechanisms of action, described as detailed as necessary • NOAEL and/or LOAEL, extrapolation model used, quantitative considerations in detail • Systematic update of key scientific factors and of criteria (e.g. carcinogenicity)

  9. Procedures Methodology • Developed by the Committee parallel to its work (started 1990 as SEG) • Published in 1999 and continuously updated since then • Includes criteria on: • General principles • Uncertainty factors • Time-weighted (8-hours) average values (TWA) • Short term exposure (generally 15min) levels (STEL) • Absorption through the skin • Toxicity to reproduction • Respiratory sensitisers • BLVs (Biological Limit Values) / BGVs (Biological Guidance Values) • Carcinogenic and mutagenic substances / risk assessment

  10. B:Situation not clear  LNT as default Dose-Effect Relations in the Low Dose Range and Risk Evaluation (Concept adopted by SCOEL – published in Archives of Toxicology 82: 61-64, 2008) Chemical carcinogen, causing tumours in humans and/or experimental animals Non-genotoxic Genotoxic DNA reactive, causing mutations Genotoxicity only on chromosome level (e.g. spindle, topoisomerase) Clearly DNA-reactive & initiating Weak genotoxin, secondary mecha- nisms important Borderline cases A:No threshold, LNT model to apply C:Practical/apparent thresholdlikely D:Perfect/statistical thresholdlikely Numerical risk assessment,  risk management procedures NOAEL  health-based exposure limits

  11. Groups of Carcinogens and Examples No threshold, LNT (Linear Non-Threshold) model to apply: A vinyl chloride / vinyl bromide (risk assessment)MDA dimethyl / diethyl sulfate1,3-butadiene (risk assessment) 12 LNT as „default assumption“: B • acrylonitrile benzene (provisional assignment)arsenic • naphthalene hexavalent chromium o-anisidine • 2,6-dimethylaniline (insuff. data)naphthalene 11 Practical/apparent threshold: C • formaldehyde vinyl acetate nitrobenzene pyridine silica lead (provisional OEL); lead chromateTRI DCM • Ni glyceryl trinitrate 10 Perfect/statistical threshold: D 4 carbon tetrachloride chloroform 1,4-dichlorobenzene Important distinction between B and C!

  12. Example for „C“: Vinyl acetate (SCOEL 2005/2006): Local metabolism: • Local tumours at the point of entry into the organsim • No systemic bioavailability upon inhalation

  13. Reasoning: Vinyl acetate, B or C ? • Local tumours in animals upon inhalation and oral dosing • Local hydrolysis to acetaldehyde and acetic acid • Local genotoxicity of acetaldehyde plus cytotoxicity by cell acidification (M. Bogdanffy, EUROTOX Budapest 2002) Argumentation by von SCOEL (2005) • Cell proliferation / irritation necessary for tumour developmpent • No evidence of systemic effects Group C: OEL = 5 ppm

  14. Example for „B“: Acrylonitrile • Carcinogenic in rats (oral and inhalation dosing) • Weak mutagen, but mutagenic epoxide metabolite Argumentation concerning brain tumours: • No DNA adducts in brain • Oxidative DNA damage in astrocytes in vitro • Reversible „gap junctions“ damage in exposed astrocytes • Dose-effect-curve sublinear • Genotoxicity in vivo not clear But: multi-organ carcinogen! Acute toxicity through cyanide metabolite ! Gruppe B; no health-based OEL

  15. Summary of the SCOEL Strategy for Carcinogens • The scientific development allows to identify carcinogens • with a threshold-type mode of action. For these compounds • health based OELs (and BLVs, where appropriate) can be • derived. • Such a mechanism-based assignment is independent of the • formal classification of carcinogens (i.e., former EU cate- • gories 1, 2 or 3, equivalent to GHS categories 1A, 1B, 2)! • When derivation of a health-based OEL/BLV is not possible, • SCOEL assesses the quantitative cancer risk, whenever • data are sufficient. • When data are not sufficient for a risk assessment, SCOEL • gives recommendations on possible strategies for risk • minimisation, if possible.

  16. Special SCOEL Topics (withsupportof JRC, Ispra) • Further development of biological monitoring • Sensitising compounds (diisocyanates and others) • PSLT = Poorly Soluble Low Toxicity („inert“) dusts • Nanomaterials and carbon nanotubes • Asbestos • Bitumen • Rubber industry and related compounds • Diesel exhaust • Aviation-related questions: aviation fuels, exhaust, oils and hydraulic fluids

  17. Biological Monitoring:13 Compoundswith BLVs / BGVs (Feb. 2014) Acrylamide (BGV), aniline, benzene, Be, Cd, carbon disulphide, N,N-dimethylformamide, 4,6-dinitro-o-cresol, 2-ethoxyethanol (and acetate), hexachlorobenzene, hydrogen fluoride / fluorides, lead compounds, including lead chromate

  18. Debate on Nanomaterials • EU definition: particlessized 1 - 100 nm • (Off J Eur Union L 275: 38-40) • Scientific discussion: increasingnumbersofpublications, conferences, • congresses (seeFoth et al. ArchToxicol 86:983-984, 2012) • Present SCOEL discussionpoints: • Toxicokinetics different fromthoseof larger materials. • Accumulation in cells / organs? • Cardiovasculareffects? • Effectthresholds? Aug. 25, 2014

  19. Nanomaterials Recent MAK Commission Report (DFG 2013) Open questions concerning measurement: aggregation, agglomeration, - relation to mass (mg/m3) not optimal! In principle similar effects of nanoparticles and microparticles, but quantitative differences (e.g. inflammation, oxidative stress, genotoxicity). Special problems in case of metal-based nanoparticles! Local / systemic effects? Definition of research needs Aug. 25, 2014

  20. Nanoparticles may have local and systemic effects Systemic effects not well investigated In discussion (SCOEL): • Transport via olfactoric nerve into CNS • Cardiovascular effects • Persistence in organs

  21. Experimental Rodent Studies withCarbonNanotubes Local inflammation effects in the lung N(L)OAEL: 0.1 mg/m3 Agglomerates! Aug. 24, 2014

  22. Carbon Nanotubes: Summary for SCOEL State of discussion: • Low localskinandeyetoxicity • CNT not sensitisingthemselves, but • amplifyingeffectpossible • Low experimental toxicity, but chronic • effects not wellinvestigated • Effects on foetusonly after i.v.dosing • Carcinogenicityandgenotoxicity ? Aug. 25, 2014

  23. Summary:Exposure Limits in Europe • Since 1990 SCOEL has developed a methodology to derive OELs. • SCOEL closely cooperates with national scientific OEL panels (especially MAK, DECOS, ANSES, Nordic Exports). • Continuous review of chemicals of key interest • Further development of biological monitoring • Establishment of a new procedure for carcinogens • Development of broader topics of key interest, partly on request by European official bodies (Commission, Parliament) • Current discourse with ECHA on coherence with REACH procedures, especially the derivation of „DNELs“vs. OELs

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