Web links, documents and free of charge tools

The documents and tools listed below support a qualitative and quantitative, occupational exposure risk assessment.
They are grouped in the following Click-and-go headers:
1. Exposure assessment and compliance testing strategies
2. Sampling and analytical methods
3. Exposure databases
4. Occupational Exposure Limit Values (OELV)
5. Exceedance and Compliance
---5.3 App's for (log)normal compliance testing
6. Distributional fit and exposure variability
7. Compliance for mixtures
8. Exposure modeling
9. Chemical identification, physchem properties and hazard information.

For Specific Dutch tools click here (in het Nederlands).

1. Exposure assessment and compliance testing strategies
Not free of charge, but recognized standards are:

In addition the following public available, free of charge documents can be used:
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2. Sampling and analytical methods
Free of charge sources with measurement methods are: 3. Exposure databases
For prior knowledge on substance workplace air exposures (raw and aggregated data), consult:

Public and private occupational Exposure Databases may be based on the US and EU guidelines on core information for workplace exposure measurements on chemical agents, which made it possible to construct exposure distributions per SEG.

4. Occupational Exposure Limits Values (OELV)
An employer needs to have an OELV for all chemicals to which workers are exposed at the premises or under his responsibility.
As a license to operate, a reference value to assess workers health risk and for legal compliance.

4.1. Finding the best suitable Public or Private OELV
There are (too) many organisations around the world that provide public and private OELV's
Legal limits (national or federal) established by government are called public. All other OELV's are called private. There are several registers (printed, on- and offline database applications) that give overviews of international OELV's based on their network or what they can find, for example:

OELV's differ in goal and quality and should therefore be chosen carefully.
In the paragraphs below the OELV sources are grouped according to the hierarchy of reliability.

4.1.1 Unbiased health based only OELV's
"Health based only" means that no political, socioeconomic, corporate or technical feasibility factors have influenced the value (level & duration). Unbiased means at or close to the real workers no-effect/no-response level for long-term shift exposure levels. OELV's published before 1997 may suffer from limited quality control and transparency. The web sites below contain several hundreds of OELV documents often, however, on the same chemical substances. The OELV's proposed for the same chemical substances may differ in value, reflecting differences in scientific sources used, different hazard assessment techniques (i.e. safety factors used) and differences in hazard and health risk perception. Compliance with these limits may safeguard the employer from liability for health claims. 4.1.2 Health/Toxicology based
For the OELV's below the independency from interest groups and/or unbiased science is not guaranteed.

4.1.3 Regulatory OELV's in the EU
Most countries within and outside the EU have regulatory limits. Exceeding the legal OELV may lead to a law enforcement penalty. See 5.1.
The GESTIS database provides insight in the range of regulatory OELV's that are used in different EU countries .
Gestis does not indicate if technical and/or economical feasibility is included in the national OELV's
One should be aware that if socio-economical feasibility has lead to a legal level exceeding the unbiased health based level, then legal non-exceedance prevents a penalty but may not safeguard the employer from liability if the exposure distribution (See 5.2 and 5.3) is not in compliance with the health based OELV.

  • EU Binding occupational exposure Limit Values.
  • EU Indicative Occupational Limits Values. adopted as regulatory limits in most EU countries.
  • Germany TRGS 900.
  • UK EH40/2005 Workplace exposure limits. Table 1 WEL (air). Table 2: Biological monitoring guidance values (BMGV's)
  • France valeurs limites d'exposition professionnelle (VLEP) indicative (VL), binding indicative (VRI) or binding restricted (=réglementaires contraignantes) (VRC).
  • Netherlands Cumulative list of legal limits (in Dutch)
  • Belgium KB Chemical agents.
  • Italy legislation for OELV.
  • Norway Limit values.
  • Sweden OELV's.

  • 4.1.4 USA federal OELV's
  • OHSA-PEL The federal OELV's. Different states like Texas and California have there own OELV's.

    4.1.5 Kick-off
    The sources in 4.1.1 through 4.1.4 disclose OELV's of the more data-rich substances.
    Many substances lack sufficient and relevant high quality human health & toxicology data.
    If, however, GHS or CLP health H3##-statements are known, then Kick-off levels can be established.
    H3##-statements to derive a Kick-off can be found in the ECHA database with hazard classification and labeling information for all harmonized (6000) and notified (>100,000) dangerous substances in the EU.
    Kick-off levels are used as a conservative starting point for compliance testing.

    4.2 Guidance to deduce kickoff or OELV's
    Although many tens of thousands of suitable OELV's or kickoff's can be found with the hierarchical approach described in 4.1, there are still substances without a public OELV or GHS/CLP health hazard classifications.
    Theo following documents may help to fill this gap

    NIOSH Occupational Exposure Banding
    The NIOSH Occupational Exposure Banding process and its e-Tool offers a framework to apply toxicology and potency information to generate quantitative exposure levels in a tiered approach. Not surprisingly the tiered approach is comparable to However the NIOSH document does indicate how and where to find the GHS and toxicological information
  • The following tools will help you to establish a limit value if an OELV is not established but health hazard information is available

    Paul Scheepers, associate professor Health Evidence at the RadboutUMC Nijmegen (the Netherlands), developed a structural search tool of human health toxicity data for chemical substances.
    The flow chart of Patchwork 2.8 (2022) guides you through the free accessible online scientific databases.

    Kickoff levels can be derived based on existing GHS classification For higher hierarchy OELV scientific literature needs to be screened and evaluated.

    ECETOC Data-poor substances guidance
    A guidance for setting occupational exposure limits for data-poor substances has been developed by ECETOC, see TR-101

    Characterisation of dose [concentration] - response for human health (Chapter R.8 2012) DN/MEL's
    Appendix to Chapter R8 (2019) Characterisation of dose [concentration] - response for human health: RAC Occupational exposure limits
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    5. Compliance and exceedance
    In some countries, workplace air exposure exceeedance can be controlled through single sample exceedance tests.
    In Europe compliance control is performed using hybrid decision schemes or SEG exposure distribution compliance testing by the employers them selves or by social security sponsored institutes like INRS (Fr) and IFA (Ge).

    5.1 Single sample Exceedance test
    Most working conditions legislation worldwide demands 'immediate action' if exposure exceeds a legal OELV.
    Exceedance leads in some countries to penalties if established by law enforcement.
    As with speed traps, comparing a single workplace air measurement with the OELV must be adjusted for sampling and analytical error (OSHA OTM Section II: Chapter 1, IV. Post-Inspection Activities, D. Receive sample results, 3.Calculations for Full-Period, Continuous Single Samples).
    See also the compliance officer test.

    Measurement uncertainty
    To include measurement uncertainty in OELV exceedance testing and the EN689 preliminary test, several standards are available

  • The EN 689 states that the workplace air measurement procedures shall comply with EN482 that limits the relative expanded uncertainty for the measurement range around to the OELV.
  • ISO 22065 and the downloadable IFA Excel application helps to calculate the expanded measurement uncertainty for gasses and vapors.
  • NPR-CEN/TR 17055:2017.describes how the measuring procedures for chemical agents complying with the requirements given in EN 482 and either one of EN 838, EN 13890, EN 13936 and/or the EN 13205 series, as far as applicable, have been chosen.
    NPR-CEN/TR 17055:2017 also lists additional sources for 2. Sampling and analytical methods

  • Other standards on measurement uncertainty in workplace air sampling
  • The updated GUM 98: ISO - ISO/IEC Guide 98-3:2008 - Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement. Based on JCGM 100
  • for Dutch labs NEN 7779:2018 'Environment, food and feed - Measurement uncertainty' applies for chemical substances in workplace air as well.
  • NIOSH 77-173 table D-1 displays CVt for a large number of substance measurement methods
  • OSHA calculates the upper and lower confidence in the same way as NIOSH 77-173, but does not provide which methods the Salt Lake Technical Center (SLTC) uses to establish the sampling and analytical error (SAE).
  • Measurement uncertainty of equipment to calibrate the flow of the pumps according to EA-4/02

    5.2 Hybrid decision schemes
    The EN689 'preliminary test' (clause 5.5.2)
    The new EN689:2018 introduces a 'preliminary test' (clause 5.5.2) that compares the maximum value of three to five PAS workplace air measurements with the OELV and with a fraction (0.1 to 0.2) of the OELV.
    For the comparison of the maximum value with the OELV measurement uncertainty should be taken into account in the same way as in compliance officer test. (see 5.1 Single measurement Exceedance)
    This is, however, not described in the standard. Decision scheme aim to test compliance with the OELV without using a mathematical statistical distribution adjusting for the day-by-day exposure distribution. The EN689 preliminary test is a modification of the French test which is partly validated by INRS.
    The Hybrid decision schemes (including the BOHS/NVvA screening test and the French Code de Travail Annexe 1.1.2 Demarché de control) are not only inaccurate, they are also ineffective. They delay a compliance decision unnecessarily and are more expensive compared to the (log)normal statistical test as they demand in most cases more measurements. The decision schemes also underestimates workers' health risk and delays necessary control measures for GSD>6.

    5.3 SEG exposure distribution based statistical compliance testing
    Since the introduction of HYGINIST at the AIHCe 1990 in Anaheim, several app's are developed that establish the long-term shift exposure of employees in a SEG and the confidence/credibility that exposure complies with the OELV (see the limited list below)
    Distribution based statistical tests can be applied on 2 or more, strategically well performed PAS measurements.
    Some tools are fit for both the EN689 C95%,70% and the AIHA's C95% exposure categories. HYGINIST and IHStat-Bayes provide practically the same results, although they use quite different numerical methods. IHDA-AIHA results are also comparable as long as the GSD in parameter space boundary is maximised at four.

    App's for (log)normal SEG exposure distribution compliance testing 6. Distributional fit and exposure variability
    Based on observations in different countries and many situations (Oldham UK 1953, Coenen GE 1966, Leidel US 1977) it is widely accepted that the body of a workplace air exposure distribution is well represented by the lognormal distribution, if exposure variability is influenced by the multiplicative interactions of workplace factors.
    In the tails of the exposure distribution (<5% or >95%) the (log)normal shape may not fit due to systemic or random measurement uncertainty or since statistical probabilities can predict non-existing or non-realistic concentrations.
    For example: concentrations that exceed physicochemical limitations like maximum dustiness for airborn solids, the atmospheric pressure for a gas or the saturation concentration for vapours.
    A normal distribution may appear in constant workplace conditions, with high control of workplace factors or if the influence of workplace factors is outshined by the background concentration or the random variation in the measuring procedure.
    In these cases the day-by-day exposure variability is so small that the differences between the normal or lognormal C95% are negligible.

    The sample Geometric Standard Deviation (GSD) is the lognormal descriptive statistic for the variability (=dispersion) of the exposure data.
    The GSD is:
  • the antilog (=EXP) of the standard deviation (s) of the logarithms of the results EXP(s)
  • the unbiased estimator of the population GSD [EXP(σ)] with minimum variance. This means the most efficient estimator with an expectation equal to the population EXP(σ). And this means in simple wording that the GSD equals EXP(σ) on the average for every sample size.
  • by definition larger than one plus the analytical coefficient of variation (1+CVt) (NIOSH 77-173 p124) .
  • considered to be an intrisic property for every substance/Similar Exposure Group(SEG) combination, or its REACH equivalent the workers task/activity Contributing Scenario (t-CS).

  • The numerical value of population GSD [EXP(σ)] of a substance air exposure distribution in a SEG/t-CS depends on workplace factors in the exposure profile like :
  • the the number of different tasks/handlings included and sequentially performed during the observation period (task, shift and/or the working week),
  • in- or outdoor,
  • industrial or professional setting
  • technical and organisational risk management measures (ventilation, instruction etc),

  • But also on:
  • the way workers do their job (between worker differences),
  • Space-time factors like global positioning and altitude, local climat and its variability througout the year.

    Reliable EXP(σ) per SEG/t-CS may be retrieved from the institutional databases [see 3. Exposure databases], as they are based on guidelines on core information for workplace exposure measurements on chemical agents
    GSD's of well defined SEG/t-CS's are also published in peer review, scientific journals. Two leading articles are:
  • Kromhout and Rappaport (1993 table 6). The median (50%-tile) GSD's found for different production factors within single workplace SEGs range between 1.7 and 3.6 .
  • Tielemans (2008) established reasonable worst case (RWC) total variances (σ2) in well defined, but multiple workplace SEGs using a relative small but high quality database, corresponding with a GSD=5.4 for solids and GSD=8.2 for liquids
    These GSDs may even be too low as 0.5*LOD was used for the non-detectables up to 25%.
    TWA8 hours PAS measurements of SEG's in modern chemical industry using well performed sampling plans and regression statistical analysis for non-detects show GSD's up to 14. See BOHS Conference 2013, GSDs in the real world and The distribution of long-term GSD's in chemical industry SEG's (in Dutch , English summary).

    AIHA's IHStat states that GSD>3 indicates "process out of control or poorly defined groups". Low GSDs are to be expected in:
  • highly controlled indoor workplaces, clean rooms etc.
  • REACH t-CS, assessing a single combination of Operational Conditions (OC) and Risk Management Measures (RMM) in industrial use
  • SEG's of workers performing only a single-task at a fixed workplace
  • workplaces with a relatively high constant background that camouflage all spatial and temporal variability of workers activity

  • So in a clean room and other situations where one would expect a GSD at or just above 1+CVt, higher GSDs may indicate suboptimal controls or bad technical sampling and/or laboratory handling.

    GSD<1.5 in other situations then mentioned above may indicate "poor sampling strategy" or "poor data handling" in example by:
  • small sample size underestimating the GSD
  • short sampling campaigns with measurements only on one or a few consecutive days (auto-correlation)
  • sloppy handling of non-detectables
  • 2-decades analytical detection methods (like gravimetric dust and inorganic acid)
  • using EM in stead of PAS
    The resistance against high GSDs in IHStat may also be caused by the bad performance of the two noncompliance statistics with GSD>3 and sample size <6.

    Low GSDs occured in the ancient industrial hygiene era:
  • when workers in process industry and assembly lines performed a single task during a whole shift,
  • with high background levels camouflaging the variability of workers activity,
  • when sampling techniques were insensitive, and
  • when officers in charge forbid their industrial hygiene sergeants to report GSD>2.
    EN 689 (2018) supports a preliminary test in 5.5.2 for sample size 3,4 and 5. Its use is justified by the INRS document ND 2231. The document shows that the use of the preliminay test is only justified for GSDs below 3-4.

    Industrial Hygienist are advised, before testing compliance, to compare the GSD found with an expected value, using:
  • measurement series performed before
  • GSDs reported in literature or if possible in large exposure databases
  • Read across with comparable substances and workplaces
  • Modeling, if possible
  • Physical-Chemical properties

  • Tools to calculate and compare GSD's, and to test the Lognormal goodness-of-fit can be found in 5. Compliance testing statistical tools
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    7. Compliance for mixtures
    There are several methods for compliance testing of mixtures in the workplace air: The three methods above imply, that the appraiser samples all components in the mixture. Another approach for vapors with comparable effects is to select the most critical component (based on the saturation concentration and the OELV) and to adjust its OELV to the composition of the mixture in the air. XLUNIFAC is the method of preference. The methods above do not include synergy or antagonism, the phenomena that the toxicokinetics and/or -dynamics of the health effects change due to the interaction of the components in the mixed exposures
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    8. Exposure modeling
  • TREXMO (TRanslation of EXposure MOdels) integrates six commonly used occupational exposure models: ART v.1.5, STOFFENMANAGER® v.5.1, ECETOC TRA v.3, MEASE v.1.02.01, EMKG-EXPO-TOOL and EASE v.2.0.
  • AIHA Tools and Links for Exposure Assessment Strategies
  • Chesar
  • Advanced REACH Tool
  • Stoffenmanager
  • SkinPerm Estimates the flux and the quantity penetrating the skin from the air or from a liquid/solution in contact with the skin
  • UPERCUT A hazard identification tool for toxic risk following dermal penetration of chemicals
  • Seirich Un outil pour évaluer et prévenir les risques chimiques de travail
  • IndusChemFate
  • EPA ExpoBox (A Toolbox for Exposure Assessors)
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    9. Chemical identification, physchem properties and hazard information
    ECHA's Information on Chemicals with the REACH and CLP information on >200,000 substances used in the EU. Check every EU Safety Data Sheet (SDS) or the harmonized classification information using this site on recent changes
    GESTIS-database with nearly 10,000 substances, including information on occupational chemical loads without an EU SDS obligation, like welding fumes or wood dust
    IARC Monographs Evaluation of Carcinogenic Risk to Humans
    Health Council of the Netherlands Evaluation of the carcinogenity, genotoxicity and reprotoxicity, including non-REACH substances
    Dohsbase contains substance identity information of >260,000 chemicals, health hazard information of 110,000 and physchem information of 40,000 substances
    NIOSH Pocket Guide to Chemical Hazards
    Safe work Australia

    Useful free of charge physchem online databases are:
    eChemPortal. A public web site with information on chemical properties. ECHA is a key collaborator in the development of the OECD physchem software and hosting
    PubChem the open chemistry database at the National Institutes of Health (NIH).
    Accessing ChemIDplus Content from PubChem. ChemIDplus content is being migrated to PubChem.
    NIST Chemistry WebBook. The US National Institute of Standards and Technology (NIST)
    ChemView . Information on chemical health and safety data received by EPA and EPA's assessments and regulatory actions for specific chemicals
    FatePointer . The US SCR Syrres subsstance properties databases
    EPI Suite is not only a large database with measured physchem data but also with physchem estimates based on the SMILES code.
    ToxCast™ Data Chemical details for 8,599 unique substances (GSIDs) and DSSTox standard chemical fields (chemical name, CASRN, structure, etc) for EPA ToxCast chemicals and the larger Tox21 chemical list
    ChemBioFinder.com The CambridgeSoft chemistry and biology reference database

    Useful free of charge toxicological databases are
    ATSDR Toxic Substances Portal

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    Specifiek Nederlands
    Zelfinspectie I-SZW. In vier stappen beoordelen of uw bedrijf gezond en veilig werkt met gevaarlijke stoffen volgens de Arbeidsinspectie
    Databank Grenswaarden Stoffen op de Werkplek van de Social Economische Raad (SER-GSW) met Europese werkplek atmosfeer grenswaarden en REACH DNELs.
    DOHSBase Database met het grootste en hierarchisch opgebouwd bestand aan grenswaarden en meetmethoden
    AI interne instructie (2007). Beoordeling van de blootstelling aan gevaarlijke stoffen en het toetsen van de meetresultaten aan luchtgrenswaarden
    Kennisdossier Gevaarlijke Stoffen Tot stand gekomen door multidisciplinaire samenwerking tussen de beroepsverenigingen van arbeids- en organisatiedeskundigen, bedrijfsartsen, arbeidshygiënisten en veiligheidskundigen

    NVvA en Arbo-pagina
    Wil je meer weten over de Arbeidshygiëne in Nederland dan zoek dan op de webstee van de Nederlandse Vereniging voor Arbeidshygiëne. Voor Arbo in het algemeen is er de Startpagina dochter Arbo

    De website van de Belgische Arbeidshygiene vereniging BSOH ontsluit een groot aantal pratische tools

    Bij de beoordeling van de blootstelling is voor veel stoffen de bijdrage van de opname via de intacte maar onbeschermde huid belangrijk. Van de homepage van Wil ten Berge is het freeware programma SKINPERM te downloaden dat op grond van een aantal fysisch chemische parameters de potentiële huiddoorlatendheid van een gas, damp of een vloeistof schat. En met aanvullende gegevens over kleding, besmet oppervlak e.d. wordt de mogelijke opname in het lichaam geschat. Een goede aanvulling dus op NEN 689 die volledig op de werkplekatmosfeer is gefocust.

    U vindt dit programma door te surfen naar http://home.planet.nl/~wtberge/

    SKINPERM schat de hoeveelheid van een chemische stof die via huid in het lichaam wordt opgenomen indien het agens:

    De opname van vaste stoffen en aerolsolen is niet met SKINPERM te schatten.