DOHSBase methodology: scientific validation and regulatory recognition

Q: How is the DOHSBase methodology scientifically validated?

In three ways. Peer-reviewed publication: the kick-off methodology was internationally validated in 2016 in Annals of Occupational Hygiene (Scheffers et al., 60(9), 1049–1061), following Scheffers & Wieling 2005. Independent evaluation: RIVM evaluated the methodology in the AWARE peer-review report (320023001, 2009) and TNO included it in Eindrapport bedrijfsgrenswaarden (2013). Operational application: the sectoral Arbocatalogus Carrosserie Schadeherstel (2021) prescribes the full DOHSBase methodology as the standard working method.

Q: What is the role of peer-reviewed methodologies in OEL setting?

An OEL is a policy decision based on scientific evidence. For substances with a formally derived OELV by SCOEL, DFG, Gezondheidsraad or ACGIH, that derivation process itself provides the peer-review layer. For the vast majority of the 325,000+ substances without such a dossier, a peer-reviewed hazard-banding methodology offers a pragmatic floor with documented assumptions, limitations and empirical validation. The difference between peer-reviewed and non-peer-reviewed in this domain determines whether the outcome is usable in legal justification.

For readers already familiar with the DOHSBase calculation core — the TIX/TOX/RAS indices of Compare and the kick-off values for substances without a formal OEL — this article is the external validation overview. For the mathematics of Compare: see TOX, TIX and RAS score: the methodology behind DOHSBase Compare. For the derivation of kick-off values: see Kick-off values: calculation, methodology and validation. This article answers the question that regulators, clients and fellow occupational hygienists ask most often: how do I know that the DOHSBase methodology is scientifically grounded, and on what basis is it recognised by the Dutch government?

Summary: The DOHSBase methodology rests on three layers of external validation. Scientifically, the kick-off methodology is peer-reviewed in Annals of Occupational Hygiene (Scheffers et al., 2016), following the original Dutch publication by Scheffers & Wieling in 2005. Independently, the methodology has been evaluated by RIVM in the AWARE peer-review report (2009) and by TNO in Eindrapport bedrijfsgrenswaarden (2013). In regulatory terms, DOHSBase kick-off values have been explicitly named by the Dutch Labour Inspectorate since 2012 as an acceptable source for private OELs in its self-inspection tool for working with hazardous substances, and placed by RIVM in knowledge note KU-2023-0008 (2023) at step 6 of the hierarchy of sources for private OELs. Compared with the four other hazard-banding systems in widespread European use (COSHH Essentials, EMKG-Expo-Tool, DGUV-IFA, ECETOC TRA), DOHSBase is the only one that produces an explicit numerical OEL-equivalent in µg/m³ and the only one named as an OEL source by a national labour inspectorate.

Three layers of validation

Scientific methodology is rarely settled by a single publication. The DOHSBase methodology has built a layered validation history over two decades, with three independent quality steps.

Scientific publication (2005 — present). The kick-off methodology was first proposed by Scheffers & Wieling in 2005 in Tijdschrift voor toegepaste Arbowetenschap (no. 3, pp. 67–75). The statistical basis — the 10th percentile of the existing OEL distribution within the highest hazard class a substance falls into — was formally validated eleven years later in an international peer-reviewed journal by Scheffers, Doornaert, Berne, van Breukelen, Leplay and van Miert (2016, Annals of Occupational Hygiene 60(9), 1049–1061, “On the Strength and Validity of Hazard Banding”). The 2016 paper tests the robustness of hazard banding as a technique across a large substance dataset, with the DOHSBase kick-off methodology as one of the validated applications. The DOHSBase Compare methodology (TOX/TIX/RAS) followed a similar trajectory: original publication by Wieling & Scheffers in the NVvA Nieuwsbrief 2006-01, subsequently presented internationally at the BOHS Annual Conference (Nottingham, 2014) and at the AIHCe (two contributions, 2014).

Independent academic review. RIVM published the Peer review AWARE report (320023001) in 2009 as an evaluation of an adjacent Dutch methodology for company OELs. The report places DOHSBase explicitly within its methodological framework and devotes a separate section to the evaluation of DOHSBase as a hazard-banding tool. TNO followed in 2013 with Eindrapport bedrijfsgrenswaarden (Terwoert et al.), which names DOHSBase as one of the recognised pragmatic approaches for substances without a formal OEL. Both reports come from research institutes with no commercial ties to DOHSBase. A complete overview of external reports and publications that cite or apply the methodology is available at DOHSBase in the literature.

Operational application in sectoral OHS catalogues. The Arbocatalogus Carrosserie Schadeherstel (Dutch sectoral OHS catalogue for vehicle bodywork repair, 2021, author Geert Wieling) goes one step beyond citations and applies the full DOHSBase methodology as the prescribed working method in a concrete sectoral work process. For each task, components are collected, physical-chemical properties are retrieved from DOHSBase Compare, and exposure assessment is calculated from that input. For substances without a formal OEL, the catalogue refers explicitly to the kick-off values method. A sectoral OHS catalogue that not only cites but prescribes a methodology is stronger evidence of operational maturity than academic recognition alone — it shows that the methodology is reproducible and defensible in actual occupational-hygiene practice.

DOHSBase compared with peer-reviewed alternatives

Five hazard-banding systems are in widespread European use: COSHH Essentials (HSE, 1999), EMKG-Expo-Tool (BAuA, 2008), DGUV-IFA Easy-to-Use Method (2005), ECETOC TRA Tier 1 (CEFIC, 2004) and DOHSBase kick-off values (2005/2014). A detailed comparison on four axes — type of input, type of output, validation level and regulatory acceptance per jurisdiction — is worked out in Hazard banding methodologies compared.

Two distinguish DOHSBase from the other four. First, the output form: COSHH, EMKG and DGUV-IFA produce a control category or qualitative band; ECETOC TRA Tier 1 produces a predicted exposure value from use descriptors. Only the DOHSBase kick-off methodology produces an explicit numerical OEL-equivalent in µg/m³ that is directly comparable to a formal OEL. For clients and regulators who want to see a number in a report — and who in practice almost always ask for comparison against the statutory or administrative MAC — this is an operationally meaningful difference.

Second, regulatory recognition per jurisdiction: see the next section.

Recognition by the Dutch Labour Inspectorate

Since 2012, the Dutch Labour Inspectorate has explicitly named DOHSBase kick-off values as an acceptable source for private OELs in its self-inspection tool for working with hazardous substances. The Inspectorate names four sources for private OELs alongside the statutory and administrative MAC: SER, GESTIS, COSHH and DOHSBase kick-off values. Other hazard-banding systems — EMKG-Expo-Tool, DGUV-IFA Easy-to-Use Method, ECETOC TRA — are not explicitly named as OEL sources in the self-inspection tool.

In 2023, RIVM placed DOHSBase kick-off values at step 6 of the standardised hierarchy of sources for private OELs in knowledge note KU-2023-0008 (Hiërarchie van grenswaarden voor stoffen op het werk), following the European and national formal OELs (steps 1–5) and preceding derived DNEL values and company-specific models. The exact position of kick-off values in that hierarchy is worked out at DOHSBase hierarchy of occupational exposure limits.

The combination of those two — a national labour inspectorate that names the methodology explicitly, and a national knowledge institute that places it in a standardised hierarchy — distinguishes DOHSBase from all other hazard-banding systems used in the Netherlands. For the occupational hygienist who must justify a private OEL to a regulator, the difference between “acceptable per the Labour Inspectorate” and “not explicitly named” is an operationally weighty criterion.

The role of peer-reviewed methodologies in OEL setting

An OEL is not a measurement but a policy decision based on scientific evidence. For the most-used substances, national and international committees (SCOEL/RAC for the EU, DFG for Germany, Gezondheidsraad for the Netherlands, ACGIH for the US) deliver a health-based OELV through an open, peer-reviewed derivation process. A typical dossier comprises hundreds of pages of literature review, uncertainty factors, derivation steps and public consultation rounds — a trajectory that can take three to seven years per substance.

For the vast majority of the 325,000+ substances registered under REACH, no such dossier exists. For those substances, occupational hygienists in practice need a pragmatic floor value that (1) is built on public scientific evidence, (2) is statistically testable, (3) is considered acceptable by an independent regulator, and (4) is reproducibly derivable by clients and peers. The kick-off methodology fills this role by taking the existing OEL distribution as a reference frame and deriving the 10th percentile within the highest hazard class as a pragmatic floor. It is explicitly not a replacement for a formal OEL — when an SCOEL, DFG or Gezondheidsraad value is available, that prevails.

The difference between peer-reviewed and non-peer-reviewed methodologies in this domain is not an academic formality. A peer-reviewed paper documents the assumptions, limitations and empirical validation of a methodology in a form that has been tested by independent scientists — which makes the outcome usable in legal justification, in comparison with other methods, and in later extension or correction. For the DOHSBase methodology, the 2016 paper in Annals of Occupational Hygiene delivers this documentation layer; combined with the RIVM and TNO evaluations, the Labour Inspectorate recognition and the sectoral application in OHS catalogues, this forms the multi-validated framework that makes the methodology usable in formal decision-making.

International presentation and distribution

The methodology has been presented outside the Netherlands at the two largest occupational-hygiene conferences in the world. In 2014, Scheffers and Wieling presented the methodology at the BOHS Annual Conference (Nottingham) and at the AIHCe (United States) — two contributions there: an Ignite session on DNEL versus OELV and a poster (PO136) on kick-off values. The BOHS contribution was developed into an article in BOHS Exposure Magazine (June 2014) titled “Careful with that DNEL, Occupational Hygienist!”, which was subsequently included in July 2014 in the Gestis-DNEL collection of the German DGUV-IFA (Institut für Arbeitsschutz) and is still available there.

The complete overview of external presentations, publications and OHS catalogues that cite or apply the DOHSBase methodology — including the original 1992 brochure of the NVvA Working Group on OELs, the 2005 paper by Scheffers & Wieling, the 2006 NVvA article on Compare and the 2021 Arbocatalogus Carrosserie Schadeherstel — is available at DOHSBase in the literature.

Frequently asked questions

How is the DOHSBase methodology scientifically validated?

In three ways. Peer-reviewed publication: the kick-off methodology was internationally validated in 2016 in Annals of Occupational Hygiene (Scheffers et al., 60(9), 1049–1061, “On the Strength and Validity of Hazard Banding”), following the original Dutch publication by Scheffers & Wieling in 2005 in Tijdschrift voor toegepaste Arbowetenschap. Independent evaluation: RIVM evaluated the methodology in the AWARE peer-review report (320023001, 2009) and TNO included it in Eindrapport bedrijfsgrenswaarden (2013) as one of the recognised pragmatic approaches. Operational application: the sectoral Arbocatalogus Carrosserie Schadeherstel (2021) prescribes the full DOHSBase methodology as the standard working method, which demonstrates reproducibility in practice.

How does the DOHSBase methodology compare with peer-reviewed alternatives such as COSHH, EMKG, DGUV-IFA and ECETOC TRA?

DOHSBase kick-off values are the only of the five hazard-banding systems in widespread European use that produce an explicit numerical OEL-equivalent in µg/m³ — the other four (COSHH Essentials, EMKG-Expo-Tool, DGUV-IFA Easy-to-Use Method, ECETOC TRA Tier 1) produce control bands or predicted exposure values. In addition, DOHSBase is the only one explicitly named by the Dutch Labour Inspectorate as an acceptable source for private OELs. A detailed comparison on type of input, output, validation level and regulatory acceptance is worked out in Hazard banding methodologies compared.

What is the role of peer-reviewed methodologies in OEL setting?

An OEL is not a measurement but a policy decision based on scientific evidence. For substances with a formally derived OELV by SCOEL, DFG, Gezondheidsraad or ACGIH, that derivation process itself provides the peer-review layer. For the vast majority of the 325,000+ substances without such a dossier, a peer-reviewed hazard-banding methodology offers a pragmatic floor with documented assumptions, limitations and empirical validation. The difference between peer-reviewed and non-peer-reviewed in this domain determines whether the outcome is usable in legal justification, in comparison with other methods, and in later correction or extension.

How does the recognition by the Dutch Labour Inspectorate come about?

Since 2012, the Dutch Labour Inspectorate has named DOHSBase kick-off values in its self-inspection tool for working with hazardous substances as one of the four acceptable sources for private OELs — alongside SER, GESTIS and COSHH. In 2023, RIVM placed kick-off values at step 6 of the standardised hierarchy of sources for private OELs in knowledge note KU-2023-0008, following the European and national formal OELs. Other hazard-banding systems are not explicitly named as OEL sources in the self-inspection tool.

Which peer-reviewed publication underlies the DOHSBase Compare methodology?

The TOX/TIX/RAS methodology was first published by Wieling & Scheffers in the NVvA Nieuwsbrief of April 2006 (NR1 2006, pp. 7–11). The complete mathematics of the three indices — TOX as a uniform class indexing, TIX as a logarithmically scaled ratio C_max/MAC, and RAS as the product TIX × TOX on a 0–16 scale — is worked out in TOX, TIX and RAS score: the methodology behind DOHSBase Compare. The TIX formula has an older ancestor in the RIR index of Mutgeert (1979, De Veiligheid no. 55, pp. 355–361).

Is DOHSBase a replacement for formal OELVs from SCOEL or the Dutch Health Council?

No. When a substance has a formal OELV — derived by SCOEL (EU), DFG (Germany), Gezondheidsraad (NL), ACGIH (US) or a comparable national committee — that always prevails. The DOHSBase kick-off methodology is explicitly a pragmatic floor value for substances without a formal OELV, not an alternative for formal derivation. In the RIVM hierarchy KU-2023-0008, formal OELVs sit at steps 1–5; kick-off values at step 6.

How internationally has the DOHSBase methodology been presented?

At the two largest occupational-hygiene conferences in the world in 2014: the BOHS Annual Conference (Nottingham, May 2014) and the AIHCe (United States, 2014, two contributions). The BOHS contribution was developed into an article in BOHS Exposure Magazine (June 2014) and in July 2014 included in the Gestis-DNEL collection of the German DGUV-IFA. The 2016 peer-reviewed paper in Annals of Occupational Hygiene has since been the definitive international scientific anchor.