18. Rules compared: one benchmark, five variants
For all Member States, Directive 2004/37/EC in its current version applies as the overarching instrument. Since 17 January 2025 it sets a binding limit value of 0.005 mg/m³ for chromium(VI) compounds; before that 0.010 mg/m³ applied, and 0.025 mg/m³ for welding and plasma cutting. [86]
The benchmark for the question dealt with here is set by Germany. The German Hazardous Substances Ordinance (GefStoffV) and the German TRGS 561 are the only body of rules among these that expressly addresses the formation of chromium(VI) compounds on chromium alloyed hot components and derives a protective regime from it without requiring a prior measurement. For chromium(VI) compounds there is no acceptance concentration; the German TRGS 561 uses 0.001 mg/m³ in the inhalable fraction as its assessment benchmark, which corresponds to the tolerance concentration of the German TRGS 910. [87]
The remaining bodies of rules can be read as mirrors of it.
| Framework | Basis | Airborne limit value |
|---|---|---|
| Netherlands | Arbobesluit, SZW list of carcinogenic substances | 0.001 mg/m³ as Cr |
| United Kingdom | COSHH Regulations 2002, EH40 | 0.01 mg/m³, 8-hour average; 0.025 mg/m³ process generated [42] |
| United States | OSHA 29 CFR 1910.1026 | PEL 5 µg/m³, action level 2.5 µg/m³ |
The numerical values differ by a factor of 10. All of them refer to the chromium content and none to the specific compound. The distance is smaller than it looks, however: the United Kingdom has the highest value but, under the COSHH Regulations, also requires carcinogens to be minimised to the lowest level that is reasonably practicable, so that the limit value there does not describe a permissible working level. The leaflet INDG346 of the same authority still gives the value of 0.05 mg/m³ that applied until 17 January 2020 [88].
The airborne concentration describes only one of two exposure routes. Chromium(VI)-containing dusts are not distributed evenly across a working area, and in work on insulated hot components the dermal exposure may have to be rated higher than the inhalation exposure. Both routes are to be assessed separately. The American rule prescribes protective clothing, change and washing facilities and a prohibition on blowing down with compressed air; the German rules list chromium(VI) compounds as skin absorbing and require corresponding measures under the German TRGS 401.
The same applies to combustion ashes. There too the inhalation and dermal hazards are to be assessed separately, and particular weight attaches to preventing carry-over from the contaminated area, which concerns occupational and environmental protection alike.
Procurement law: the US clause DFARS 252.223-7008
Alongside occupational safety, procurement law applies in the United States. Clause DFARS 252.223-7008 “Prohibition of Hexavalent Chromium” has been in force since 5 May 2011 and is inserted into Department of Defense contracts as prescribed at DFARS 223.7306; the most recent change is dated 25 April 2024. It rests on the memorandum “Minimizing the Use of Hexavalent Chromium” of the Under Secretary of Defense for Acquisition, Technology and Logistics of 8 April 2009. [89, 90]
The clause prohibits the supply of a deliverable or construction material containing hexavalent chromium “in a concentration greater than 0.1 percent by weight in any homogenous material”, and likewise the supply of items that would require hexavalent chromium to be removed or reapplied during later sustainment phases. Under the definition in paragraph (a), a homogeneous material is one that cannot be mechanically disjointed and is uniform in composition throughout; surface coatings count expressly as a homogeneous material in their own right. The exception in paragraph (b)(2) covers “hexavalent chromium produced as a by-product of manufacturing processes”. Paragraph (d) requires flowdown to all subcontracts for supplies, maintenance and repair services, or construction materials. [89]
Three points follow for insulated hot components. The reference mass for the 0.1 per cent is the homogeneous material, so a thin chromate-containing deposit or coating layer is weighed against the mass of that layer and not against the mass of the component. The exception is written for manufacturing processes and on its wording does not cover chromate that forms only in service. The flowdown extends the clause to maintenance and repair services. Whether calcium-containing insulation on a chromium alloyed hot component, which requires chromate to be removed at every overhaul, falls under the second limb of the prohibition is a question of interpretation that the wording permits.
Sources cited in this section
- 42.Health and Safety Executive (Great Britain): EH40/2005 Workplace exposure limits, fourth edition 2020; Table 1 with the entry “Chromium (VI) compounds (as Cr)”, 0.01 mg/m³ as an eight-hour average and 0.025 mg/m³ for process generated exposure, and Table 2, Biological monitoring guidance values, with chromium in urine.
- 86.Directive (EU) 2017/2398 amending Directive 2004/37/EC on the protection of workers from the risks related to exposure to carcinogens or mutagens at work; binding limit value for chromium(VI) compounds.
- 87.Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA): chromium(VI) compounds, assessment benchmarks under TRGS 910 and TRGS 561.
- 88.Health and Safety Executive (UK): Chromium and you, INDG346; workplace exposure limit under EH40 and the COSHH Regulations 2002.
- 89.DFARS 252.223-7008, Prohibition of Hexavalent Chromium; prescribed at DFARS 223.7306, as amended by the DFARS change of 25 April 2024.
- 90.Defense Federal Acquisition Regulation Supplement: Minimizing the Use of Hexavalent Chromium (DFARS case 2009-D004, RIN 0750-AG35), final rule of 5 May 2011, Federal Register Volume 76, Number 87; refers to the memorandum of the Under Secretary of Defense (Acquisition, Technology and Logistics) of 8 April 2009.