22. State of knowledge in Europe on combustion residues
| Region / source | Documented knowledge | Significance for the assessment |
|---|---|---|
| EU, 2019: JRC-BREF [34] | The reference document for waste incineration names hexavalent chromium among the problematic metals with regard to leaching from bottom ash. | Explicit environmental reference. Eluate/environmental assessment does not replace an assessment of dust exposure during maintenance and overhaul. |
| United Kingdom: HSE / practical case [30, 40] | HSE requires the assessment of fly ash risks and the avoidance of airborne ash. The practical case reports Cr(VI) in deposits during overhaul work. | Geographically Europe, legally separate from the EU. The case describes a specific activity; it is not a representative investigation of the protection regime. |
European environmental literature also expressly names Cr(VI): in the 2019 European BAT reference document for waste incineration (JRC-BREF), it is listed alongside copper, molybdenum and zinc as a problematic substance with regard to leaching from bottom ash. For this statement, the corresponding officially indexed passage was evaluated, not the entire extensive document. The environmental perspective answers different questions from the activity-related occupational safety and health assessment. [34]
The Euro-Environmental article has been taken into account: it describes Cr(VI)-positive deposits in boiler passes 2-6 of an unnamed British operator and the exposure during maintenance and overhaul. The cooling described there concerns the flue gas path through successive boiler passes; it is not to be read as a measurement of new chromate formation during shutdown over time. Air/ambient monitoring, biomonitoring, ferrous sulphate treatment, extraction and enclosed areas are reported. Numerical before/after values are missing; the yellow colour does not provide a reliable identification of the salt. The case documents the handling of a specific overhaul hazard and supplements the separate question of residues on the grate. [30]
Field observations on the protection regime
Field observations at European waste incineration plants show that protection against chromate exposure is implemented at best partially. This does not involve a systematic sample of plants, specific series of measurements or an assessment of individual operators.
The resulting question for investigation is whether the risk assessments also cover overhaul, boiler opening, removal of deposits, cleaning, ash handling and spreading of contamination. The residue fraction concerned in each case, analytical speciation, release during the work process and the protective measures actually used would need to be recorded. This can be traced on the basis of existing work permits, measurement reports and overhaul documentation.
Sources cited in this section
- 30.Euro Environmental Ltd.: Managing Chromium VI Exposure in Waste Recycling Incinerators. Undated British practical case report; accessed 7 October 2026.
- 34.European Commission / JRC: Best Available Techniques (BAT) Reference Document for Waste Incineration, 2019, JRC118637. Evaluated officially indexed passage: leaching of bottom ash, explicit mention of hexavalent chromium. No complete comparison of the document.
- 40.Health and Safety Executive (Great Britain): Waste management: Disposal and energy recovery. Official guidance on fly ash and dust exposure; accessed 7 October 2026.