dinsdag 24 november 2015
International study shows high scores for Stoffenmanager®
In the Stoffenmanager November newsletter we paid particular attention to the final report of the International eteam study that compared several different models that are accepted in the REACH guidance R.14. for occupational exposure estimation.
What these results mean in real terms is clear as Henri Heussen, CTO at Cosanta and member of the eteam Scientific Advisory Board, explains the main conclusions. “You can already see that Stoffenmanager® in itself is regularly the topic of scientific studies. The tool was earlier the focus of a Swiss study and a Swedish study.”
Henri Heussen: “Both studies reveal the excellent performance of the Stoffenmanager® model. The variability between users may well be considerable but the Stoffenmanager® model is the most reliable and the chances of erroneous assessments much less than compared with other tools.“
“Of course, we are pleased with the fact that the recent eteam study also confirmed this.” This study compared the models accepted in the REACH Guidance R.14 – ECETOC TRA, MEASE, EMKG-EXPO-TOOL, STOFFENMANAGER® and RISKOFDERM – in terms of ease of use, variability between users and external validation, or the reliability of the estimates.
Reliability is defined here as:
Three levels of conservatism were distinguished in the study:
High – where ≤ 10% of the measurement results exceeded the model estimates;
Medium - where 11 - ≤ 25% of the measurement results exceeded the model estimates;
Low – where >25% of the measurement results exceeded the model estimates.
The external eteam validation study (click here) revealed that “overall, the STOFFENMANAGER® tool appeared most consistently conservative across all exposure categories, except for non-volatile liquids….. The tool appeared least conservative when estimating exposures during activities involving non-volatile liquids, which were evaluated only for the MEASE and STOFFENMANAGER® tools and metal abrasion (ECETOC TRAv2 and v3 tools).”
If we restrict ourselves to the estimation of exposure via the airways, the main results regarding in conservatism are that Stoffenmanager® scores with volatile liquids and 90-percentile, 11%. So of 1854 (!) measurements only about 209 were higher than the estimation. Henry: “If you consider this not conservative enough you could easily estimate by using the 95-percentile. The researchers didn’t report this but of course you can easy apply it.”
The last column (%M>T) shows that the Stoffenmanager® 90-percentile model estimates come out very well for powder handling. The score is even 3%! So out of 1101 measurements only 33 were higher than the estimation. So obviously this shows that the 90-percentile model-estimations are really very good, high - medium conservative.
Henri Heussen: “These results are very pleasing! In short, by using Stoffenmanager® the exposure is not overestimated by much and certainly not underestimated.”
For low volatile liquids the estimates are medium conservative, 15% out of 324 measurements were higher than the Stoffenmanager estimate. It should be noted here that this measurement dataset comprised largely spraying operations. The International Scientific Advisory Board will examine these and possibly new data before deciding on whether, and how, the calculation rule for low volatile liquids should be modified.”Obviously one could use the 95-percentile estimation here as well.”
From the report: Table 4.43 Proportion of measurements exceeding the tool estimate, by exposure category (individual and aggregated measurements combined)
nM= number of measurements
nM>T= number of measurements exceeding the tool estimate;
%M>T= Percentage of measurements exceeding the tool estimate
Finally, Henri expresses his pleasure in these research results and the final conclusion. “We are proud that Stoffenmanager® has performed so well, something that is again underlined by this report. Objectiveness is a very valuable facet of our work. And, as we have said before, we develop by responding immediately to suggested improvements.“
Lamb, J., K.S. Galea, B.G. Miller, S. Spankie, M. van Tongeren, G. Hazelwood (2014). e-team project -deliverable D22, Report on Between-User Reliability Exercise (BURE) and Workshop, Institute of Occupational Medicine.
Lamb, J., B. Miller, S Rashid, L. MacCalman, M. van Tongeren (2015). Evaluation of Tier 1 Exposure Assessment Models under REACH (ETEAM) Project . Final report on external validation exercise.
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