The Advanced REACH Tool<br />John Cherrie<br />
Summary…<br />Background<br />The concept of ART<br />The mechanistic model tool<br />Dispersion, an example of the work t...
Background…<br />ART is a generic higher tier tool<br />Included in the REACH Guidance<br />Applicable for exposure to dus...
The conceptual basis…<br />Based on the premise that both models and measurement data can be informative about exposure<br...
Combining data reduces uncertainty<br />+<br />BDA<br />Uncertainty<br />Model            Data  <br />Updated estimate<br />
The ART approach…<br />Exposure database, with contextual information<br />Model <br />Similarity module to select data fo...
Modelling the exposure distribution<br />Scenario<br />Median exposure<br />Mechanistic model<br />Information from <br />...
Model specification…<br /><ul><li>Between-companyvariability</li></ul>- Between-workervariability<br />- Within-workervari...
Underpinning the mechanistic model…<br />The early work by Cherrie, Schneider et al<br />Developed a model for use in epid...
An example of the use of this model…<br />1000.0<br />100.0<br />10.0<br />Estimated exposures (ppm)<br />1.0<br />0.0<br ...
Validation of the model…<br />
The ART mechanistic model…<br />
The mechanistic model…<br />Far-field<br />Source barrier<br />Personal barrier<br />Surfaces<br />LCIR<br />Source<br />2...
Nine modifying factors…<br />Intrinsic emission potential (E)<br />Activity emission potential (H)<br />Local controls (LC...
Three basic equations…<br />
Substance emission potential…<br />
Substance emission potential…<br />Partial vapour pressure of <br />substance i in mixture<br />Mole fraction<br />Vapour ...
Activity emission potential…<br />Powders<br />Liquids<br />Solid objects<br />Hot / molten <br />metal<br />
Local controls…<br />No localized controls<br />Suppression techniques<br />Wetting at the point of release<br />Knockdown...
Dispersion…<br />QFF<br />QNF<br />eT<br />Indoor<br />Outdoor<br />Spray booth<br />
Calibration with measurements…<br />Using multiple sources<br />Also including measurements in the low range<br />Only goo...
Bayesian updating…<br />Bayesian techniques allow for different types of information to be integrated in a theoretically r...
ART output…<br /><ul><li>Explicit treatment of variability and uncertainty
Percentile of distribution
Uncertainty of estimate</li></ul>Variability<br />Bayesian update<br />90th , 75th , 50th percentile<br />Uncertainty<br /...
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3. The Advanced REACH Tool (ART)

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The third lecture on modelling exposure for a course held in Norway 2011

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3. The Advanced REACH Tool (ART)

  1. 1. The Advanced REACH Tool<br />John Cherrie<br />
  2. 2. Summary…<br />Background<br />The concept of ART<br />The mechanistic model tool<br />Dispersion, an example of the work to underpin the model<br />Bayesian updating<br />Model output<br />
  3. 3. Background…<br />ART is a generic higher tier tool<br />Included in the REACH Guidance<br />Applicable for exposure to dust, vapour, mist, and fumes<br />Co-development project funded by:<br />Shell, GSK, Eurometaux, Cefic<br />HSE, Dutch government, Afsset<br />BOHS<br />Delivered by:<br />TNO, IOM, HSL, BAuA, UU and NRCWE<br />
  4. 4. The conceptual basis…<br />Based on the premise that both models and measurement data can be informative about exposure<br />Set within a Bayesian framework<br />
  5. 5. Combining data reduces uncertainty<br />+<br />BDA<br />Uncertainty<br />Model Data <br />Updated estimate<br />
  6. 6. The ART approach…<br />Exposure database, with contextual information<br />Model <br />Similarity module to select data for risk assessment<br />Bayesian process to combine data and model output<br />Exposure estimates for risk assessment<br />
  7. 7. Modelling the exposure distribution<br />Scenario<br />Median exposure<br />Mechanistic model<br />Information from <br />meta-analysis<br />Exposure variability<br />
  8. 8. Model specification…<br /><ul><li>Between-companyvariability</li></ul>- Between-workervariability<br />- Within-workervariability<br />
  9. 9. Underpinning the mechanistic model…<br />The early work by Cherrie, Schneider et al<br />Developed a model for use in epidemiological studies<br />Multiplicative deterministic model<br />Near-field/Far-field<br />Relied on the assessor to choose the parameters<br />Validated in a number of different situations<br />Dispersion parameters derived from a 2-box model<br />Cherrie and Schneider. (1999) Validation of a new method for structured subjective assessment of past concentrations. The Annals of Occupational Hygiene;43 (4):235-245.<br />Cherrie. (1999) The effect of room size and general ventilation on the relationship between near and far-field concentrations. Applied occupational and environmental hygiene; 14 (8): 539-46.<br />
  10. 10. An example of the use of this model…<br />1000.0<br />100.0<br />10.0<br />Estimated exposures (ppm)<br />1.0<br />0.0<br />01<br />0.0<br />0.1<br />1.0<br />10.0<br />100.0<br />1<br />0.1<br />0.01<br />0.001<br />Measured exposures (ppm)<br />
  11. 11. Validation of the model…<br />
  12. 12. The ART mechanistic model…<br />
  13. 13. The mechanistic model…<br />Far-field<br />Source barrier<br />Personal barrier<br />Surfaces<br />LCIR<br />Source<br />2nd<br />Personal behaviour<br />Near-field<br />RPE<br />Inhalation boundry<br />
  14. 14. Nine modifying factors…<br />Intrinsic emission potential (E)<br />Activity emission potential (H)<br />Local controls (LC)<br />Separation (Sep) <br />Segregation (Seg)<br />Surface contamination (Su)<br />Dilution (D)<br />Personal behavior (P)<br />RPE<br />
  15. 15. Three basic equations…<br />
  16. 16. Substance emission potential…<br />
  17. 17. Substance emission potential…<br />Partial vapour pressure of <br />substance i in mixture<br />Mole fraction<br />Vapour pressure <br />of substance i<br />Activity coefficient<br />UNIFAC<br />
  18. 18. Activity emission potential…<br />Powders<br />Liquids<br />Solid objects<br />Hot / molten <br />metal<br />
  19. 19.
  20. 20. Local controls…<br />No localized controls<br />Suppression techniques<br />Wetting at the point of release<br />Knockdown suppression<br />Containment (non-extracted)<br />Local ventilation systems<br />Receiving hoods<br />Capturing hoods<br />Enclosing hoods<br />Efficacy = 0.5<br />Efficacy = 0.0001<br />
  21. 21. Dispersion…<br />QFF<br />QNF<br />eT<br />Indoor<br />Outdoor<br />Spray booth<br />
  22. 22. Calibration with measurements…<br />Using multiple sources<br />Also including measurements in the low range<br />Only good quality data: N~2,500<br />Quantification in units (mg/m3)<br />Provides model uncertainty<br />Separate predictions for:<br />Dust<br />Vapour<br />Mist<br />Fumes<br />
  23. 23.
  24. 24. Bayesian updating…<br />Bayesian techniques allow for different types of information to be integrated in a theoretically rigorous way via probability theory<br />Bayes approach takes account of the relative strength of the different information sources<br />Bayesian module is integrated in ART to update model estimate with user’s own data<br />
  25. 25.
  26. 26. ART output…<br /><ul><li>Explicit treatment of variability and uncertainty
  27. 27. Percentile of distribution
  28. 28. Uncertainty of estimate</li></ul>Variability<br />Bayesian update<br />90th , 75th , 50th percentile<br />Uncertainty<br />Inter-quartile, 80 %, 90 %, 95 % CI<br />
  29. 29. Key scientists involved in ART…<br />Erik Tielemans (TNO)<br />John Cherrie (IOM) <br />WouterFransman (TNO)<br />Hans Marquart (TNO) <br />JodySchinkel (TNO) <br />Thomas Schneider (NRCWE)<br />Martin Tischer (BaUA<br />Martie van Tongeren (IOM)<br />Nick Warren (HSL)<br />
  30. 30. Acknowledgements…<br /><ul><li>S. Bailey (GSK, UK)
  31. 31. D. Brouwer (TNO, The Netherlands)
  32. 32. M. Byrne (University of Galway, Ireland)
  33. 33. D. Dahmann (Bochum University, Germany)
  34. 34. J. Dobbie (BP, UK)
  35. 35. D. Gazzie (Industrial Health Control, UK)
  36. 36. A. Gillies (Gillies AssociatesLtd, UK)
  37. 37. E. Joseph (GSK, UK)
  38. 38. I. Kellie (OHS Scotland Ltd, UK)
  39. 39. D. Mark (HSL, UK)
  40. 40. P. McDonnell (University of Galway, Ireland)
  41. 41. M. Newell (Bayer Crop Sciences, UK)
  42. 42. M. Nicas (University of California, USA)
  43. 43. D. O’Malley (Genesis EnvironmentalLtd, UK)
  44. 44. M. Piney (HSL, UK)
  45. 45. A. Robertson (IOM, UK)
  46. 46. J. Saunders (HSL, UK)
  47. 47. M. Smith (Bayer Crop Sciences, UK)
  48. 48. H. Tinnerberg (Lund University, Sweden)
  49. 49. H. Westberg (ÖrebroUniversityHospital, Sweden)
  50. 50. A. Wolley (Wolley Associates, UK)
  51. 51. J. Wren (GSK, UK)
  52. 52. D. Iddon (Lilly, UK)
  53. 53. D. Noy (Dow chemicals, NL)
  54. 54. J. Urbanus (Shell, NL)
  55. 55. R. Battersby (EBRC consulting, Germany)</li>

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