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Bioaccumulation Criteria

Bioaccumulation Criteria. Jon Arnot Frank Gobas Barry Kelly James Armitage. Overview. Why, What, Where, When and How of bioaccumulation (‘B’) regulatory criteria Current criteria concerns for assessments Bioaccumulation workgroup Bioconcentration Factor (BCF) Air breathing organisms

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Bioaccumulation Criteria

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  1. Bioaccumulation Criteria Jon Arnot Frank Gobas Barry Kelly James Armitage

  2. Overview • Why, What, Where, When and How of bioaccumulation (‘B’) regulatory criteria • Current criteria concerns for assessments • Bioaccumulation workgroup • Bioconcentration Factor (BCF) • Air breathing organisms • Future considerations • Comments

  3. Why do ‘B’ criteria exist? • Bioaccumulation is the net result of competing processes of chemical uptake and elimination in an organism • “Dose” (Paracelsus) • Identify chemicals that are bioaccumulative hazards for risk assessment • (e.g., CEPA 1999)

  4. What ‘B’ measurements are included in regulations? Where is this applied?

  5. BAF CB / CW (all routes) What ‘B’ measurements are included in regulations? Where is this applied? Canada

  6. BAF BCF CB / CW (water only) What ‘B’ measurements are included in regulations? Where is this applied? Canada United States European Union

  7. BAF BCF KOW CO / CW What ‘B’ measurements are included in regulations? Where is this applied? Canada United States European Union

  8. BAF BCF KOW BMF CPredator / CPrey What ‘B’ measurements are included in regulations? Where is this applied? Canada United States European Union Currently not used

  9. 1970s – today When and How have ‘B’ assessments evolved? 1960 – 1970s

  10. n ~2,400 (390 chemicals) ~3% DSL

  11. n ~1,300 (340 chemicals)

  12. Bioavailability (Ctotal vs Cfd) • Analytical • Metabolic transformation • Kinetics • Growth

  13. ~0.3% DSL

  14. Dietary uptake = 5000 Organism-water partitioning

  15. What are ‘B’ criteria trying to identify? • Chemicals with biomagnification potential • Beyond the scope of BCF data • By design they don’t include dietary exposure • Technical difficulties for high KOW chemicals • water concentrations low and variable • bioavailable fraction, exposure duration • Very $$ • BCFs are no substitute for BAFs

  16. Aquatic Terrestrial Lipid-water exchange Lipid-air exchange

  17. Observations of low KOW chemicals that biomagnify in terrestrial and marine mammalian food webs but not in aquatic food webs

  18. Chemicals with Biomagnification Potential Water ‘breathers’: log KOW > 5 and log KOW < 9 and TM,1/2 > ~10 d Air ‘breathers’: log KOA > 5 and log KOW > 2 and TM,1/2> ~7 d In: QSAR Comb. Sci. 22: 337-345 & 346-351.

  19. Canada’s Domestic Substance List 12,000 Organic Chemicals ~40% 17.8% In: QSAR Comb. Sci. 22: 346-351.

  20. Future considerations • BCF measurements alone are insufficient for assessing bioaccumulation / biomagnification potential • Don’t include dietary uptake • Restricted to aquatic species • ~3% of chemicals have empirical BCF data • For log KOW > 4-5 ~0.3% of empirical data • Since we have to use models lets use those that have the potential to identify bioaccumulative hazards

  21. Future considerations • Key partitioning processes for air breathing organisms are important (i.e., KOA) and are not explicitly included in regulatory criteria • Numerous incentives ($$) to establish consistent criteria in various jurisdictions

  22. Future considerations • Criteria need to effectively identify potential hazards for chemical risk assessment • A single, universal BMF criterion (e.g., 1) can be broadly applied to all species and identify those chemicals with biomagnification potential • Based on this strategy chemicals could be more effectively prioritized for assessment (e.g., BMF of 0.001 vs. 10 vs. 80) • Other criteria could also be developed • FWMF, kM, ?

  23. Thank you Comments?

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