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 Future considerations Comments

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)

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

BAF C B / C W (all routes) Where is this applied? Canada What ‘B’ measurements are included in regulations?

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

BAF BCF K OW C O / C W Where is this applied? Canada United States European Union What ‘B’ measurements are included in regulations?

BAF BCF K OW BMF C Predator / C Prey Where is this applied? Canada United States European Union Currently not used What ‘B’ measurements are included in regulations?

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

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

n ~1,300 (340 chemicals)

–Bioavailability (Ctotal vs Cfd) –Analytical –Metabolic transformation –Kinetics –Growth

~0.3% DSL

Dietary uptake Organism-water partitioning = 5000

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 K OW chemicals water concentrations low and variable bioavailable fraction, exposure duration Very $$ BCFs are no substitute for BAFs

Aquatic Lipid-water exchange Lipid-air exchange Terrestrial

Chemicallog K OW log K OA BMF (lipid/lipid) Species ß-HCH wolves  HCH ~8Ringed seals  HCH ~2Beluga whale  -endosulphan ~10Ringed seals Tetrachlorobenzene ~7Arctic wolves Pentachlorobenzene Arctic wolves PFOS~ 312>> 1Various Observations of low K OW chemicals that biomagnify in terrestrial and marine mammalian food webs but not in aquatic food webs

Water ‘breathers’: log K OW > 5 and log K OW < 9 and T M,1/2 > ~10 d Air ‘breathers’: log K OA > 5 and log K OW > 2 and T M,1/2 > ~7 d Chemicals with Biomagnification Potential In: QSAR Comb. Sci. 22: &

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

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 K OW > 4-5 ~0.3% of empirical data Since we have to use models lets use those that have the potential to identify bioaccumulative hazards

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

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 vs. 10 vs. 80) Other criteria could also be developed FWMF, k M, ?

Thank you Comments?