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Lipids

Lipids. Water. GILL UPTAKE. Cwater. GILL ELIMINATION. Fish-Water Two Compartment Model dC F / dt = k 1 .C W – k 2 .C F. C F : Concentration in Fish C W : Concentration in Water k 1 : Uptake clearance rate k 2 : Elimination rate constant. C F = C W (k 1 /k 2 ).(1 - exp(- k 2 .t)).

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Lipids

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  1. Lipids Water

  2. GILL UPTAKE Cwater GILL ELIMINATION Fish-Water Two Compartment Model dCF / dt = k1.CW – k2.CF CF: Concentration in Fish CW: Concentration in Water k1 : Uptake clearance rate k2 : Elimination rate constant CF = CW (k1/k2).(1 - exp(- k2.t))

  3. Slope = - k2

  4. Bioconcentration : Equilibrium Partitioning fbiota fwater

  5. Woodwell, (1967) Sci Amer.

  6. Biomagnification : fbiota fwater fpredator fprey

  7. Criteria for Bioaccumulation* Parameter Value Bioaccumulation Factor BAF > 5,000 Bioconcentration Factor BCF > 5,000 Octanol - Water Partition log KOW> 5 Coefficient * - BAF is better than BCF is better than KOW

  8. Calves are born in June and weaned after 130 days • Grazing: Lichen Diet (C. rangiferina, and C. nivalis)

  9. Female wolves gives birth in may (litter of 2 to 7 pups, 0.5 kg each) • Pups are weaned after 70 days • 100% caribou diet (GD) =1.5 kg/day: 5 calves, 2 yearlings and 16 adults)

  10. Field Study Results: Spatial distribution of PCB 153 Inuvik Cambridge Bay Bathurst Inlet Lichen Caribou Wolf

  11. Observed biomagnification in Bathurst Inlet food-chain Chemical logKOW 4.0 4.0 4.5 5.5 6.9

  12. BMF - KOW relationship BMF - KOA relationship

  13. Metabolism (kM) Growth Fecal Excretion (mol d-1) Air (mol d-1) GIT G Diet (mol d-1) Lactation (mol d-1) L Urine (mol d-1)

  14. Canada’s Domestic Substance List

  15. PCBs (PNVs) (NPNVs) (PVs) (NPVs)

  16. United Nations LRTAP POPs Protocol (1998) Targets chemicals that are: Persistent Bioaccumulative Toxic

  17. no further action under this program Canadian Environmental Protection Act: Framework for Evaluating DSL Chemicals Substances on the DSL Persistent and or Inherently Toxic PHASE 1: Bioaccumulative Categorization No Yes PHASE 2: Screening level Screening Assessment risk assessment Priority No Further Action List of Toxic Substances Outcomes at this Time Substances List

  18. Measures of Bioaccumulation Bioconcentration Factor: BCF = CF / CW Biomagnification Factor: BMF = CF / CDiet Bioaccumulation Factor : BAF = CF / CW Biota-Sediment Accumulation Factor : BSAF = CF / CS Octanol-Water Partition Coefficient: Kow = CO / CW

  19. Units of Bioaccumulation BCF or BAF = CFish / CWater CFish = g substance/ kg wet weight organism CWater = g substance / L water BCFWW = L/kg wet weight CFish = g substance/ kg lipid CWater = g substance / L BCFL = L/kg lipid BCFWW = L.BCFL BCFWW : Wet weight based BCF BCFL : Lipid weight based BCF L: Lipid content organism (kg lipid/kg wet weight organism)

  20. Units of Bioaccumulation BSAF = CBiota / CSediment CBiota = g substance / kg wet weight biota CSediment = g substance / kg dry sediment BSAF = kg dry sediment/kg wet weight biota CFish = g substance / kg lipid CSediment = g substance / kg organic carbon BSAFL = kg organic carbon L/kg lipid

  21. Units of Bioaccumulation BSAFWW = (L/OC).BSAFL BSAFWW : Wet weight based BSAF (kg dry sediment/kg wet weight biota) BSAFL : Lipid & Organic carbon normalized BSAF (kg organic carbon/ kg lipid) L: Lipid content biota (kg lipid/kg wet weight biota) OC : Organic carbon content sediment (kg organic carbon/kg dry weight sediment)

  22. Units of Bioaccumulation BMF = CF / CD CF = g / kg wet weight CW = g / L BCFW = L/kg wet weight CF = g / kg lipid CW = g / L BCFL = L/kg lipid BCFW = L.BCFL BCFW : Wet weight based BCF BCFL : Lipid weight based BCF L: Lipid content organism (kg lipid/kg wet weight organism)

  23. Read Environ. Sci. Technol. 16: 274-278 (1982)

  24. Read: Environ. Sci. Technol. 22: 99-103 (1988)

  25. Trophic Dilution

  26. Criteria for Bioaccumulation UNEP & CEPA* Parameter Value Bioaccumulation Factor BAF > 5,000 Bioconcentration Factor BCF > 5,000 Octanol - Water Partition log KOW> 5 Coefficient * - BAF is better than BCF is better than KOW

  27. Aquatic organisms Air-breathing animals Lipid-Water partitioning (KOW) Lipid-Air partitioning GIT GIT • (KOA) may better assess bioaccumulation potential in air- breathing animals

  28. Conclusions • Food-Chain Biomagnification is observed for chemicals with a log Kow as low as 3.8. • Koa is a better predictor of bioaccumulation in terrestrial food-chains than Kow • Current bioaccumulation protocols in CEPA & UNEP do not identify low Kow- high Koa substances that have a biomagnification potential in terrestrial food-chains • Preliminary data and models indicate that in absence of metabolism, chemicals with log Koa > 4 biomagnify in terrestrial food-chains.

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