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Understanding BAF. BioAccumulation Factors. Understanding BAF. Important to estimate human pollutant exposure from consumption of contaminated food material; Part of the Ambient Water Quality Criteria (AWQC);. BW. AWQC = RfD x RSC. DI + ∑ (FI x BAFi). Understanding BAF. Where:
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UnderstandingBAF BioAccumulation Factors
Understanding BAF • Important to estimate human pollutant exposure from consumption of contaminated food material; • Part of the Ambient Water Quality Criteria (AWQC); BW AWQC = RfD x RSC DI + ∑ (FI x BAFi)
Understanding BAF • Where: • RfD = reference dose for noncancer human health effects • RSC = relative source contribution to account for non-water sources of exposure • BW = human body weight • FI = food intake • BAFi = bioaccumulation factor for chemical “i”
Method for Estimating BAF • Three approaches: • Direct • Indirect • Conversion (modified direct)
Direct Method • Calculated using simple ratio of the chemical concentration in tissue and water. BAF = Ct / Cw Where : Ct = concentration of the chemical in the wet tissue (either whole organism or specified tissue) Cw = concentration of chemical in water
Indirect Method • Used if: • No such field data • Unreliable field data • Used for the development of wildlife criteria • Estimated by multiplying a BCF by a FCM
Formula for FCM • Factor used yo account for the food chain interaction and biomagnification • Example: FCM TL 2 = (BMF TL2) FCM TL 3 = (BMF TL2) (BMF TL3) FCM TL 4 = (BMF TL2) (BMF TL3) (BMF TL4) FCM = food chain multiplier for designated trophic level (TL2, TL3 or TL4); BMF = biomagnification factor for designated trophic level (TL2, TL3 or TL4)
Formula for BMF • Basic difference between FCM and BMF • FCM : related back to trophic level one; • BMF : always related back to next lowest trophic level (BMF TL2) = (C TL2) / (C TL1) (BMF TL3) = (C TL3) / (C TL2) (BMF TL4) = (C TL4) / (C TL3)
Conversion Method • Used if unavailable concerning data • Example total mercury, dissolved total mercury or total methylmercury instead of methylmercury form.
Biomaginification of DDT (ppm) Fish-eating birds (0.17 – 2.07) Fish (0.17 – 2.07) Mud snail 0.26 Clam 0.42 Insects 0.23 – 0.3 shrimp 0.16 Organic debris 0.3 – 13.0 Cladophore 0.03 Plankton 0.04 Marsh plants 0.33 – 2.8 Sea-water 1 x 10-6 Fresh-water 1 x 10-5 (Preston, 1989)
ACCUMULATION VALUE • Terms of Accumulation • BAF = Bioaccumulation Factors • BCF = Bioconcentration Factors • BMF = Biomagnification Factors • FCM = Food Chain Multipliers