Understanding BAF Bio Accumulation Factors Understanding BAF Important

Understanding BAF Bio. Accumulation Factors

Understanding BAF Important to estimate human pollutant exposure from consumption of contaminated food material; u Part of the Ambient Water Quality Criteria (AWQC); u BW AWQC = Rf. D x RSC DI + ∑ (FI x BAFi)

Understanding BAF u Where: u u u Rf. D = 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 u Three approaches: – Direct – Indirect – Conversion (modified direct)

Direct Method u 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 u Used if: – No such field data – Unreliable field data u Used for the development of wildlife criteria u Estimated by multiplying a BCF by a FCM

Formula for FCM Factor used yo account for the food chain interaction and biomagnification u Example: u FCM TL 2 = (BMF TL 2) FCM TL 3 = (BMF TL 2) (BMF TL 3) FCM TL 4 = (BMF TL 2) (BMF TL 3) (BMF TL 4) FCM = food chain multiplier for designated trophic level (TL 2, TL 3 or TL 4); BMF = biomagnification factor for designated trophic level (TL 2, TL 3 or TL 4)

Formula for BMF (BMF TL 2) = (C TL 2) / (C TL 1) (BMF TL 3) = (C TL 3) / (C TL 2) (BMF TL 4) = (C TL 4) / (C TL 3) u Basic difference between FCM and BMF – FCM : related back to trophic level one; – BMF : always related back to next lowest trophic level

Conversion Method u Used if unavailable concerning data u 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) shrimp Mud snail Clam Insects 0. 16 0. 26 0. 42 0. 23 – 0. 3 Organic debris Cladophore Plankton Marsh plants 0. 3 – 13. 0 0. 03 0. 04 0. 33 – 2. 8 Sea-water Fresh-water 1 x 10 -6 1 x 10 -5 (Preston, 1989)

ACCUMULATION VALUE u Terms – BAF – BCF – BMF – FCM of Accumulation = Bioaccumulation Factors = Bioconcentration Factors = Biomagnification Factors = Food Chain Multipliers