CRA

Differences between BCF, BAF and BMF

Little Pro on 2017-04-25

Bio-concentration factor (BCF), bio-accumulation factor (BAF) and biomagnification factor (BMF) can be used in assessing the bioaccumulation potential of a substance. In this article, we will summarize their definition and differences.

Comparison of BCF, BAF and BMF

BCF, BAF and BMF all belong to bio-accumulation data and they are obtained from different studies. Their units are also different. In EU, a valid BCF or BAF > 2000 or 5000 indicates bio-accumulative (B) or very bio-accumulative (vB).

Item Definition Unit Testing Method

BCF*

Concentration of test substance in fish or other tissue (mg/kg)/Concentration of the substance in water (mg/L). L/kg
  • OECD TG 305-I: Aqueous Exposure Bioconcentration Fish Test 
BMF ** Concentration of a substance in a predator (mg/kg)/Concentration in the predator’s prey (or food) at steady-state (mg/kg) Unitless
  • OECD TG 305-III: Dietary Exposure Bioaccumulation Fish Test
BAF *** Concentration of test substance in the test organism (g/kg)/Concentration of the substance in the surrounding medium such as sediment or soil (g/kg). Unitless
  • OECD TG 315 Bioaccumulation in Sediment-dwelling Benthic Oligochaetes
  • OECD TG 317 Bioaccumulation in Terrestrial Oligochaetes 

* BCF is the result of a balance between the rate of chemical uptake from the water via the respiratory surface of the test organism (i.e, gills and/or skin) and the elimination of the chemical from the organism. It may also be expressed as the ratio of the uptake rate constant(k1) to the depuration rate constant (k2). 

** For strongly hydrophobic substances (Log Kow > 5 or high Koc and a water solubility below ~ 0.01-0.1 mg/L), testing via aqueous exposure is difficult. In this case, a dietary study in fish is better. A BMF will be identified instead of BCF.

*** BAF is a result of both bio-concentration and bio-magnification. It takes into account of both the exposure from respiratory surface and the dietary exposure. 

Reference

ECHA guidance on information requirements and chemicals safety assessment R.11 PBT assessment

Having Questions?

We do not provide consultancy services. If you have questions or need any help, please contact our sponsor. You may also find an expert in CSP business directory below. If you are a consultant, you may get yourself listed in CSP business directory (free) or sponsor this page to leave your contact info on this page..

 Tags: Topics - CRAEnvironmental Risk Assessment