Bioconcentration Factor in Solvents
Definition
Measure of the tendency for a substance in water to accumulate in fish tissue or in issues of other organisms. The equilibrium concentration of a substance in fish can be estimated by multiplying the concentration of the substance in the surrounding water by the fish bioconcentration factor for that chemical. This parameter is an important determinant for human intake by the aquatic food ingestion route. After USEPA, 1986.
Rationale
Bioconcentration potential describes the tendency of certain substances to concentrate within biological tissues. These materials then have the potential to propagate through the food chain and end up in higher-level organisms. This is of particular concern if these substances have any known toxic effects.
Substances with bioconcentration factors (BCF > 500) coupled with moderate to high toxicity and slow biodegradation pose higher risk to human health and ecosystems than substances without these properties. Substances with low Kow (or Pow) values <3 or <7 have little potential to bioconcentrate.
Listing Requirements
- If (L/E/IC50) ≤ 1 ppm, then may be acceptable if biodegradation occurs within a 10-day window and BCF < 1000.
- If (L/E/IC50) > 1 ppm and ≤ 10 ppm, then biodegradation must occur within a 10-day window and BCF < 1000.
- If (L/E/IC50) > 10 ppm and < 100 ppm, then biodegradation must occur within 28 days without products of concern and BCF < 1000.
- If (L/E/IC50) ≥ 100 ppm, then biodegradation need not occur within 28 days if there are no products of concern and half-life < 180 days and BCF < 1000.
Data and Submission Guidance
There are three ways to derive bioconcentration factor (BCF): by direct measurement, by estimation from a log Kow value, or by estimation through modeling.
Some of the available test methods include, in order of preference:
Some of the available test methods include, in order of preference:
- Measurement of BCF using OECD Test No. 305
- Estimation of BCF from log using OECD Test No. 107 or OECD Test No. 117
- Modeling of BCF using EPA’s BCFWIN model or OASIS CATABOL