Test No. 315: Bioaccumulation in Sediment-dwelling Benthic Oligochaetes
This Test Guideline describes a method to assess bioaccumulation of sediment-associated
chemicals in endobenthic oligochaetes worms. It applies to stable, neutral organic
chemicals having log Kow values between 3.0 and 6.0, superlipophilic substances that
show a log Kow of more than 6.0, or stable metallo-organic compounds which tend to
associate with sediments.
The test consists of two phases. During the uptake phase, worms are exposed to sediment
spiked with the test substance, topped with reconstituted water and equilibrated as
appropriate. Groups of control worms are held under identical conditions. The duration
of the uptake phase is by default 28 days, unless a steady-state has been reached
before. For the elimination phase, the worms are transferred to a sediment-water-system
free of test substance. This second phase is terminated when either the 10% level
of steady state concentration, or of the concentration measured in the worms on day
28 of the uptake phase, is reached, or after a maximum of 10 days. Change of the concentration
of the test substance in/on the worms is monitored throughout both phases of the test.
The uptake rate constant (ks), the elimination rate constant (ke) and the kinetic
bioaccumulation factor (BAFK = ks/ ke) are calculated. Radiolabelled test substances
may be used to determine whether metabolites identification and quantification should
be made. The minimum number of treated replicates for kinetic measurements should
be three per sampling point throughout uptake and elimination phase. To ensure the
test validity (cumulative mortality of the worms < 20% of the initial number), toxicity
tests should also be conducted at regular intervals. Besides, the worm lipid content,
the sediment total organic carbon content and the residue level in worms at the end
of the elimination phase are useful for the interpretation of the results.
Published on October 16, 2008Also available in: French
In series:OECD Guidelines for the Testing of Chemicals, Section 3: Environmental fate and behaviourview more titles