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EC number: 273-227-8
CAS number: 68953-84-4
Key study - exposure via the diet: : bioaccumulation study in rainbow trout with radiolabeled R-898, K2, GLP, OECD guidelines followed where possible.* BMFL (lipid normalized growth corrected biomagnification factor): 0.174* BMFK (growth corrected dietary kinetic biomagnification factor): 0.065* Fish-growth corrected half life of 4.58 days.
bioaccumulation potential of DAPD is assessed in fish exposed via the
water as well as via the diet.
bioaccumulation study with exposure via the water (Tadokoro, 1998) is
considered to be unreliable based on the following observations:
Due to the tendency of DAPD to adsorb to glass surfaces and organic
matter, difficulties were faced with maintaining a stable test substance
concentration. As a result, the validity criterion regarding the
measured concentrations of the test substance in the water is not
The reliability of the BCF values calculated in this aquatic
bioaccumulation study is low due to:
two fish replicates per sampling occasion,
in the measured concentrations of the test substance in the water exceed
the allowed level of variation described in the OECD guideline, and
variations in the measured concentrations of the test substance in the
two fish at each sampling occasion were observed where concentrations up
to 50% greater were seen in the second fish at that sampling occasion.
The BCF values that are calculated from the aquatic bioaccumulation
study are overestimates due to a combined exposure of the test fish via
the food and the water.
based on the observed deviations from the OECD 305 guideline and on the
physico-chemical properties indicating the risk for combined exposure of
the fish via both aquatic and dietary routes, the BCF study by Tadokoro
is considered to be not reliable and should be disregarded in the
assessment of the bioaccumulative properties of DAPD.
dietary bioaccumulation study by Vaughan was conducted according to the
OECD 305 guideline published in October 2012 without any significant
deviations from the protocol.
substances with a physico-chemical profile including low water
solubility and a high tendency for sorption to soils, sediment, and
other solids, a dietary bioaccumulation study is recommended by OECD.
More reliable results will be obtained for these substances when
bioaccumulation is examined following exposure via the diet as the
technical difficulties associated with the formation of stable test
substance concentration in the water are avoided.
the dietary bioaccumulation experiment, radio-labelled R-898 was mixed
with the fish feed. Rainbow trout were dosed with this feed for 14 days,
followed by a 14 day depuration period. The presence of the radioactive
tracer in the exposed fish was examined using liquid scintillation
growth-corrected depuration rate constant of 0.151/day was derived from
the measured concentrations of DAPD equivalents in fish body tissue
during depuration. A fish growth corrected half life of 4.58 days,
substance assimilation efficiency of 0.491 and growth corrected/lipid
normalised growth corrected kinetic biomagnification factors ( 0.0065
and 0.174, respectively) were calculated.
estimated bioconcentration factor of 2107 (fish body tissue) was also
determined. In order to determine a bioconcentration factor an uptake
rate constant is estimated based on fish weight and using key
assumptions, such as the uptake rate constant obeying first order
kinetics. While an estimated bioconcentration factor may be useful in
predicting the bioaccumulative nature of a test substance, the
biomagification factor is considered a more appropriate measure in the
case of a dietary bioaccumulation test.
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