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Read across from a structurally similar Quats (DODMAC) can be applied.

The following table gives an overview of the available data on bioconcentration/bioaccumulation of DODMAC as listed in the EU Risk Assessment DODMAC (EU, 2002) and the ECETOC Technical Report No. 53 (ECETOC, 1993). References mentioned below can be found in these two reports as well.

Env. Compartment Endpoint Type Value Accumulation
potential
Remark
           
Freshwater BCFfish measured 13 L/kg wwt. low Lewis et al, 1983
Freshwater sediment BSAFsediment measured 0.28 low Conrad, 1999
Freshwater sediment BSAFsediment measured 0.78 low Comber, 2000
Soil BCFworm estimated 3 L/kg wwt. low estimated from
BCFfish

In the EU Risk Assessment DODMAC the following assessment of the data is given.

Lepomis macrochiruswas exposed to14C-DHTDMAC for 49 days in a continuous flow-through system in river water and laboratory water with mean concentrations in the test period of 18 µg/l and 16 µg/l respectively (no solvent carrier, Lewis & Wee, 1983). The river water was sampled at Town River, Massachusetts, and contained 2-84 mg/l suspended solids, 0.04-0.59 mg/l methylene blue active substances - MBAS and 10-15 mg/l disulfine blue active substances - DBAS (pH = 6.4-7.7, total hardness = 14-38 mg/l CaCO3). In river water BCFs of 13 l/kg in the whole body and 94 in the inedible tissue (viscera) were estimated based on measured concentrations. When laboratory water was used the respective BCFs were 32 and 256 l/kg. In both waters DODMAC did not concentrate to a significant degree in edible tissue (BCFof the fillets < 5 l/kg). In a depuration phase in well water 93% of the accumulated radioactivity was eliminated from the inedible tissues after 14 days.

The short-term uptake (24h) of DODMAC by juvenilePimephales promelaswas assessed in a flow-through system with laboratory water and two different concentrations of humic acids (Versteeg & Shorter, 1992). A depuration phase of 72 hours followed. Compared with the laboratory water controls 6.8 mg/l humic acids decreased the uptake rate by a factor of 20 and increased the depuration rate twofold.

These values indicate the dependence of theBCF-values on the surrounding medium which is also obvious in ecotoxicological testing (see below). Based on test results with laboratory water, a bioaccumulation is indicated, but it is assumed that it is low under environmental con­ditions. A BCF of 13 l/kg is used in the risk assessment (related to PECbulk), assuming fish to be representative for all aquatic organisms. It should be pointed out, that for the diversity of organisms and environmental conditions the bioaccumulation potential (bioconcentration and biomagnification) is not known. A relatively simple microcosm study might clarify these uncertainties.

Bioaccumulation of14C-labelled DODMAC by Lumbriculus variegatus from a natural sediment was measured over a period of 28 days. The total organic carbon content of the sediment was 1.73 %. Worms were exposed to DODMAC concentrations in the sediment in the range of 150 - 5800 mg/kg dw. After 28 days the DODMAC tissue concentration in the worms was measured by liquid scintillation counting. A Biota Sediment Accumulation factor (BSAF) of 0.28 was derived from the experimental data. As the concentration in the worms was only measured at the end of the 28 day test period it is not clear whether equilibrium was reached (Conrad et al., 1999).

The aim of a second experiment was the identification of the main uptake routes of DODMAC by Lumbriculus variegatus from the sediment. For this test feeding and non-feeding worms were exposed to a sediment containing 8.7 mg/kg of DODMAC. A viable non-feeding worm was generated by removing the head of an intact feeding worm. The new worm is unable to ingest sediment for up to 6 - 8 days. The use of non-feeding worms allows the contribution of ingestion as an uptake route to be assessed. A 13 day bioaccumulation study with feeding and non-feeding Lumbriculus variegatus showed that the main route of uptake for DODMAC was via sediment ingestion. At day 5 a comparison of tissue concentrations between the feeding and non-feeding worms showed that around 86 % of the body burden in the feeding worms could be attributed to ingestion (Conrad et al., 1999).

Bioaccumulation of14C-labelled DODMAC by Tubifex tubifex from a natural sediment was measured over a period of 28 days. The total organic carbon content of the sediment was 1.73 %. Worms were exposed to DODMAC concentrations in the sediment in the range of 300 - 5000 mg/kg dw. After 28 days the DODMAC tissue concentration in the worms was measured by liquid scintillation counting. A Biota Sediment Accumulation factor (BSAF) of 0.78 was derived from the experimental data. As the concentration in the worms was only measured at the end of the 28 day test period it is not clear whether equilibrium was reached (Comber/Conrad, 2000).

To evaluate the uptake of DODMAC (purity > 98%) by plants, soil experiments were conduc­ted with tomato, bean, cucumber and radish seedlings. DODMAC was applied to soil adsor­bed to activated sludge (2 g/kg) and a concentration of 2 mg DODMAC/kg soil was achieved. Concentrations of 0.02 to 0.05 mg/kg were found in the shoots of the plant seedlings and the radish roots after 28 to 36 days exposure (Lötzsch et al., 1984).

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