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Environmental fate & pathways

Bioaccumulation: terrestrial

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There are no reliable bioaccumulation studies for terrestrial organisms for DMDMH or the hydrolysis product, DMH. Further studies for bioconcentration are triggered only if the risk assessment indicates a concern for predators from secondary poisoning, the substance has a high log Kow or direct or indirect exposure of the terrestrial compartment is likely. Due to the rapid hydrolysis of DMDMH to DMH the active substance would not be available for bioconcentration to occur therefore exposure to the degradation product, DMH, is considered.The potential for bioconcentration of DMH is low based on the calculated BCFearthworm value of 0.087. Furthermore DMH is readily biodegradable, has high water solubility and is unlikely to be applied directly or indirectly to the soil compartment. The risk assessment has not shown any concern for the terrestrial compartment based on the equilibrium partitioning method. The calculated PEC/PNEC ratio is < 1. It is therefore considered that DMH would not bioconcentrate in terrestrial organisms based on these assessments and further studies on terrestrial bioconcentration are scientifically unjustified.

Key value for chemical safety assessment

Additional information

There are no reliable bioaccumulation studies for terrestrial organisms for DMDMH or the hydrolysis product, DMH. Further studies for bioconcentration are triggered only if the risk assessment indicates a concern for predators from secondary poisoning, the substance has a high log Kow or direct or indirect exposure of the terrestrial compartment is likely. Due to the rapid hydrolysis of DMDMH to DMH the active substance would not be available for bioconcentration to occur therefore exposure to the degradation product, DMH, is considered.

For information, a BCFearthworm has been calculated using the logKow for DMH. Due to the rapid hydrolysis of DMDMH to DMH the test substance would not be available for bioconcentration to occur therefore exposure to the degradation product is considered. According to the TGD (EC (2003), part III, chapter 4, p.34) a model was developed by Connell & Markwell (1990) for BCFearthworm using data on pesticides with a log Kow range of 1 to 6. In this model the BCFearthworm was calculated using the following QSAR approach:

BCFearthworm = 1.0.logKow -0.6.

According to the TGD this model can be used to derive a first estimation of the bioconcentration factor in worms in the terrestrial compartment. Applying the experimental derived log Kow for DMH of -0.46 results in the following:

logBCFearthworm(DMH) = 1.0.-0.46-0.6

logBCFearthworm (DMH)= -1.06

BCFearthworm (DMH) = 0.087

The potential for bioconcentration of DMH is low based on the calculated BCFearthworm value of 0.087. Furthermore DMH is readily biodegradable, has high water solubility and is unlikely to be applied directly or indirectly to the soil compartment. The risk assessment has not shown any concern for the terrestrial compartment based on the equilibrium partitioning method. The calculated PEC/PNEC ratio is < 1. It is therefore considered that DMH would not bioconcentrate in terrestrial organisms based on these assessments and further studies on terrestrial bioconcentration are scientifically unjustified.