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Sediment toxicity

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Description of key information

PNEC for bethic organisms can be calculated applying the equilibrium partitioning method using a Kpsed or Kdsed of 4526 L/kg (or Koc of 90520 L/kg) this leads to a PNEC of 0.171 mg/kd dw including the additional correction factor of 10 for additional exposure via ingestion. 
Two valid long-term test have been performed. One with Lumbriculus variegatus, an endobenthic worm, and resulted in an EC10 of 84.6 mg/kg dw and one with Caenorhabditis elegans which resulted in an EC10 of 219 mg/kg dw. From this endpoint a PNEC of 1.692 mg/kg dw can be calculated applying an assessment factor of 50. As the test substance is an ionic substance the reliability of the actual test is considered to be higher than the reliability of the EPM based PNEC.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:
84.6 mg/kg sediment dw

Additional information

PNEC sediment based on EPM

In the absence of measured data the PNECsedcan be provisionally calculated using the equilibrium partitioning method (EPM). According to the TGD this method uses the PNECaquaticand the sediment/water partitioning coefficient as inputs. However, since the available PNECaquaticis based on the bulk concentration present in surface water a re-calculation is necessary first:

PNECaquatic, dissolved               =        PNECaquatic bulk/ (1 + Kpsusp* SUSPwater* 10-6)

Where:        

PNECaquatic bulk =      0.214 µg/l

 Kpsusp            =      9052 l.kg-1

 SUSPwater        =      15 mg.l-1(EU TGD, 2003)

The PNECsedis then calculated using the equations detailed in the TGD (2003):

 PNECsed                         =   Ksusp-water* PNECaquatic dissolved* 1000 * 1 / RHOsusp

Where:      

PNECaquatic dissolved =      0.188µg/l

Ksusp-water             =      2264 m3.m-3

RHOsusp               =      1150 kg.m-3(TGD, equ. 18)

PNECsed-EPM                     = 0.372 mg/kg ww = 1.71 mg/kg dw without correction for additional exposure via ingestion

PNECsed-EPM                     = 0.0372 mg/kg ww  = 0.171 mg/kg dw with correction for additional exposure via ingestion

Two valid long-term test have been performed. One with Lumbriculus variegatus, an endobenthic worm, and resulted in an EC10 of 84.6 mg/kg dw and one with Caenorhabditis elegans which resulted in an EC10 of 219 mg/kg dw. From this endpoint a PNEC of 1.692 mg/kg dw can be calculated applying an assessment factor of 50. As the test substance is an ionic substance the reliability of the actual test is considered to be higher than the reliability of the EPM based PNEC.