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Sediment toxicity

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Reference
Endpoint:
sediment toxicity: long-term
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline available
Principles of method if other than guideline:
Based on a method described by Phipps GL; Ankley GT; Benoit DA; Mattson VR. 'Use of the aquatic oligochaete Lumbriculus variegatus for assessing the toxicity and bioaccumulation of sediment-associated contaminants'. Environ.Toxicol.Chem., Vol.12, 1993, 269-79 and aspects of OECD draft guideline no. 218 (2001)
GLP compliance:
yes (incl. QA statement)
Details on sediment and application:
A suspension of sphagnum peat and finely leaves of stinging nettle (Urtica sp) was prepared in reconstituted water. This suspension was used to prepare the artificial sediment which consisted of sand: clay: peat [75:20:5 by dry weight]. The reconstituted water was a solution of recommended quantities of specified inorganic salts in deionised water and was prepared according to OECD Guidleine 203 (1992)
Test organisms (species):
Lumbriculus variegatus
Study type:
laboratory study
Test type:
static
Water media type:
freshwater
Type of sediment:
artificial sediment
Duration:
28 d
Exposure phase:
total exposure duration
Hardness:
Measured at the beginning and end of the 28 d exposure period.
Test temperature:
19.5°C (mean value from 36 measurements)
19.1°C - 19.7°C
pH:
Measured at the beginning and end of the 28 d exposure period.
Dissolved oxygen:
Measured every few days of the 28 d exposure period.
Nominal and measured concentrations:
Loadings of 3.75, 7.5, 15, 30 and 60 mg MDA.kg-1 sediment (dry weight).
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
>= 60 mg/kg sediment dw
Basis for effect:
mortality
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
< 3.75 mg/kg sediment dw
Basis for effect:
other: biomass, dry weight
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
42.6 mg/kg sediment dw
Basis for effect:
other: biomass, dry weight
Remarks on result:
other: calculated
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
3.75 mg/kg sediment dw
Basis for effect:
reproduction
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
14.1 mg/kg sediment dw
Basis for effect:
reproduction
Remarks on result:
other: calculated
Duration:
28 d
Dose descriptor:
LOEC
Effect conc.:
3.75 mg/kg sediment dw
Basis for effect:
other: biomass, dry weight
Details on results:
Analysis for MDA was not carried out as in the first study with Lumbriculus variegatus (Egeler & Ginzburg 2001) it had been clearly demonstrated that MDA was strongly adsorbed/bound to the sediment.

Description of key information

Three key studies with different species are available. To assume a worst-case scenario the most sensitive value 3.75 mg/kg dw (Egeler, 2002) achieved with Lumbriculus variegatus was used for PNEC derivation.

Key value for chemical safety assessment

EC50 or LC50 for freshwater sediment:
14.1 mg/kg sediment dw
EC10, LC10 or NOEC for freshwater sediment:
3.75 mg/kg sediment dw

Additional information

Experimental non-guideline studies on three different species representing different feeding and living types associated with sediment are available. The studies were conducted according to GLP regulations and generally accepted scientific principles. All studies are deemed to be long-term and NOEC values ranging from 3.75 to 500 mg MDA/kg sediment (dry weight) were obtained (Egeler, 2002; Egeler & Gilberg, 2005a,b). To assume a worst-case scenario the most sensitive value 3.75 mg/kg dw  based on reproduction (Egeler, 2002) achieved with Lumbriculus variegatus was used for PNEC derivation.


Two other non-guideline, GLP study with Lumbriculus variegatus obtained a NOEC of 50.3 mg/l based on survival, reproduction, and biomass after 28 d of exposure to the test item (ECT, 2000) and 25.2 mg/kg dw based on reproduction (Egeler & Ginzburg, 2001). These studies revealed less sensitive values and were therefore used only as additional information and not for PNEC derivation.