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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations:0-0.46-0.29-0.2-0.1-0.05-0.025 mg/L
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
Species: Daphnia magna DM 04 02 K36
Test organisms are grown at the VITO laboratory facility .
For the test neonate organisms (< 24 hours of age) were used.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Reference substance (positive control):
no
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
CdTe
Basis for effect:
mortality
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
0.29 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
CdTe
Basis for effect:
mortality
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
CdTe
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
0.29 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
CdTe
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
LC50
Effect conc.:
0.25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
CdTe
Basis for effect:
immobilisation
Details on results:
There was no mortality and no effect on reproduction outcome in the concentrations 0.025-0.2 mg/L when compared to the control. At the next concentration (0.29 mg CdTe/L) mortality is 90% by the end of the test.
Reported statistics and error estimates:
Mortality of the parent organisms.
Reproduction output is assessed:
a) time to first brood
b) total number of live offspring produced per living parent organism after 21 days of exposure (mean of 10 replicates).
LOEC and NOEC values for mortality and reproduction effects were established using students t-test to identify statistically significant differences when compared to the control values.
LT50 values were derived for the test concentrations that caused >50 % mortality during the exposure period.

Mortality and reproduction impairment both manifest themselves in the same concentration range, and effects on reproduction can therefore not be assessed seperately. The water fraction of DA of 0.2 mg CdTe/L has no effect on mortality nor reproduction output, while the water fraction of DA of 0.29 mg CdTe/L has a high effect on mortality and also reduces the number of offspring in the one surviving organism. This range (0.2 -0.29 mg CdTe/L) is very narrow and it was decided not to repeat the test with concentrations in between.

Mean number of offspring per surviving parent for the different test conditions. SD= standard deviation, t-test= two -tailed t-test.

 concentration (DA mg/L) mean  SD  t-test   
81  14     
0.025  99  19  0.033  stimulating effect 
0.05  100  25  0.057   no effect 
0.1  117  23  0.001  stimulating effect 
0.2  101  24  0.043  no effect 
0.29  25  na  effect 
Validity criteria fulfilled:
yes
Conclusions:
Test done according standard protocol. Study considered useful for classification.
Executive summary:

The water soluble fraction of CdTe after DA was toxic to Daphnia. NOEC and LOEC for reproduction and mortality was 0.2 and 0.29 mg CdTe/L respectively. This is also the EC50 range for effects on reproduction.

Description of key information

Only one test was available with Daphnia magna as test organism and CdTe as toxicant.

The NOEC was 0.2 mg CdTe/L. No marine data was available.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
0.2 mg/L

Additional information

The water soluble fraction of CdTe after DA was toxic to Daphnia. NOEC and LOEC for reproduction and mortality was 0.2 and 0.29 mg CdTe/L respectively. This is also the EC50 range for effects on reproduction.

As Cd2+ ion determines ecotoxicity, the PNEC deriviation will be based on the Cd 2+ ion as determined in the RA (ECB 2007).