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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Remarks:
study on C12 naphthalene
Adequacy of study:
key study
Study period:
from 21 January 2013 to April 11, 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: guidance test with GLP compliance
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Qualifier:
according to guideline
Guideline:
other: Commission Regulation (EC) No 440/2008 of 30 May 2008, Part C: Methods for the determination of ecotoxicity, Publication No. L142, C.2. "Daphnia Sp. Acute Immobilisation Test".
Qualifier:
according to guideline
Guideline:
other: ISO International Standard 6341: "Water quality - Determination of the inhibition of the mobility of Daphnia magna Straus - Acute toxicity test, Third edition, 1996-04-01.
Qualifier:
according to guideline
Guideline:
other: Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23, December 14, 2000.
GLP compliance:
yes
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
no data
Analytical monitoring:
yes
Details on sampling:
Frequency: at t=0 h and t=48 h
Volume: 1 ml from the approximate centre of the test vessels
Storage: Samples were stored in a freezer until analysis.
Vehicle:
no
Details on test solutions:
All test solutions were individually prepared. Preparation of test solutions started with loading rates that were magnetically stirred for one day to ensure reaching maximum dissolution in test medium. This resulted in clear solutions containing a floating layer. Consequently, these were left to settle for another day after which the clear and colourless Water Accommodated Fractions (WAFs) were collected by means of siphoning. The final test solutions were all clear and colourless.
Test organisms (species):
Daphnia magna
Details on test organisms:
Species: Daphnia magna (Crustacea, Cladocera) (Straus, 1820), at least third generation, obtained by acyclical parthenogenesis under specified breeding conditions.
Source: In-house laboratory culture with a known history.
Validity of batch: Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs of stress such as mortality >20 %, presence of males, ephippia or discoloured animals and there was no delay in the production of the first brood.
Characteristics: For the test selection of young daphnids with an age of < 24 hours, from parental daphnids of more than two weeks old.
Feeding: Daily, a suspension of fresh water algae
Medium: M7
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
180 mg/l expressed as CaCO3
Test temperature:
The temperature of the test medium was 19.8-19.9°C at the start of the test. The temperature continuously measured in a temperature control vessel varied between 19.1 and 19.7°C during the test.
pH:
7.9-8.0
Dissolved oxygen:
8.6-9.5 mg/l
Salinity:
no data
Nominal and measured concentrations:
nominal: WAFs prepared at loading rates of 10, 18, 32, 56 and 100 mg/l.
measured: 0.62 mg/l
Details on test conditions:
Controls: Test medium without test substance or other additives.
Test vessels: 100 ml, all-glass. A net was included just below the surface as a physical barrier.
Medium: Adjusted ISO medium
Number of daphnids: 20 per concentration
Loading: 5 per vessel containing 80 ml of test solution
Light: 16 hours photoperiod daily
Feeding: No feeding
Aeration: No aeration of the test solutions
Introduction of daphnids: Within 22 minutes after preparation of the test solutions.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
NOELR
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
0.62 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 0.62 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
Analysis of the samples taken at the start of the final test showed measured concentrations for peak 1 varying between 0.087 and 2.6 mg/l without a clear relation to the loading rate. After 48 hours these concentrations had all decreased to 13-21 % of initial. Similar results were obtained for peak 2. Initially, concentrations ranged between 0.078 and 1.3 mg/l. These concentrations decreased to 19-23 % of initial after 48 hours. The actual test range was based on average exposure concentrations of peak 2, being a worst-case approach (lowest concentrations measured). The range tested corresponded with 0.16, 0.44, 0.29, 0.034 and 0.62 mg/l at the loading rates of 10, 18, 32, 56 and 100 mg/l, respectively.
Despite the presence of a more pronounced floating layer (compared to the combined limit/range-finding test) from 24 hours onwards in the various WAFs prepared, no significant effects were observed in any of the solutions tested. This was likely a result of the use of nets that prevented daphnia reaching the surface. Hence, no effects occurred up to the limit of solubility in test medium.
Results with reference substance (positive control):
The 48 h-EC50 was 0.38 mg/l with a 95 % confidence interval between 0.34 and 0.45 mg/l.
The actual responses in this reference test with K2Cr2O7 were in the lower range of the expected historical responses at the different concentrations, i.e. a 48h-EC50 between 0.3 and 1.0 mg/l. Hence, the sensitivity of this batch of D. magna was in agreement with the historical data collected at WIL
Research Europe.
Reported statistics and error estimates:
No statistical was used because the test substance proved to be non-toxic (EC50 > maximum soluble concentration).

Combined limit/range-finding test

No immobility was observed in WAFs prepared at loading rates of 1.0 and 10 mg/l. In the WAF prepared at 100 mg/l a total of 70 % of the organisms became immobilised. It was however observed that many organisms became trapped at the surface of the treated solutions and in addition floating material deriving from the test substance was observed at the surface of the replicates incubated with the WAF prepared at 100 mg/l. The latter might have affected the mobility of the daphnia despite the fact that microscopic observations showed that no test substance particles were stuck to the antenna of the daphnia or its filtering system.

Validity criteria fulfilled:
yes
Conclusions:
The 48 h-EC50 exceeded 0.62 mg/l, being the average measured concentration in a WAF prepared at a loading rate of 100 mg/l. (EL50)
Executive summary:

The acute toxicity test with Daphnia magna was performed according to OECD guideline No. 202 under GLP compliance. The result showed the test substance did not induce acute immobilisation of Daphnia magna at 0.62 mg/l, being the average measured concentration in a WAF prepared at a loading rate of 100 mg/l after 48 hours of exposure (NOEC). The 48 h-EC50 exceeded 0.62 mg/l, being the average measured concentration in a WAF prepared at a loading rate of 100 mg/l (EL50).

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across: supporting information
Remarks:
read-across details
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Remarks on result:
not measured/tested
Remarks:
based on read-across
Conclusions:
Based on a read-across the EL50 of the substance is set at >100 mg/L

Description of key information

In a study on an analogue, the 48 h-EC50 exceeded 0.62 mg/l, being the average measured concentration in a WAF prepared at a loading rate of 100 mg/l.

The EL50 is 100 mg/L.

The data on the analogue can be used as read-across to assess the toxicity towards daphnia (see section 13)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
100 mg/L

Additional information

The acute toxicity test with Daphnia magna was performed according to OECD guideline No. 202 under GLP compliance. The result showed the test substance did not induce acute immobilisation of Daphnia magna at 0.62 mg/l, being the average measured concentration in a WAF prepared at a loading rate of 100 mg/l after 48 hours of exposure (NOEC). The 48 h-EC50 exceeded 0.62 mg/l, being the average measured concentration in a WAF prepared at a loading rate of 100 mg/L (EL50).