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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 6th June 2007 to 26th July 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study in compliance with international guidelines
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: OECD Guidance Document No. 23 “Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures” (September 2000)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information): not applicable
Analytical monitoring:
yes
Details on sampling:
After the test sample was added into the dilution water filled in Erlenmeyer flask with micro volumeter (Eppendorf Co., Ltd) to prepare test solution of 100 mg/L as nominal concentration, the flask was immediately sealed with a plug not to produce head space. The solution was gently stirred by magnetic stirrer for approx. 24 hours under 20 ±1 °C to produce dispersed solution with suspended test item. After cease of stirring, the solution was settled for approx. 1 hour and then test solution was prepared by taking out from the middle layer of the settled solution. The prepared test solution was immediately divided into each test vessel and covered with glass lid not to produce head space.
Vehicle:
no
Details on test solutions:
No correction with purity was done for the preparation of the test concentration. The test sample was employed in terms of volume using the density [1.554 g/cm3(25 °C)] for the preparation of test solution.
After the test sample was added into the dilution water filled in Erlenmeyer flask with micro volumeter (Eppendorf Co., Ltd) to prepare test solution of 100 mg/L as nominal concentration, the flask was immediately sealed with a plug not to produce head space. The solution was gently stirred by magnetic stirrer for approx. 24 hours under 20 ±1 °C to produce dispersed solution with suspended test item. After cease of stirring, the solution was settled for approx. 1 hour and then test solution was prepared by taking out from the middle layer of the settled solution. The prepared test solution was immediately divided into each test vessel and covered with glass lid not to produce head space.
Test organisms (species):
Daphnia magna
Details on test organisms:
Young daphnids produced by parents which were cultured in the Kurume Laboratory were used. Daphnids [Daphnia magna (Clone A)] originally came from the University of Sheffield (Address: Sheffield SlO 2UQ, United Kingdom). The parents to obtain young daphnids were bred in the same quality of water (dechlorinated tap water), water temperature (20 ±1 °C), photoperiod (16-hour light/8-hour dark) as used in the test. Parents used for the test were same lot and bred for more than 14 days, and their age and survival rate were 14-day old and 100%, respectively. Chiorella vulgaris of 0.1 to 0.2 mgC/day per daphnia was fed to the parents once a day. A 48-hour acute immobilization test of K2Cr2O7 (Reagent grade, Wako Pure Chemical Industries, Ltd.) with the test organisms was conducted (on April 9 to April 11, 2007) to confirm the reproducibility of the test conditions. The 48-hour EC50 of K2Cr2O7 was 0.270 mg/L. This value was within the normal range in this laboratory (mean ± 2S.D.: 0.122 to 0.350 mg/L) [mean ± S.D.: 0.236± 0.057 mgIL (n=58)].
Test type:
semi-static
Limit test:
yes
Total exposure duration:
48 h
Post exposure observation period:
not applicable
Hardness:
as CaCO3: 41.9 mg/L
Test temperature:
20 ± 1 °C
pH:
7.9 at 22 °C
Dissolved oxygen:
The study was performed in the condition where dissolved oxygen concentration was more than 60% of the saturation at the test temperature. No aeration was used for the test during the exposure.
Salinity:
no data
Nominal and measured concentrations:
The test sample and dilution water were mixed to prepare 100 mg/L (nominal concentration), and they were stirred under closed system for approx.24 hours. After settlement for approx. 1 hour, test solution was prepared by taking out from the middle layer.
Solubility of the test item in dilution water (20 ±1 °C) 0.181 mg/L
Concentration of test item in test solution (Percentage of concentration at preparation)
At the start of the exposure and after the renewal 0.193 and 0.127 mg/L
Before the renewal and at the end of the exposure 0.157 and 0.103 mg/L
(81.4 and 81.3%)
Concentration of 13F-EtOH (hydrolized test material) in test solution
At the start of the exposure and after the renewal 0.0178 and 0.0126 mg/L
Before the renewal and at the end of the exposure 0.0459 and 0.0208 mgIL
Details on test conditions:
Observation of test organisms
Immobility and symptom were observed at 24 and 48 hours after the exposure. Daphnids were considered immobile if they were not able to swim within 15 seconds after gentle agitation of the test vessel.
Appearance of test solution
Appearance of the test solutions was observed at the start and before the renewal (after 24 hours).
Condition of test solutions
Dissolved oxygen concentration, pH and temperature of the test solutions were measured at the start of the exposure, before and after the renewal, and at the end of the exposure (twice of a set of preparation and 24 hours after). At the start of the exposure, another solution sampled from the container for preparation was used for the measurement. At 24 hours after the preparation, the measurement was carried out for one test vessel in each level. The dissolved oxygen concentration measurements were carried out with an oxygen meter (YSI Model 58, YSI Incorporated.). The pH measurements were carried out with a pH meter (Model HM-21P, DKK-TOA). The temperature measurements were carried out with a calibrated red alcohol thermometer of glass stick type.
Reference substance (positive control):
not specified
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 0.141 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 0.141 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
No immobility of the test organism was observed in the exposure level during exposure. Immobility at 24 and 48 hours are shown in Table 1. In the control, no trapping daphnids at the surface was observed, and immobility during the exposure was 0%, which meets the criterion for the validity of the test (i.e. not more than 10%).
Observed abnormal response
There was no abnormal response in the control.
The following results of observation were based on the comparison with the control organisms. No abnormal responses were obtained in the test level during exposure.
Results with reference substance (positive control):
not applicable
Reported statistics and error estimates:
no data

This study was conducted as a limit test in order to confirm the effect of the test item on the test organisms at the concentration around the solubility of the test item in dilution water. Although one of the measured concentrations of the test item during the exposure was low (0.127 mgIL) compared with the solubility (0.181 mg/L) measured concurrently with the definitive study, it was thought that the concentrations of the test item in the test solution at the preparation were around the solubility because the values measured in the solubility study fluctuated and the concentration of 0.124 mg/L was in them. The measured concentrations at 24 hours after the preparation decreased but not so much as it was predicted from the result of the preliminary studies. Since no adverse effect was found under the condition in the definitive study, it was concluded that the test item had no adverse acute effect on the test organisms at the concentration around the solubility in dilution water. On the other hand, the concentration of 13F-EtOH which was hydrolyzed product of the test item tended to increase in test solution, and the measured concentrations were 0.0126 to 0.0459 mg/L. However, it was concluded that the hydrolyzed product had no adverse effect on the test organisms due to the result of the study.

Validity criteria fulfilled:
yes
Conclusions:
In this limit test with daphnids for acute toxicity no effects were observed up to the limit of solubility (LC50 >0.141 mg/L). The nominal concentration applied was 100 mg/L.
Executive summary:

This study was conducted as a limit test at the concentration around solubility of the test item in dilution water to confirm the effect on the test organisms. It was concluded that the test item has no acute toxicity to the test organisms at the concentration around water solubility, since the measured concentrations of the test solutions at the preparation were around the solubility in dilution water and no effect on the test organisms was observed under the test condition.

Description of key information

EC50 (48 hrs, Daphnia magna)_OECD guideline 202 (Daphnia sp. Acute Immobilisation Test) >0.141 mg/L (geom. mean of measured concentration), limit test.
Since this concentration was considered to be around solubility of the substance, the EC50 (48h, nominal) was considered >100 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
100 mg/L

Additional information

The GLP study was conducted as a limit test in order to confirm the effect of the test item on the test organisms at the concentration around the solubility of the test item in dilution water. Although one of the measured concentrations of the test item during the exposure was low (0.127 mg/L) compared with the solubility (0.181 mg/L) measured concurrently with the definitive study, it was thought that the concentrations of the test item in the test solution at the preparation were around the solubility because the values measured in the solubility study fluctuated and the concentration of 0.124 mg/L was in them. The measured concentrations at 24 hours after the preparation decreased but not so much as it was predicted from the result of the preliminary studies. Since no adverse effect was found under the condition in the definitive study, it was concluded that the test item had no adverse acute effect on the test organisms at the concentration around the solubility in dilution water. On the other hand, the concentration of 13F-EtOH which was hydrolyzed product of the test item tended to increase in test solution, and the measured concentrations were 0.0126 to 0.0459 mg/L. However, it was concluded that the hydrolyzed product had no adverse effect on the test organisms due to the result of the study.