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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:
2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study carried out according to existing guidelines and GLP.
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
The daphnids were exposed to the water accomodated fraction according to OECD 2000.
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
no data
Vehicle:
no
Details on test solutions:
As the test material was considered poorly soluble, the organisms were exposed to the Water Accomodated Fraction (WAF). In this approach aquous media are prepared by by mixing the test item for a prolonged period of time. At completion of the mixing and settlement the test item phase is then separated and the organisms are exposed to the aquous phase or WAF. Exposures are expressed in terms of the original concentration of the test item in water at the start of the mixing period.
Test organisms (species):
Daphnia magna
Details on test organisms:
The test was carried out with 1-st instar Daphnia magna, which were derived from in-house laboratory cultures.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
not applicable
Hardness:
ca 250 mg/L expressed as CaCO3
Test temperature:
21°C
pH:
7.8
Dissolved oxygen:
saturated
Salinity:
no data
Nominal and measured concentrations:
Nominal concentrations were: 0 (control), 0.10, 0.18, 0.32, 0.56, 1.0, 1.8, 3.2, 5.6, 10 mg/L
Details on test conditions:
Day/night cycle of 16/8 hrs with 20 min dawn and dusk transition periods. During the test the daphnids received no food.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
1.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 1.3 - 1.5 mg/L
Details on results:
The 48 hr EL50 of DBPP are based on the Water Accomodated Fraction.
Results with reference substance (positive control):
The 48 hr EC50 (immobilisation) of potassium dichromate for Daphnia magna was 1.5 mg/L (95% CI 1.3 - 1.7 mg/L).
Reported statistics and error estimates:
Confidence limits were calculated by the trimmed Spearman-Karber method with the ToxCalc computer software.
Validity criteria fulfilled:
yes
Conclusions:
The 48 hr EL50 of DBPP for Daphnia Magna was 1.4 mg/L based on the WAF.
Executive summary:

In a test performed according to OECD guideline 202 Daphnia magna were exposed to dibutyl phenyl phosphate using a Water Accomodated Fraction approach, the 48 hr EL50 of DBPP for Daphnia magna was shown to be 1.4 mg/L (95% CI: 1.3 - 1.5 mg/L).

Description of key information

Different tests assessing the acute aquatic toxicity towards Daphnia magna are available (Goodband and Mullee, 2011; McAllister et al., 1978; Heidolph et al., 1982; LeBlanc, 1980). The most recent study was determined as the Key study with an EL50 (48h) of 1.4 mg/L as this study is performed according to the most recent guidelines.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
1.4 mg/L

Additional information

Short-term toxicity tests (48h LC50) on Daphnia magna are available in which different conditions are evaluated (different types of water, with or without food). The most recent study (Goodband and Mullee, 2011) is regarded as the key study as this study was performed according to the most recent guidelines. The EL50 value reported in this study was not the lowest in comparison to the other studies, however it can be regarded as the most thrust worthy result. Additionally, although a Water Accomodated Fraction was used, based on the water solubility of the substance, the EL50 can be regarded as equal to the EC50. Nevertheless, all LC50 values reported in the other studies (McAllister et al., 1978; Heidolph et al., 1982 and LeBlanc, 1980) all presented EC50 values within a similar range of toxicity. The average EC50 over all tests was 1 mg/L.