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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:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Remarks:
KL2 due to RA
Justification for type of information:
Refer to the Quaternary ammonium salts (QAS) category or section 13 of IUCLID for details on the category justification. The study with the read across substance is considered sufficient to fulfil the information requirements as further explained in the provided endpoint summary.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
not specified
Analytical monitoring:
yes
Vehicle:
yes
Test organisms (species):
Daphnia magna
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Remarks on exposure duration:
Because of the very rapid removal of the test substance from the water column, the geometric mean of the 0, 24 and 48-h concentrations was considered to be the overall exposure concentration in the acute toxicity tests.
Hardness:
Laboratory blended water (total hardness ~150 mg/L)
Southwest well water (total hardness ~350 mg/L)
River water (total hardness ~300-350 mg/L)
Nominal and measured concentrations:
Please refer to the table 1 of the attached background material for details on nominal and measured concentrations of all three test water types.
Details on test conditions:
Three water types were used in this test: laboratory blended water (total hardness ~150 mg/L), Southwest well water (total hardness ~350 mg/ L) and river water (total hardness ~300-350 mg/L).

The river water, exemplifying a natural surface water that received sewage effluent, was collected from the White River (Indiana) and transported for cold storage (~4°C).

Acute toxicity tests of 48-h duration were conducted in each water type employing seven concentrations of test substance plus control and an isopropanol (IPA) control. The tests were repeated to ensure reproducibility. The same procedures were utilized in the repeat tests with the exception of testing a more recently collected batch of White River water. There was no renewal of test waters throughout the 48-h test period. Mortality was recorded daily and water chemistry measurements were taken at the beginning and conclusion of the test period for control waters only. Each test substance concentration was verified by radiochemical counting of triplicate 10 mL samples collected from the fresh stock solution (0 h) and from a randomly selected beaker after 24 and 48 h.
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
17.5 µg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
mortality
Remarks on result:
other: In Southwest well water (LC50 values in the initial and repeat tests were 19.8 and 15.3 μg/L, respectively).
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
12.6 µg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
mortality
Remarks on result:
other: In blended water (LC50 values in the initial and repeat tests were 16.3 and 8.8 μg/L, respectively).
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
98.9 µg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
mortality
Remarks on result:
other: In river water (initial test result only).
Details on results:
In the initial acute toxicity tests, little difference existed between LC50 values for blended and well waters. The river water LC50, however, was 5 to 11 times higher, possibly related to the presence of solids causing test substance adsorption and reduced bioavailability. An additional factor may have been that the river water contained endogenous nutritional sources perhaps enhancing daphnid resistance to the effects of the test substance.

Please refer to the table 2 of the attached background material for mortality data.
Reported statistics and error estimates:
The 48-h LC50 values were determined by probit analysis based on the geometric mean of the 0, 24 and 48-h concentrations to reflect overall exposure concentrations.
Conclusions:
Based on the results of the read across study, the 48 h LC50 values for the test substance, Oleyl TMAC, is considered to be 0.0175 mg a.i./L in Southwest well water, 0.0126 mg a.i./L in blended water and 0.0989 mg a.i./L in river water.
Executive summary:

A guideline equivalent study was performed to assess the acute toxicity of the read across substance, C16-18 and C18-unsatd. TMAC (acitve: 48.4%), to Daphnia magna under static conditions. Twenty Daphnids were exposed to seven concentrations of the test substance in three different water types (i.e., laboratory blended water, Southwest well water and river water). The tests were repeated to ensure reproducibility. Mortality was recorded daily and water chemistry measurements were made at the beginning and end of the test period for control waters only. Analytical determination of test substance was performed. Test substance concentrations were verified by radiochemical counting of triplicate 10 mL samples collected from the fresh stock solution (0 h) and from a randomly selected beaker after 24 and 48 h. Under the test conditions, the 48 h LC50was 0.0175 mg a.i./L in Southwest well water, 0.0126 mg a.i./L in blended water and 0.0989 mg a.i./L in river water (Valentine and Bishop, 1992). Based on the results of the read across study, similar 48 h LC50 values can be considered for the test substance, Oleyl TMAC, for short-term toxicity to Daphnia..

Description of key information

Based on the results of the read across study, the 48 h LC50 values for the test substance, Oleyl TMAC, is considered to be 0.0175 mg a.i./L in Southwest well water, 0.0126 mg a.i./L in blended water and 0.0989 mg a.i./L in river water.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.013 mg/L

Additional information

A guideline equivalent study was performed to assess the acute toxicity of the read across substance, C16-18 and C18-unsatd. TMAC (active: 48.4%), to Daphnia magna under static conditions. Twenty Daphnids were exposed to seven concentrations of the test substance in three different water types (i.e., laboratory blended water, Southwest well water and river water). The tests were repeated to ensure reproducibility. Mortality was recorded daily and water chemistry measurements were made at the beginning and end of the test period for control waters only. Analytical determination of test substance was performed. Test substance concentrations were verified by radiochemical counting of triplicate 10 mL samples collected from the fresh stock solution (0 h) and from a randomly selected beaker after 24 and 48 h. Under the test conditions, the 48 h LC50was 0.0175 mg a.i./L in Southwest well water, 0.0126 mg a.i./L in blended water and 0.0989 mg a.i./L in river water (Valentine and Bishop, 1992). Based on the results of the read across study, similar 48 h LC50 values can be considered for the test substance, Oleyl TMAC, for short-term toxicity to Daphnia..