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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
Study period:
From 1980 to 1981
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Principles of method if other than guideline:
Daphnia magna were exposed to six concentrations of the test substance in a 21-d static, daily renewal test. Control and isopropanol control (vehicle; IPA) groups were also evaluated. Three water types were utilised 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 natural surface water that received sewage effluent, was collected from the White River (Indiana) and transported for cold storage (~4°C). The test in blended water was discontinued after 14 d due to inadequate reproduction by control organisms. Mortality was monitored daily and the number of young produced in each beaker was recorded after which they were discarded. Temperature was recorded daily and pH, dissolved oxygen and hardness were determined on alternate days in control waters, both fresh and 24 h old. Daphnid 21-d length was also determined by the use of an ocular micrometer measuring from the base of the spine to the apex of the helmet. Because no statistically significant differences in daphnid length occurred as a result of exposure to increasing concentrations of the test substance, this parameter was not measured in the well water.
GLP compliance:
not specified
Analytical monitoring:
yes
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Isopropanol
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna (< 24 h old)

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
Water hardness value: 332 mg CaCO3/L
Upper water hardness value: 364 mg CaCO3/L
Test temperature:
Temperature value: 19.2°C
Upper temperature value: 21.2°C
pH:
pH Value: 7.5
Upper pH Value: 8.3
Dissolved oxygen:
8.8 - 9.2 mg/L
Nominal and measured concentrations:
Nominal concentrations (μg/L):
Southwest well water: 2.5, 5.0, 10.0, 20.0, 40.0 and 80.0 μg/L
River water: 74.4, 110.4, 146.4, 218.4, 290.4 and 578.4 μg/L
Measured concentrations (μg/L; values represent the geometric mean of the 0- and 24-h concentration analyses):
Southwest well water: 1.6, 3.1, 6.8, 14.6, 30.6 and 60.8 μg/L
River water: 35.7, 53.4, 68.3, 99.1, 122.3 and 309.3 μg/L
Details on test conditions:
TEST SYSTEM
- Renewal rate of test solution (frequency/flow rate): Static (daily renewal)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality was monitored daily and the number of young produced in each beaker was recorded after which they were discarded. Temperature was recorded daily and pH, dissolved oxygen and hardness were determined on alternate days in control waters, both fresh and 24 h old. Daphnid 21-day length was also determined by the use of an ocular micrometer measuring from the base of the spine to the apex of the helmet.

VEHICLE CONTROL PERFORMED: yes (isopropanol)
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
6.8 µg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: Mortality and total number of young produced
Remarks on result:
other: test conducted with Southwest well water.
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
99.1 µg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: Mortality and total number of young produced
Remarks on result:
other: test conducted with river water.
Details on results:
Please refer to the table 1 of the attached background material for detail.
Reported statistics and error estimates:
Mortality data were analysed by probit analysis to derive a 21-d NOEC value and associated 95% confidence interval. t-tests were used to analyse statistically significant differences in other tested parameters including days to first reproduction, total young production, mean brood size, and 21-d length.
Conclusions:
Under the test conditions, the 21-d NOEC of the test substance was found to be 6.8 and 99.1 μg a.i./L (i.e., equivalent to 0.0068 and 0.099 mg a.i./L) in Southwest well and river water, respectively. The number of days until the first reproduction was similar across all groups within the Southwest well water group and river water group (i.e., 11 d and 8-9 d, respectively).
Executive summary:

A study was conducted to determine the long-term toxicity of the test substance, C16-18 and C18-unsatd. TMACto aquatic invertebrates, according to OECD Guideline 211.Daphnia magnawere exposed to six concentrations of the test substance in a 21-day static-daily renewal test in three different water types (i.e., laboratory blended water, Southwest well water and river water). Analytical determination of the test substance was performed. Measured concentrations (μg/L; values represent the geometric mean of the 0- and 24-hour concentration analyses) were: Southwest well water: 1.6, 3.1, 6.8, 14.6, 30.6 and 60.8 μg a.i./L, River water: 35.7, 53.4, 68.3, 99.1, 122.3 and 309.3 μg a.i./L. The test in blended water was discontinued after 14 d due to inadequate reproduction by control organisms. Mortality was monitored daily and the number of young produced in each beaker was recorded. Test substance concentrations were verified by analysis and represent the geometric mean of the 0 and 24 h concentration. Under the test conditions, the 21d NOEC of the test substance to Daphnia magna was found to be 6.8 and 99.1 μg/L (i.e., equivalent to 0.0068 and 0.099 mg a.i./L) in Southwest well and river water, respectively. The number of days until the first reproduction was similar across all groups within the Southwest well water group and river water group (i.e., 11 days and 8 - 9 days, respectively) (Valentine and Bishop, 1992).

Description of key information

The 21 d NOEC of the test substance to Daphnia magna was determined to be 6.8 and 99.1 μg a.i./L (i.e., 0.0068 and 0.0991 mg a.i./L) in Southwest well and river water, respectively.     

Key value for chemical safety assessment

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

Additional information

A study was conducted to determine the long-term toxicity of the test substance, C16-18 and C18-unsatd. TMAC to aquatic invertebrates, according to OECD Guideline 211. Daphnia magna were exposed to six concentrations of the test substance in a 21-day static-daily renewal test in three different water types (i.e., laboratory blended water, Southwest well water and river water). Analytical determination of the test substance was performed. Measured concentrations (μg/L; values represent the geometric mean of the 0- and 24-hour concentration analyses) were: Southwest well water: 1.6, 3.1, 6.8, 14.6, 30.6 and 60.8 μg a.i./L, River water: 35.7, 53.4, 68.3, 99.1, 122.3 and 309.3 μg a.i./L. The test in blended water was discontinued after 14 d due to inadequate reproduction by control organisms. Mortality was monitored daily and the number of young produced in each beaker was recorded. Test substance concentrations were verified by analysis and represent the geometric mean of the 0 and 24 h concentration. Under the test conditions, the 21 d NOEC of the test substance to Daphnia magna was found to be 6.8 and 99.1 μg/L (i.e., equivalent to 0.0068 and 0.099 mg a.i./L) in Southwest well and river water, respectively. The number of days until the first reproduction was similar across all groups within the Southwest well water group and river water group (i.e., 11 d and 8 - 9 d, respectively) (Valentine and Bishop, 1992).