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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:
February to March 2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This robust summary has a reliability rating of 1 because the study followed a standard guideline, followed GLP, and was conducted without deviations that would invalidate the study.
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
according to guideline
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Analytical measurements were taken to confirm test material presence in test solutions and absence in control. Samples were taken from each test and control solution on Days 0, 7, 14, and 20 and the corresponding old solutions (three individual replicates) on Days 1, 8, 15 and 21, unless complete mortality occurred prior to the sampling event. Twenty-four samples from each group were analyzed during the twenty-one day study.
Vehicle:
no
Details on test solutions:
The exposure solutions were generated by aerating the test substance alone in a closed system using air stones at an air flow rate of 45 +/-5 cc/min. The vapor generated of the test substance from the aeration procedure flowed into aspirator bottles and bubbled through vehicle/dilution medium (reconstituted water). The test substance saturated vapor passed through air stones near the bottom of the aspirator bottles providing maximum contact between the test substance in the vapor phase and the vehicle/dilution medium. The systems were allowed to aerate/equilibrate for one day prior to preparing the exposure solutions for the first time. Ten replicates per treatment were tested.
Test organisms (species):
Daphnia magna
Details on test organisms:
Test organisms were cultured at the test facility. The original culture was supplied by Aquatic Biosystems, Inc., Fort Collins, Colorado, USA and received at the test facility on 11 April 2002.
For the test, eight adult daphnids were kept in 1-liter glass culture beakers with approximately 800 mL of reconstituted water (study vehicle/dilution water). The culture chamber was maintained at 20 ± 1 degrees C under a 16 hour light 8 hour dark photoperiod (10 - 20 foot/candles, 108 - 215 Lux). Day 0 cultures were started daily (at least five days per week) using eight <24 hour old neonates from culture beakers between 12 and 18 days old, exhibiting ≤20% adult mortality. Cultures were transferred to fresh reconstituted water on regular intervals to ensure that ≤24 hour old neonates are available for studies and to start new cultures.
Cultures of Daphnia magna were fed Pseudokirchneriella subcapitata (approximately 4.5 x 105 cells/mL) and 4.0 mL of a yeast / salmon starter / wheat grass (YTC) mixture per 800 mL daily (five days per week at a minimum). YTC and algae were supplied by Aquatic Biosystems, Inc., Fort Collins, Colorado, USA.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
None
Hardness:
The hardness of the dilution water during the study was 150 mg/L as CaCO3.
Test temperature:
19.2 to 19.9 degrees C for test substance systems.
19.2 to 19.9 degrees C for control systems.
pH:
8.0 to 8.6 for test substance systems.
8.0 to 8.6 for control systems.
Dissolved oxygen:
7.8 to 9.2 mg/L for test substance systems.
7.9 to 9.1 mg/L for control systems.
Nominal and measured concentrations:
Nominal loading rates were control, 0.020, and 0.040 mg/L, which measured 0.0, 0.011, and 0.015 mg/L.
Details on test conditions:
Ten replicates per treatment were tested. One <24 hour old daphnid was added to each replicate. The adults were transferred to fresh solution daily. The test chambers were 125 mL capacity clear glass bottles containing approximately 125 mL of solution (no headspace). The test chambers were closed with foil lined screw type lids to minimize contamination, evaporation, and/or volatilization. A separate set of test chambers was used on a rotating basis for renewals. Feed was first added to each test chamber. Test chambers were filled with the appropriate amount of vehicle/dilution water. The adult Daphnia magna from the old test solution were transferred to the vehicle/dilution water using a glass pipette.
Diurnal light: approximately 16 hours light and 8 hours dark. Daylight intensity ranged from approximately 16 to 19 µE•m-2•s-1 during full daylight periods of the study.
Reference substance (positive control):
no
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.011 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks:
The test substance also showed no effects based on growth at 0.011 mg/L.
Details on results:
The following are the endpoint results for the control and test solutions:
Adult Neonates Adult
Group Group Immobilization per Ave. Length
(nominal) (meas.) (%) Adult (mm)
Control 0.0 µg/L 0 119 4.6
20 µg/L 11 µg/L 0 125 4.5
40 µg/L 15 µg/L 100 n/a n/a

The control daphnids released their first brood between days 7 and 10. The coefficient of variation (cv) for control fecundity was 16%, the guideline indicates that the cv for control reproduction in a “well run” study should be ≤25%. The test was considered acceptable as less than 20% of control organisms were immobilized and mean reproduction in the controls exceeded 60 young per adult.
Results with reference substance (positive control):
None used
Reported statistics and error estimates:
The chronic survival and reproduction NOEC for each test substance was based on empirical observation. The length NOEC was determined using the Bonferroni t-test using TOXSTAT software.
Validity criteria fulfilled:
yes
Conclusions:
The test substance showed no effects on survival, reproduction, or length at nominal and measured concentrations of 0.020 and 0.011mg/L, respectively. Therefore, the 21-Day No Observed Effect Loading Rate (NOELR) and No Observed Effect Concentration (NOEC) values are 0.020 and 0.011 mg/L, respectively, for these endpoints based upon nominal loading rates and measured (geometric means) concentrations.
Executive summary:

The test substance showed no effects on survival, reproduction, or length at nominal and measured concentrations of 0.020 and 0.011mg/L, respectively. Therefore, the 21-Day No Observed Effect Loading Rate (NOELR) and No Observed Effect Concentration (NOEC) values are 0.020 and 0.011 mg/L, respectively, for these endpoints based upon nominal loading rates and measured (geometric means) concentrations. The next highest loading rate and concentration tested, 0.040 and 0.015 mg/L, respectively, produced 100% immobilization of the adults exposed.

Description of key information

Hydrocarbons, C10-C12, isoalkanes, <2% aromatics, showed no effects on survival, reproduction, or length at nominal and measured concentrations of 0.020 and 0.011mg/L, respectively. Therefore, the 21-Day No Observed Effect Loading Rate (NOELR) and No Observed Effect Concentration (NOEC) values are 0.020 and 0.011 mg/L, respectively, for these endpoints based upon nominal loading rates and measured (geometric means) concentrations.

Key value for chemical safety assessment

Additional information

Hydrocarbons, C10-C12, isoalkanes, <2% aromatics, showed no effects on survival, reproduction, or length at nominal and measured concentrations of 0.020 and 0.011mg/L, respectively. Therefore, the 21-Day No Observed Effect Loading Rate (NOELR) and No Observed Effect Concentration (NOEC) values are 0.020 and 0.011 mg/L, respectively, for these endpoints based upon nominal loading rates and measured (geometric means) concentrations.