Hydrocarbons, C11-C13, isoalkanes, <2% aromatics

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001

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.

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

No analytical measurements were taken. The low solubility of the test substance at the loading level tested was expected to result in exposure levels below the analytical detection limit for Total Organic Carbon (TOC) or Dissolved Organic Carbon (DOC).

Vehicle:

no

Details on test solutions:

Individual treatment solutions were prepared by adding the test substance, via syringe, to 4 L of laboratory blend water in glass aspirator bottles that were sealed with stoppers to minimize volatile loss of test material. The stock solutions were mixed for 24 hours. Mixing was performed using a magnetic stir plate and Teflon stir bar. After mixing, the solutions were allowed to settle for one hour at test temperature. The Water Accommodated Fraction (WAF) was then removed through the outlet at the bottom of the mixing vessel and added to the test chambers.

Test organisms (species):

Daphnia magna

Details on test organisms:

The Daphnia were cultured in-house, were <24 hours old, and were from 17-day old parents. Test organisms were fed daily when solutions were renewed with Pseudokirchneriella subcapitata to provide approximately 4.7 x 10E5 cells/mL. The daphnia were fed a carbon equivalent of approximately 0.5 mg C per adult per day which is purposely higher than the guideline to achieve an acceptable level of neonate production.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

21 d

Post exposure observation period:

None

Hardness:

The hardness of the dilution water during the study was 114-120 mg/L as CaCO3.

Test temperature:

Mean test temperature was 20.6 degrees C (S.D. = 0.3) for test substance and control systems.

pH:

7.0 to 7.9 for test substance and control systems.

Dissolved oxygen:

7.3 to 8.7 mg/L for test substance and control systems.

Nominal and measured concentrations:

Nominal loading rates were control and 1 mg/L. Analytical measurements were not taken.

Details on test conditions:

The test chambers were 55 mL capacity glass Erlenmeyer flasks with ground glass stoppers (no headspace). One daphnid was added to each of 10 replicates. The test was performed using a static daily renewal of exposure solutions. Observations for abnormal or immobilized daphnids and neonates were made on each replicate at approximately 24-hour intervals. Diurnal light: approximately 17 hours light and 7 hours dark. Water Quality was measured twice per week.

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOELR

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

The test substance also showed no effects based on growth.

Details on results:

The following are the endpoint results for the control and test solution:
Adult Neonates
Group Immobilization per
(%) Adult
Control 20 61
1 mg/L 10 47

The control daphnids released their first brood between days 7 and 9. The coefficient of variation (cv) for control fecundity was 33%. The test was considered acceptable as control organisms immobilization did not exceed 20% and mean reproduction in the controls exceeded 60 young per adult.

Results with reference substance (positive control):

None used

Reported statistics and error estimates:

Statistical analyses were conducted using the T-test for reproduction from ToxStat 3.4 (West Inc. 1994).

Validity criteria fulfilled:

yes

Conclusions:

The test substance showed no effects on survival, reproduction, or length at a nominal loading of 1 mg/L. Therefore, the 21-Day No Observed Effect Loading Rate (NOELR) = 1.0 mg/L for these endpoints based upon nominal loading levels.

Executive summary:

The test substance showed no effects on survival, reproduction, or length at a nominal loading of 1 mg/L. Therefore, the 21-Day No Observed Effect Loading Rate (NOELR) = 1.0 mg/L for these endpoints based upon nominal loading level.

Description of key information

Hydrocarbons, C11-C13, isoalkanes, <2% aromatics, showed no effects on survival, reproduction, or length at a nominal loading of 1 mg/L. Therefore, the 21-Day No Observed Effect Loading Rate (NOELR) = 1.0 mg/L for these endpoints based upon nominal loading levels.