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Ecotoxicological information

Toxicity to other aquatic organisms

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Administrative data

Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well-documented publication/study report which meets basic scientific principles

Data source

Reference
Reference Type:
publication
Title:
Bioavailability of sediment-sorbed and aqueous surfactants to Chironomus riparius (midge).
Author:
Pittinger, C.A., Woltering, D.M., and Masters, J.A.
Year:
1989
Bibliographic source:
Environ. Toxicol. Chem. 8:1023-1033.

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Tests were conducted as an aqueous fraction in the presence of sediment.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
C11.8 LAS; 30.4% activity; mean molecular weight = 346

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
not specified
Details on test solutions:
Natural stream sediments (71% clay, 19% fine silt, 4% medium sand, 6% fine sand) were collected from a pristine site in Rapid Creek, SD. Before testing, wet sediment was autoclaved for 40-60 minutes to reduce microbial populations and minimize initial rates of surfactant biodegradation.

Test organisms

Test organisms (species):
other: Chironomus riparius

Study design

Test type:
other: flow-through closed system
Water media type:
not specified
Limit test:
no
Total exposure duration:
24 h
Remarks on exposure duration:
average

Test conditions

Hardness:
"monitored frequently"
Test temperature:
"monitored frequently"
pH:
"monitored frequently"
Dissolved oxygen:
"monitored frequently"
Nominal and measured concentrations:
Test concentrations were control, 8, 42, 146, 319, and 993 ppm.
Details on test conditions:
LAS was added to a sediment slurry at a nominal concentration and stirred overnight, then 350 g was poured into each test chamber and allowed to settle. The organic carbon content of the test sediment was 4.2% prior to testing. A flow-through diluter system delivered test material in water to glass containers with 120-140 cm² bottom surface area each. Intact egg masses were incubated in Petri dishes containing 20-30 mL of dilution water at 22 °C until hatching commenced. Newly hatched larvae were allowed to mature 72 hours before testing. Twenty larvae were randomly distributed to each duplicate test chamber for each of five test concentrations plus the controls. Larvae were fed daily until emergence of the first adult in each chamber. Tests were continued until each midge emerged as an adult or larvae were determined to be dead.
Reference substance (positive control):
yes

Results and discussion

Effect concentrationsopen allclose all
Key result
Dose descriptor:
NOEC
Effect conc.:
319 other: ppm in sediment
Basis for effect:
other: emergence
Dose descriptor:
LOEC
Effect conc.:
993 other: ppm in sediment
Basis for effect:
other: emergence
Details on results:
Adults typically emerged 12-14 days after hatching. Control values for adult emergence were similar to or exceeded the historical average observed in their laboratory (>90%). Percent emergence was 98, 95, 90, 90, 90, and 73 for the control, 8, 42, 146, 319, and 993 ppm concentrations, respectively. For comparison, additional flow-through studies were conducted without sediment.

Any other information on results incl. tables

Results indicate that sorption onto sediment significantly mitigates LAS bioavailability.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The NOEC for Chironomus riparius in sediment was 319 ppm, and the LOEC was 993 ppm based on emergence.
Executive summary:

LAS was added to a sediment slurry at a nominal concentration and stirred overnight, then 350 g was poured into each test chamber and allowed to settle. The organic carbon content of the test sediment was 4.2% prior to testing. A flow-through diluter system delivered test material in water to glass containers with 120-140 cm² bottom surface area each. Intact egg masses were incubated in Petri dishes containing 20-30 mL of dilution water at 22 °C until hatching commenced. Newly hatched larvae were allowed to mature 72 hours before testing. Twenty larvae were randomly distributed to each duplicate test chamber for each of five test concentrations plus the controls. Larvae were fed daily until emergence of the first adult in each chamber. Tests were continued until each midge emerged as an adult or larvae were determined to be dead.

Adults typically emerged 12-14 days after hatching. Control values for adult emergence were similar to or exceeded the historical average observed in their laboratory (>90%). Percent emergence was 98, 95, 90, 90, 90, and 73 for the control, 8, 42, 146, 319, and 993 ppm concentrations, respectively. For comparison, additional flow-through studies were conducted without sediment.

The NOEC for Chironomus riparius in sediment was 319 ppm, and the LOEC was 993 ppm based on emergence.