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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June 2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
GLP compliance:
not specified
Remarks:
Study conducted to a high scientific standard and findings presented in a comprehensive test report.
Specific details on test material used for the study:
Not specified
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 10 serial dilutions
- Sample storage conditions before analysis: Fresh stock solutions of EMs were prepared by adding EMs to water and stirred up to 10 d. Then, each stock solution was filtered using syringes and 0.45 μm filter units. For DNAN samples, aliquots were mixed (1:1) with acetonitrile, and diluted if needed using a mixture of acetonitrile water (1:1).
Vehicle:
yes
Remarks:
acetonitrile
Details on test solutions:
none
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
none
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Post exposure observation period:
none
Hardness:
not specified
pH:
4.96 - 3.67
Dissolved oxygen:
not specified
Salinity:
not specified
Conductivity:
not specified
Nominal and measured concentrations:
not specified
Details on test conditions:
TEST SYSTEM
- Test vessel: 96-well microplate
- Material, size, headspace, fill volume: 200 µL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

OTHER TEST CONDITIONS
- Sterile test conditions: not specified
- Adjustment of pH: yes
- Photoperiod: 24h
- Light intensity and quality: 5000 lux

Reference substance (positive control):
yes
Remarks:
zinc sulfate
Key result
Duration:
96 h
Dose descriptor:
LOEC
Effect conc.:
2.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
1.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
2.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
96 h
Dose descriptor:
EC20
Effect conc.:
1.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
none
Results with reference substance (positive control):
none
Reported statistics and error estimates:
none

none

Validity criteria fulfilled:
not specified
Conclusions:
Individual exposure of DNAN inhibited P. subcapitata growth in the 96-h exposure test. It was found that the LOEC, NOEC nad EC50 were 2.3 mg/L, 1.2 mg/L and 2.2 mg/L, respectively.
Executive summary:

The present report summarizes findings on the environmental fate and ecological impact of DNAN. Firstly, aqueous solubility (Sw), octanol/water partition coefficients (Kow), sorption and stability of the chemical in two soils (DRDC-08 and DRDC-09 as provided by DRDC) were measured. Secondly, the toxicity of DNAN on various ecological receptors including earthworms, alga, and bacteria were determined. Preliminary findings indicated that DNAN has a higher sorption coefficient indicating that this chemical will stay close to the soil surface. However the test item was found to photodegrade at wavelengths within the range of solar irradiation. Also indigenous bacteria in soil were found capable of degrading DNAN. These preliminary experimental findings indicate that DNAN may not stay in the open environment indefinitely but rather they can photodegrade (soil surface) and biodegrade. For the ecotoxicological evaluation, preliminary experiments were done using DNAN dissolved in water. Acute toxicity tests using Vibrio fisheri(Microtox), Pseudokirchneriella subcapitata, and Eisenia andreiwere done. In addition, SOS chromotest was performed to evaluate genotoxic effects of the test chemicals. Preliminary results indicated that DNAN is toxic to the three test species, and was genotoxic to bacteria.

Description of key information

96-h exposure test found that NOEC and EC50 of DNAN were 1.2 mg/L and 2.2 mg/L, respectively.

Key value for chemical safety assessment

EC50 for freshwater algae:
2.2 mg/L
EC10 or NOEC for freshwater algae:
1.2 mg/L

Additional information