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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:
1994-02-01 to 1994-02-04
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes
Specific details on test material used for the study:
- Name of test material (as cited in study report): WITAMOL 118
- Substance type: product
- Physical state: liquid
- Stability under test conditions: no data
- Storage condition of test material: no data
- Other: none
Analytical monitoring:
yes
Details on sampling:
- Concentrations: WAF
- Sampling method: A sample for analysis was prepared identically to the test solution but without algal inoculation.
- Sample storage conditions before analysis: not mentioned
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 1 g/L test substance was mixed with deionised water, stirred for 18 hours and subsequently filtered.
- Controls: yes, synthetic freshwater
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Green algae
- Strain: Scenedesmus subspicatus (CHODAT (86.81 SAG))
- Source (laboratory, culture collection): Institut für Wasser-, Boden- und Lufthygiene, Berlin; subsequently in-house breeding
- Method of cultivation: in sterile-aerated Erlenmeyer flasks on light benches


ACCLIMATION
- Acclimation period: A preculture is withdrawn from a stock culture by tranfer 3 days prior to the beginning of the test from which preculture the test cultures are inoculated at a cell density of approximately 20 000 cells/mL.
- Culturing media and conditions (same as test or not): not mentioned
- Any deformed or abnormal cells observed: no data
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
none
Hardness:
Growth/test medium chemistry as described in guideline 92/69/EEC (C.3.), no further details mentioned
Test temperature:
24 +/- 2 °C
pH:
8.0 - 8.6 (start of test), 8.7 - 9.3 (end of test)
Dissolved oxygen:
not mentioned
Salinity:
not mentioned
Nominal and measured concentrations:
Nominal: WAF
Measured: 0.83 mg/L (geometric mean of values from the beginning and the end of the test)
Details on test conditions:
TEST SYSTEM
- Test vessel: sterile-aerated Erlenmeyer flasks
- Initial cells density: 2x10E4 cells/mL
- Control end cells density: 88x10E4 cells/mL
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 8
- No. of vessels per vehicle control (replicates): not applicable


GROWTH MEDIUM
- Standard medium used: yes


TEST MEDIUM / WATER PARAMETERS
no details mentioned


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: not adjusted
- Photoperiod: not specified
- Light intensity and quality: approx. 8000 lux, white


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Cell numbers for exposure times of 24, 48, 72 h
- Determination of cell concentrations: The cell numbers were determined photometrically at a wavelenght of 685 nm
- Chlorophyll measurement: no
- Other: none


TEST CONCENTRATIONS
- Spacing factor for test concentrations: not mentioned
- Range finding study: not applicable
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 0.83 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 0.83 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no observations made
- Any stimulation of growth found in any treatment: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no

Effective concentrations on the basis of cell growth:
EbC50 (72 h) > 0.83 mg/L
EbC10 (72 h) > 0.83 mg/L
EbC90 (72 h) > 0.83 mg/L
Effective concentrations based on the specific growth rate µ:
ErC50 (0-72 h) > 0.83 mg/L
ErC10 (0-72 h) > 0.83 mg/L
ErC90 (0-72 h) > 0.83 mg/L
Results with reference substance (positive control):
no reference substance tested
Reported statistics and error estimates:
no statistical evaluation performed

Table #1: Cell density data:

 concentration

[mg/L]

 cell number (x 10E4 cells/ml) after        
  0 h   24 h  48 h  72 h
 control  2  13  28  88
0.83  2  10  37  114

                                                                                 

Table #2: Growth curves:

concentration[mg/L]   biomass (area under the growth curve) inhibition of biomass [%]   growth rate µ (0 - 72 h)  inhibition of growth rate [%]
 control  80  -  1.261  -
 0.83  99  -23.8  1.348  -6.9

The cloudiness of the test solution due to the product was considered

Validity criteria fulfilled:
yes
Conclusions:
In the range of water solubility not toxic under test conditions.
Executive summary:

The substance was n the range of water solubility not toxic under test conditions. The EC50 of 1,2-Benzenedicarboxylic acid, di-C8-10-alkyl esters was in excess of 0.81 mg/L.

Description of key information

The substance was in the range of water solubility not toxic under test conditions. The EC50 of 1,2-Benzenedicarboxylic acid, di-C8-10-alkyl esters was in excess of 0.81 mg/L.

Key value for chemical safety assessment

Additional information

The substance was in the range of water solubility not toxic under test conditions. The EC50 of 1,2-Benzenedicarboxylic acid, di-C8-10-alkyl esters was in excess of 0.81 mg/L. Furthermore the toxicity of structurally related phthalates has been evaluated in several algae tests according to accepted guidelines with similar findings.

The ErC 50 for 1,2-Benzenedicarboxylic acid, di-C6-C10-alkyl esters in algae is above the limit of water solubility (ErC50 > 2.8 mg/l). These findings are supported by published data for this substance (Adams et al., 1995), resulting in EC50(96) > than the limit of water solubility. For 1,2-Benzenedicarboxylic acid, diundecyl ester there is only an acute effect level based on the cell number available resulting in EbC50 (96h) >2.1 mg/L. And the 96h-EC50 for 1,2-Benzenedicarboxylic acid, dihexyl ester was found to be greater than the highest concentration tested (>0.33 mg/l) and hence above the limit of water solubility.

The results are supported by results summarized in review articles for phthalates with an alkyl chain length of C6 and above.