N,N'-propane-1,3-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide]

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Justification for type of information:

Additional documentation, provided within the IUCLID Assessment Reports (Section 13), supports the read-across approach.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

other: 87/302/EEC

Deviations:

no

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 2.0 g of the test substance and 18 g of 0.4% Arkopal were mixed together, by means of a marble-mill during about 72 hours. 1 mL of this blend were mixed and made up to 1000 mL with water (stock solution 1 for all test concentrations). Calculated amounts of the stock solution to produce the desired test concentrations were given into the water and were homogeneously distributed. The algae were then transfered into the flasks. The test substance was homogeneously distributed in the test vessels at test concentrations of 1.23 and 3.7 mg/L.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): alkylphenolpolyglykolether 0.4% (Arkopal)
- Concentration of vehicle in test medium: 0.4% (stock solution)
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): Small parts of the test substance were on the surface of the test water at test concentrations of 11, 33, and 100 mg/L.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Source (laboratory, culture collection): CIBA-GEIGY Ltd., testing facility
- Method of cultivation: according to guideline

ACCLIMATION
- Acclimation period: 3 days under test conditions.
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: none reported

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

not reported

Test temperature:

23±0.5°C

pH:

0 Hr: 7.6-7.9
72 Hr: 7.1-7.2

Dissolved oxygen:

not reported

Nominal and measured concentrations:

Nominal: 1.23, 3.7, 11, 33, 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL Erlenmeyer flasks, stoppered with aluminium caps, on Lab-shaker
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 100 mL filled with 50 mL test solution
- Initial cells density: 7000 cells/mL
- Control end cells density: 1032000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: none
- Photoperiod: continuous
- Light intensity and quality: cold white fluorescent light, 121 µE/m2 sec (approx.. 8000 lux)

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: cell densities were measured at 24, 48, and 72 hours of exposure on a “TOA” cell counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3
- Test concentrations: 1.23, 3.7, 11, 33, 100 mg/L

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

45 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% CL: 35-78 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

11 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): none reported
- Unusual cell shape: none reported
- Colour differences: none reported
- Flocculation: Small parts of the test substance were swimming on the surface of the test water at test concentrations of 11, 33, and 100 mg/L.
- Adherence to test vessels: none reported
- Aggregation of algal cells: none reported
Other: No toxicity was observed in the range of solubility. In spite of the small effect of the vehicle, the EbC50 is between 33 and 10 mg/L.

Reported statistics and error estimates:

The EbC50 values were calculated according to the maximum likelihood method, probit model.

Validity criteria fulfilled:

yes

Conclusions:

72-hour EbC50: 45 mg/L

Executive summary:

In a 72-hour acute toxicity study, cultures of Scenedesmus subspicatus were exposed to the test substance at nominal concentrations of 0, 1.23, 3.77, 11, 33 and 100 mg/L under static test conditions in accordance with EEC guideline 302/87.  Cell densities were measured at 24, 48, and 72 hours on a “TOA” cell counter. The EbC50 and NOEbC 45 and 11 mg/L, respectively. 

Description of key information

No acute fish toxicity study with the test substance is available. A study in accordance with Guideline 87/302/EEC with N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide] was used as read across to fulfil the data gap for the test substance. The underlying hypothesis supporting read-across from the source (N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide]; CAS 23128-74-7) to the target (N,N'-propane-1,3-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide]; CAS 69851-61-2) includes the following: (1) Structural similarity, (2) Source and target are expected to hydrolyse in a similar fashion, (3) Source and target have similar predicted metabolism, (4) Source and target have similar physicochemical properties, (5) Source and target have similar calculated chemical descriptors, and (6) Source and target have similar predictions for the endpoints of concern. Additional documentation, provided within the IUCLID Assessment Reports section, supports the read-across approach.

In a 72-hour acute toxicity study, cultures of Scenedesmus subspicatus were exposed to the test substance at nominal concentrations of 0, 1.23, 3.77, 11, 33 and 100 mg/L under static test conditions in accordance with Guideline 87/302/EEC. Cell densities were measured at 24, 48, and 72 hours on a “TOA” cell counter. The EbC50 and NOEbC were 45 and 11 mg/L, respectively

Key value for chemical safety assessment

EC50 for freshwater algae:

45 mg/L