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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:
05/2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
This study was carried out according to OECD guideline no. 201. This study was also carried out according to GLP standards with the exception of the analytical measurements of test concentrations.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Samples for analysis were taken at test initiation (0 h) and test termination (72 h). Samples were only taken from the lowest and highest test concentrations (12.5 mg/L and 200 mg/L respectively).
Vehicle:
no
Details on test solutions:
Test solutions were prepared on the day of test initiation by adding 400 mg of the test substance to 400 ml of aerated M7-media and stirring for 10 minutes. The solution was then membrane filtered (0.45 µm) and used as stock solution. The nominal concentration of the stock solution was 580 mg/L of test substance. Test concentrations were made by dilution of the stock solution with growth media.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
The test organism was a laboratory culture of the green alga Pseudokirchneriella subcapitata. The inoculum was taken from Toxicon's culture of P. subcapitata (NIVA CHL 1), which originates from NIVA, Oslo, Norway.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
No information provided
Hardness:
No information provided
Test temperature:
21-24 ± 2°C
pH:
0 hours: 7.6-8.1
72 hours: 6.5-9
Dissolved oxygen:
No information provided
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentrations: 12.5, 25, 50, 100 and 200 mg/L
Measured concentrations were found to be within 20% of nominal concentrations.
Details on test conditions:
See methods below
Reference substance (positive control):
not specified
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
76 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
165 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
A 72-hour ErC50 of 165 mg/L was found for the response variable average specific growth rate when exposed to 2-oxepanone, polymer with 1,4-butanediol. The 72-hour NOEC was found to be 25 mg/L.
Results with reference substance (positive control):
No information provided
Reported statistics and error estimates:
For control and treatment groups, a mean value for growth rate along with variance estimate was calculated. The specific growth rate for each test concentration is related to the growth rate of the controls:

%Ir = (µc-µr)/µc * 100

Where:
%Ir = percent inhibition in average specific growth rate
µc = mean value for average specific growth rate (µ) in the control group
µr = average specific growth rate (µ) for the treatment replicate

Table 1: nominal NOEC and ErC values in mg/l, determined after 72 hours exposure to the test substance 2-Oxepanone, polymer with 1,4-butanediol (Capa 2043).

   72 h NOEC (mg/L)  72 h ErC10 (mg/L) 72 h ErC50 (mg/L) 
 Average specific growth rate, EC-values  25  76  165

Table 2: Calculated response variables for the treatment group and the control group (mean ± coefficient of variation) after 72 hours exposure to 2 -oxepanone, polymer with 1,4 -butanediol.

 Concentration  72 h specific growth rate (µ) Mean ± CV (%)
 Control 1.67  ± 2.4
 12.5 mg/L 1.66 ± 1.2
 25 mg/L 1.68 ± 1.8
 50 mg/L 1.57 ±5.0
 100 mg/L 1.46 ± 5.4
 200 mg/L 0.59 ± 15

Table 3: Results of TOC determination of saturated 2-Oxepanone, polymer with 1,4-butanediol (Capa 2043) solutions and the measured concentrations in test solutions.

 Nominal test concentration TOC (mg/L)  Capa 2043 concentration (mg/L)   Nominal value ± 20°C
12.5 mg/L (0 h) 7.7 12.6 10 -15
12.5 mg/L (72 h)  8.2 13.4 10 -15
 200 mg/L (0 h) 120 197 160 -240
200 mg/L (72 h)  120 197 160 -240
Validity criteria fulfilled:
yes
Conclusions:
A 72-hour ErC50 of 165 mg/L was found for the response variable average specific growth rate when exposed to 2-oxepanone, polymer with 1,4-butanediol. The 72-hour NOEC was found to be 25 mg/L. As the ErC50 was found to be greater than 100 mg/L, the test substance can be regarded as non-toxic to the green algae Pseudokirchneriella subcapitata according to 67/548/EEC (KIFS 2005:7) and EC 1272/2008 (CLP).
Executive summary:

A 72-hour toxicity test was carried out to determine growth inhibition effects of 2-Oxepanone, polymer with 1,4-butanediol on the green alga Pseudokirchneriella subcapitata. The study was carried aout according to OECD guideline no. 201. Test solutions were created by diluting a stock solution of the test substance in growth media. The duration of exposure was 72 hours and test solutions were kept on a shaking table at 21-24 ± 2°C throughout. Illumination was approximately 100 µE m-2 s-1.m. Six replicates were used for the control and three for the test solutions.

The pH was measured at test initiation and also at test termination. Samples for analytical determination of test concentration were also taken from the highest and lowest concentrations at this time. These samples were analysed separately at a non-GLP laboratory.

The 72-hour ErC50 of 165 mg/L was found for the response variable average specific growth rate when exposed to 2-oxepanone, polymer with 1,4-butanediol. The 72-hour NOEC was found to be 25 mg/L. As the ErC50 was found to be greater than 100 mg/L, the test substance can be regarded as non-toxic to the green algae Pseudokirchneriella subcapitata according to 67/548/EEC (KIFS 2005:7) and EC 1272/2008 (CLP).

Description of key information

The 72-hour ErC50 was found to be 165 mg/L, while the NOEC was observed to be 25 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
165 mg/L
EC50 for marine water algae:
25 mg/L

Additional information

A 72-hour toxicity test was carried out to determine growth inhibition effects of 2-Oxepanone, polymer with 1,4-butanediol on the green alga Pseudokirchneriella subcapitata. The study was carried out according to OECD guideline no. 201. Test solutions were created by diluting a stock solution of the test substance in growth media. The duration of exposure was 72 hours and test solutions were kept on a shaking table at 21-24 ± 2°C throughout. Illumination was approximately 100µE m-2 s-1.m. Six replicates were used for the control and three for the test solutions.

The pH was measured at test initiation and also at test termination. Samples for analytical determination of test concentration were also taken from the highest and lowest concentrations at this time. These samples were analysed separately at a non-GLP laboratory.

The 72-hour ErC50 of 165 mg/L was found for the response variable average specific growth rate when exposed to 2-oxepanone, polymer with 1,4-butanediol. The 72-hour NOEC was found to be 25 mg/L. As the ErC50 was found to be greater than 100 mg/L, the test substance can be regarded as non-toxic to the green algae Pseudokirchneriella subcapitata according to 67/548/EEC (KIFS 2005:7) and EC 1272/2008 (CLP).