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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:
2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: according to EC Directive 92/69/EEC and Regulation EC/440/2008 guideline methods under GLP conditions
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Concentrations of the test substance were measured in media samples collected at test initiation
(5 rnL in volume) and termination (15 mL in volume) from the low, middle and high testing treatments, as well as from the controls. Freshly prepared solutions were sasnpled for chemical
aina!ysis prior to distribution to the replicate test chambers. At test termination, replicate test
chambers were composited prior to sampling. 'The stock utilized during the definitive test was
thc high test treatment.
Vehicle:
no
Details on test solutions:
The base water for the test medium was deionized water. The base water was enhanced with
reagent-grade nutrients as described in ASTM (1 990). The pH of the test medium was adjusted
to 7.5 prior to use in the test. The test medium was filtered and sterilized through a 0.45 pm
membrane filter prior to use:
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
The freshwater alga tested was the green alga, Selenastrum capricornutum (CBS #SEC 99-36B).
The culture, which originated from an inoculum received from the Carolina Biological Supply
Co., has been maintained since December 3, 1999. The algae were cultured in freshwater algal
medium (ASTM, 1990) under continuous illumination yielding approximately 120 micromols
per square meter per second (pmol/m2/s). Cultures were maintained at approximately 23 k 2°C
prior to test initiation. The inoculum culture was 7 days old at test initiation.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
0 hours: 23.4 °C
24 hours 23.3 °C
48 hours 25.2 °C
72 hours 25.6 °C
pH:
0 hours: 6.5 - 6.9
72 hours: 7.4 - 7.5
Nominal and measured concentrations:
Nominal:
control, 6.25, 25.0, 100 mg ai/L

Measured day 0:
<2.15, 6.25, 28.3, 110 mg ai/L

Measured day 3:
<2.07, 7.29, 28.0, 111 mg ai/L

Mean:
<2.11 +/-(---), 6.77 +/- (0.735), 28.2 +/- (0.212), 111 +/- (0.707)
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 127 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
6.25 mg/L
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Validity criteria fulfilled:
yes
Conclusions:
The no-observable-effect concentration (NOEC) was 6.25 mg ai/L (nominal concentration) based on a lack of significant reduction in growth (cell density) at this testing concentration. The ErC50 (24-72 hours) was estimated to be 127 mg ai/L.
Executive summary:

The no-observable-effect concentration (NOEC) was 6.25 mg ai/L (nominal concentration) based on a lack of significant reduction in growth (cell density) at this testing concentration. The ErC50 (24-72 hours) was estimated to be 127 mg ai/L.

Description of key information

The no-observable-effect concentration (NOEC) was 6.25 mg ai/L (nominal concentration) based on a lack of significant reduction in growth (cell density) at this testing concentration. The ErC50 (24-72 hours) was estimated to be 127 mg ai/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
127 mg/L
EC10 or NOEC for freshwater algae:
6.25 mg/L

Additional information