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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:
1993-11-15 till 1994-01-10
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
(1984)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
(1988)
Deviations:
no
Qualifier:
according to guideline
Guideline:
ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)
Version / remarks:
(1989)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
In the range-finding test growth of Selenastrum capricornutum was inhibited at test concentrations of 20 and 40 mg/L.
Hence, the definitive algal growth inhibition test has been performed using the following nominal test concentrations: 7.9, 11.9, 17.8, 26.7 and 40.0 mg/L.
Vehicle:
no
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Source and maintenance of algae:
The test was carried out with the freshwater unicellular green algae Selenastrum capricornutum (CCAP 276/48) obtained from the Culture Collection of Algae and Protozoa, The Ferry House, Cumbria, Ambleside, United Kingdom on 1991.09.20. This strain was maintained on sloped agar tubes in the light at room temperature for 2 weeks. After this period the sloped agar tubes are stored at 4 °C until required.

Preparation of the inoculum:
The initial stock culture was inoculated with Selenastrum capricornutum from a sloped agar tube and checked for purity by microscopic means.
This algal stock culture ( 40 mL) of Seienastrum capricornutum was regularly transferred to fresh mineral medium to act as inoculum for the test.
The extinction of an exponentially growing stock culture was measured. The cell density was determined using the calibration curve described above. From this algal culture a dilution was prepared to obtain an Initial cell density of 10000 cells/mL in the medium of the definitive test.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
pH:
Control: 8.3 at 0 hour and 9.2 - 9.3 at 96 hours
Test concentrations: 8.0 - 8.3 at 0 hour and 8.6 - 9.3 at 96 hours
Nominal and measured concentrations:
- Concentrations: 7.9, 11.9, 17.8, 26.7 and 40.0 mg/L (nominal)
- Concentrations: 7.14, 11.18, 15.68, 23.53 and 35, 92 mg/L (measured; 88 -84 % of nominal concentration)
Details on test conditions:
The culturing apparatus was a temperature-controlled illuminated orbital incubator in which the temperature was maintained at 24 °C ± 2 °C, and a continuous uniform illumination was provided in the spectral range of 400 to 700 nm by using 30 W fluorescent lamps of the type 'universal white' [colour temperature of approximately 4000 K), at a distance of 0.35 m from the algal cultures. The culture flasks were rotated continuously at 100 revjmin to prevent sedimentation of the algae.

The test was performed in 100 mL Erlenmeyers containing 40 mL of mineral salts medium. The test flasks were closed with cotton-wool stoppers.

Cell concentrations were determined photometrically. The spectrophotometer was a UV/VIS Spectrophotometer. Measurements were carried out at 436 nm in a cuvette with a light path of 4 cm.
Reference substance (positive control):
yes
Remarks:
potassium dichromate (purity: 99.5 %; Lot no. H 0234 from J.T. Baker Chemicals BV, Deventer, The Netherlands)
Duration:
96 h
Dose descriptor:
other: ErC20
Effect conc.:
32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (27 - 39)
Key result
Duration:
96 h
Dose descriptor:
other: ErC50
Effect conc.:
67 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (51 - 122)
Duration:
96 h
Dose descriptor:
other: ErC80
Effect conc.:
140 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (87 - 427)
Duration:
96 h
Dose descriptor:
LOEC
Effect conc.:
7.9 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.:
< 7.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Results with reference substance (positive control):
Concentration/effect relationship of potassium dichromate calculated from the percentages of inhibition of the specific growth rate of Selenastrum capricornutum at various concentrations.
ErC20 = 0.7 mg/L (0.6 - 0.8); ErC50 = 1.3 mg/L (1.1 - 1.5) and ErC80 = 2.6 mg/L (2.2 - 3.1)
Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity to algae (Selenastrum capricornutum) of 1,3-bis(3-methyl-2,5-dioxo-1H-pyrrolinylmethyl)benzene was determined for a period of 96 hours and under static conditions. The measurement showed values of an ErC20 of 32 mg/L, an ErC50 of 67 mg/L and an ErC 80 of 140 mg/L; a LOEC of 7.9 mg/L and a NOEC of <7.9 mg/L were calculated.
Executive summary:

In order to test acute toxicity to algae of 1,3-bis(3-methyl-2,5-dioxo-1H-pyrrolinylmethyl)benzene Selenastrum capricornutum was exposed to the test solution of five nominal concentration of the test substance (7.9, 11.9, 17.8, 26,7 and 40.0 mg/L) and a blank control solution for a period of 96 hours und static conditions. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. The measured concentrations confirmed that deviation fron the nominal concentration was less than 30 % (measured concentrations were in the range of 88 - 94 % of nominal concentrations).

1,3-bis(3-methyl-2,5-dioxo-1H-pyrrolinylmethyl)benzene showed an ErC20 of 32 mg/L, an ErC50 of 67 mg/L and an ErC 80 of 140 mg/L. A LOEC of 7.9 mg/L and a NOEC of < 7.9 mg/L were calculated.

Description of key information

The acute toxicity to algae (Selenastrum capricornutum) of 1,3-bis(3-methyl-2,5-dioxo-1H-pyrrolinylmethyl)benzene was determined for a period of 96 hours and under static conditions. The measurement showed values of an ErC20 of 32 mg/L, an ErC50 of 67 mg/L and an ErC 80 of 140 mg/L; a LOEC of 7.9 mg/L and a NOEC of <7.9 mg/L were calculated.

Key value for chemical safety assessment

EC50 for freshwater algae:
67 mg/L
EC10 or NOEC for freshwater algae:
7.9 mg/L

Additional information

The key value for NOEC was reported as <7.9 mg/L.

The exposure time of the test was 0 - 96 hours.

The indication of the extinction of the growth rate was reported at 24 hour intervals.

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