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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
For this endpoint a one-to-one read across was performed to a chemical similar compound of the same chemical class with a comparable phys. chem. profile and similar response in biological assays. The relevant study was considered to be acceptable, well documented publication which meets basic scientific principles.
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
a detailled justification for the analogue approach can be found in Iuclid section 13 of the dossier.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
not specified
Analytical monitoring:
no
Vehicle:
not specified
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: CCAP 278/4


CULTURE CONDITIONS
Stock cultures of Selenastrum capricornutum CCAP 278/4 were maintained at 22 degrees celcius under constant illumination from two 30 W fluorescent tubes, on slopes of Oxoid No. 3 agar containing BBM. 7 days before the innoculum was required, 2 conical flasks containing 90 mL particle free BBM were aseptically inoculated with Selenastrum capricornutum from stock cultures. The cultures were incubated at 22 degrees celcius and shaken at 175 rpm under constant illumination of 4000 lux. Sub-cultures were made into fresh media 2 days before inoculations of the test flasks and incubated under identical conditions.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
6 d
Test temperature:
22 °C
Nominal and measured concentrations:
nominal 0, 100, 200, 300, 400, 500, and 600 mg/L
Details on test conditions:
TEST SYSTEM
- Material, size, headspace, fill volume: glass 250 mL conical flasks, fill volume 100 mL
- Initial cells density: 1000 cells/mL
- No. of vessels per concentration (replicates): 3

GROWTH MEDIUM
- Standard medium used: no
- Detailed composition if non-standard medium was used: see Table 1 under "Any other information on materials and methods incl. tables"

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionised, particle free water
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Photoperiod: constant illumination
- Light intensity and quality: 4000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter (Elzine 80 XY particle counter, Particle data Ltd); cell counts were made every 24 hours



Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
473 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Recalculated, using ToxRat v2.10, based on measured cell counts provided in original reference. 95% CL: 429 - 533 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
397 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Recalculated, using ToxRat v2.10, based on measured cell counts provided in original reference. 95% CL: 254 - 906 mg/L
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Recalculated, using ToxRat v2.10, based on measured cell counts provided in original reference.

Table 1: Mean cell concentrations of 3 replicates of Selenastrum capricornutum cultures at different days after exposition to the test substance.

Concentration (mg/L)

Cell concentration (x 105 cells/mL)

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

0

0.51

1.69

13.7

48.8

94.2

137

100

0.61

1.65

11.9

46.8

90.2

100

200

0.65

1.62

10.7

28.2

75.2

82.6

300

0.64

1.61

8.64

29.9

62.5

69.8

400

0.65

1.61

7.64

21.9

60.9

67.5

500

0.60

1.42

6.32

21.2

56.1

67.1

600

0.61

1.36

6.00

21.4

54.3

68.6

Description of key information

No study with algae is available for TRIS HCl. Therefore, the assessment of toxicity to algae was based on a studies conducted with the structurally similar substance TRIS AMINO. There is one study available on the toxicity of 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS AMINO) to algae, which was used as key study. The study published by Adams et al. (1985) was conducted following standard procedures similar to the OECD guideline 201, using Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata) as test organism. Algal cultures were exposed to six different test concentrations from 100 to 600 mg/L during six days. The cell counts determined daily for each treatment are reported in the publication. Since no effect concentrations are reported, the growth rate based EC50 and NOEC were calculated from the provided cell count data, using the sofware ToxRat v2.10. For 72 hours exposure an ErC50 of 397 mg/L and a NOEC of 100 mg/L were obtained.

Key value for chemical safety assessment

EC50 for freshwater algae:
397 mg/L
EC10 or NOEC for freshwater algae:
100 mg/L

Additional information