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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Taken from OECD SIDS (OECD Guideline study)
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes
Analytical monitoring:
no
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Supplier/Source (Strain Number): ATCC 22662
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2 900 mg/L
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
1 000 mg/L
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 4 000 mg/L
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
27 000 mg/L
Basis for effect:
growth rate
Table: Measured algal cell densities
--------------------------------------------------
Nominal test Cell density x 10^4 (cells/ml)
concentration
--------------------------------------------------
(mg/l) Day 1 Day 2 Day 3
--------------------------------------------------
0 2.494 15.24 77.62
0 2.324 13.05 61.49
0 2.282 14.10 68.88
0 2.409 15.44 74.73
0 2.536 16.15 81.91
0 2.367 13.62 63.51

1000 1.859 9.106 39.74
1000 2.240 13.43 70.85
1000 2.071 12.02 60.09

1400 1.902 10.99 48.54
1400 1.859 10.19 46.84
1400 1.817 10.86 48.29

2000 1.859 17.49 33.98
2000 2.113 15.82 43.79
2000 1.902 12.52 32.03

2800 1.986 12.52 44.04
2800 2.155 8.389 30.73
2800 1.732 9.645 26.78

4000 1.775 8.299 19.88
4000 1.563 6.336 19.26
4000 1.732 11.93 18.35
----------------------------------------------------

Table: Percent biomass inhibition per concentration
----------------------------------------------------
Nominal test Percent growth inhibition
concentration
----------------------------------------------------
(mg/l) Area under the growth curve
----------------------------------------------------
0 0
1000 21.2
1400 33.6
2000 35.6
2800 47.1
4000 64.9
----------------------------------------------------

Table: Water parameters of test solutions
----------------------------------------------------
concentration Temperature pH
CaCl2 (mg/l) (°C)
----------------------------------------------------
0 22.2 8.5
1000 22.2 7.5
1400 22.4 7.8
2000 22.2 7.9
2800 22.3 7.9
4000 22.3 7.8
----------------------------------------------------

Table: EC50 and EC20
----------------------------------------------------
Hours of EC50 EC20
exposure (mg/l) (mg/l)
----------------------------------------------------
72 2900 1000
----------------------------------------------------

Table: Percent growth rate inhibition per concentration
-------------------------------------------------------
Nominal test Percent growth inhibition
concentration
(mg/l) Growth rate
-------------------------------------------------------
0 0
1000 4.9
1400 9.9
2000 15.5
2800 17.6
4000 31.0
-------------------------------------------------------


Table: EC50 and EC20
---------------------------------------
Hours of EC50 EC20
exposure (mg/l) (mg/l)
---------------------------------------
72 > 4000 2700
---------------------------------------

Description of key information

Among the available studies, only one study with freshwater algae, Pseudokirchneriella subcapitata (as Selenastrum capricornutum) (de Groot, 1998) was conducted according to OECD guideline 201 and thus selected as key study. The 72-hour EC50 based on biomass and growth rate were 2900 and >4000 mg/L respectively. The 72-hour EC20 obtained on the basis of biomass and growth rate were 1000 mg/L and 27000 mg/L, respectively. The growth rate value was chosen as key value. Note that as in this case no NOEC was presented in the study, the EC20 value was used as surrogate for the NOEC to be reported in the key value for chemical safety assessment.

Key value for chemical safety assessment

EC50 for freshwater algae:
4 000 mg/L
EC10 or NOEC for freshwater algae:
27 000 mg/L

Additional information