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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Link to relevant study record(s)

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
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes
Analytical monitoring:
no
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella 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