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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:
guideline study
Remarks:
A GLP study conducted in accordance with an international test guideline and confirmatory analysis of test solution concentrations.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Samples of test medium taken at 0 and 72 hours,
Vehicle:
yes
Details on test solutions:
Test solutions were prepared at 23 +/_ 2 degree C by dissolution of weighed test item into solvent dimethylformamide (DMF) stock and dilution in diluent medium (OECD culture medium)
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Internal stock cultures held since 20 June 1996 originating from American Type Culture Collection (ATCC 22662)

Preculture period; May 7, 2004 to May 11, 2004
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
NA
Hardness:
NA
Test temperature:
21.9 to 23.1
pH:
0 hours: 7.6 to 7.9
72 hours: 7.8 to 9.2
Dissolved oxygen:
NA
Salinity:
NA
Nominal and measured concentrations:
Nominal concentrations: Control, Solvent control, 0.0500, 0.110, 0.230, 0.480, 1.00, 2.20, 4.70, 10.0 mg/L

Initial measured concentrations at 0 hours: 0.0552, 0.122, 0.254, 0.530, 1.11, 2.46, 5.25 and 11.1 mg/L, equivalent to 110, 111, 110, 110, 111,
112, 112 and 111% of nominal.

72 hour measured concentrations:0.0303, 0.0804, 0.176, 0.375, 0.748, 1.57, 3.75 and 9.7 mg/L equivalent to 61, 73, 77, 78, 75, 71,80 and 97% of
nominal
Geometric mean measured concentrations: 0.041, 0.099, 0.211, 0.446, 0.911, 1.97, 4.44 and 10.4 equivalent to 82, 90, 92, 93, 91, 89, 94 and 104%
of nominal.

Details on test conditions:
3 replicate test vessels per test concentration including controls (diluent and solvent control) with an initial starting cell density of 1 x 10^4 cells/mL. The test was conducted in 300 mL Erlenmeyer flasks containing 100 mL test medium maintained at 23 +/_ 2 degrees C with a constant illumination and light intensity of 4000 Lux Test vessels were shaken at 100 rpm for 72 hours
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2.15 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
0-72 hours
Remarks on result:
other: 1.86 to 2.48 mg/L
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
7.07 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
7.73 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
1.11 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.46 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.53 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
No cell abnormalities reported.
The cell concentration in a control and solvent control increased 299 times, and therefore showed normal growth under the test conditions.
Results with reference substance (positive control):
A test with a reference material was conducted at approximatley six monthly intervals using potassium dichromate and the susceptibility of the test organism was investigated. The 72-hour 50% growth inhibition concentration (EbC50) in November, 1996 and afterwards was as follows.
Average ± standard deviation = 0.432 ± 0.0740 mg/L, n= 14
Reported statistics and error estimates:
Bartlett test for homogeneity followed by ANOVA and multiple comparisons test (Williams) using Yukms software Statlight 1 (YukinsCorp, Tokyo)

Analytical results

Nominal concentration (mg/L) Measured concentrations (mg/L)
0 hours (mg/L) % nominal 72 hours % nominal geometric mean measured (mg/L) overall % nominal
0.05 0.0552 110.4 0.0303 60.6 0.041 81.8
0.11 0.122 111 0.0804 73.1 0.099 90.0
0.23 0.254 110 0.176 76.5 0.211 91.9
0.48 0.53 110 0.375 78.1 0.446 92.9
1 1.11 111 0.748 74.8 0.911 91.1
2.2 2.46 112 1.57 71.4 1.97 89.3
4.7 5.25 112 3.75 79.8 4.44 94.4
10 11.1 111 9.7 97.0 10.4 104
Validity criteria fulfilled:
yes
Conclusions:
Test acceptable
The lowest test 72 -hour EC50 was determined to 2.15 mg/L, based on biomass (EbC50).
The 72 -hour ErC50 (based on growth rate) was determined to be 7.73 mg/L.
The lowest test 72 -hour NOEC was determined to 0.53 mg/L, based on biomass.
The 72 -hour NOEC based on growth rate was determined to be 2.46 mg/L.
Executive summary:

A GLP compliant OECD 201 algal inhibition assay (Pseudokirchneriella subcapitata) with 4,4 -biphenol was conducted with confirmation of test solution concentrations at 0 and 72 hours. The test was conducted at nominal concentrations of Control, solvent control, 0.05, 0.11, 0.23, 0.48, 1.0, 2.2, 4.7 and 10 mg/L the concentration range was based on the results of a range finding test.

The results were based on initial measured concentrations at 0 hours: 0.0552, 0.122, 0.254, 0.530, 1.11, 2.46, 5.25 and 11.1 mg/L, equivalent to 110, 111, 110, 110, 111, 112, 112 and 111% of nominal.

The cell concentration in a control and solvent control increased 299 times, and therefore showed normal growth under the test conditions. Based on initial measured concentrations at 0 hours the lowest test endpoint was determined to be the 72 -hour ErC50 of 2.15 mg/L. The 72 -hour ErC50 (based on growth rate) was determined to be 7.73 mg/L.

The lowest test 72 -hour NOEC was determined to 0.53 mg/L, based on biomass. The 72 -hour NOEC based on growth rate was determined to be 2.46 mg/L.

Description of key information

The test was conducted in accordance with GLP and an international test guideline (OECD 201). The test species was Pseudokirchneriella subcapitata and the 72h-EC50 and NOEC values of 7.73 and 0.53 mg/L were based on growth rate as requited by the ECHA endpoint specific guidance.

Key value for chemical safety assessment

EC50 for freshwater algae:
7.73 mg/L
EC10 or NOEC for freshwater algae:
0.53 mg/L

Additional information

A GLP compliant OECD 201 algal inhibition assay (Pseudokirchneriella subcapitata) with 4,4 -biphenol was conducted with confirmation of test solution concentrations at 0 and 72 hours. The test was conducted at nominal concentrations of Control, solvent control, 0.05, 0.11, 0.23, 0.48, 1.0, 2.2, 4.7 and 10 mg/L the concentration range was based on the results of a range finding test.

The results were based on initial measured concentrations at 0 hours: 0.0552, 0.122, 0.254, 0.530, 1.11, 2.46, 5.25 and 11.1 mg/L, equivalent to 110, 111, 110, 110, 111, 112, 112 and 111% of nominal.

The cell concentration in a control and solvent control increased 299 times, and therefore showed normal growth under the test conditions.

Based on initial measured concentrations at 0 hours the test endpoints were determined to be the 72 -hour EbC50 and ErC50 of 2.15 and 7.73 mg/L respectively.

The 72h NOEC was determined to be 0.53 mg/L and 2.46 mg/l based on biomass and on growth respectively.