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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
Study period:
From January 11, 2010 to March 25, 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
- Source: In-house laboratory culture
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
0, 24, 48 and 72 hours
Nominal and measured concentrations:
0.1, 1.0, 10 and 100 mg/l
Details on test conditions:
- Test vessel: 250ml tissue culture flask
- Test volume: 30 mL
- No. of vessels per concentration (replicates): 6 replicates for the highest test concentration and 3 replicates for other test concentration
- No. of vessels per control (replicates): 6
- Light intensity: 114-127 μE.m-2.s-1
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
72 h
Dose descriptor:
EC50
Remarks:
for growth rate reduction
Effect conc.:
> 92 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Duration:
72 h
Dose descriptor:
EC50
Remarks:
for yield inhibition
Effect conc.:
>= 8.4 - <= 92 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Results with reference substance (positive control):
The EC50 for growth rate reduction (ERC50: 0-72h) was 1.2 mg/l and the EC50 for yield inhibition (EYC50: 0-72h) was 0.65 mg/l.

Table 1.Mean cell densities (× 104 cells/ml)

Average conc.

Test substance

(mg/l)

Exposure time (hours)

0

24

48

72

Control

1.0

10.0

95.9

488.8

0.083

1.0

8.2

78.6

435.2

0.84

1.0

8.4

82.1

448.3

8.4

1.0

8.7

72.5

339.3

92

1.0

8.9

58.0

137.7

Table 2. Percentage reduction of growth rate (total test period) and percentage inhibition of yield

Average conc.

Test substance

(mg/l)

Mean growth rate

Yield (0-72 h)

μ (0-72 h)

Reduction (%)

×104cells/ml

Inhibition (%)

Control

0.08599

 

487.80

 

0.083

0.08438

1.9

434.20

11.0

0.84

0.08479

1.4

447.32

8.3

8.4

0.08093

5.9

338.34

30.6

92

0.06837

20.5

136.70

72.0

Table 3. Effect parameters

Parameter

Concentration

Everzol Red CDN Crude(mg/l)

72h-ERC50

> 92

72h-EY50

8.4-92

Validity criteria fulfilled:
yes
Conclusions:
According to OECD 201 test method, the 72h-ERC50 and the EYC50 of Everzol Red CDN Crude was >92 mg/L and 8.4-92 mg/L respectively.
Executive summary:

This test using the procedures outlined in the NOTOX Study Plan for 492365 and OECD 201 (OECD, 2006). The results of this OECD 201 test for Everzol Red CDN Crude show that test validity criteria was met. In the alga growth inhibition test, the nominal test article concentrations applied were 0.1, 1.0, 10 and 100 mg/L. The average exposure concentration were calculated: 0.083, 0.84, 8.4 and 92 mg/L. Under the test conditions, the EC50 for growth rate reduction and for yield inhibition of Everzol Red CDN Crude was >92 mg/L and 8.4-92 mg/L respectively.

 

Description of key information

Respectively, the 72h-ERC50 and the 72-EYC50 of Everzol Red CDN Crude was >92 mg/L and 8.4-92 mg/L for Pseudokirchneriella subcapitata (OECD TG201).

Key value for chemical safety assessment

Additional information

The cell densitiesin the control have increased by an average factor of at least 16 within 2 days. The mean coefficient of variation for section-by-section specific growth rates in the control group were not exceed 35%. The coefficient of variation of average specific growth rates during the whole test period in replicate control groups were not exceed 7%. This test validity criteria was met. Under the test conditions, the EC50 for growth rate reduction and for yield inhibition of Everzol Red CDN Crude was >92 mg/L and 8.4-92 mg/L respectively.