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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
Study period:
24 Nov 2006 - 15 Dec 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)
Version / remarks:
The pH of the alga medium at the start of the definitive test was 7.1, prior to alga inoculation. This value is outside of the recommended limits stated within the OPPTS test guideline, of pH 7.4 – 7.6. It is the opinion of the Study Director, that although the pH is outside of this range, the test species will still thrive at the test media pH of 7.1. This is further supported by the test species satisfying the OPPS test guideline (850.5400) recommendation of achieving at least 3.5x10^6 alga cell/mL in the control treatment at the 96 hours.
Deviations:
yes
Remarks:
This deviation in alga medium pH is not considered to have affected the integrity of the study.
GLP compliance:
yes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 09898602
- Expiration date of the lot/batch: >6 month from receipt date 25°C
- Date received: 6 Nov 2006
- Physical Appearance: colourless liquid
- Purity: 99.8%
- Storage: refrigerated, 1-10°C
Analytical monitoring:
yes
Details on sampling:
- Limit of detection: 0.01 mg/L
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
A stock media was prepared by adding test item to a 2-litre volumetric flask and making up to a volume with alga (EC) media. The flask contents were treated with 30 min ultrasound and stirred overnight in the dark. A serial dilution of the stock was then prepared in 2-litre volumes to achieve the nominal concentrations. Volumes (100mL) of the appropriate test media were dispensed into test vessels.
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protazoa SAMS Research Services Ltd., Obam, UK
Test type:
static
Water media type:
not specified
Limit test:
no
Total exposure duration:
96 h
Remarks on exposure duration:
24, 48, 72 and 96 h sampling
Post exposure observation period:
N/A
Test temperature:
23.6 - 24.3°C
pH:
7.1 - 9.7
Nominal and measured concentrations:
Range finder test (nominal) (mg/L): 0, 0.1, 1.0, 10.0, 100.0 and 1000
Definitive test (nominal) (mg/L): 0, 0.625, 1.25, 2.5, 5.0 and 10.0
Definitive test (measured) (mg/L): 0, 0.147, 0.471, 3.06, 6.39 and 12.9
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer (conical) flask
- Volume: 250mL

- Initial cells density: 1x10^4cells/mL
- Control end cells density: 376x10^4cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes

- Photoperiod: 24h light
- Light intensity and quality: approx 4000 lux, 400-700 nm

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter
- intervals: sampling at 24, 48, 72 and 96h

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study: yes
Reference substance (positive control):
no
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
ca. 3.04 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
24 h
Dose descriptor:
NOEC
Effect conc.:
ca. 1.25 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
ca. 2.24 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
ca. 0.625 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 2.25 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 0.625 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
ca. 2.7 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
ca. 0.625 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
ca. 2.14 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
24 h
Dose descriptor:
NOEC
Effect conc.:
ca. 0.625 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
ca. 1.14 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
ca. 0.625 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 1.17 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 0.625 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
ca. 0.941 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
ca. 0.625 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
No algal cell morphology differences were observed when comparing with samples of algal cell at each treatment with control samples, with exception that cells were paler in colours with increasing concentration.
Results with reference substance (positive control):
Not specified
Reported statistics and error estimates:
EC50 toxicity values were established using a Probit method of analysis (Stephen et al (1978)). Achieved using a linear regression of transformed (natural logarithm) mean measured concentrations against the percentage of inhibition (in either the area under the growth curve and the growth rate) relative to the control for each treatment level.
Validity criteria fulfilled:
yes
Conclusions:
The growth rate and yield of Pseudokirchneriella subcapitata were affected by the presence of MEDOL-10 at measured test concentrations upto 12.9 mg/L, the highest two concentrations tested. The 72-hour EC50 and NOEC for growth rate were 2.25 and 0.625 mg/L, respectively.
Executive summary:

Introduction


The objective of the study was to determine the effects of Medol-10(the Subject Chemical) on the growth of the unicellular green alga Pseudokirchneriella subcapitata during a 96-hour acute growth inhibition toxicity test. 


Results


The mean measured concentrations of the Subject Chemical in unfiltered samples oftest media were 0.147, 0.471, 3.06, 6.39 and 12.9 mg/L, respectively, corresponding to 24, 38, 122, 128 and 129% of the nominal concentrations. 


No algal cell morphology differences were observed when comparing samples of algal cells at each treatment with control samples, with the exception that cells were paler in colour with increasing concentration.


Conclusion


The Subject Chemical was considered to be toxic to P. subcapitata at measured concentrations up to 12.9 mg/L as significant growth inhibition relative to the control treatment was observed.



The validity criterion of achieving an increase in control cell density by at least a factor of 16 was achieved. Therefore, the environmental conditions of the test were considered acceptable. 

Description of key information

72-hours Inhibition of Growth Rate :

ErC50: 2.25 mg/L; 95% confidence limits 1.89 to 2.61 mg/L

NOEC: 0.625 mg/L

 

72-hours Inhibition of Biomass:

EbC50: 1.17 mg/L; 95% confidence limits 0.992 to 1.38 mg/L

NOEC: 0.625 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:
2.25 mg/L
EC10 or NOEC for freshwater algae:
0.625 mg/L

Additional information

An algal growth inhibition study was conducted (Covance Laboratories Ltd, 2007, Study 2777/003-D2149) to determine the effect of MEDOL-10 on the growth of Pseudokirchneriella subcapitata.The study was conducted according to EPA test guideline 850.5400 and in compliance with GLP.

 

Following a preliminary range-finding test, triplicate algal cultures were exposed to aqueous solutions of the test item at nominal concentrations of 0, 0.625, 1.25, 2.5, 5.0 and 10.0 mg/L for 96 hours at a temperature of 23 °C under static test conditions and constant illumination. Six replicate control cultures were also incubated concurrently with the test samples.

 

Analysis of the fresh and old test preparations showed the measured concentrations were outside the 80 – 120 % range; hence, the results are expressed in terms of geometric measured concentrations.

 

The growth rate and yield of Pseudokirchneriella subcapitata were affected by the presence of MEDOL-10 at measured test concentrations upto 12.9 mg/L, the highest two concentrations tested.

The EC50 and NOEC for growth rate were 2.25 and 0.625 mg/L, respectively.