Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-07-10 - 2017-11-01
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
Also used for preparation of the test substance: Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23, 2000
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
not specified

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Source (laboratory, culture collection): Charles River Laboratory

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h

Test conditions

Test temperature:
22-23°C
pH:
7.4-8.1
Nominal and measured concentrations:
Nominal concentrations: 0.10, 0.32, 1.0, 3.2 and 10 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 40 mL vials, all-glass, airtight closed, containing 40 mL of test solution
- Type: closed
- Initial cells density: 1 x 104 cells/mL

GROWTH MEDIUM
- Standard medium used: Adjusted M2

OTHER TEST CONDITIONS
- Light intensity and quality: Continuously using TLD-lamps with a light intensity within the range of 88 to 91 µE.m-2.s-1
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.74 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.87 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.69 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
biomass
Details on results:
1st test: Due to high variation in cell densities in the three replicates of 0.32 mg/L, being essential for the EC-value calculation the 72h-EC50values for both growth rate and yield inhibition could only be estimated and no confidence intervals could be set. The EC50values were estimated to correspond with 0.39 mg/L and 0.32 mg/L, for growth rate and yield respectively. The NOEC for effects on growth rate was 0.32 mg/L, while the NOEC for effects on yield was 0.10 mg/L. The test was repeated to ensure more accurate determination of the EC values.

2nd test: Growth rates were in the range of the controls at the concentrations of 0.10 and 0.32 mg/L during the 72-hour test period, whereas the growth rate of algae exposed to 1.0 mg/L and higher were increasingly reduced. Statistically significant inhibition of growth rate was found at test concentrations of 1.0 mg/L and higher.

Any other information on results incl. tables

Percentage Inhibition of Growth Rate During the Range-Finding Test

Tri-n-butyl phosphine

Nominal concentration (mg/L)

Mean

Std. Dev.

n

%Inhibition

Control

1.857

0.0144

3

1.0

1.695

0.0554

3

8.7

10

0.233

0.2793

3

87

100

0.287

0.1959

3

85

Percentage Inhibition of Growth Rate During the 1stfull test

Tri-n-butyl phosphine

Nominal concentration (mg/L)

Mean

Std. Dev.

n

%Inhibition

Control

1.841

0.0312

6

 

0.10

1.895

0.0218

3

-2.9

0.32

1.609

0.1315

3

13

1.0

0.000

0.0000

3

100

3.2

0.000

0.0000

3

100

10

0.000

0.0000

3

100

Growth Rate and Percentage Inhibition During the 2nd full test

Tri-n-butyl phosphine

Nominal concentration (mg/L)

Mean

Std. Dev.

n

%Inhibition

Control

1.930

0.0108

6

0.10

1.945

0.0012

3

-0.8

0.32

1.951

0.0048

3

-1.1

1.0

1.413

0.0853

3

27*

3.2

0.055

0.0841

3

97*

10

0.000

0.0000

3

100*

* - effect was statistically significant


Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
72-h NOEC for growth rate 0.32 mg/L; 72-h EC10 for growth rate 0.74 mg/L; 72-h EC50 for growth rate 1.3 mg/L
Executive summary:

In conclusion, under the conditions of the present study with Pseudokirchneriella subcapitata, Tri-n-butyl phosphine reduced growth rate and inhibited the yield of this fresh water algae species significantly at nominally 1.0 mg/L and higher. The EC50for growth rate inhibition (72h-ERC50) was 1.3 mg/L with a 95% confidence interval ranging from 1.3 to 1.4 mg/L. The EC50for yield inhibition (72h-EYC50) was estimated to correspond with 0.87 mg/L. The 72h-NOEC for both growth rate inhibition and yield inhibition was 0.32 mg/L.