Tributylphosphine

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

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

Test material information

Constituent 1

Reference substance name:

Tributylphosphine

EC Number:

213-651-2

EC Name:

Tributylphosphine

Cas Number:

998-40-3

Molecular formula:

C12H27P

IUPAC Name:

tributylphosphane

Test material form:

not specified

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella 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 concentrations

Effect concentrations 1

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

Effect concentrations 2

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

Effect concentrations 3

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

Effect concentrations 4

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

Effect concentrations 5

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

Effect concentrations 6

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 1^stfull 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-E_RC₅₀) was 1.3 mg/L with a 95% confidence interval ranging from 1.3 to 1.4 mg/L. The EC₅₀for yield inhibition (72h-E_YC₅₀) 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.