Reaction products of triphenyl phosphite and isodecanol (1:2)

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test was run at concentrations well in excess of the water solublity limit.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: 87/302/EEC, Algal inhibition test [Comparable to OECD 201]

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Reaction products of triphenyl phosphite and isodecanol (1:2)

EC Number:

701-374-4

Cas Number:

25550-98-5

Molecular formula:

C26H47O3P

IUPAC Name:

Reaction products of triphenyl phosphite and isodecanol (1:2)

Details on test material:

- Name of test substance: Irgastab CH 300 (CAS# 25550-98-5)- Commercial, purity: Stated to be ‘within specifications’- Commercial batch no. 09520538 (Test identification code: TK 11211) - Supplier: Ciba-Geigy, Ltd, Basel, Switzerland

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

not specified

Details on test solutions:

The stock solution was made up of 100.2 mg of test substance mixed into 1000 mL of water. Calculated amounts of the stock solution to produce the desired test concentrations were added to the water and were homogeneously distributed.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Green algae
- Strain:
- Source: Pflanzenphysiologisches Institut Univerity, Gottingen, Germany
- Age of inoculum (at test initiation):
- Method of cultivation:


ACCLIMATION
- Acclimation period:
- Culturing media and conditions (same as test or not):
- Any deformed or abnormal cells observed:

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

No data

Test temperature:

23 +/- 1oC

pH:

The pH values of the water ranged from 7.8-7.9 at 0 hours and 8.5 to 9.0 at 72 hours

Dissolved oxygen:

No data

Salinity:

No data

Nominal and measured concentrations:

The measured test substance concentrations were determined by HPLC to be <0.01, 1, 3.8, 12.1, 33.7, and 107.8 mg/L at 0 hours and <0.01, 0.3, 2.0, 5.9, 21.4, and 75.6 mg/L at 72 hours for the blank and the target concentrations of 1.23, 3.7, 11, 33, and 100 mg/L, respectively.
Nominal target concentrations of 1.23, 3.7, 11, 33, and 100 mg

Details on test conditions:

The algae were transferred into the flasks for a total duration of 72 hours. Samples of each test concentration were drawn immediately before exposure and at the end of the experiment and kept at 18-22 oC until analysed.

TEST SYSTEM
- Test vessel: 100-mL Erlenmeyer flasks
- Type: closed, stoppered with aluminum caps
- Material, size, headspace, fill volume: 50 mL of test solution per flask.
- Initial cells density: initial cell density of 10100 cells/mL were used in this experiment.
- No. of vessels per concentration (replicates): Nominal target concentrations of 1.23, 3.7, 11, 33, and 100 mg of test substance/L were used and each test concentration was tested in 3 replicates.
- No. of vessels per control (replicates): The blank control (water) was tested in 6 replicates.

OTHER TEST CONDITIONS
- Light intensity and quality: continuous illumination of white fluorescent light (approx. 8000 lux)

EFFECT PARAMETERS MEASURED: Cell densities were measured at 24, 48, and 72 hours on a “TOA” cell counter. The EC-50 values were calculated according to the maximum likelihood method, logit model.

Reference substance (positive control):

not specified

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

45 mg/L

Basis for effect:

growth rate

Remarks on result:

other: 25-67 mg/L

Effect concentrations 2

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.3 mg/L

Basis for effect:

growth rate

Any other information on results incl. tables

The mean cell densities (cells/mL x 10000) were as follows:

24 hr              48 hr              72 hr

Blank                         6.0                  27.1               147.3

0.3 mg/L                    5.2                  28.3               142.8

2.0 mg/L                    5.2                  26.3               19.5

5.9 mg/L                    5.1                  23.7               122.7

21.4 mg/L                 4.6                  23.5               102.8

75.6 mg/L                 2.9                  10.5               41.7

The mean inhibition levels for the blank control and the 0.3, 2.0, 5.9, 21.4, and 75.6 mg/L test substance groups were 0.0, 1.8, 15.0 16.0, 26.2, and 69.6%, respectively.

Applicant's summary and conclusion

Validity criteria fulfilled:

no

Conclusions:

72-hr EC50 = 45 mg/L. This study was run at concentrations well in excess of the water solubility limit of this phosphite and therefore the results are questionable. Regardless, this study supports the conclusion that this substance is not toxic to aquatic plant life at or below its water solubility limit.

Executive summary:

72-hr EC50 = 45 mg/L. This study was run at concentrations well in excess of the water solubility limit of this phosphite and therefore the results are questionable. Regardless, this study supports the conclusion that this substance is not toxic to aquatic plant life at or below its water solubility limit.