5-methyl-2-(1-methylbutyl)-5-propyl-1,3-dioxane

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:

From 1st April 2014 to 28th November 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to the OECD Guideline 201 and it is GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

The concentration of NaHCO3 was increased to be twice of that indicated in the Guideline 201. This concentration has been found to be optimal.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

5-methyl-2-(1-methylbutyl)-5-propyl-1,3-dioxane

EC Number:

279-482-1

EC Name:

5-methyl-2-(1-methylbutyl)-5-propyl-1,3-dioxane

Cas Number:

80480-24-6

Molecular formula:

C13H26O2

IUPAC Name:

5-methyl-2-(1-methylbutyl)-5-propyl-1,3-dioxane

Details on test material:

- Name of test material (as cited in study report): Troenan
- Physical state: Colourless liquid
- Stability under test conditions: This is the subject of this study
- Storage condition of test material: At 2-8°C (4°C) protected from light

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

A sample of the test item will be archived at SGS INSTITUT FRESENIUS GmbH, Im Maisel 14, D-65232 Taunusstein, Germany for a period of time according to a time specified in German GLP-regulations. After this period, the samples will be disposed of in the correct way.

Test solutions

Vehicle:

not specified

Details on test solutions:

Principle of the Test:

The unicellular algae Desmodesmus subspicatus were exposed to different concentrations (aqueous eluates, called “WAF” [water accommodated fraction] from different amounts of the test item) of the test item for 72 hours at 24.1 – 25.5 ºC at constant illumination.
After 24.75 hr, 48.5 hr and 72 hr the numbers of algal cells was recorded.
The determination of cell concentration was performed by photometrical measurement using a calibration curve prepared by using a spectrophotometer at 578 nm.
From these results the yield and thus the growth rates of the algae were determined after 72 hours incubation.
Algae in a solution without any test item served as a reference.


Test System:

Desmodesmus subspicatus CHODAT was used as the test system (Origin: Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen [SAG], Strain-No. 86.81). The algae were cultivated under aseptic / sterile conditions.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Desmodesmus subspicatus CHODAT was used as the test system (Origin: Sammlung von Algenkulturen, Pflanzenphysiologiches Institut der Universität Göttingen [SAG], Strain-No. 86.81). The algae were cultivated under aseptic / sterile conditions.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

Temperature in the incubation chamber was measured by the use of a min/max thermometer and documented by the data logger system ELPRO. The temperature was in the range of 24.1°C to 25.5°C (mean value 24.6 ºC). A graphical representation of the temperatures is given in chapter 15.2 of this report.

pH:

As an additional determination, within this test, pH was measured at t0 and after 72 hours of incubation in the test solutions. There was an increase of pH due to growth of the algae. Max. pH=10.02
pH values increased during the course of the study upon growth of the algae. pH increased in the controls by 1.64 units. Thus, the pH exceeds the range of 1.5 being set by 0.14 units and is not considered to have an influence on the integrity of the results of the test.

Nominal and measured concentrations:

Nominal concentations from 0.625 to 10 mg/L

Details on test conditions:

For the definitive test, “WAFs” of the following amounts of test item were prepared as described above:
[1] 25.0 mg / 2000 mL ultrapure water (resulting 10 mg/L final nominal conc.)
[2] 500 mL of [1] + 500 mL ultrapure water (resulting 5 mg/L final nominal conc.)
[3] 250 mL of [1] + 750 mL ultrapure water (resulting 2.5 mg/L final nominal conc.)
[4] 125 mL of [1] + 875 mL ultrapure water (resulting 1.25 mg/L final nominal conc.)
[5] 62.5 mL of [1] + 937.5 mL ultrapure water (resulting 0.625 mg/L final nominal conc.)

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.43 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.28 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: yield

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.19 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.69 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Any other information on results incl. tables

On the Basis of thenominal Concentrations [mg”TROENAN” /L]		On the Basis of themeasured Concentrations[mg”TROENAN” /L]
Yield (0 - 72 h)                                                             EL10            1.62           95%-CL    lower            1.39                            upper            1.77                                          EL20            1.84           95%-CL    lower            1.64                            upper            1.98                                          EL50            2.33           95%-CL    lower            2.26                            upper            2.38                             Yield   LOEL            2.50                           NOEL            1.25 Section-by-section growth rate (48.5-72h)                             EL10            2.24           95%-CL    lower            1.86                            upper            2.54                                          EL20            2.70           95%-CL    lower            2.35                            upper            2.98                              EL50           3.85           95%-CL    lower           3.55                            upper           4.15                             LOEL        ≤ 0.63                           NOEL        < 0.63   Growth rate (0 - 72 h)                                                  EL10            1.88           95%-CL    lower            1.73                            upper            2.02                              EL20            2.61           95%-CL    lower            2.46                            upper            2.75                              EL50           4.90           95%-CL    lower           4.72                            upper           5.08     Growth rate   LOEL            2.50                           NOEL            1.25		Yield (0 - 72 h)                                                            EC10            1.28           95%-CL    lower            1.06                            upper            1.39                                         EC20            1.41           95%-CL    lower            1.23                            upper            1.50                                         EC50            1.69           95%-CL    lower            1.64                            upper            1.73                             Yield  LOEC            1.79                           NOEC            1.01 Section-by-section growth rate (48.5-72h)                            EC10            1.62           95%-CL    lower            1.38                            upper            1.81                                         EC20            1.91           95%-CL    lower            1.69                            upper            2.08                             EC50           2.61           95%-CL    lower           2.43                            upper           2.79                            LOEC        ≤ 0.51                           NOEC        < 0.51   Growth rate (0 - 72 h)                                                 EC10            1.43           95%-CL    lower            1.34                            upper            1.51                                         EC20            1.88           95%-CL    lower            1.80                            upper            1.96                             EC50           3.19           95%-CL    lower           3.10                            upper           3.28                            LOEC            1.79                           NOEC            1.01

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

As a conclusion of the analytical part of this study, recoveries of the concentrations of ”TROENAN” determined after 72 hours were not all at ≥ 80 % of those determined at time t0. Furthermore, the measured concentrations of ”TROENAN” within the treatments partially deviated more than 20 % from the nominal values probably due to the filtration step necessary for the treatment preparation and the poor water solubility character of the test item. The results of the analytical work indicate that the test item exhibits high stability during incubation. On the other hand, due to the limited water solubility of the test item the theoretical concentrations calculated could not be achieved in the treatments. At the nominal concentration of 10 mg/L <60% of the test item was measured at both times t0 and t72hr. Therefore the results of the biological part of the test should be based on the measured concentrations. The validity criteria for the study as given by the OECD Guideline 201 were met and the study is therefore considered to be valid.

Executive summary:

The toxicity of the substance towards algae was tested according to OECD-Guideline No. 201. The toxic effect was investigated by determination of the inhibition of the growth rate of the algae and the yield during the exposure period of 72 hours. As the test item exhibits a limited water solubility it was tested using aqueous extracts (“WAFs”) at nominal concentrations up to and including 10 mg test item/L (final concentration). The main test was performed using “WAFs” with nominal concentations from 0.625 to 10 mg/L of the test item.

As a conclusion of the analytical part of this study, recoveries of the concentrations of ”TROENAN” determined after 72 hours were not all at ≥ 80 % of those determined at time t0. Furthermore, the measured concentrations of ”TROENAN” within the treatments partially deviated more than 20 % from the nominal values probably due to the filtration step necessary for the treatment preparation and the poor water solubility character of the test item. The results of the analytical work indicate that the test item exhibits high stability during incubation. On the other hand, due to the limited water solubility of the test item the theoretical concentrations calculated could not be achieved in the treatments. At the nominal concentration of 10 mg/L <60% of the test item was measured at both times t0 and t72hr. Therefore the results of the biological part of the test should be based on the measured concentrations. The validity criteria for the study as given by the OECD Guideline 201 were met and the study is therefore considered to be valid.