Octanal, 7-hydroxy-3,7-dimethyl-, reaction products with 1H-indole

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

η-1H-indol-3-yl-α,α,ε-trimethyl-1H-indole-3-heptanol

EC Number:

267-434-2

EC Name:

η-1H-indol-3-yl-α,α,ε-trimethyl-1H-indole-3-heptanol

Cas Number:

67860-00-8

Molecular formula:

C26H32N2O

IUPAC Name:

8,8-di(1H-indol-3-yl)-2,6-dimethyloctan-2-ol

Constituent 2

Reference substance name:

Indole

EC Number:

204-420-7

EC Name:

Indole

Cas Number:

120-72-9

Molecular formula:

C8H7N

IUPAC Name:

1H-indole

Constituent 3

Reference substance name:

7-hydroxycitronellal

EC Number:

203-518-7

EC Name:

7-hydroxycitronellal

Cas Number:

107-75-5

Molecular formula:

C10H20O2

IUPAC Name:

7-hydroxy-3,7-dimethyloctanal

Constituent 4

Reference substance name:

1-(1H-indol-1-yl)-3,7-dimethyloctane-1,7-diol

Cas Number:

1642782-49-7

Molecular formula:

C18H27NO2

IUPAC Name:

1-(1H-indol-1-yl)-3,7-dimethyloctane-1,7-diol

Constituent 5

Reference substance name:

Unknown constituents

IUPAC Name:

Unknown constituents

Specific details on test material used for the study:

Test Item Name: Indolene
Givaudan Product Code: 1490963
Batch Number: VE00434647
Composition: Reaction products from Octanal, 7-hydroxy-3,7-dimethyl with 1H-indole
Appearance: Green yellow liquid
Density: 1017.5 kg/m3 at 20 °C
Expiration Date: June 24, 2018
Storage Conditions (as provided by the Sponsor): Dry, well ventilated, hermetically sealed. Ambient temperature / 10-30 °C. Protect against light.
Storage Conditions (as handled at IES Ltd): At room temperature at approximately 20 °C. Protect against light.
IES Code: 10438

Sampling and analysis

Details on sampling:

Indolene consists of 1H-indole, 7-hydroxy-3,7-dimethyl- and their reaction products. The chromatographic profile of the test item consisted of several peaks. Therefore, the characterization of the WAFs was based on the sum of peaks of the different constituents.

For this, duplicate samples were taken from each treatment at the start of the test. At the end of the test (after 72 hours) stability samples were taken in duplicate from each treatment. For the stability samples with algae, the contents of the respective replicates were combined prior to sampling.

All samples were stored deep-frozen (at about -20 °C) immediately after sampling. Based on pre-experiments for investigation of the storage stability, the analyzed compounds were found to be stable in the test water under these storage conditions.

The concentrations of the analyzed compounds of the test item Indolene were analytically measured in one or two of the duplicate samples taken from all loading rates.

From the control, one of the duplicate samples was analyzed per sampling time.

Test solutions

Details on test solutions:

For preparation of the WAFs in the main test, individual dispersions of the test item with the loading rates were prepared:

Loading Rate [mg/L] Preparation
3.2 7.6 mg test item in 2340 mL test water
10 23.3 mg test item in 2320 mL test water
32 74.2 mg test item in 2320 mL test water
100 229 mg test item in 2290 mL test water

The dispersions were stirred following the slow-stirring method (see Section 5.5) for 48 hours at room temperature in the dark to dissolve a maximum amount of the different compounds of the test item in the dispersions. Then, an additional filtration step was added as a precaution and
to remove undissolved fraction in the test media. The dispersions were filtered through membrane filters (Whatman, Type NC45, pore size 0.45 μm) under reduced pressure (200 mbar) after preconditioning of the filter with about 300 mL of the dispersions (as a precaution to avoid losses of the test item components due to adsorption on the filter material).

The undiluted filtrates were tested as WAFs. Due to technical reasons (operational constraints on the precision of direct weighing of test item), the WAF with the lower loading rate of 1.0 mg/L was prepared as dilution of the WAF with the loading rate of 3.2 mg/L.

The test media were prepared just before the start of the exposure.

The preparation of the test media was based on the OECD Guidance Document No. 23 on Aquatic Toxicity Testing of Difficult Substances and Mixtures, 2000.

Test organisms

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

The test organism used for the study was Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum), Strain No. 61.81 SAG, supplied by the Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Göttingen, 37073 Göttingen / Germany). The algae were cultivated at IES Laboratories under standardized conditions according to the test guidelines.

An inoculum culture was set up three days before the start of the exposure. The algae were cultivated under the test conditions and were kept in the exponential growth phase until inoculation of the test solutions.

For evaluation of the algal quality and experimental conditions, potassium dichromate is tested as a positive control twice a year to demonstrate satisfactory test conditions. The 72-hour EC50 for growth rate in the reference test IES Study Number 20160066 was 1.0 mg/L (July 2016)
and showed that the sensitivity of the test system was within the range recommended by the guideline (72-hour EC50 for the growth rate 0.92-1.46 mg/L).
The test method and the test species are recommended by the test guidelines.

Study design

Test type:

static

Water media type:

other: Reconstituted test water (AAP Medium)

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Hardness:

The water hardness (calculated) of the test water was 0.15 mmol/L (= 15 mg/L as CaCO3).

Test temperature:

The test flasks were incubated in a temperature controlled orbital shaker (Multitron-Pro, Infors HT, Bottmingen/Switzerland) at a temperature of 23 °C.

pH:

The pH of the test media was in the range of 7.3 to 8.4 during the test period

Nominal and measured concentrations:

Indolene consists of several constituents with different solubilities. Therefore, Water Accommodated Fractions (WAFs) with the loading rates of 1.0, 3.2, 10, 32 and 100 mg/L were tested to assess the toxicity of Indolene to algae.

Sample analyses was performed using HPLC-UV/VIS.

At the start of the test, the measured test item concentrations in the test media with the loading rates of 1.0, 3.2, 10, 32 and 100 mg/L were 0.12, 0.34, 1.4, 1.8 and 3.3 mg/L, respectively. The concentrations determined at the end of the test were below the limit of quantification (LOQ = 0.0562 mg/L) for the WAFs with the loading rates of 1.0 and 10 mg/L. At the loading rates of 3.2, 32 and 100 mg/L, 60, 49 and 79% of the initially measured values were found, respectively.

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EL50

Remarks:

based on Loading Rate

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EL50

Remarks:

based on Loading Rate

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Effect concentrations 3

Key result

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOELR

Remarks:

based on Loading Rate

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Effect concentrations 5

Key result

Duration:

72 h

Dose descriptor:

EL10

Remarks:

Based on loading rate

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 6

Duration:

72 h

Dose descriptor:

EL10

Remarks:

Based on loading rate

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Details on results:

Since Indolene consists of several constituents with different solubilities and the analytical method is based only on some of these constituents, the absolute amount of test item could not be analytically determined and the measured test item concentrations should be regarded as approximated values. Therefore, all reported biological results were based on the loading rates of the test item. This procedure of evaluation of data ofWAFs is based on recommendations of the OECD Guidance Document No. 23 on Aquatic Toxicity Testing of Difficult Substances and Mixtures, 2000.

The test item had no statistically significant inhibitory effect on the growth of the algae (average growth rate and yield) during the test period of 72 hours up to and including the highest loading rate of 100 mg/L (results of Williams t-tests, one-sided, α = 0.05).

The loading rate of 100 mg/L was, therefore, determined to be the 72-hour NOELR. This value might even be higher, but concentrations of the test item exceeding 100 mg/L were not tested, in accordance with the test guidelines. The 72-hour LOELR was higher than the loading rate of 100 mg/L.

The microscopic examination of the algal cells at the end of the test showed no difference between the algae growing at the loading rate of 100 mg/L and the algal cells in the control. The shape and size of the algal cells were obviously not affected by the test item up to at least this concentration.

The pH was 7.3 in the control at test start and 8.4 at test end fulfilling the requirement of the OECD guideline that the pH of the control medium should not increase by more than 1.5 units during the test. The pH of the test media was in the range of 7.3 to 8.4 during the test period.
The water temperature during the test was maintained at 23 °C.

Any other information on results incl. tables

The values for the validity criteria of the test were calculated by the statistic program ToxRat Professional®.

In the control, the biomass increased by a factor of 146 over 72 hours. The validity criterion of increase of biomass by at least a factor of 16 within three days was fulfilled.

The mean coefficient of variation of the daily growth rates in the control (section-by-section growth rates) during 72 hours was 20%. According to the OECD test guideline, the mean coefficient of variation must not be higher than 35%. Thus, the validity criterion was fulfilled.

The coefficient of variation of the average specific growth rates in the replicates of the control after 72 hours was 1.7%. According to the OECD test guideline, the coefficient of variation must not be higher than 7%. Thus, the validity criterion was fulfilled.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the test item Indolene had no toxic effects on Pseudokirchneriella subcapitata during the 72-hour test period up to and including the loading rate of 100 mg/L.