12-oxahexadecan-16-olide

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:

April 10 to September 19, 2017

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 (Alga, 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:

12-oxahexadecan-16-olide

EC Number:

229-755-6

EC Name:

12-oxahexadecan-16-olide

Cas Number:

6707-60-4

Molecular formula:

C15H28O3

IUPAC Name:

1,6-dioxacycloheptadecan-7-one

Test material form:

liquid

Specific details on test material used for the study:

Test material name (as stated in the report): Cervolide
Batch No.:VE00445215
Expiry date:June 07, 2018

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Test samples and control samples (50 mL) were extracted directly after sampling with 1 or 5 mL of internal standard (cylcohexane solution containing 8.08 mg/L of 2,4-DiChloroBenzene internal standard) solution giving a sample preparation factor of 0.02 or 0.1. The organic phase was separated and analyzed by GC with FID detection.

Test solutions

Vehicle:

no

Details on test solutions:

Since the test item was determined to be volatile, glass stoppered Erlenmeyer flasks were used completely filled (without headspace) with about 60 mL of test medium and tightly sealed with glass stoppers to avoid losses of the volatile substance by evaporation (closed system)

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

The test organism used for the study was Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum, occasionally also listed as Raphidocelis subcapitata), 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 under the test conditions. The inoculum culture was diluted threefold one day before the start of the test to ensure that the algae were in the exponential growth phase when used to inoculate the test solutions.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

0.15 mmol/L / 15 mg CaCO3/L

Test temperature:

24 °C

pH:

7.5 to 7.7

Nominal and measured concentrations:

This equilibrated aqueous phase with a loading rate of 100 mg/L, containing dissolved test item only, was used as the highest test concentration and was diluted with test water to obtain the additional dilutions 1:2.3, 1:5.3, 1:12, 1:28, 1:64 and 1:148.
Measured concentrations (Time weighted average mean): 0.028,0.051, 0.087, 0.16, 0.27, 0.63, 1.2 mg/L

Details on test conditions:

The test flasks were incubated in a temperature controlled orbital shaker (Multitron-Pro, Infors HT, Bottmingen/Switzerland) at a temperature of 24 °C. The test flasks were positioned randomly and repositioned daily. They were continuously illuminated by LED light installed above the test flasks. The light intensity at the level of the test solutions was approximately 64 μE s-1 m-2 (range: 62 to 66 μE s-1 m-2, measured at nine places in the experimental area). The light intensity over the incubation area was within a ±15 %-deviation from the average light intensity as recommended by the guideline.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.48 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI 1.1 - 1.2 mg/L

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.16 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.51 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Remarks on result:

other: 95% CI 0.48 - 0.55 mg/L

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.24 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.16 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Details on results:

Effects based on yield were also reported (see attached full study report and executive summary). However, the preferred observational endpoint in the algal inhibition study is growth rate because it is not dependent on the test design (ECHA guidance Chapter R.7b v1.1). The EU CLP regulation (No 1272/2008 and its adaption 286/2011) also states that classification should be based on the ErC50. Thus only the effects based on growth rate are presented in the above "effects concentration" table. Furthermore, the preferred observational endpoint in long-term studies is the EC10 value because it is derived from the dose response curve. In contrast the NOEC strongly depends on the experiment design (e.g. the concentrations used in the test). Thus the 72-h EC50 and EC10 based on growth rate are selected as key results for classification purposes.

Results with reference substance (positive control):

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 20170077 was 1.0 mg/L (May 2017)
and showed that the sensitivity of the test system was within the range recommended by the guideline (72-hour EC50 for the growth rate 0.9-1.5 mg/L).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In this study, CERVOLIDE was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (based on time weighted average mean measured test item concentrations): The EC50 values with 95 % confidence intervals for inhibition of growth rate (ErC50) after 72 hours was 1.2 mg/L. The NOEC-values for inhibition of growth rate and yield after 72 hours were for both 0.16 mg/L.
The preferred observational end point in the algal growth inhibition test is growth rate because it is not dependent on the test design (ECHA guidance Chapter R.7b v1.1). The EU CLP regulation (No 1272/2008 and its adaption 286/2011) also states that classification should be based on the ErC50. The preferred observational endpoint in long-term studies is the EC10 value because it is derived from the dose response curve. In contrast the NOEC strongly depends on the experiment design (e.g. the concentrations used in the test). Thus the 72-h EC50 and EC10 based on growth rate are used for classification purposes, which were determined in this study to be1.2 mg/L and 0.48 mg/L, respectively..

Executive summary:

The toxicity of CERVOLIDE to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 761/2009 Method C.3.

This equilibrated aqueous phase with a loading rate of 100 mg/L, containing dissolved test item only, was used as the highest test concentration and was diluted with test water to obtain the additional dilutions 1:2.3, 1:5.3, 1:12, 1:28, 1:64 and 1:148.

Measured concentrations(Time weighted average mean): 0.028,0.051, 0.087, 0.16, 0.27, 0.63, 1.2 mg/L

CERVOLIDE was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (based on time weighted average mean measured test item concentrations): The EC50 values with 95 % confidence intervals for inhibition of growth rate (ErC50) after 72 hours was 1.2 mg/L. The NOEC-values for inhibition of growth rate and yield after 72 hours were for both 0.16 mg/L.

The preferred observational end point in the algal growth inhibition test is growth rate because it is not dependent on the test design (ECHA guidance Chapter R.7b v1.1). The EU CLP regulation (No 1272/2008 and its adaption 286/2011) also states that classification should be based on the ErC50. The preferred observational endpoint in long-term studies is the EC10 value because it is derived from the dose response curve. In contrast the NOEC strongly depends on the experiment design (e.g. the concentrations used in the test). Thus the 72-h EC50 and EC10 based on growth rate are used for classification purposes, which were determined in this study to be1.2 mg/L and 0.48 mg/L, respectively.