N,2-dimethyl-N-phenylbutyramide

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:

2003

Report date:

2003

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-ethyl-N-methyl-N-(3-methylphenyl) butanamide

EC Number:

446-190-2

EC Name:

2-ethyl-N-methyl-N-(3-methylphenyl) butanamide

IUPAC Name:

446-190-2

Constituent 2

Reference substance name:

406488-30-0

Cas Number:

406488-30-0

IUPAC Name:

406488-30-0

Test material form:

other: liquid

Details on test material:

Sponsor's identification: M 019087
Description: clear colourless liquid
Batch No.: 01/02
Date received: 30 May 2002
Storage conditions: approximately 4 °C, in the dark

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

The test samples were analysed following filtration through glass wool in order to remove the algal cells. A volume of the saturated solution sample was diluted with test media to give a final theoretical concentration of 32 mg/L.

Test solutions

Vehicle:

yes

Details on test solutions:

A modification of the standard method for the preparation of aqueous media was performed. An approach endorsed by several important regulatory authorities in the EU and elsewhere (ECETOC 1996 and OECD 2000), is to expose organisms to a saturated solution of the test material in cases where the test material is of high purity and is poorly soluble in water.
The test material solutions were prepared by shaking an excess (2000mg/l) of test material in culture medium at 300 rpm at a temperature of 30'C for 24 hours prior to removing any undissolved test material by filtration through a pre-conditioned filter to produce a saturated solution. This saturated solution was then further diluted as necessary to prepare the required test concentrations.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

The test was carried out using Scenedesmus subspicatus strain CCAP 276/20. Liquid cultures of Scenedesmus subspicatus were obtained from the Culture Collection of Algae and Protozoa (CCAP), Insititue of Freshwater Ecology, The Ferry House, Far Sawrey, Cumbria. Cultures were maintained in the laboratory by the periodic replenishment of culture medium. The culture was maintained in the laboratory at a temperature of 21 ± 1 °C under continuous illumination (intensity approximately 7000 lux) and constant aeration.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

None

Test conditions

Test temperature:

The flasks were incubated at 24 ± 1°C

pH:

The pH of each control and test flask was determined at initiation of the test and after 72 hours exposure. The pH was measured using a WTW pH 320 pH meter. The pH values of the control cultures were observed to increase from pH 7.1 at 0 h to pH 8.4 at 72 h. The pH deviation in the control cultures was less than 1.5 pH units after 72 hours and therefore within the limits given in the test guidelines.
The test material vessels showed an increase in pH over the 72-hour test period following a concentration dependent pattern with the lower test material concentrations exhibiting a greater increase in pH. This effect was considered to be due to there being greater numbers of viable cells in the lower test concentration and hence utilisation of carbonates and bicarbonates from photosynthesis/respiration.

Nominal and measured concentrations:

Nominal concentrations:
Range-finding test: 0.1, 1.0, 10 and 100 mg/L
Definitive test: 6.25, 12.5, 25, 50 and 100

Chemical analysis of the solutions at 0 and 72 hours showed measured concentrations to be in the range of 85 to 92 % of nominal and so the results are based on nominal test concentrations only.

Reference substance (positive control):

not specified

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

30 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 27-33

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

26 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% CL: 23 - 29 mg/L

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

12.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and biomass

Details on results:

Chemical analysis of the solutions at 0 and 72 hours showed measured concentrations to be in the range of 85 to 92 % of nominal and so the results are based on nominal test concentrations only.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In a guideline study, conducted according to GLP, Paradisamide was found to have an EbC50 (72 hr) of 26 mg/L and an ErC50 (72 hr) of 30 mg/L. The No Observed Effect Concentration at 72 hours was 12.5 mg/L.

The preferred observational end point in this study is algal growth rate inhibition 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 the 72-h EC50 and NOEC based on growth rate are used for classification purposes

Executive summary:

Paradisamide was evaluated for its inhibition to algae in a study conducted according to OECD Guideline 201 and EU method C.3 of EC Directive 92/69/EEC (1992), and performed to GLP. Paradisamide was tested at nominal concentrations of 6.25, 12.5, 25, 50 and 100 mg/L for 72 hr in a static system. Paradisamide was found to have an EbC50 (72 hr) of 26 mg/L and an ErC50 (72 hr) of 30 mg/L. The No Observed Effect Concentration at 72 hours was 12.5 mg/L.

Chemical analysis of the solutions at 0 and 72 hours showed measured concentrations to be in the range of 85 to 92 % of nominal and so the results are based on nominal test concentrations only.