N,N''-hexane-1,6-diylbis[N'-benzylurea]

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:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

N,N''-hexane-1,6-diylbis[N'-benzylurea]

EC Number:

254-274-3

EC Name:

N,N''-hexane-1,6-diylbis[N'-benzylurea]

Cas Number:

39072-70-3

Molecular formula:

C22H30N4O2

IUPAC Name:

N',N'''-hexane-1,6-diylbis(1-benzylurea)

Details on test material:

Description White powder (determined at NOTOX)
Batch 259-635
Purity > 90%

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Frequency at t=0 h, t=24 h and t=72 h
Volume 2 ml
Storage Samples were stored in a freezer until analysis.

Test solutions

Vehicle:

no

Details on test solutions:

Preparation of test solutions started with loading rates of 1.0 and 100 mg/l applying a 10-minute treatment period with ultrasonic waves followed by magnetic stirring for two subsequent days to ensure achieving maximum dissolution in test medium. This resulted in a hazy dispersion with undissolved particles floating at the surface and precipitated at the bottom of the tank for the 100 mg/l loading rate or a clear solution with a slight floating layer and precipitate for the 1.0 mg/l loading rate. Both dispersions were filtered through a 0.45 µm membrane filter (Whatman, RC55) which resulted in clear and colourless solutions that were used for testing and for preparation of the lower test concentrations (1 and 10-fold dilutions).

Test organisms

Test organisms (species):

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

Details on test organisms:

Species Pseudokirchneriella subcapitata, strain: NIVA CHL 1
Source In-house laboratory culture.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

24 mg CaCO3/L

Test temperature:

22.1 - 22.6°C

pH:

8.0 - 8.1

Nominal and measured concentrations:

Analysis of the samples taken from the filtrates prepared at 1.0 and 100 mg/l showed that measured concentrations decreased slightly during the 72-hour test period. Measured concentrations decreased from 31.1 µg/l at the start to 23.0 µg/l after 24 hours and further to 11.5 µg/l after 72 hours in the filtrate prepared at 1.0 mg/l. Measured concentrations in the filtrate prepared at 100 mg/l decreased from 19.1 µg/l at the start to 17.3 µg/l after 24 hours and further to 13.7 µg/l after 72 hours. The average measured concentrations were calculated to correspond to 20 and 16 µg/l for the filtrates prepared at 1.0 and 100 mg/l, respectively.

Details on test conditions:

Test vessels 100 ml, all-glass, containing 50 ml of test solution
Medium M2
Cell density An initial cell density of 1 x 104 cells/ml.
Illumination Continuously using TLD-lamps of the type ‘Cool-white’ of 30 Watt, with a light intensity within the range of 92 to
97 E.m-2.s-1.
Incubation Capped vessels were distributed at random in the incubator and as such were daily repositioned. During incubation the algal cells were kept in suspension by continuous shaking.

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

> 100 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The EC50 for both growth rate reduction (ERC50: 0-72h) and yield inhibition (EYC50: 0-72h) exceeded an average exposure concentration of 20 µg/l. Based on Loading rates, the EL50 exceeded a 0.45 µm filtered solution prepared at a loading rate of 100 mg/l.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes