2,4(1H,3H)-Pyrimidinedione, 1-(3,5-di-O-acetyl-2-deoxy-.beta.-L-erythro-pentofuranosyl)-5-methyl-

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26.5.2009 - 29.5.2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Samples for possible analysis were taken from all test concentrations and the control:
Frequency at t=0 h, t=24 h and t=72 h
Volume 1.5 ml

Vehicle:

yes

Remarks:

M2

Details on test solutions:

Preparation of test solutions started with the highest test concentration of 100 mg/L. No special treatment other than careful shaking 5 min of ultrasonic treatment were applied to completely dissolve the test substance in the test medium. The lower test concentrations were prepared by subsequent dilutions in test medium. The final test solutions were all clear and colourless.

Test organisms (species):

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

Details on test organisms:

Pseudokirchneriella subcapitata, strain: NIVA CHL 1
Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light in a climate room at a temperature of 21-24°C.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

22.1 - 23.1 °C

pH:

8.1

Nominal and measured concentrations:

Analysis of the samples taken from the highest test concentration of 100 mg/I showed that the measured concentration was relatively stable and in agreement with nominal during the test period (83-99%).
Nominal test concentrations: 1, 10, 100 mg/L

Details on test conditions:

The pH was within the limits prescribed by the protocol (6.0-9.0, preferably not varying by more than 1.5 unit). The temperature of the test medium was 23.1 °C at the start of the test. During the exposure period the temperature measured in the incubator was maintained between 22.1 and 23.1 °C.
Temperature remained within the limits prescribed by the protocol (21-24 °C, constant within
2°c).

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Results with reference substance (positive control):

ErC50 = 1.8 mg/L (date of the experiment: 6 April 2009)

The EC50 for growth rate reduction (ERC50: 0-72h) was 1.8 mg/I with a 95 % confidence interval ranging from 1.4 to 2.5 mg/I. The historical ranges for grow1h rate reduction lie between 0.82 and 2.3 mg/I. Hence, the ERC50: 0-72h for the present batch corresponds with this range.
The EC50 for yield inhibition (EvC50: 0-72h) was 0.6 mg/I with a 95 % confidence interval ranging from 0.5 to 0.9 mg/I.

Under the conditions of the present study with Pseudokirchnerella subcapitata exposed to the test substance, both the EC50 for growth rate reduction and the EC50 for yield inhibition exceeded an analytically confirmed concentration of 100 mg/l.

Effects of the test substance on algal growth were minimal with 5.8% reduction of growth and 26% inhibition of yield at the highest test concentration of 100 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the present study with Pseudokirchnerielfa subcapitata exposed to LDT600 C3, both the EC50 for growth rate reduction (ErC50: 0-72h) and the EC50 for yield inhibition (EyC50: 0-72h) exceeded an analytically confirmed concentration of 100 mg/I.
According to the classification criteria described in REGULATION (EC) No 1272/2008 (CLP) the product has not to be classified.

Description of key information

Under the conditions of the present study with Pseudokirchnerielfa subcapitata exposed to LDT600 C3, both the EC50 for growth rate reduction (ErC50: 0-72h) and the EC50 for yield inhibition (EyC50: 0-72h) exceeded an analytically confirmed concentration of 100 mg/I.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

10 mg/L