Atrazine

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:

from 12 December 1988 to 20 April 1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Report date:

1989

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Atrazine

EC Number:

217-617-8

EC Name:

Atrazine

Cas Number:

1912-24-9

Molecular formula:

C8H14ClN5

IUPAC Name:

6-chloro-N2-ethyl-N4-(propan-2-yl)-1,3,5-triazine-2,4-diamine

Details on test material:

Batch n. Lot 210200
Purity: 98.2%
Appaerance: white powder
Solubility in water: 30 mg/L
Storage: room temperature

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Duplicate samples (ca. 50 ml) were taken at 0h and 72 h.
Samples for analysis were taken at the start and at the end of the exposure.

Test solutions

Vehicle:

yes

Details on test solutions:

The nominal test concentrations (mg/L): 0.0037, 0.011, 0.033, 0.10, 0.30.
Calculated amounts of stock solution to produce the desired test concentrations were given into the water and were homogeneously distributed.
The stock solution has been prepared mixing 10 mg of atrazine with 4 mg of alkylphenol-polyglykol-ether and made up to 1000 ml with water. This solution was diluted to 0.303 mg/L with water.
Controls:
The blank was water
The vehicle: 0.12 mg alkylphenol-polyglykol-ether per liter water in the concentration used for the highest test concentration.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Test system: Scenedesmus subspicatus
Strain / Origin:276/20
Initial cell density: 1.2 * 10000 cells/ml
Culture: According to OECD-Guideline No. 201,1984
Preculture: 3 days under test conditions

Study design

Test type:

not specified

Water media type:

not specified

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

see salinity

Test temperature:

23 ± 2°C, The temperature has been measured in continuous.

pH:

pH
Conc. Nominal mg/L 0 h 72 h
Blank 7.4 10.2
Vehicle 7.4 10.0
0.0037 7.4 10.1
0.011 7.4 10.1
0.033 7.4 9.5
0.10 7.4 7.9
0.30 7.4 7.8
The pH has been measured at the start and at the and of the exposure.

Dissolved oxygen:

no data

Salinity:

Composition of water according to OECD-Guideline No. 201, Paris 1984

Nominal and measured concentrations:

The content of atrazine was found to vary between 91 and 102% of the nominal concentrations in the day 0 samples and between 78 and 93 % of the nominal concentrations in the day 3 samples.

Details on test conditions:

Exposure : 100 ml Erlenmeyer flasks. stoppered with aluminium caps, on lab-shaker, 50 ml test solution
Water : Composition according to: OECD-Guideline No. 201,1984
Temperature : 23 ± 2°C
Aeration : None
Light : Continuous illumination, cold white fluorescent light, 120 sE/m2sec ± 20% (approx. 8000 lux)
Duration : 72 hours
Each test concentration was tested in 3 replicates, the blank control in 6.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.043 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks on result:

other: none

Effect concentrations 2

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.011 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

cell number

Details on results:

EC50 (0 - 72h) calculated: 0.043 mg/L
EC50 (0 - 72h) graphically determined: 0.045 mg/L
NOEC (0 - 72h): 0.011 mg/L

Comparison of areas under the growth curve according to OECD-Guideline No. 201,1984.
The EC-50 values were calculated according to BERKSON, JASA 48 (1953), 569-599.
EC-values were graphically determined on gausso-logarithmic probabilitypaper.
The NOEC was calculated according to DUNNETT, C.W., JASA 50 (1955), 1096-1121, Biometrics 20 (1964), 482-491, and modified by MARCUS et al.,Biometrika 63 (1976), 655-660.

Results with reference substance (positive control):

Not applicable

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified