Urea

Toxicity to aquatic plants other than algae

Administrative data

Endpoint:

toxicity to aquatic plants other than algae

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2011

Materials and methods

Principles of method if other than guideline:

Automatic biotest ECOTOX.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Urea

EC Number:

200-315-5

EC Name:

Urea

Cas Number:

57-13-6

Molecular formula:

CH4N2O

IUPAC Name:

urea

Test material form:

not specified

Sampling and analysis

Analytical monitoring:

not specified

Test organisms

Test organisms (species):

other: Euglena gracilis

Details on test organisms:

E. gracilis KLEBS, strain Z from University of Göttingen

Study design

Test type:

not specified

Water media type:

freshwater

Total exposure duration:

24 h

Remarks on exposure duration:

4 different time intervals: 0 h, 1 h, 6 h, 24 h

Post exposure observation period:

Recovery tests were performed with 3 concentrations for the 24 hour exposure group. The cells were transferred to deonized water and recovery was observed after 24 and 72 hours.

Test conditions

Test temperature:

20 °C

Nominal and measured concentrations:

Test concentrations:
1,05; 1,7; 3; 2,5; 6; 10,5; 17; 25; 35; 45 g/l
Recovery group:
8,5; 17; 34 g/l

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

1 h

Dose descriptor:

EC50

Effect conc.:

17.182 g/L

Basis for effect:

other: Inhibition of motility

Remarks on result:

other: 97% CL

Effect concentrations 2

Duration:

6 h

Dose descriptor:

EC50

Effect conc.:

14.945 g/L

Basis for effect:

other: Inhibition of motility

Remarks on result:

other: 99% CL

Effect concentrations 3

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

16.949 g/L

Basis for effect:

other: Inhibition of motility

Remarks on result:

other: 96% CL

Effect concentrations 4

Duration:

1 h

Dose descriptor:

NOEC

Effect conc.:

10.5 g/L

Basis for effect:

other: Inhibition of motility

Remarks on result:

other: 97% CL

Effect concentrations 5

Duration:

6 h

Dose descriptor:

NOEC

Effect conc.:

10.5 g/L

Basis for effect:

other: Inhibition of motility

Remarks on result:

other: 99% CL

Effect concentrations 6

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

10.5 g/L

Basis for effect:

other: Inhibition of motility

Remarks on result:

other: 97% CL

Applicant's summary and conclusion

Executive summary:

The effect of two commonly used fertilizers, DAP (diammonium phosphate) and urea was studied on the freshwater flagellate Euglena gracilis using the automatic biotest ECOTOX. NOEC and EC50 values for various parameters like motility, velocity, cell shape and gravitaxis were calculated. The NOEC and EC50 values obtained for DAP were much lower than those for urea; i.e. DAP showed a stronger inhibitory effect as compared to urea. The inhibition caused by DAP increased with increasing exposure time over 24 h but urea showed no augmentation with increasing exposure time. Application of DAP resulted in an increased pH and high concentrations of ammonia but urea did neither affect the pH nor affect the ammonia concentration. Recovery experiments in deionized water after urea application showed a reconstitution of motility after 72 h. After an application of 1.35 g L−1 (24 h EC50 for motility) DAP motility recovered after 72 h but motility did not recover when the concentration was doubled (2.7 g L−1). The EC50 values obtained were compared with the EC50/LC50 values reported for other aquatic organisms and were found to be comparable with the reported values.

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