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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 16 May 1995 to 14 June 1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study is well detaled and results fully described. The study doesn't follow the EU methods however it refers to EPA method.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report Date:
1995

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
other: Toxic Substance Control act No. 139 of 21/12/94 by the Istituto Brasilero do Meio Ambiente e dos Recursos Naturais Renovaveis - IBAMA, Brazil.
Deviations:
not specified
Qualifier:
according to
Guideline:
other: EPA.U.S. Environmental Protection Agency. Aerobic aquatic biodegradation. Federal Register (USA),50 (188):39277-80, 1985.
Deviations:
not specified
Qualifier:
according to
Guideline:
other: LARSON, R.J. Estimation of biodegradation potential of xenobiotic organic chemicals. Appl. Environ. Microbial.,38:11531161, 1979.
Deviations:
not specified
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Material tested: Atrazina Tecnica OXON
Common name: Atrazine
Chemical name: 2-chloro-4-ethylamine-6-isopropylamine-1,3,5-triazine
Lot: M-353
Molecular weight: 215.7 g/mol
Declared purity: 94.7%
Analysed purity (BIOAGRI): 94.2%

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic, non-adapted
Details on inoculum:
Source of inocolum:
A mixture of microorganisms was collected in the Piracicaba river at a site with a high concentration of domestic raw sewage.
Inocolum preparation:
One liter of that water was centrifugated, the supernatant was discarded and the pellet was resuspended in nutrient solution in order to inoculate the flasks used in the assay. The number of inoculated microorganisms was 5.2 x 10^6 viable cells/ml. The enumeration of the microorganisms was carried out using the direct plate counting in Petri dishes with nutrient agar (NA).
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
10 mg/L
Based on:
other: carbon from the real concentration of the product
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
The assay was conducted to determine the the metabolization of Atrazina Tecnica OXON in a mineral nutrient solution by a mixture of environmental microrganisms. The study lenght was 28 days in an incubation chamber at a controlled temperature (ca 25°C). Two replicates of four treatments: (a - test substance, b - glucose, c - inhibition and d - check) were used containing 3 liters of nutrient solution inoculated with microorganisms. the CO2 evolved from all the treatments was captured in Ba(OH)2 and determined by HCl titration.
Reference substance
Reference substance:
other: glucose

Results and discussion

Preliminary study:
Preliminary study not performed.
Test performance:
The assay was carried out according to the following system:
six plastic bottle were filled with 700 ml 6N NaOH and connected in series using rubber tubing, to a pressurized free-CO2 air source.
the assay was carried out in completly darkness with 2 replicates in 4 L vessels, containing 3 liters of basal culture and adjusted to the test temperature (ca 25°C) in a flow-through system during 28 days.
A. Check - basal culture medium
B. Standard product - glucose at the concentration of 20 mg carbon per liter of solution.
C. Test substance - the test substance was Atrazina tecnica OXON at a concentration of 10.0 mg carbon from the real concentration of the product being tested, per liter of solution.
D. Inhibition assay - glucose was used as carbon source (20.0 mg C7L) and the test substance Atrazina tecnica OXON (10.0 mg C/L).
The solution was inoculated with a small number of microorganisms from a mixed polulation and aerated with CO2 - free air for 24 hours, to purge the system of carbon dioxide at ca 25°C, in dark condition.
After inoculation, 71.28 mg of test compound were added into the all treatments. Then 3 CO2 absorber bottles were filled with 100 ml 0.025N Ba(OH)2 and connected in series to the exit air line of each test treatments.
The biodegradation was analysed by the amounts of CO2 evolved and captured in Ba(OH)2 from all the treatments during all test period trhough HCl titration.
% Degradationopen allclose all
Parameter:
% degradation (CO2 evolution)
Value:
0.4
Sampling time:
1 d
Parameter:
% degradation (CO2 evolution)
Value:
9.86
Sampling time:
28 d

Any other information on results incl. tables

Percentage of CO2 evolved from glucose, Atrazina Tecnica OXON and inhibition solution, as related to the theoretically expected CO2, during 28 days incubation period:

CO2(mg)

Days

Glucose

Atrazina Tec. OXON

Inhibition

01

16.26

31.21

0.80

0

8.17

6.87

02

37.99

35.94

1.65

0.15

22.45

22.12

03

54.02

51.22

1.70

0.20

30.10

28.40

04

62.60

60.35

1.75

1.65

34.26

33.16

05

68.31

67.41

4.16

3.65

37.32

38.52

08

72.23

71.83

6.91

6.80

45.31

45.41

12

75.13

74.13

7.01

7.40

51.01

51.71

16

76.06

75.56

7.16

8.55

55.96

56.89

20

78.34

76.93

8.81

10.70

60.61

61.14

24

79.81

78.51

8.86

10.75

65.23

64.46

28

80.29

79.14

8.91

10.80

65.64

68.34

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The test was considered valid because the CO2 evolved from the standard solution was greater than 70% within 10 days interval after the date when the CO2 evolved reached 10%.
Interpretation of results:
other: under test contidions any biodegradation was observed
Conclusions:
According to the results, the product Atrazina Tecnica OXON had low evolution of carbon dioxide through out incubation period. This chemical had a total of 9.86% CO2 evolved from total carbon by the end of the assay. The glucose control had 79.71% and the inhibition test had 66.99% indicating Atrazina Tecnica OXON not toxic to microorganisms.