Chlorimuron ethyl

Toxicity to soil microorganisms

Administrative data

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The effect of the test substance on soil microflora activity was tested during a 28-day period by exposing to the recommended maximum application rate, 10X the recommended maximum application rate and a reference substance (Pentaphenate (NaPCP)) known to effect soil microflora activity.
Soil microflora activity was evaluated by three procedures:
1) determination of soil respiration in a short term test;
2) determination of nitrogen mineralization by measuring relative proportion of ammonium nitrate and nitrite in soil; and
3) determination of microbial biomass measured by CO2 production.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

ethyl 2-({[(4-chloro-6-methoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)benzoate

EC Number:

618-690-2

Cas Number:

90982-32-4

Molecular formula:

C15H15ClN4O6S

IUPAC Name:

ethyl 2-({[(4-chloro-6-methoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)benzoate

Test material form:

solid: granular

Details on test material:

25% by weight

Sampling and analysis

Analytical monitoring:

no

Test substrate

Vehicle:

yes

Remarks:

Deionized water

Test organisms

Test organisms (inoculum):

other: Microflora in soil

Study design

Total exposure duration:

28 d

Test conditions

Test temperature:

20 ± 2 °C

Moisture:

60%

Nominal and measured concentrations:

9 and 90 g a.i./ha (equivalent to 36 and 360 g/2.205x10e9 g)

Reference substance (positive control):

yes

Remarks:

Pentaphenate (NaPCP)

Results and discussion

Effect concentrations

Key result

Duration:

28 d

Remarks on result:

other: No significant effects observed on soil microflora activity when applied at either the recommended maximum application rate or 10X the recommended maximum application rate

Applicant's summary and conclusion

Conclusions:

The test results show that the test substance did not have any significant effects on soil microflora activity when applied at either the recommended maximum application rate or 10X the recommended maximum application rate during the 28 day experimental period.

Executive summary:

The effect of the test substance on soil microflora activity was tested during a 28 day period. A test soil was exposed to the recommended maximum application rate, 10X the recommended maximum application rate and a reference substance (Pentaphenate (NaPCP)) known to effect soil microflora activity. All chemical treatments were compared to a control treatment.

Soil microflora activity was evaluated by three procedures:

1) determination of soil respiration in a short term test;

2) determination of nitrogen mineralization by measuring relative proportion of ammonium nitrate and nitrite in soil; and

3) determination of microbial biomass measured by CO2 production.

 All test procedures followed the required protocol issued by the Pest Management Regulatory Agency (PMRA).

Application of the test substance to a sandy loam test soil at both the maximum application rate and 10X the maximum rate did not effect the nitrogen mineralization or respiration activity of microflora during the experimental period with only one exception. On day 14 of the experiment, nitrate concentration in soil exposed to the recommended maximum rate of application was greater than that of soils not exposed to the test substance. However, the increased nitrate concentration did not result in an increase in the total inorganic nitrogen concentration on that day.

The microbial biomass carbon content of the test soil was not effected by exposure to the test substance applied at both the recommended application rate and 10X the recommended application rate with three exceptions. On Day 0 of the experiment, microbial biomass carbon content in soil exposed to 10X the recommended maximum rate of application was lower than that of control soil. This effect was not realized on subsequent sampling days. On days 7 and 28, microbial biomass carbon content was higher in soils exposed to the test substance at the recommended application rate compared with that of control soils (p ≤0.05). This effect was not significant at p ≤0.01.

In conclusion, the test results show that the test substance did not have any significant effects on soil microflora activity when applied at either the recommended maximum application rate or 10X the recommended maximum application rate during the 28 day experimental period.