O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate

Toxicity to soil microorganisms

Administrative data

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Whilst this study was not performed to GLP or to a regulatory guideline, the results are considered to be scientifically valids.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1976

Report date:

1976

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

A sandy loam and a silt loam soil were obtained from dry land agricultural fields. These soils were treated at rates of 0, 50 and 250 ppm CGA-15324 and the effects on the microbial populations, the nitrification capacity of the microbial population and the level of cellulolytic fungi were assessed

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate

EC Number:

255-255-2

EC Name:

O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate

Cas Number:

41198-08-7

Molecular formula:

C11H15BrClO3PS

IUPAC Name:

4-bromo-2-chlorophenyl ethyl (propylsulfanyl)phosphonate

Test material form:

liquid

Sampling and analysis

Analytical monitoring:

no

Test substrate

Vehicle:

yes

Details on preparation and application of test substrate:

AMENDMENT OF SOILA sandy loam and a silt loam were used to test all three parametersAPPLICATION OF TEST SUBSTANCE TO SOIL- Method: The 50 ppm concentration was obtained by transfering 10g dsoil to a beaker, and adding 0.6 ml of acetone solution containing 8.33 mg of CGA-1523/mL. This was mixed thoroughly, air dried and returned to the 100 g soil sample for further mixing. The 250 ppm concentration was obtained by repeating these steps with the exception that 3.0 mL of acetone solution containing 8.33 mg/ CGA-15324/mL was added.In preparing the soil for nitrification, 2 kg of soil was added to 2 kg of acid washed sand. 4 g ammomium silphate and 1 g calcium carbonate were then added to thew soil mixtures. Soil moisture was then adjusted to 65% of field capacity. 30 mL of CGA 15324 in acetone (8.33 mg/mL) was distributed to 1 kg of the ammended soil to prepare the 250 ppm concentration. 200g of 250 ppm soil was mixed with 800 g of ammended soil to prepare the 50 ppm soil. VEHICLE:- Chemical name of vehicle: acetone- Evaporation of vehicle before use: Yes

Test organisms

Test organisms (inoculum):

soil

Study design

Remarks:

Enumeration of the microbial population took place over a 56 day period. Soil Nitrification was measured over a 10 week period. The effect on the cellulolytic fungal population was assessed after 11 days exposure.

Test conditions

Test temperature:

Enumeration of microbial population and Measurement of soil nitrificatio were performed at 28°CCelulolytic fungi study, incubation was at 25°C and exposure was at 24°C

Moisture:

For enumeration of the soil microbial poulations, the soil moisture was adjusted to 75% of field capacity at the beginning of the exposure period. For the microbial nitrification study, soil moisture was at 65% of field capacity at the beginning of the exposure period.

Details on test conditions:

TEST SYSTEM- Testing facility: ELARS Bioresearch Laboratories - Test container: For the enumeration of soil microbial population test exposure took place in 250 mL Erlenmeyer flask, the microbial nitrification study took place in 15 cm glass petri plates and the cellulolytic fungi study took place in 100 mL erlenmeyer flasks.- Amount of soil: 100g samples were used for the enumeration of soil microbial population and the soil nitrification studies- No. of replicates per concentration: The enumeration of the soil microbial population used 3 replicates per concentration. Microbial nitrification used 6 replicates per concentrationSOIL INCUBATION- Method: Soil preparations were made in bulk and samples were taken from these mixtures.SOURCE AND PROPERTIES OF SUBSTRATE (if soil)- Geographical reference of sampling site: The sandy loam soil is from Platteville Colorado, and is describeds as A horizon od the Vona sandy loam. The silt loam is from Burlington Colorado and is described as A horizon of the Colby loam. - History of site: Dry land agricultural fields- Vegetation cover:- % sand: Sandy loam 82 % Silt loam 22 %- % silt: Sandy loam 10 % Silt loam 54 %- % clay: Sandy loam 8 Silt loam 24 %- pH: Sandy loam7.2 Silt loam 7.1

Nominal and measured concentrations:

Nominal concentrations of 0, 50 and 250 ppm

Results and discussion

Effect concentrations

Duration:

10 wk

Dose descriptor:

NOEC

Effect conc.:

50 other: ppm

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Effects on population structure and soil nitrification

Any other information on results incl. tables

Enumeration of microbial populations:
Sandy Loam Soil: The major effect seen was a reduction on fungi and actinomycetes following treatment at the 250 mmm level. Reductions in fungal colonies were seen at 14, 28 and 56 days post treatment with reductions of 0.24, 0.36 and 0.40 log units respectively when compared to the control and 50 ppm treatment groups. Reductions of actinomycetal populations by 0.16 and 0.15 log units at 28 and 56 days were also considered to be significant. considered to be significant.

The 50 ppm group sohowed no significant difference to the control.

Silt Loam Soil: CGA15324 treatment of silt loam soil had no detectable effect on the bacterial or actinomycetal populations at concentrations of 50 or 250 ppm. Fungal populations were not affected by exposure to 50 ppm, however at 250 ppm there was a reduction after 14 days exposure. At other time periods the reduction was not statistically significant.

Soil Nitrification Study: A decrease in the nitrification ability of the 250 ppm treatment group was seen at 21 days post treatment in the sandy loam soil. and this effect eremained troughout the study. A slight effect was seen in the 50 ppm group but this has diminished by the end of the sampling period.

An effect on the nitrification ability of the silt loam soil was seen between 14 and 28 days in the 250 ppm group, with a much smaller effect seen on the 50 ppm group. After 42 days there was little difference between the treatment groups and the control.

Cellulolytic Activity:

No adverse effects were seen in any of the treatment groups.