Potassium triboron pentaoxide

Toxicity to soil microorganisms

Administrative data

Endpoint:

toxicity to soil microorganisms

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: No guideline followed. No details on test conditions.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1978

Materials and methods

Test guideline

Qualifier:

no guideline followed

Deviations:

not applicable

Principles of method if other than guideline:

nitrification test

GLP compliance:

no

Test material

Test material information

Constituent 1

Details on test material:

- test material Na2B4O7
- Fisher certified reagent-grade chemicals

Sampling and analysis

Analytical monitoring:

no

Test substrate

Vehicle:

no

Details on preparation and application of test substrate:

The test compound was added in solution to the soil (dropwise, without mixing). Ammonium sulfate was added as a substrate

Test organisms

Test organisms (inoculum):

soil

Study design

Total exposure duration:

10 d

Test conditions

Test temperature:

30°C

Moisture:

+/- 60% of WHC

Details on test conditions:

TEST SYSTEM
- Test container (type, material, size): 250ml franch square bottle, stoppered and incubated at 30°C. Aerated every 2 days by flushing the bottle with air
- Amount of soil: 10g


SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
3 natural surface soils from USA:
- Depth of sampling: surface: 0-15 cm
- pH water (1:2.5):
- Webster: 5.8
- Harps: 7.8
- Okoboji: 7.4
- clay:
- Webster: 23%
- Harps: 30%
- Okoboji: 34%
- silt:
- Webster: 39%
- Harps: 44%
- Okoboji: 50%
- sand:
- Webster: 38%
- Harps: 26%
- Okoboji: 16%

- Pretreatment of soil: air dried and crushed through 2mm screen

After 10 days incubation, the inorganic N content of the soil was measured.
All experiments were done in duplicate.

Nominal and measured concentrations:

control and one nominal dose was tested (54.1 mg B/kg dw).

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

10 d

Dose descriptor:

other: EC92

Effect conc.:

54.1 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

B

Basis for effect:

nitrate formation rate

Remarks:

(nitrification)

Remarks on result:

other: Webster soil

Effect concentrations 2

Duration:

10 d

Dose descriptor:

other: EC74

Effect conc.:

54.1 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

B

Basis for effect:

nitrate formation rate

Remarks:

(nitrification)

Remarks on result:

other: Harps soil

Effect concentrations 3

Duration:

10 d

Dose descriptor:

other: EC74

Effect conc.:

54.1 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

B

Basis for effect:

nitrate formation rate

Remarks:

(nitrification)

Remarks on result:

other: Okoboji soil

Details on results:

inhibition of nitrification at 54.1 mg B/kg dw compared to control varied between 74 and 92% among soils.

Reported statistics and error estimates:

no statistics were reported on difference in nitrification between control and B amended treatments.Only the % inhibition compared to control treatment was calculated for single dose tested. The NOEC/LOEC values were derived based on a 10% inhibition treshold.

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Conclusions:

This study was considered unreliable because it does not follow standard guidelines, only 1 dose was tested and there is no information on replicates of Boron treatments. Results for the Okoboji soil are not considered because the clay content is above the 10-90th percentile bounderies for the EU.