3- Hydroxy-4-methyoxypyrdine-2-carboxylic acid

Toxicity to soil microorganisms

Administrative data

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)

Version / remarks:

2000

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

3-hydroxy-4-methoxypyridine-2-carboxylic acid

Cas Number:

210300-09-7

Molecular formula:

C7H7NO4

IUPAC Name:

3-hydroxy-4-methoxypyridine-2-carboxylic acid

Specific details on test material used for the study:

Substance name: X696476
Lot #: XS9-109113-80 (TSN300901)
Purity: 100%

Sampling and analysis

Analytical monitoring:

no

Test substrate

Vehicle:

yes

Remarks:

Deionised water

Test organisms

Test organisms (inoculum):

soil

Study design

Total exposure duration:

28 d

Test conditions

Test temperature:

20 to 22°C

Moisture:

Soil moisture: 47 to 50% of its maximum water holding capacity (MWHC)

Nominal and measured concentrations:

Low Dose: 0.107 mg/kg soil dry weight (corresponding to the PEC for 2 applications)
High Dose: 0.533 mg/kg soil dry weight (corresponding to 10x the single application PEC)

Reference substance (positive control):

yes

Remarks:

The inhibition of nitrogen transformation by sodium chloride at a concentration of 16 g/kg soil dry weight will be determined at least once a year

Results and discussion

Effect concentrations

Key result

Duration:

28 d

Remarks on result:

other: test substance had no impact on soil nitrate content and soil nitrate formation rate of soil microflora when applied up to 0.533 mg/kg soil dry weight. It can be concluded that the test substance will not have any long term influence on soil microorganism

Results with reference substance (positive control):

The reference item sodium chloride has a significant impact on nitrogen turnover and respiration activities of soil microflora when applied at 16 g/kg soil dry weight. The reference item sodium chloride has long term influence on soil microflora and confirms the sensitivity of the test system (assessed in a previous study).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Based on the results of this study, it is concluded that the test substance had no impact on soil nitrate content and soil nitrate formation rate of soil microflora when applied up to 0.533 mg/kg soil dry weight. It can be concluded that the test substance will not have any long term influence on soil microorganisms.

Executive summary:

The effects of the test substance on soil microflora were assessed in accordance with the OECD Guidelines 216.

Determination of nitrogen-transformation (ammonium-, nitrite and nitrate-nitrogen levels) in soil enriched with lucerne meal (concentration in soil 0.5%). Comparison of test item treated soil with a non-treated soil. Three replicates per treatment and concentration. NH4-, NO2- and NO3-nitrogen formed from the nitrification process was determined by means of a Continuous Flow Analyzer system (AA3, XY-2 / XY-3 Sampler).

Sampling scheme: 0, 7, 14 and 28 days after treatment; Subsamples were withdrawn from the soil bulk batches and subjected to analysis.

Soil Nitrate Content: No adverse effects of the test substance on nitrogen transformation in soil could be observed in both test item concentrations (0.107 mg/kg dry soil and 0.533 mg/kg dry soil) after 28 days. Only slight and not significant deviations from the control of 1.06% (lower rate) and 1.24% (higher rate) were measured at the end of the 28-day incubation period.

Nitrate Formation Rate: The soil nitrate formation rates were calculated on an incremental basis (i.e. between successive sampling dates). In the last interval between days 14 and 28, the deviations from control were -3.85% and 1.92% for the lower and higher test concentration of the test substance.

Thus, the difference in the soil nitrate formation rates between the control and both test item treatments was clearly below the OECD guideline 216 trigger value of 25% at the 14 to 28 day interval. These deviations were not statistically significant different (Student t-test, α = 0.05).

Validity Criteria: The variation between the replicate control samples was within the validity criterion of 15% for the nitrogen transformation test (OECD test guidelines 216) throughout the test. The validity of the test system was further confirmed by the sensitivity established in separate positive control experiments using sodium chloride at a concentration of 16 g/kg soil dry weight.

Based on the results of this study, it is concluded that the test substance had no impact on soil nitrate content and soil nitrate formation rate of soil microflora when applied up to 0.533 mg/kg soil dry weight. It can be concluded that the test substance will not have any long term influence on soil microorganisms.