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Ecotoxicological information

Toxicity to soil microorganisms

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Administrative data

Endpoint:
toxicity to soil microorganisms
Type of information:
experimental study
Adequacy of study:
other information
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Peer reviewed in Eu Risk assessment, but original report not available

Data source

Referenceopen allclose all

Reference Type:
secondary source
Title:
Unnamed
Year:
2006
Reference Type:
study report
Title:
Unnamed
Year:
2000

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
Study on the effect of freshly applied and aged residues of 3,4-DCA on microbial mineralization of nitrogen in
soil.
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
3,4-dichloroaniline
EC Number:
202-448-4
EC Name:
3,4-dichloroaniline
Cas Number:
95-76-1
Molecular formula:
C6H5Cl2N
IUPAC Name:
3,4-dichloroaniline

Sampling and analysis

Analytical monitoring:
not specified

Test organisms

Test organisms (inoculum):
soil

Study design

Total exposure duration:
28 d

Results and discussion

Effect concentrationsopen allclose all
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
32 mg/kg soil dw
Conc. based on:
test mat.
Basis for effect:
nitrate formation rate
Remarks on result:
other: fresh treated soil
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
100 mg/kg soil dw
Conc. based on:
test mat.
Basis for effect:
nitrate formation rate
Remarks on result:
other: 5 week aged soil
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
32 mg/kg soil dw
Conc. based on:
test mat.
Basis for effect:
nitrate formation rate
Remarks on result:
other: 5 week aged soil

Any other information on results incl. tables

The effect of freshly applied and 5 weeks aged residues of 3,4-DCA was investigated in a loamy sand soil with an organic carbon content of 0.7% (Bayer 2000). In the experiment with fresh residues, a loamy sand soil was treated with 0, 1, 3.2, 10, 32 and 100 mg a.i. 3,4-DCA/kg dw soil and immediately amended with lucerne-grassgreen meal (5 g/kg dw soil). Soils were extracted 28 days later, and the quantities of NO3 in the extract were determined. In the experiment with aged residues, the same quantities of 3,4-DCA were added to the loamy sand soil and allowed to age 5 weeks. After 5 weeks, the soil was mixed with Lucerne-grass-green meal to stimulate microbial metabolism. Soil was extracted 28 days later, and the quantities of NO3 in the extracts were determined. In the fresh-treated test, after 28 days, soil samples with 1, 3.2, 10 und 32 mg/kg dw soil contained more NO3 than in the untreated control. The quantities of NO3 increased as the concentration of 3,4-DCA increased. In soil treated with 100 mg/kg soil there was 91% less NO3 than in the control. The reason for the increasing nitrate concentration was not determined. However, the authors speculate that immediately after treatment, small quantities of the 3,4-DCA were available to ¿ and were degraded by ¿ the soil microflora. In addition, 3,4-DCA might have killed some microbial cells. In this case, these too would become available for degradation and mineralisation to release NO3-N. In the aged-residue test, after 5 weeks incubation, only the soil containing 100 mg/kg dw soil contained 40% less NO3 than the control. 14 days after addition of the plant meal, differences between the sample treated with 100 mg/kg dw soil and the control (and the remaining samples) were strongly reduced, and after 28 days, differences between treated and control samples were no longer significant. An exact ID50 could not be calculated. However, the data show that the ID50 for 3,4-DCA lies between 32 and 100 mg/kg dw soil (Bayer 2000). From these studies a 28-day NOEC of 32 mg/kg soil for inhibition of nitrification can be deduced for fresh treated soil. For the 5 week aged soil a 14-day NOEC of 32 mg/kg and a 28-day NOEC of 100 mg/kg can be deduced. The studies show that aged residues of 3,4-DCA in soils, up to 100 mg/kg soil, do not have long-term influence on nitrogen mineralisation in soil.

Applicant's summary and conclusion