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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:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Already evaluated by the Competent Authorities for Biocides and Existing Substance Regulations.

Data source

Reference
Reference Type:
publication
Title:
Untersuchungen über die toxische Wirkung der in Siedlungsabfällen häufigen Schwermetalle auf die Bodenmikroflora
Author:
Beck, T.
Year:
1981
Bibliographic source:
Journal Z. Pflanzenernähr. Bodenk., 1981; 144:613-627

Materials and methods

Principles of method if other than guideline:
In several series the influence of soluble salts of Cd, Cr, Zn, Cu, Ni and Hg in various concentrations was tested on the development of bacteria and fungi in cultural studies and in soil model systems. In addition, the changes in microbial biomass, in the activity of oxidoreductases and hydrolases, and in nitrification were measured in five soils.

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test organisms

Test organisms (inoculum):
soil

Results and discussion

Effect concentrations
Dose descriptor:
NOEC
Effect conc.:
100 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
other: no bio-availability correction possible- no clay content

Any other information on results incl. tables

see Executive summary

Applicant's summary and conclusion

Conclusions:
Reliability: high quality NOEC value of 100 mg/kg is noticed.
No bioavailability correction possible as clay content is not given.
Executive summary:

In several series the influence of soluble salts of Cd, Cr, Zn, Cu, Ni and Hg in various concentrations was tested on the development of bacteria and fungi in cultural studies and in soil model systems. In addition, the changes in microbial biomass, in the activity of oxidoreductases and hydrolases, and in nitrification were measured in five soils.

Comparison of the results of bacteria-plate-counts in the presence of heavy metals in agar-media and in soils demonstrated that all tested elements have a more toxic effect on isolated soil microorganisms under culture conditions than when tested after heavy metal application to soils. Beside Hg, eukaryotic soil fungi proved to be 10-50fold more resistant to heavy metals in vitro as well as in situ.

For calculating the effect of heavy metals on soil microbial activity soil enzymatic methods are not reliable and can be used only to some extent, because some cellfree enzymes in the soil are activated or inactivated immediately by heavy metals.

In long-term experiments, the microbial biomass and nitrification in soil is not significantly influenced by the elements Cd, Cu and Ni in the concentration range of the tolerable limit content. In contrast, Cr, Zn and Hg reduced these microbiological properties more or less distinctly.