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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:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Publication has been subject to peer and adminsitrative review.

Data source

Reference
Reference Type:
secondary source
Title:
Environmental Health Criteria 224: Arsenic and arsenic compounds, 2nd edition
Author:
World Health Organization Geneva
Year:
2001
Bibliographic source:
http://www.inchem.org/documents/ehc/ehc/ehc224.htm [checked 2012-03-21]

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
review of literature data on arsenic substances

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Assessment based on literature data of As substances

Results and discussion

Effect concentrationsopen allclose all
Duration:
17 d
Dose descriptor:
EC50
Effect conc.:
247 kg/ha
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
other: fungal growth of Hebeloma crustuliniforme
Remarks on result:
other: based on study by Sharples et al (1999)
Duration:
17 d
Dose descriptor:
EC50
Effect conc.:
996 kg/ha
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
other: fungal growth of Hymenoscyphus ericae
Remarks on result:
other: based on study by Sharples et al (1999)
Duration:
8 wk
Dose descriptor:
NOEC
Effect conc.:
48 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
other: fungal growth of Cladosporium herbarum
Remarks on result:
other: based on study by Da Costa (1972)

Applicant's summary and conclusion

Conclusions:
The toxicity of arsenate (As(V)), as measured by retardation or inhibition of growth in 8-week tests, showed wide variation among different species of fungi. Toxicity was consistently reduced by the addition of phosphate with both arsenate-sensitive and arsenate-tolerant strains. Poria monticola, an arsenate-sensitive fungus, was completely inhibited by 187.5 mg As(V)/kg (0.0025 mol/litre) but was progressively less inhibited as the phosphate concentration increased and some growth occurred at 3000 mg As(V)/kg (0.04 mol/litre) when 0.16 mol/litre potassium phosphate was added. An arsenate-tolerant fungus, Cladosporium herbarum, showed 36% reduction in growth at 6000 mg As(V)/kg (0.08 mol/litre) but when 0.01 mol/litre phosphate was added there was no effect on growth at arsenate concentrations of 48 g As(V)/kg (0.64 mol/litre). Addition of phosphate also reduced the toxicity of arsenite (As(III)) but not DMA (Da Costa, 1972). The counteracting effect of phosphate on arsenate toxicity was found to occur with all of the fungi tested and with the bacteria Bacillus subtilis and P. aeruginosa.

Sharples et al. (1999) found EC50s for arsenate, based on growth inhibition, for the endomycorrhizal fungus Hymenoscyphus ericae and the ectomycorrhizal fungus Hebeloma crustuliniforme to be 99.6 mg As(V)/litre (1.33 mol/m3) and 24.7 mg As(V)/litre (0.33 mol/m3) respectively. The presence of phosphate (0.01–1.0 mol/m3) in the media ameliorated the toxic effects of arsenate.