Vanadium oxysulphate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Peer reviewed publication assessing effects of heavy metals on sewage respiration

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Principles of method if other than guideline:

Oxygen consumption measured as well as microscopic observations for activity of micro-organisms
Experiment was based on slowly increasing concentration of vanadium until reduction in oxygen consumption was noted. Total period of testing was over 110 days.

GLP compliance:

no

Specific details on test material used for the study:

Noted to be hygroscopic and difficult to handle as solid.

Analytical monitoring:

yes

Details on sampling:

Verification of starting concentrations

Vehicle:

no

Test organisms (species):

activated sludge

Details on inoculum:

Source not specified in terms of domestic or industrial

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

50 d

Remarks on exposure duration:

Experiment was based on slowly increasing concentration of vanadium until reduction in oxygen consumption was noted. Exposure not started until day 60 and ended day 110.

Nominal and measured concentrations:

Maximum addition rate of 200 mg/l vanadium

Reference substance (positive control):

no

Duration:

50 d

Dose descriptor:

EC10

Effect conc.:

ca. 20 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Remarks:

Vanadium

Basis for effect:

inhibition of total respiration

Remarks on result:

not determinable

Duration:

50 d

Dose descriptor:

EC50

Effect conc.:

ca. 100 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Remarks:

Vanadium

Basis for effect:

inhibition of total respiration

Key result

Duration:

50 d

Dose descriptor:

EC50

Effect conc.:

ca. 340 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Remarks:

Registered substance

Basis for effect:

inhibition of total respiration

Details on results:

The report does not indicate the time duration between sequential increases in concentration and the reduction in inhibiton and the 'duration' of 50 days indicated in the results table relates to the period of exposure to vanadium.

Although there was a significant reduction of up to 50% in respiration rate at 100 mg/l vanadium, additional concentrations over the following 20 days or so with concentration ramping up to 200 mg/l failed to reduce the oxygen consumption further and there was an indication of adaption with the respiration actually increasing over the longer period.

Conclusions:

Although the cited research uses unconventional methods, it demonstrates that vanadium has a significant impact on sludge respiration from about 20 mg/l and a 50% reduction was seen at ca 100 mg/l vanadium (estimated ca 340 mg/l using the nominal molecular weight of 173 for the registed substance)

Description of key information

Although the cited research uses unconventional methods, it demonstrates that vanadium has a significant impact on sludge respiration from about 20 mg/l and a 50% reduction was seen at ca 100 mg/l vanadium (estimated ca 340 mg/l using the nominal molecular weight of 173 for the registed substance)

Key value for chemical safety assessment

EC50 for microorganisms:

340 mg/L

EC10 or NOEC for microorganisms:

68 mg/L