Feldspar minerals, magnetite and quartz, calcination products of copper mining residues.

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Ciliated protozoan populations were tested in spiked activated sludge mixed liquor, which is relevant for the effects assessment of STPs. Lead concentrations were measured, and relevant endpoint/end parameter are reported. followed methodology is well described

Qualifier:

no guideline followed

Guideline:

other: method described in the publication

Principles of method if other than guideline:

Ciliated protozoa populations are exposed for 24 to lead chloride, using activated sludge mixed liquor (containing bacteria as food source) as test medium

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

50 mL of activated sludge mixed liquor was filtered (0.45 ug/L)

Vehicle:

no

Details on test solutions:

250 mL sample of activated sludge mixed liquor

Test organisms (species):

other: Aspidisca lynceus

Details on inoculum:

Protozoan community living in the activated sludge mixed liquor collected from the aeration basin of the sewage treatment plant in Roncocesi, Reggio Emilia (Italy), treating urban and industrial waste.
The whole sludge microbial community, maintained into the original microbiota, was tested; tests are therefore more similar to field tests than to lab tests.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

24 h

Hardness:

no data

Test temperature:

20 +/- 2 °C

pH:

7.6 +/- 0.2

Dissolved oxygen:

continuous aeration

Salinity:

no data

Nominal and measured concentrations:

nominal: 150, 200, 300, 400, 500 mg/L
measured after 24h in activated sludge: 1.50, 1.98, 2.79, 3.09, 6.98 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 mL glass flask containing 250 mL activated sludge mixed liquor
- Control: sample of untreated activated sludge mixed liquor


- No additional feeding during the test; normal bacterial population present in the test medium

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : number of surviving organisms was determined by microscopic observations at 100 x magnification.
Non-motile cells on the surface of the flock were regarded as dead
For each concentration the estimate of protozoan numbers was based on enumerations from sub-samples.
For each concentration two subsamples (replicates) were counted

Duration:

24 h

Dose descriptor:

other: LC50

Effect conc.:

3.78 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Basis for effect:

other: mortality

Remarks on result:

other: 95% CL: 3.07 - 5.08

Details on results:

no additional remarks

Reported statistics and error estimates:

LC50s were determined using a probit analysis computer (Finney, 1978)

Validity criteria fulfilled:

not specified

Conclusions:

The test method is well described, and a LC50 was determined for this test species. Values are based on measured Pb-levels. Due to the followed test method, the results are more field data than lab data.

Description of key information

Values are based on data for lead. Data stems from toxicity tests with bacterial and protozoan species in STP.

Key value for chemical safety assessment

EC50 for microorganisms:

1 mg/L