Registration Dossier

Administrative data

Endpoint:
toxicity to microorganisms
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
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

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1996

Materials and methods

Test guideline
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 hours to lead chloride, using activated sludge mixed liquor (containing bacteria as food source) astest medium
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
ACS reagent grade

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
50 mL of activated sludge mixed liquor was filtered (0.45 ug/L)

Test solutions

Vehicle:
no
Details on test solutions:
250 mL sample of activated sludge mixed liquor

Test organisms

Test organisms (species):
other: Opercularia minima-Opercularia coarctata-Aspidisca lynceus-Vorticella convallaria-Trochilia minuta-Chilodonella uncinata-Euplotes sp.-Vorticella octava
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.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
24 h

Test conditions

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

Results and discussion

Effect concentrationsopen allclose all
Duration:
24 h
Dose descriptor:
other: LC50
Effect conc.:
5 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Basis for effect:
other: mortality
Remarks on result:
other: 95% CL: 3.57 - 10.2 Species: Opercularia minima
Duration:
24 h
Dose descriptor:
other: LC50
Effect conc.:
3.28 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Basis for effect:
other: mortality
Remarks on result:
other: 95%CL: 2.56-3.55 Species: Opercularia coarctata
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 Species: Aspidisca lynceus
Duration:
24 h
Dose descriptor:
other: LC50
Effect conc.:
2.29 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Basis for effect:
other: mortality
Remarks on result:
other: 95%CL: 2.01-2.61 Species: Vorticella convallaria
Duration:
24 h
Dose descriptor:
other: LC50
Effect conc.:
< 1.5 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Basis for effect:
other: mortality
Remarks on result:
other: Species: Trochilia minuta
Duration:
24 h
Dose descriptor:
other: LC50
Effect conc.:
< 1.5 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Basis for effect:
other: mortality
Remarks on result:
other: Species: Chilodonella uncinata
Duration:
24 h
Dose descriptor:
other: LC50
Effect conc.:
< 1.5 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Basis for effect:
other: mortality
Remarks on result:
other: Species: Euplotes sp.
Duration:
24 h
Dose descriptor:
other: LC50
Effect conc.:
2.81 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Basis for effect:
other: mortality
Remarks on result:
other: 95%CL: 2.28-3.55 Species: Voricella octava
Details on results:
no additional remarks
Reported statistics and error estimates:
LC50s were determined using a probit analysis computer (Finney, 1978)

Any other information on results incl. tables

LC50 determined for each type of organisms

Type of test organisms

LC50 (mg/L)

Opercularia minima

5

Opercularia coarctata

3.28

Aspidisca lynceus

3.78

Vorticella convallaria

2.29

Trochilia minuta

<1.5

Chilodonella uncinata

<1.5

Euplotes sp.

<1.5

Voricella octava

2.81

Applicant's summary and conclusion

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.