Fenamiphos

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

Study period:

1999-04-19 to 1999-04-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: ETAD 103

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

not specified

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Version / remarks:

not specified

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- CAS no.: 22224-92-6

Analytical monitoring:

no

Details on sampling:

analytical monitoring not performed

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: test item directly weighed in
- Controls: negative control, reference control, physiochemical oxygen consumption control (sterile control)
- Test concentration separation factor: < 2
- Evidence of undissolved material: not specified

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: aeration tank of a waste water plant treating predominantly domestic sewage (Wupper area water authority)
- Pretreatment: none
- Initial biomass concentration: 320 mg activated sludge/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

Post exposure observation not performed

Hardness:

not specified

Test temperature:

20.8 - 20.9 °C

pH:

7.8 - 8.0

Dissolved oxygen:

7.06 (mean, start) to 4.18 (mean, end) mg/L

Salinity:

not applicable

Conductivity:

not specified

Nominal and measured concentrations:

Nominal: 560, 1000, 1800, 3200 and 5600 mg/L; measured values are not available

Details on test conditions:

TEST SYSTEM
- Test vessel: not specified
- Aeration: permanent aeration
- No. of vessels per concentration: 1
- No. of vessels per control: 2 (negative control) and 1 per concentration of reference control
- No. of vessels per abiotic control: 1

Reference substance (positive control):

yes

Remarks:

3.5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

2 300 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

The results for the negative controls of the experimental study were re-assessed by Lattimore (2017) as requested by the Rapporteur Member State in the course of the EU PP Renewal Dossier for Fenamiphos.

Control 1 mg O₂/L/hour = (((5.0-2.5)/5)*60)/0.32 = 93.75

Control 2 mg O₂/L/hour = (((5.6-2.5)/6)*60)/0.32 = 96.875

Mean = 95.3 & CV = 2.3%

It can therefore be concluded that the results of the study are valid and the endpoints suitable for risk assessment.

Validity criteria fulfilled:

yes

Conclusions:

In a study saccording to OECD TG 209 the 3-hour EC50 of the test item was determined as 2030 mg/L, indicating no toxicity of fenamiphos to activated sludge.

Executive summary:

In a valid GLP-comliant study according to OECD TG 209 activated sludge of a laboratory waste water treatment plant was exposed for 3 hours to nominal test item concentrations ranging from 560 to 5600 mg test substance/L. The EC₅₀ was determined as 2030 mg/L, indicating no toxicity of fenamiphos to activated sludge. 

Description of key information

In a study saccording to OECD TG 209 the 3-hour EC50 of the test item was determined as 2030 mg/L, indicating no toxicity of the test substance to activated sludge.

Key value for chemical safety assessment

EC50 for microorganisms:

2 030 mg/L

Additional information

In a valid GLP-comliant study according to OECD TG 209 activated sludge of a laboratory waste water treatment plant was exposed for 3 hours to nominal test item concentrations ranging from 560 to 5600 mg test substance/L. The EC₅₀ was determined as 2030 mg/L, indicating no toxicity of the test substance to activated sludge (Müller, 1999).