Reaction products of phosphoryl trichloride and 2-methyloxirane

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:

1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Principles of method if other than guideline:

method corresponds in most parts to OECD TG 209

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge

Details on inoculum:

- laboratory scale sewage treatment plant treating synthetic sewage (OECD 209)
- Initial biomass concentration: 6.0 g/L (dry weight)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20.2 - 20.7 °C

pH:

7.5 - 7.6

Dissolved oxygen:

O2 - Start: 4.3 - 6.9
O2 - End: 2.1 - 6.1

Nominal and measured concentrations:

Nominal conc.: 100, 180, 320, 560 and 1000 mg/L

Reference substance (positive control):

yes

Remarks:

3.5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

784 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

191 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Reported statistics and error estimates:

Statistical analysis is summarised in the attached document.

Result:

Testing concentration (mg/L) (nominal)	Respiration rate [mg/L*h]	Inhibition ( % )
100	28.8	4.0
180	28.0	6.7
320	22.8	24.0
560	19.5	35.0
1000	12.0	60.0

Validity criteria fulfilled:

yes

Remarks:

on the basic of graphic evaluation

Conclusions:

Toxicity to microorganisms was assessed in a test with activated sludge and a duration of 3 hours was performed according to ISO 8192 (Test for Inhibition of Oxygen Consumption by Activated Sludge) using TCPP as test susbstance. An EC50 of 784 mg/L and an EC10 of 191 mg/L was determined.

Executive summary:

Toxicity to microorganisms was assessed in a test with activated sludge and a duration of 3 hours was performed according to ISO 8192 (Test for Inhibition of Oxygen Consumption by Activated Sludge) using TCPP as test susbstance. An EC50 of 784 mg/L was determined.TCPP was applied by direct weighing. 3,5 -Dichlorophenol is used as positive control.

Description of key information

ISO 8192 (Bayer AG, 1990): 3h EC50 = 784 mg/L; 3h EC10 = 191 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

784 mg/L

EC10 or NOEC for microorganisms:

191 mg/L

Additional information

Toxicity to microorganisms was assessed in a test with activated sludge and a duration of 3 hours was performed according to ISO 8192 (Test for Inhibition of Oxygen Consumption by Activated Sludge) using TCPP as test substance (Bayer AG, 1990). An EC50 of 784 mg/L and an EC10 of 191 mg/L was determined.TCPP was applied by direct weighing. 3,5 -Dichlorophenol is used as positive control. There is another test available presenting a lower effect value, but according to the Guidance on information requirements and chemical safety assessment (R.7b, ECHA, 2014) Vibrio fisheri is considered of low relevance for STP since they require a high salinity environment. Thus, the test system used is unsuitable to assess the risk towards microorganisms in a STP and was scored as not reliable.