(R)-α-phenylethylammonium (-)-(1R, 2S)-(1,2-epoxypropyl)phosphonate monohydrate

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:

June 23, 1998 - June 24, 1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
Test material (Fosfomycin PEA salt): 100 ml of an aqueous Fosfomycin PEA salt stock solution at 500 mg/l were prepared and transferred to the suitable 500 ml beaker and kept gently stirred unter the start of the contact time. The concentration of use was 100 mg/l.
Reference substance (3,5-dichlorophenol): A stock solution at 500 mg/l was prepared. 0.05 g of standard were dissolved in 1 ml 1N NaOH, diluted to about 3 ml with bidistilled water. Excess NaOH was neutralized with 1N H2SO4 to the point of incipient precipitation. Thereafter the mixture was made up to 0.1 litres.
- Controls: Yes.

Test organisms (species):

other: Activated sludge from the RBM laboratory water treatment plant.

Details on inoculum:

- Preparation of inoculum for exposure: 2 L of wet sludge were suspended in water in order to obtain an activated sludge with a liquor/suspended solids level of 4 g/l was calculated. 2 L of wet sludge were suspended in water in order to obtain an activated sludge with a liquor/suspended solids level of 4 g/l. To that mixture 50 ml/l of synthetic sewage feed were added.
- Initial biomass concentration: 4 g/l (dwt)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Remarks on exposure duration:

After 3 hours, sample's oxygen measurement at 15 minute intervals.

Test temperature:

20 ºC

pH:

6.82-7.00

Nominal and measured concentrations:

Nominal concentrations: 100 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: Beakers
- Material, size, headspace, fill volume: Glass, 500 ml
- Aeration: Air-flow using compressed air.
- No. of organisms per vessel: 4 g/l of activated sludge
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: See the table below.
Synthetic sewage feed (1 litre of water):
16 g peptone
11 g meat extract
3 g urea
0.7 g NaCl
0.4 g CaCl2·2H2O
0.2 g MgSO4·7H2O
2.8 g K2HPO4
- Intervals of water quality measurement: Starting pH of each sample.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Oxygen consumption over a period of 10 minutes

TEST CONCENTRATIONS
- Test concentrations: Nominal concentrations: 100 mg/l

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (1, 3.2, 10, 32 and 50 mg/l)

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50 was 10.8 mg/L (95% CL: 10.7-10.9)

Reported statistics and error estimates:

The EC50 was calculated by the Probit method modified by the Flemish Institue for Technological Research (VITO).

Table 2. Summary of results.

Beaker	Chemical	Concentration	Oxygen consumption (mgO2/L min)	Inhibition (%)	Starting pH
7	Fosfomycin PEA salt	100	0.45	18.9	6.82
1	Control	-	0.58	-	7.0
8	Control	-	0.53	-	7.0
2	3,5-dichlorophenol	50	0.03	95	6.96
3	3,5-dichlorophenol	32	0.10	82	6.96
4	3,5-dichlorophenol	10	0.44	20.7	6.98
5	3,5-dichlorophenol	3.2	0.45	18.9	6.97
6	3,5-dichlorophenol	1.0	0.46	17.1	6.99

Validity criteria fulfilled:

yes

Remarks:

Variation between the respiration rates of the 2 control samples < 15%. Inhibitory effect of 3,5-dichlorophenol was within the range of the EC50 value of 5 to 30 mg/l

Conclusions:

EC50 value (based on respiration inhibition) on activated sludge at 3 hours exposure period was > 100 mg/l.

Executive summary:

The assessment of the effect of the test article Fosfomycin PEA salt on microorganisms by measuring the respiration rate followed the OECD Guideline 209. 4 g/l of activated sludge from RMB laboratory sewage plant were exposed for 3 hours of aeration at 20 ºC to test material at the nominal concentration of 100 mg/l. The reference substance, 3,5 -dichlorophenol was tested at 1, 3.2, 10, 32 and 50 mg/l and two control tests were carried out.

At 100 mg/l the test article showed 18.9 % inhibition on the respiration rate. The EC50 can be defined as >100 mg/l. The EC50 of the reference compound under the same conditions was 10.8 mg/l, which is in the accepted guideline range (5 -30 mg/l).

Description of key information

Key study: Test method according to OECD Guideline 209. GLP study.

The EC50 value (based on respiration inhibition) on activated sludge at 3 hours exposure period was > 100 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

Additional information

Key study: Test method according to OECD Guideline 209. GLP study. The EC50 value (based on respiration inhibition) on activated sludge at 3 hours exposure period was > 100 mg/l.