Triisobutyl phosphate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to microorganisms, other

Remarks:

inhibition control of an OECD 301 B test

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

GLP conform OECD 301B biodegradation test, which in general do not focus on the hazard assessment towards microorganisms. However, the degradation of the inhibition control can be considered as reliable information about the toxicity of the test substance to aquatic microorganisms.

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge

Details on inoculum:

Activated sludge from laboratory wastewater plant treating municipal sewage.
Concentration of activated sludge in the test assay: 30 mg/L dry substance

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

28 d

Test temperature:

22 +/- 2°C

pH:

7.2 - 7.8

Nominal and measured concentrations:

Test concentration (nominal): 37.2 mg/L

Details on test conditions:

for details see chapter 5.2.1

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

37.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: biodegradation of aniline

- Degradation degree in the inhibition control after 14 days: 70-80 %

Conclusions:

The test substance does not inhibit activated sludge at a concentration of 37.2 mg/L.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test procedure in accordance with German national standard; no GLP

Qualifier:

according to guideline

Guideline:

other: DIN 38412, Part27; Pseudomonas Respiration Inhibition Test

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

stock solution with 100 mg/L Tween 80

Test organisms (species):

Pseudomonas putida

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Test temperature:

20 - 21°C

pH:

7.8 - 8.0

Nominal and measured concentrations:

Test concentrations (nominal): 31.3, 62.5, 125, 250, 500 and 1000 mg/L

Key result

Duration:

30 min

Dose descriptor:

EC10

Effect conc.:

280 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

443 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

other: EC90

Effect conc.:

875 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Validity criteria fulfilled:

not specified

Reference 3

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge, industrial

Details on inoculum:

sludge from BASF waste water treatment plant

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Key result

Duration:

30 min

Dose descriptor:

other: EC20

Effect conc.:

390 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Description of key information

The inhibition of the degradation activity of activated sludge is not anticipated when triisobutyl phosphate introduced in appropriate low concentrations.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

37.2 mg/L

Additional information

No microorganismen respiration inhibition test according to OECD guideline 209 is available. However, the toxicity of Triisobutyl phosphate (TriBP) was assessed based on the inhibition control of a ready biodegradation test performed according to GLP and OECD guideline 301B (BASF 2004). 37.2 mg/L test substance and aniline was mixed. No inhibition of aniline degradation was observed throughout an exposure time of 28 days. Thus the 28d-NOEC value is determined to be 37.2 mg/L. Additional data from a robra test with Pseudomonas putida (30 min-EC10 = 280 mg/L); BASF 1989) and a respiration inhibition test with activated sludge from an industrial STP (30 min-EC20 = 390 mg/L; BASF 1984) confirm the conservative assumption of no toxicity below 37.2 mg/L.