p-phenylene diisocyanate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18/01/2018 - 31/05/2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material:
UpChem Co. Ltd., 170329
- Expiration date of the lot/batch: 28-03-2018
- Purity test date:
06-04-2017

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature, away from moisture
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: not soluble
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: not observed

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

The inoculum was secondary effluent, collected from a treatment plant receiving predominantly domestic sewage. This effluent was used as test system as it is recommended in the guideline. A fresh sample of secondary effluent was collected from the treatment plant and was kept aerobic during transport.

This effluent was allowed to settle for one hour, decanted and the decanted effluent was used in the test.

Source of the Inoculum

Sewage Treatment Plant
Eurofins Advinus Limited
Bengaluru – 560 058
India

Determination of Bacterial Population in the Inoculum

The bacterial population in the inoculum was determined as colony forming units (CFU/mL) by diluting the inoculum to an appropriate dilution and then plating on nutrient agar plates.

Preconditioning of the Inoculum

The decanted effluent was preconditioned by aerating for 6 days at 22 to 24C.

The bacterial population in the inoculum was 6.0 x 107 CFU/L.

Duration of test (contact time):

28 d

Initial conc.:

0.25 g/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 4.7

St. dev.:

0.516

Sampling time:

10 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 10.46

St. dev.:

1.181

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Based on the results, it was concluded that the test item, p-phenylene diisocyanate is biodegradable but not readily biodegradable as 10.46% mean degradation was achieved at the end of test which is less than 60% pass level in 10-day window period within the 28-d period of the test.

Executive summary:

The ready biodegradability of p-phenylene diisocyanate was tested using the CO₂Evolution Test. The test item was added to two test vessels at the concentration of 25 mg/L (equivalent to 15 mg of Total Organic Carbon/L). Two control treatments containing only the inoculum, one reference item treatment and one toxicity control treatment containing the test item and the reference item were also tested. All the treatments were added with equal volume of inoculum which was collected from the secondary effluent treatment plant receiving predominantly domestic sewage.

 

Treatment mixtures were aerated for 29 days with carbon dioxide (CO₂) free air. The CO₂released was trapped in a series of bottles containing barium hydroxide, which were connected to the outlet of each test vessel. The residual barium hydroxide was measured on Days 3, 6, 8, 10, 13, 16, 20, 24, 27 and 29 after the initiation of the test.

 

The mean per cent degradation of test item was 10.46% at the end of test while, the percent degradation of reference item was 100.46% and the toxicity control was 50.18% at the end of the test. It was observed that the mean degradation of test item,p-phenylene diisocyanatewas 10.14% which is less than 60% pass level in 10-day window period within the 28-d period of the test.

 

The test fulfilled all the validity criteria.

 

Based on the results, it was concluded that the test item,p-phenylene diisocyanateis biodegradable but not readily biodegradable as 10.46% mean degradation was achieved at the end of test which is less than 60% pass level in 10-day window period within the 28-d period of the test.

Description of key information

Based on the results, it was concluded that the test item, p-phenylene diisocyanate is biodegradable but not readily biodegradable as 10.46% mean degradation was achieved at the end of test which is less than 60% pass level in 10-day window period within the 28-d period of the test.  

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater