Pentane, 1,5-diisocyanato-

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: SEPA(HJ/T 153 -2004), "The guidelines for the testing of chemicals, Degradation and Accumulation" (the 2nd edition) (Beijing: China Environment Press. 2013)

Deviations:

yes

Remarks:

The residue of test substance was determinate by TOC method, which is deviated the protocol that did not require the residue analysis.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))

Deviations:

no

Principles of method if other than guideline:

According to the information provided by sponsor, the protocol considers that POI will hydrolysis to poly-urea which is a mixture of poly-urea with different molecular weights.The poly-urea will precipitate and would be very difficult to be extracted, so TOC method may be impossible.
However, after 28 days, there was no obvious insoluble in abiotic control. So a TOC analysis was used to determinate the residue concentration of test substance.
After assessment, this deviation will not affect the scientifiness and integrity of study.

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: Mixture of activated sludge, surface soil and surface water

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): sampled from ten sites distributed in
four districts throughout Nanjing city, such as Chengdong, Chengbei, and Jiangning
- Laboratory culture:
- Method of cultivation:
- Storage conditions:
- Storage length:
- Preparation of inoculum for exposure: 1 L of the sludge, soil and water were collected and mixed thoroughly together.
- Pretreatment: After removing floating matter, the mixture was allowed to stand and then the supernatant was filtrated through filter paper. After that the filtrate was adjusted to pH 7.0 with sodium hydroxide or phosphoric acid. Finally an appropriate volume of the filtrate was transferred to a fill -anddraw
activated sludge vessel and aerated for about 23.5 h. Thirty minutes after stopping the aeration, about one third of the whole volume of
supernatant was discarded. Then an equal volume of synthetic sludge (a solution at pH 7.0 containing 0.1 % each of glucose, peptone and potassium orthophosphate) was added into the settled material which was then aerated again. This procedure was repeated once per day during one month. Before use the mixture was allowed to stand, and the supernatant was removed. A small quantity of sludge was taken to be centrifuged (2500 r/minx 10 min) and then weighed. Then the sludge was dried in the oven and weighed again in order to calculate the content of dry sludge was 10.8 %.
- Concentration of sludge: 4000 mg/L dry weight

Duration of test (contact time):

28 d

Initial conc.:

50 mg/L

Based on:

test mat.

Details on study design:

TEST CONDITIONS
- Composition of medium: Based Salt Medium (BSM)
- Test temperature:25 ± 2 °C
- pH: 7.30-7 .94
- Aeration of dilution water: jes
- Suspended solids concentration: 4000 mg/L dry weight
- Continuous darkness: yes
- Test Substance was added to the test bottles directly.
- Concentration of reference chemicals: 100 mg/L (W N)
- Concentration of activated sludge in "test" and "blank inoculum control": 100 mg/L (WN)
- Concentration of activated sludge in "reference": 30 mg/L (W N)

TEST SYSTEM
- Culturing apparatus: 1 L volumetric flask
- Number of culture flasks/concentration: 3 (Testmaterial), 1 (blank inoculum control, abiotic control and Reference substance)
- stirring with mechanical stirrer
- The temperature, the operation of the stirrer and recorder was checked daily. Any changes in colour of the contents of the vessels were recorded. The BOD for the bottles were determined and recorded.

SAMPLING
- Sampling frequency: daily

CONTROL AND BLANK SYSTEM
- Inoculum blank: activated sludge suspension
- Abiotic control: test material and deionised water.
- Reference control: Aniline in BSM and activated sludge

STATISTICAL METHODS:

Reference substance:

aniline

Key result

Parameter:

% degradation (O2 consumption)

Value:

8.61

Sampling time:

28 d

Parameter:

% degradation (TOC removal)

Value:

2.58

Sampling time:

28 d

Details on results:

- recovery rate of residual amount of the test compound in the "abiotic control" test was found to be more than I 0% after 28 days.

Results with reference substance:

- biodegradation of the reference substance, aniline, was 76.2 % after 7 days(> 40%), and 88.5 % after 14 days(>65%)

A series of standard solutions with concentration at 5.0, I 0, 30, 50 and 100 were measured

under the TOC conditions mentioned above. Based on the test result, a linear regression

equation was obtained with the peak area vs. standard solution concentration, A =798c -

1279, with good linearity of r² = 0.9984, where A represents peak area (AU), and c is TOC

concentration (mg/L). The results show that linearity for concentration range of 5.0 mg/L

to 100 mg/Lis good

Validity criteria fulfilled:

yes

Remarks:

biodegradation of the reference substance reached> 40% and > 65% on day 7 and day 14, respectively, and recovery rate of residual amount (experimental, mg) of the test compound in the "abiotic control" is found to be more than 10%.

Interpretation of results:

not inherently biodegradable

Conclusions:

The BOD results showed that inherent biodegradation of the test substance (POI) was 8.61 % after 28 days.The TOC results showed that inherent biodegradation of the test substance (POI) was 2.58 % after 28 days.

Executive summary:

The inherent biodegradation test on 1,5-Diisocyanatopentan (PDI) was performed according to "The guidelines for the testing of chemicals" SEPA(HJ/T 153 -2004), "The guidelines for the testing of chemicals, Degradation and Accumulation" (the 2nd edition) (Beijing: China Environment Press. 2013), and Procedure 302C of the 'Guidelines for Testing of Chemicals' of the OECD: "Inherent Biodegradability: Modified MITI Test (II)" (1981). Test solutions were prepared in an inorganic salts medium, inoculated with a number of micro-organisms collected from 10 places in Nanjing city. During the test, the temperature was kept at (25±2) °C. The test was valid because the level of biodegradation of the reference substance aniline was 76.2% after 7 days (> 40%), and 88.5 % after 14 days (>65% ), and the recovery rate of residual amount of the test compound in the "abiotic control" is found to be more than 10% after 28 days.

The BOD results showed that inherent biodegradation of the test substance (POI) was 8.61 % after 28 days.

The TOC results showed that inherent biodegradation of the test substance (POI) was 2.58 % after 28 days.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline Study

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): aeration tank of a wastewater plant treating predominantly domestic sewage (Wupper area water authority, WWTP Odenthal)
- Storage conditions: before use, the inoculum was stored at room temperature under continuous stirring with aeration.
- Storage length: one day
- Pretreatment: The sludge was washed twice by adding mineral medium and centrifuging for 10 min at 2000 rpm and 20 °C and decanting off the supernatant. An aliquot of the wet sludge was dried in order to determine the wet weight / dry weight ratio of the sludge and to prepare a stock suspension (activated sludge) of 3 g dw/L. The calculated amount of sludge, needed to achieve 300 mL of this stock suspension, was dissolved in mineral medium and then filled up to a defined end volume.
- Concentration of sludge: 30 mg/L suspended solids
- Date of collection : 2015-12-07

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Details on study design:

Pre-treatment of the test item:
- 25 mg of the test item were weighed out and added to the test flasks, filled with 200 mL of mineral medium. Afterwards the volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg test item/L.

Pre-treatment of the reference compound:
25 mg of the reference compound were weighed out and added to the test flasks, filled with 200 mL of mineral medium. Afterwards the volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg reference compound /L.

Pre-treatment of the toxicity control:
25 mg of the test item and 25 mg of the reference compound were weighed out and added to the test flasks, filled with 200 mL of mineral medium. Afterwards the flask volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg test item and reference compound/L.

Exposure conditions:
Test volume : 250 mL
Test apparatus : OxiTopControl System (WTW)
Mixing : 1 magnetic stirrer per test vessel
Incubation time : 28 days
Incubation temperature : 22 ± 1 °C
test item and inoculum blank were carried out in triplicate and of reference compound in duplicate

Reference substance:

benzoic acid, sodium salt

Remarks:

(Purity : 99.9 %, Batch-no. (Acros Organics): A0357641)

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

7

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

10

Sampling time:

21 d

Parameter:

% degradation (O2 consumption)

Value:

26

Sampling time:

28 d

Results with reference substance:

The reference compound sodium benzoate showed 83 % degradation after 14 days.

Validity criteria fulfilled:

yes

Remarks:

(-Ready biodegradability of reference compound 60 percent within 14 days. -In the toxicity control degradation rates > 25 % within 14 days. -Replicates difference< 20% . -Oxygen uptake of blank inoculum=< 60mg/l. -No pH influence)

Interpretation of results:

other: Not Readily Biodegradable

Conclusions:

Within 28 days, a degradation rate of 26 % was determined. Therefore the substance is considered to be "Not Readily Biodegradable".

Executive summary:

According to OECD Guidelin 301F a suspension of 100 mg/L PDI in a mineral medium, equalling to 50-100 mg ThOD or COD/Litre as the nominal sole source of organic carbon, was stirred in a 250 ml closed flask in the dark with an inoculum originally collected from a local, predominantly municipal wastewater treatment plant. In this assay, biodegradation was estimated by biological oxygen demand (BOD) over time. BOD was measured daily by a manometer. The incubation temperature was (22 ± 1 °C), ph 7.2 -8.0. The concentration of innoculum was 30 mg /L suspended solids. The endogenous activity of the inoculum was checked running parallel blanks with inoculum but without test item. A reference compound (sodium benzoate) was run in parallel to check the operation of the procedures. A toxicity control (test item and reference compound mixed, one replicate) was run in parallel, to ensure that the chosen concentration of the test item was not inhibitory to microorganisms. Because of the nature of biodegradation and of the mixed bacterial populations used as inoculum, determinations of test item and inoculum blank were carried out in triplicate and of reference compound in duplicate. The test item is an N-containing substance. Therefore, the concentration of nitrite and nitrate was determined at the start of the test. The oxygen consumed by nitrification was not determined after 28 days, because low degradation of the test item was observed. Within 28 days, a degradation rate of 26 % was determined. The substance is considered to be "Not Readily Biodegradable".

Description of key information

Within 28 days, a degradation rate of 26 % was determined (Spoo-Klöppel, 2016). Therefore the substance is considered to be "Not Readily Biodegradable".

In an inherent biodegradation test a BOD result of 8.61 % after 28 days and a TOC result of 2.58 % after 28 days was measured (Zhou, 2017). The substance is not inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The substance is considered to be "Not Readily Biodegradable". The substance is "Not Inherently Biodegradable".