1,3-diisopropylbenzene

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1 JUN 1957 - 9 JUL 1957

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: According to the decomposition test of chemical substances by microorganisms, etc.

Deviations:

not specified

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Remarks:

active sludge 100 ppm

Details on inoculum:

10 µg of the substance to be tested was prepared by a microphone syringe and added to each culture bottle.
Calculation formula: 10 µL x 0,86 = 86 mg specific gravity)

Duration of test (contact time):

14 d

Initial conc.:

50 mg/L

Based on:

test mat.

Details on study design:

- Set-up of the BOD measuring device.
During preparation: the sample floated on the surface of the liquid.
Midway: the sample was diffused in the water.
At the end of the day: the sample diffused into the water and in the sludge system then sludge increased. In the sludge system, there was no increase in sludge.

TEST SYSTEM
- Test performed in closed vessels due to significant volatility of test substance: Closed system oxygen consumption measurement device for volatile substances

Parameter:

% degradation (O2 consumption)

Value:

0

Validity criteria fulfilled:

yes

Remarks:

Degree of degradation of aniline on day 7: 70 %.

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The results by oxygen consumption is 0 % . This Indicates no decomposition of both m and P.

Executive summary:

Bioderadation study was performed in closed system. GC analysis was used. The results by oxygen consumption is 0 % . This Indicates no decomposition of both m and P.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
In this justification, the read-across (bridging) concept is applied. Please refer to a full version of Read-across statement attached in the section 13 "Assessment reports".

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The underlying hypothesis for the read-across is that the target and the source substance have similar toxicological properties (including the same target organs) due to their structural similarity, resemblance to their chemical reactivity, and therefore a similar mode of action.
The source substance 1,4-diisopropylbenzene is a structural isomer of the target substance 1,3- diisopropylbenzene. The only difference between the target and this source substance is the position of the two isopropyl groups. While for 1,4-diisopropylbenzene both isopropyl groups are in para position at the benzene ring for 1,3-diisopropylbenzene they are in meta position.
The justification is based on similarity of chemical structure, physical-chemical properties and toxicokinetic behavior. As a conclusion, it is scientifically justified to address the endpoint Biodegradation in water: screening tests with data on this substance.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)


source substance: 1,4-diisopropylbenzene (or p-DIPB)
structural formula: C12H18
Smiles: CC(C)c1ccc(cc1)C(C)C
Molecular weight: 162 g/mol
CAS 100-18-5
EC No 202-826-9
purity: not specified

target substance: 1.3-diisopropylbenzene (or m-DIPB)
structural formula: C12H18
Smiles: CC(C)c1cccc(c1)C(C)C
Molecular weight: 162 g/mol
CAS 99-62-7
EC No 202-773-1
purity: not specified

No additional information is available on purity of the source and the target substances. Both substances are normally of high purity, containing only minor amounts of impurities that do not influence the read-across validity.

3. ANALOGUE APPROACH JUSTIFICATION
Please refer to the full version of the read-across statement attached in the section 13 "Assessment reports".


4. DATA MATRIX
Please refer to the full version of the read-across statement attached in the section 13 "Assessment reports".

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

28 d

Details on results:

The oxygen depletion of the inoculated control did not exceed 1.5 mg O2/L after 28 days, the residual oxygen concentration in the test bottles remained at 3.60 mg O2/L or greater in all test vessels and the difference between the extremes of replicate oxygen depletion values at the end of the test was less than 20 % in all vessels thereby satisfying the validation criteria. The test item attained 3 % degradation after 28 days and therefore cannot be considered as readily biodegradable under the strict terms and conditions of OECD Guideline 301D. The toxicity control attained 26 % degradation after 14 days therefore confirming that the test item was not toxic to the sewage treatment micro-organisms used in the test. The reference item, sodium benzoate, attained 88 % degradation after 14 days and 85 % degradation after 28 days thereby confirming the suitability of the test method and culture conditions. The decrease in degradation between Days 14 and 28 was considered to be due to normal biological variation.

Validity criteria fulfilled:

yes

Conclusions:

The test item attained 3 % degradation after 28 days and therefore cannot be considered as readily biodegradable under the strict terms and conditions of OECD Guideline No 301D.

Executive summary:

A study was performed to assess the ready biodegradability of p-diisopropyl benzene using the Closed Bottle Test (OECD 301D). The test item, at a concentration of 1.5 mg/L, was exposed to sewage treatment micro-organisms with culture medium in sealed culture vessels in the dark at approximately 21 for 28 days. Following the recommendations of the International Standards Organisation (ISO 1995), the test item was dissolved in an auxiliary solvent prior to being adsorbed onto a filter paper and subsequent dispersal in inoculated culture media. Using this method the test item is evenly distributed throughout the test medium and the surface area of test item exposed to the test organisms is increased thereby increasing the potential for biodegradation. The degradation of the test item was assessed by the determination of the amount of oxygen consumed. Control solutions with inoculum and the reference item, sodium benzoate, together with a toxicity control were used for validation purposes. The test item attained 3 % degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301 D.

Description of key information

An OECD 301D ready biodegradation study is available for p-diisopropylbenzene, a structural isomer analogue. The test item attained 3% degradation after 28 days and therefore cannot be considered as readily biodegradable under the strict terms and conditions of OECD Guideline No 301D.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

An OECD 301D ready biodegradation study was conducted on p-diisopropylbenze, a structural isomer analogue. The results of that study showed only 3 % degradation over 28 days. The substance exhibits a low potential for biodegradation. However, the lack of degradation exhibited in the ready biodegradation study may be affected by the low water solubility of the substance, 0.0405 mg/L.