N-(1,4-dimethylpentyl)-N'-phenylbenzene-1,4-diamine

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets generally accepted scientific principles

Guideline:

other:

Principles of method if other than guideline:

Shake Flask Carbon Dioxide Evolution Procedure:
American Society for Testing Materials, Proposed Standard Practice for the Determination of the Ultimate Biodegradability of Organic Chemicals,
Draft No. 3, ASTM E35.24 Subcommittee, Aquatic Biotransformation Task Group, 2/80.

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

other: soil, raw sewage, and activated sludge non adapted

Duration of test (contact time):

35 d

Initial conc.:

20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

35 d

Results with reference substance:

Positive Control: in the range of 75 - 95%

Validity criteria fulfilled:

yes

Remarks:

Carbon dioxide evolution for the positive control was in the expected 70-95 percent range.

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

N-(1,4-dimethylpentyl)-N'-phenylbenzene-1,4-diamine showed 0 % degradation after 35 days, (Monsanto, 1981).

Executive summary:

In a test conducted according to the American Society for Testing Materials, Proposed Standard Practice for the Determination of the Ultimate Biodegradability of Organic Chemicals, Draft No. 3, ASTM E35.24 Subcommittee, Aquatic Biotransformation Task Group, 2/80, N-(1,4-dimethylpentyl)-N'-phenylbenzene-1,4-diamine (7PPD) showed 0 % degradation after 35 days.

The result of this study indicates that 7PPD (Santoflex 14) may persist as either the parent compund or slightly altered intermediates in a natural aquatic environment, (Monsanto, 1981).

Description of key information

A study designated as the Key Study for 7PPD indicates that the substance is not readily biodegradable with 0 % biodegradation after 35 days.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Additional tests are available for 6PPD. Due to the analogous structure to 6PPD (the difference is an additional methyl group in 7PPD) the study from the supporting substance was used to read across. Both substances have similar physico-chemical properties. They hydrolyse rapidly and have a common hydrolysis product. The test conducted according to the OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) showed a 2 % degradation for 6PPD after 4 weeks, and the following degradation products were detected: Phenylbenzoquinone imine and 1,3-dimethylbutylamine. Further degradation products were stated: p-benzoquinone, 4-hydroxydiphenylamine, aniline.

As 7PPD is known to hydrolyze rapidly (half-life 7 h), the occurrence of the respective amine of 7PPD (1,4-dimethylpentylamine) would be expected also in biodegradation tests. As such amines are readily biodegradable, this would normally be reflected in a higher biodegradation rate. According to stoichiometric relations a biodegradation of about 40 % could theoretically be achieved. The data from different sources however clearly show, this is not the case. A possible explanation of this fact that ready biodegradation tests are performed typically in concentrations of 100 mg/L which is far above the solubility of 7PPD in water (0.7 mg/L).