Adipic acid, compound with hexane-1,6-diamine (1:1)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Meets generally accepted scientific standards, well documented and acceptable for assessment.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Duration of test (contact time):

14 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter:

% degradation (O2 consumption)

Value:

56

Sampling time:

14 d

Parameter:

% degradation (TOC removal)

Value:

97

Sampling time:

14 d

Interpretation of results:

readily biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

mixture of sewage, soil and natural water

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): In March, June, September, and December, sludge was sampled at the following 10 places in Japan: 1. Fukogawa city sewage plant, 2. Fukashiba industry sewage plant, 3. Nakahama city sewage plant, 4. Ochiai city sewage plant, 5. Kitakami river, 6. Shinano river, 7. Yoshino river, 8. Lake Biwa, 9. Hiroshima bay, 10. Dookai bay; sampling: 1. City sewage: Returned sludge from sewage plants was taken. 2. Rivers, lake and sea: Surface water and surface soil which were in contact with atmosphere were collected.
- Method of cultivation: About 30 minutes after ceasing aeration to the sludge mixture, supernatant corresponding to about 1/3 of the whole volume was removed. Then the equal volume of dechlorinated water was added to the remaining portion and aerated again, followed by addition of synthetic sewage at a concentration of 0.1% (w/v). This procedure was repeated once every day. The culturing was carried out at 25 ± 2 °C. 5 L of the filtrate of the supernatant of old activated sludge was mixed with 500 mL of the filtrate of the supernatant of new sludge and cultured at pH 7.0 ± 1.0 under sufficient aeration using prefiltered open air. During the cultivation, appearance of the supernatant, precipitability, formation of flock, pH, dissolved oxygen concentration in the solution and temperature were checked and necessary adjustments were made, Microflora in the activated sludge was microscopically observed and sludge with no abnormal symptom was used for the test.
- Concentration of sludge: 30 mg/L

Duration of test (contact time):

14 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: 3 mL each of four stock solutions, as described in JIS K 0102-1986-21, are diluted to 1000 mL with purified water
- pH: 7.0
- pH adjusted: yes
- Suspended solids concentration: determined according to Method Japanese Industrial Standards (JIS) K 0102-1986-14.1

TEST SYSTEM
- Culturing apparatus: Closed system oxygen consumption measuring apparatus (Coulometer: Ohkura Electric Co., Ltd.); 300 mL vessel, absorbent for evolving carbon dioxide Soda lime No .l (extra pure reagent, Wako Pure Chemical Industries, Ltd.).
- Number of culture flasks/concentration: 1
- Measuring equipment: Coulometer, Okhura Electric Co., Ltd.
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: soda lime, extra pure, Wako Pure Chemical Industries, Ltd.)

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
- Toxicity control: no

Reference substance:

aniline

Parameter:

% degradation (O2 consumption)

Value:

68 - 90

Sampling time:

14 d

Parameter:

% degradation (TOC removal)

Value:

97 - 99

Sampling time:

14 d

Parameter:

% degradation (test mat. analysis)

Value:

100

Sampling time:

14 d

Remarks on result:

other: HPLC analysis

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable (according to OECD criteria). 

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

There is no study available that indicates ready biodegradation of AH-salt. However, since AH-salt rapidly dissociates in aqueous solution or with soil moisture to adipic acid (CAS No: 124-04-9) and 1,6-Hexametylenediamine, (CAS No: 124 -09 -4), an assessment of biodegradability is appropriate when based on the products of dissiociation.

1) Adipic acid is readily biodegradable (according to MITI 1992). In this test, degradation of Adipic acid was measured either by oxygen consumption or by direct analysis of test substance. The oxygen consumption revealed a biodegradability of 68 -90%. By thereby the substance can be regarded as readily biodegradable according to OECD criteria (pass level > 60 % BOD/ThOD). Direct analysis revealed a degradation of >=97% when measured by HPLC or TOC, clearly showing an almost complete degradation.

2) 1,6-Hexamethylenediamine is also readily biodegradable (according to MITI 1992). In this test, degradation of 1,6 -Hexamethylenediamine was again measured either by oxygen consumption or by direct analysis of test substance. The oxygen consumption revealed a biodegradability of 55.5% and by thereby the substance would not be regarded as readily biodegradable according to OECD criteria (pass level > 60 % BOD/ThOD). However, direct analysis revealed a degradation of >90% when measured by GC or TOC, clearly showing an almost complete degradation. This observation is supported by measurements on other structurally related substances, such as Pentamethylenediamine (CAS: 110 -58 -7; 75%-93% BOD/ThOD; MITI 1992) and Trimethylenediamine (CAS: 109 -76 -2; 90 -100 DOC-removal; BASF AG 2003), which can both be considered as readily biodegradable.

In addition, in a Zahn-Wellens test (OECD 302 B) conducted with industrial activated sludge a biodegradation of 96 % after 3 days was found. From this test result it can be concluded that AH salt is inherently biodegradable. A BOD5/COD ratio of 0.61 was obtained using effluent from an industrial sewage treatment plant as inoculum.

References:

Biodegradation and Bioaccumulation Data of Existing Chemicals Based on the CSCL , Compiled under the Supervision of Chemical Products Safety Division, Basic Industries Bureau MITI, Ed. by CITI, October 1992.