p-tolualdehyde

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:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

July, 1992

Qualifier:

according to guideline

Guideline:

other: Kanpogyo Notification No. 5, Yakuhatsu Notification No. 615, and 49 Kikyoku Notification No. 392 (Biodegradation Study of Chemicals)

Version / remarks:

July, 1974

GLP compliance:

yes

Specific details on test material used for the study:

- Analytical purity: 97.2%
- Impurities: not more than 1.0% as p-toluic acid

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, adapted

Details on inoculum:

- Source of inoculum/activated sludge: sludge was obtained at the following 10 sites in Japan: Fushikokawa Sludge Plant (Sapporo, Hokkaido), Kashima Sludge Plant (Kashima-gun, Ibaraki), Nakahama Sludge Plant (Osaka City, Osaka), Ochiai Sludge Plant (Shinjuku-ku, Tokyo), Kitakami River (Ishinomaki,Miyagi), Shinano River (Nishikanbara-Gun, Niigata), Yoshino River (Tokushima City, Tokushima), Lake Biwa (Otsu, Shiga), Hiroshima Bay (Hiroshima City, Hiroshima), and Dokai Bay (Kitakyushu, Fukuoka)

- Method of cultivation: after preparation of the activated sludge, about one-third of the total volume of the supernatant was discarded after stopping aeration of the culture tank for about 30 min. Aeration was recommenced (for at least 30 min) after adding dechlorinated water to make 10 L, and 50 g/L synthetic sewage was added so that the concentration of the synthetic sewage in the added dechlorinated water was 0.1 wt%. These procedures were repeated once a day in order to obtain activated sludge by cultivation. Cultivation was conducted at 25±2 °C.

- Preparation of inoculum for exposure: Purified water (Takasugi Seiyaku Co., Ltd.; JP) was added to 3 mL each of Fluids A, B, C and D specified in the Test Methods for Industrial Wastewater: Biochemical Oxygen Consumption (21 in JIS K 0102-1993) to make 1 L, and the pH of the mixture obtained was adjusted to 7.0.

- Concentration of sludge: 30 mg/L (suspended material)

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

TOC removal

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

TEST CONDITIONS
- Composition of medium: Purified water (Takasugi Seiyaku Co., Ltd.; JP) was added to 3 mL each of Fluids A, B, C and D specified in the Test Methods for Industrial Wastewater: Biochemical Oxygen Consumption (21 in JIS K 0102-1993) to make 1 L, and the pH of the mixture obtained was adjusted to 7.0.
- Test temperature: 25 ± 1 °C
- pH: 7.0 ± 1.0
- pH adjusted: yes
- Suspended solids concentration: the concentration of suspended substances in activated sludge was 30 mg/L.
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Closed oxygen consumption measuring system: coulometer (Asahi Techneion Co., Ltd.) and data processor (Asahi Techneion Co., Ltd.)
- Number of culture flasks: 6 test vessels
- Measuring equipment: During the incubation period, test solutions were visually observed every day, and the operational status of the cultivation system was monitored as appropriate; Measurement of biochemical oxygen demand (BOD): during the incubation period, changes in test solutions’ BOD were continuously self-recorded using a data processor. Temperature in the vessel was measured and recorded every day.

STATISTICAL METHODS:
- Biodegradation by biochemical oxygen demand: degradation (%) = BOD-B/TOD (theoretical oxygen demand) *100
- Biodegradation by dissolved organic carbon: degradation (%) = DOCwater (amount of dissolved organic carbon in the water “water + test substance”) – DOC residual (residual amount of dissolved organic carbon in the “sludge + test substance”) / DOCwater (amount of dissolved organic carbon in the water “water + test substance”) * 100

Reference substance:

aniline

Test performance:

- Percent biodegradation of aniline determined by BOD on Days 7 and 14 was 43% and 80%, respectively, indicating that the testing conditions used in the present study were valid.
- Environmental factors that may have affected reliability of study results: none.

Key result

Parameter:

% degradation (TOC removal)

Value:

96

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

97

Sampling time:

28 d

Parameter:

other: HPLC

Value:

100

Sampling time:

28 d

Results with reference substance:

Percent biodegradation of aniline determined by biochemical oxygen demand (BOD) on Days 7 and 14 was 43% and 80%.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Biodegradation was 96%, 97% and 100% based on the removal of total organic carbon, consumption of oxygen and based on measurements of p-tolualdehyde with HPLC, respectively.

Executive summary:

In this GLP-compliant biodegradation study performed according to OECD guideline 301C, 100 mg/L of p-tolualdehyde was inoculated with activated sludge (obtained from 10 different sites, 30 mg/L suspended material) for a period of 28 days at 25 ± 1 °C. The following parameters were determined: biochemical oxygen demand (BOD), dissolved organic carbon (DOC) and the test substance was analysed by high-performance liquid chromatography (HPLC). After 28 days, the mean biodegradation was determined to be 96%, 97% and 100% based on the removal of total organic carbon, consumption of oxygen and based on measurements of p-tolualdehyde with HPLC, respectively. Based on these findings, the test substance was considered to be readily biodegradable.

Description of key information

The substance is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The biodegradability was determined in a GLP-compliant biodegradation study performed according to OECD guideline 301C, where 100 mg/L of p-tolualdehyde was inoculated with activated sludge (obtained from 10 different sites, 30 mg/L suspended material) for a period of 28 days at 25 ± 1 °C. The following parameters were determined: biochemical oxygen demand (BOD), dissolved organic carbon (DOC) and the test substance was analysed by high-performance liquid chromatography (HPLC). After 28 days, the mean biodegradation was determined to be 96%, 97% and 100% based on the removal of total organic carbon, consumption of oxygen and based on measurements of p-tolualdehyde with HPLC, respectively. Based on these findings, the test substance was considered to be readily biodegradable.