1-phenylethyl acetate

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

Study period:

9th July 1996 to 7th August 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- Name of test material: 1-phenylethyl acetate
- Physical state: colourless liquid
- Name of test material (as cited in study report): Gardenol
- Lot/batch No.: 260657

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aïre) was used.- Preparation of inoculum for exposure: the sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.- Concentration of sludge: the dry weight of suspended solids is determined by taking to 50 mL samples of the homogenised sludge, evaporating water on a steam bath, drying in an oven at 105 - 110 ºC for two hours and weighing the residue. Dry weight of suspended solids: 4.346 g/L. To obtain a concentration of 30 mg/L (dry weight) in a 250 mL flask, 1.73 mL of sludge is needed (inoculum).- Water filtered: the water used during this study is deionised water containing less than 10 mg/L dissolved organic carbon.

Duration of test (contact time):

28 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: prepared by mixing 50 mL of solution A and 2000 mL deionised water, adding 5 mL of each of the solutions B, C and D and making up to 5 litres with deionised water.- Test temperature: 22 ºC- pH: 7.4- pH adjusted: yes (with phosphoric acid or potassium hydroxide as necessary)TEST SYSTEM- Culturing apparatus: 250 mL volumetric flasks- Number of culture flasks/concentration: flasks were prepared in duplicate- Measuring equipment: SAPROMAT D 12, made by J. M. VOITH GmbH, D-7920 HeidenheimSTATISTICAL METHODS:Oxygen uptakes as read on the SAPROMAT meters are corrected:- by deducting the basic oxygen uptake of sludge (flasks 2/7 and 2/8)- proportionally to account for the differences between actual and nominal concentrations of test and reference substances. Averages of identical flasks have been used to obtain the graphs of BOD versus time (Figure 1) and percentage of biodegradation versus time (Figure 2).

Reference substance:

aniline

Preliminary study:

No preliminary study was performed.

Test performance:

No unusual observations were noted in the study.

Key result

Parameter:

% degradation (O2 consumption)

Value:

89

Sampling time:

28 d

Remarks on result:

other: Mean % degradation

Parameter:

% degradation (O2 consumption)

Value:

68

Sampling time:

12 d

Remarks on result:

other: Mean % degradation; 10-day window

Details on results:

1-phenylethyl acetate undergoes an average of 89% biodegradation after 28 days in the test conditions (figure 2). Biodegradation starts on day 2 and reaches 68% at the end of the 10-day window (days 2 to 12).The curve (figure 1) obtained with aniline alone and with 1-phenylethyl acetate and aniline show no toxic effect of 1-phenylethyl acetate on the micro-organisms at the test concentration.

Results with reference substance:

Degradation of aniline exceeds 40% after 7 days and 65% after 14 days: the activity of the inoculum is thus verified and the test is considered as valid.

Table 1: Actual concentrations and pH measurements

	Concentrations (mg/L)		pH
Flask number	Test substance	Reference substance	initial	final
2/5	0	100.0	7.42	7.99
2/6	0	100.0	7.40	7.91
2/7	0	0	7.37	7.48
2/8	0	0	7.34	7.40
1/11	102.1	0	7.45	7.54
1/12	100.8	0	7.43	7.46
1/9	100.2	100.0	7.47	8.29
7/10	99.4	100.0	7.47	8.46

Nominal concentrations

Test substance: 100 mg/L

Reference substance: 100 mg/L

Table 2: Biodegradation of test substance

Days:			2	7	12	14	21	28
BOD sludge	1st flask	B1	5.0	10.0	10.0	12.0	23.0	23.0
(figure 1)	2nd flask	B2	5.0	7.0	7.0	8.0	17.0	17.0
	mean	B	3.5	8.5	8.5	10.0	20.0	20.0
BOD test substance	1st flask	C1	33.4	105.9	166.6	178.4	197.2	203.1
(figure 1)	2nd flask	C2	30.8	110.2	170.7	181.6	236.3	253.1
	1st fl. corr.	C1-B	29.9	97.4	158.1	168.4	177.2	183.1
	2nd fl. corr.	C2-B	27.3	101.7	162.2	171.6	216.3	233.1
% degradation	1st flask	D1	13	42	68	72	76	78
(figure 2)	2nd flask	D2	12	43	69	73	92	100
	mean	D	12	43	68	73	84	89

B = (B1 + B2)/2

D1 = 100 * (C1 - B) / ThOD * [S]

D2 = 100 * (C2 - B)/ ThOD * [S]

D = (D1 + D2) / 2

[S] = Initial test substance concentration (mg/L)

Table 3: Biodegradation of reference substance

Days:			5	7	10	14	21	28
BOD sludge	1st flask	B1	9.0	10.	10.	12.0	23.0	23.0
(figure 1)	2nd flask	B2	6.0	7.0	7.0	8.0	17.0	17.0
	mean	B	7.5	8.5	8.5	10.0	20.0	20.0
BOD reference substance	1st flask	A1	186.9	198.9	206.9	214.9	227.9	232.9
(figure 1)	2nd flask	A2	158.9	192.9	202.9	210.9	222.9	226.9
	1st fl. corr.	A1-B	179.4	190.4	198.4	204.9	207.9	212.9
	2nd fl. corr.	A2-B	151.4	184.4	194.4	200.9	202.9	206.9
% degradation	1st flask	D1	74	79	82	85	86	88
	2nd flask	D2	63	77	81	83	84	86
	mean	D	69	78	82	84	85	87

B = (B1 + B2) / 2

D1 = 100 * (A1 - B) / ThOD * [S]

D2 = 100 * (A2 - B0 / ThOD * [S]

D = (D1 + D2) /2

[S] = initial test substance concentration (mg/L)

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the conditions of the test, 1-phenylethyl acetate undergoes an average 89% biodegradation after 28 days and meets the 10-day widow criterion. Thus the substance is considered to be readily biodegradable.

Executive summary:

The ready biodegradability of 1-phenylethyl acetate has been determined by the Manometric Respirometry Test according to the OECD Guidelines for Testing of Chemicals, Method No. 301 F.

1-phenylethyl acetate undergoes on average 89% biodegradation after 28 days in the test conditions. Biodegradation starts on day 2 and reaches 68% at the end of the 10-day window (days 2 to 12).

Thus 1 -phenylethyl acetate should be regarded as readily biodegradable according to this test.

At the concentration used in the test (100 mg/L), 1-phenylethyl acetate is not inhibitory to the micro-organisms.

Description of key information

1-phenylethyl acetate has been tested for ready biodegradability. It achieved >60 % biodegradation after 28 days and passed the 10 day window criterion in two standardised biodegradation tests. Therefore it is regarded as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

In the key study, the ready biodegradability of 1-phenylethyl acetate was determined by the Manometric Respirometry Test (OECD 301F) and the study determined that 1-phenylethyl acetate undergoes on average 89% biodegradation after 28 days under test conditions. Biodegradation starts on day 2 and reaches 68% at the end of the 10-day window (days 2 to 12). 1-phenylethyl acetate should therefore be regarded as readily biodegradable according to this test. 1-phenylethyl acetate was also determined to be readily biodegradable in the supporting test (>100% after 28 days in sealed CO₂ test, 10 day window criterion met).

A biodegradation study for the structurally closely related analogue, benzyl acetate, is also included in the dossier as relevant supporting information to strengthen the rationale for the use of read-across to benzyl acetate (source substance) in order to address short-term toxicity to aquatic invertebrates and toxicity to aquatic algae for 1-phenylethyl acetate (target substance). In an OECD Guideline 301C study, benzyl acetate was determined to be readily biodegradable. The result has been included in the data matrix of the target records for the two read-across endpoints (acute daphnia and algal inhibition).