Ethyl 3-phenyloxirane-2-carboxylate

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:

07 August 2009 - 11 November 2009

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)

Version / remarks:

1992

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum sludge: fresh activated sludge from a biological waste water treatment plant treating predominantly domestig sewage (Bois-de-Bay, Satigny, Switzerland) was used.
- Preparation of inoculum for exposure: the sludge was 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.
- Dry weight of suspended solids: 1.53 g/L, determined by drying two 50 mL samples of homogenised sludge in an oven for two hours after water was evaporated on a steam bath

Duration of test (contact time):

36 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: mineral medium according to OECD 301
- Test temperature: 22 °C
- pH: at the start: 7.6, at the end: 7.45 - 8.03
- pH adjusted: yes, the pH of the mineral medium was measured and if necessary adjusted to 7.4 +/- 0.2 with phosphoric acid or potassium hydroxide. The pH in the test solutions was not measured at the start and assumed to be the same as the pH in the mineral medium.
- Suspended solids concentration: 30 mg/L

TEST SYSTEM
- Culturing apparatus: Oxitop Control System (Wissenschaftlich-Technische Werkstätten (WTW), Weilheim, Germany)
- Number of culture flasks/concentration: 2
- Measurements: the consumption of oxygen is determined by measuring the pressure drop in the respirometer flask. The Biological Oxygen Demand (BOD), amount of oxygen taken up by the microbial population during biodegradation of the test chemical (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of ThOD (Theoretical Oxygen Demand, calculated from the elemental composition, assuming that carbon is oxidized to carbon dioxide, hydrogen to water and nitrogen to ammonium, nitrite or nitrate).

SAMPLING
- Sampling frequency: daily recording of the oxygen consumption of each flask
- Sampling method: automatic by the respirometer

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 replicates
- Toxicity control: yes, 2 replicates
- Other: positive control: yes, 2 replicates

STATISTICAL METHODS: none

Reference substance:

benzoic acid, sodium salt

Remarks:

purity: min. 99.0%

Key result

Parameter:

% degradation (O2 consumption)

Value:

76

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

83

Sampling time:

36 d

Details on results:

- The test substance showed 76% biodegradation after 28 days and 83% degradation after 36 days in the test conditions (12% biodegradation on day 4 and 55% on day 14). .

Results with reference substance:

89% biodegradation within 14 days

Functioning of the test system was checked by testing the reference substance sodium benzoate which showed a normal biodegradation curve (see attached illustration).

The toxicity control showed that the test substance was not inhibitory for the inoculum used, since O2 uptake of the toxicity control was higher than the flasks containing only mineral medium, reference substance and inoculum.

Table 1 Biodegradation results

			Days
			3	4	5	7	14	17	21	28	36
O2 uptake (mg O2/L)	Inoculum blank	1a	15.5	17.3			26.4	27.3		31.0	32.8
		2a	13.7	15.5			27.3	29.2		34.6	37.4
		Mean	14.6	16.4			26.9	28.3		32.8	35.1
	Test substance + inoculum	5a	31.5	36.8			137.0	147.0		184.0	195.0
		6a	36.8	47.3			146.9	157.9		199.8	220.8
	Test substance	5a-mean inoculum	16.9	20.4			110.2	118.8		151.2	159.9
		6a-mean inoculum	22.2	30.9			120.0	129.6		167.0	185.7
	Reference substance + inoculum	13a			136.1	146.2	178.5		178.4	188.5	193.5
		14a			141.2	152.3	172.4		172.4	178.4	172.3
	Reference substance	13a-mean inocolum			118.4	125.7	151.6		148.3	155.7	158.4
		14a-mean inoculum			123.4	131.7	145.6		142.3	145.6	137.2
	Toxicity control	17a			172.5	188.6	262.3		314.8	341.0	361.2
		18a			178.5	198.7	283.4		324.7	345.9	361.0
		Mean			175.5	193.7	272.8		319.7	343.4	361.1
Biodegradation (%)	Test substance		8	10			53	57		73	77
			11	15			58	62		80	89
		Mean	9	12			55	60		76	83
	Reference substance				71	75	91		89	93	95
					74	79	87		85	87	82
		Mean			73	77	89		87	90	89
Degradation of test substance in presence of reference substance (%)			10	17			40	50		73	81
			8	13			53	61		81	91
		Mean	9	15			47	56		77	86

Validity criteria fulfilled:

yes

Remarks:

The positive control degraded for 89% within 14 days, the difference of duplicate values for % degradation was <20% (i.e. 12%), mean oxygen uptake of the inoculum blank at day 28 was <60 mg/L (i.e. 32.8 mg O2/L)

Interpretation of results:

readily biodegradable

Conclusions:

The substance showed 76% biodegradation in an OECD TG 301F test after 28 days, therefore it is considered to be readily biodegradable.

Executive summary:

The ready biodegradability of the test substance was investigated in a study conducted in accordance with OECD TG 301F (Manometric Respirometry Test) and GLP. The concentration tested was 100 mg/L test substance, with an activated sludge concentration of 30 mg/L. The test substance biodegraded for 76% in 28 days and can be considered ready biodegradable because it is a multi-constituent, despite failing the 10 -day window (CLP, 2016, 4.1.2.9.5). The substance was not toxic to the inoculum (89% biodegradation of the benzoic acid reference substance within 14 days).

Description of key information

The ready biodegradability of the test substance was investigated in a study conducted in accordance with OECD TG 301F (Manometric Respirometry Test) and GLP. The concentration tested was 100 mg/L test substance, with an activated sludge concentration of 30 mg/L. The test substance biodegraded for 76% in 28 days and can be considered ready biodegradable because it is a multi-constituent, despite failing the 10 -day window (CLP, 2016, 4.1.2.9.5). The substance was not toxic to the inoculum (89% biodegradation of the benzoic acid reference substance within 14 days).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable