L-Tyrosine, N-acetyl-3,5-diiodo-O-(4-methoxyphenyl)-, ethyl ester

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 B (Ready Biodegradability: CO2 Evolution Test)

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

The sludge was taken from the activation basin of the sewage treatment plant in D-67480 Edenkoben.
Date of collection: 06. Apr. 2018, batch no: 20180406.

Duration of test (contact time):

28 d

Initial conc.:

50.9 mg/L

Based on:

test mat.

Remarks:

Test 1

Initial conc.:

50.9 mg/L

Based on:

test mat.

Remarks:

Test 2

Details on study design:

From each front scrubber flask, 10 samples were taken in order to determine the emitted CO2 (on day 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29). The sample volume was 1 mL. The resulting change in the volume of the front flask was considered in the calculation of emitted CO2.
On day 28, 5 mL HCl 2 M was added to each test flask in order to drive off dissolved CO2. On day 29, samples from both scrubber flasks were taken.

Reference substance:

aniline

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

10 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

8

Sampling time:

28 d

Results with reference substance:

All validity criteria were met. Degradation of the positive control was 61 % after 11 days.

In the following table, the percentage biodegradation is presented:

Table 1     Degradation values in %

Day	Positive Control 1	Positive Control 2	Positive Control Mean	Test 1	Test 2	Test Mean	Abiotic Control	Toxicity Control
2	1.8	0.9	1.4	3.1	0.8	2.0	0.3	5.1
4	6.0	10.6	8.3	3.7	1.5	2.6	1.3	23.3
7	37.1	30.8	34.0	5.3	2.1	3.7	0.9	42.3
9	50.5	55.1	52.8	5.4	2.7	4.0	0.7	44.7
11	58.1	63.4	60.8	4.9	3.5	4.2	0.6	46.6
14	66.3	68.0	67.1	6.1	4.5	5.3	0.5	53.5
18	73.8	75.5	74.7	5.7	6.1	5.9	0.2	56.6
23	76.4	75.0	75.7	7.3	6.4	6.8	-0.3	57.5
29	86.0	85.1	85.5	7.1	7.8	7.5	-0.3	58.7

 

As the measured IC values in the abiotic control are very low, measurement uncertainties lead to negative degradation values while in fact no degradation has taken place.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

• The test item L-Tyrosine, N-acetyl-3,5-diiodo-O-(4-methoxyphenyl)-, ethyl ester is considered as “not readily biodegradable“.
• The degree of biodegradation reached 8 % after 28 days.
• The 10-day-window was not detected.
• Degradation missed 60 % within 28 days, too.
• Therefore, regardless of the 10-day-window, the test item L-Tyrosine, N-acetyl-3,5-diiodo-O-(4-methoxyphenyl)-, ethyl ester is considered as “not ultimately biode-gradable within 28 days”.
• Abiotic degradation was not observed.

Description of key information

In the study conducted according to OECD 301B only 8 % of the test substance degraded after 28 d. Thus the substance has to be classified as not ultimately biodegradable within 28 days.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater