2H-Pyran, tetrahydro-3-(phenylmethyl)-

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

from July 6th to September 13th 2005

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

unsuitable test system

Remarks:

OECD guideline 301 B was followed, with GLP compliance. The Certificate of Analysis of the test substance was not provided in the study report. Moreover, the substance is adequately identified, but details on composition are missing. This study is considered not reliable due to potential of volatilisation. Indeed, with a Henry's Law Constant calculated at 1.24 Pa.m3/mol, the volatilisation becomes an important transfer mechanism, and an OECD Guideline 301B with aerated system is not acceptable for this substance.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Version / remarks:

OECD guidelines for testing of chemicals, Paris (1992). Guideline 301B: Ready biodegradability: CO2 evolution test.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Inspection between October 11th and 15th 2004. Statement signed on July 7th 2005.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

Inoculum : activated sludge
Source : aeration tank of RWZI, Zonhoven(Belgium) dealing with domestic sewage
Volume : 6 litres
Upon arrival at the laboratory, the liquor was sieved through a 0.5 mm sieve, in order to remove large particles and aerated for 4 hours before the start of the test. The pH of the liquor was 7.00. Then the liquor was homogenised and allowed to settlefor 30-60 minutes. The clear supernatant was decanted to provide sufficient volume for a 1% inoculum in each carboy.

Duration of test (contact time):

28 d

Initial conc.:

15 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Preparation and composition of medium : Mineral medium was prepared from stock solutions of appropriate concentrations of mineral components. The following stock solutions of nutrient salts were prepared by dissolving the appropriate amounts of analytical grade reagents in high quality water (HQW, freshly prepared deionised water with a low carbon content, <10% of the TOC introduced by the test item in the carboys).
Phosphate solution : KH2PO4 : 8.5 g/L ; K2HPO4 : 21.75 g/L ; Na2HPO4 : 26.64 g/L ; NH4Cl : 0.50 g/L
CaCl2.2H2O : 36.40 g/L
MgSO4.7H2O : 2250 g/L
FeCl3.6H2O : 0.25 g/L

The mineral medium contained the following amounts of stock solution per litre HQW :

10 mL of the phosphate solution ; 1 mL of the CaCl2.2H2O solution ; 1 mL of the MgSO4.7H2O solution ; 1 mL of the FeCl3.6H2O solution.

- Test temperature : recorded once every week, range of 21 - 26 °C
- pH range : 6.91 - 7.47
- Aeration : aeration with CO2-free air
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 6 test carboys were used in total ; 2 test carboys containing test item, 1 carboy containing reference item ; 2 control carboys containing inoculum only, 1 carboy containing test and reference item
- Method used to create aerobic conditions: aeration with CO2-free air ; CO2 production apparatus (carboys) : 5 L brown glass vessels with aeration tubes ; CO2 absorber vessels : 125 mL absorber vessels : 125 mL absorber vessels filled with 100 mL 0.0125 M Ba(OH)2
- Measuring equipment: TOC analyser EA1112 and Shimadzu TOC-Vcpn
- Details of trap for CO2 and volatile organics if used: 100 mL0.0125 M Ba(OH)2 was pipetted into each of the three absorber vessels. The absorber vessels were connected in series to the exit air tube of each test carboy. The brown glass carboys were shielded from direct light during the test. The test was started by bubbling CO2-free air through the solutions at a rate of 1 to 3 bubbles per second. The CO2 produced in each carboy reacted with the Ba(OH)2 in the absorber vessels and was precipitated as BaCO3. The amount of CO2 produced was determined by titration of the remaining Ba(OH)2 with 0.04 M HCl using phenolphtalein as indicator. The amount of CO2 produced by each test solution was calculated from the amount of Ba(OH)2 consumed in each absorber bottle by precipitation of BaCO3.

Periodically, the CO2 absorber closest to the carboy was removed for titration. The remaining two absorbers were then moved one place closer to the test vesseland a new absorber containing 100 mL fresh 0.0125 M Ba(OH)2 solution was placed at the far end of the series. Titrations were made before any BaCO3 precipitation was visible in the second trap.

The pH of the solution in each carboy was measured on the last day of test. After the pH measurement, 1 mL of concentrated HCl was added to each carboy to drive off inorganic carbonate. The carboys were aerated overnight and the CO2 produced was determined as described above.

3 samples of 100 mL each were taken for further determinations, on request of the sponsor.

CONTROL AND BLANK SYSTEM
1 carboy containing reference item ; 2 control carboys containing inoculum only, 1 carboy containing test and reference item

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

37

Sampling time:

28 d

Remarks on result:

other: replicate 1

Key result

Parameter:

% degradation (CO2 evolution)

Value:

41

Sampling time:

28 d

Remarks on result:

other: replicate 2

Results with reference substance:

The amount of CO2, the cumulative amoun tof CO2 and the net cumulative amount of CO2 produced by the reference item and the % biodegradation is given in Table 4.
Biodegradation (% of ThCO2) of the reference item was 67 % after 5 days and increased to 100 % by day 22. The test therefore fulfilled the necessary criteria (>60 % biodegradation by day 14).

Table 1 : pH of the test solutions at the end of the test (day 28)

Test solution	pH
Control (1)	7,46
Control (2)	7,47
Reference item	6,91
Toxicity control	6,99
Test item (1)	7,44
Test item (2)	7,43

Table 2 : CO2 production of the controls

Day of the test	Control (1)		Control (2)		Mean mg CO2 cum.
	mg CO2 found	mg CO2 cum.	mg CO2 found	mg CO2 cum.
0	0,00	0,00	0,00	0,00	0,00
1	1,25	1,25	1,3	1,3	1,28
2	1,23	2,48	1,25	2,55	2,52
3	0,46	2,94	0,69	3,24	3,09
5	0,53	3,47	0,51	3,75	3,61
7	1,27	4,74	1,07	4,82	4,78
10	1,60	6,34	1,69	6,51	6,42
15	0,79	7,13	0,86	7,37	7,25
22	0,00	7,13	-0,07	7,30	7,22
28	-0,46*	6,67	-0,25*	7,05	6,86

* : including the mean of the three CO2 absorber bottles after addition of 1 mL concentrated HCl to drive off inorganic carbonate

Table 3 : CO2 production and % biodegradation of the reference item sodium benzoate

Day of the test	Sodium benzoate
	mg CO2 found	mg CO2 cum.	mg CO2 cum. netto	mg CO2 cum.
0	0,00	0,00	0,00	0,00
1	5,00	5,00	3,72	2,30
2	41,34	46,34	43,82	26,70
3	38,56	84,90	81,81	49,90
5	28,09	112,99	109,38	66,70
7	24,43	137,42	132,64	80,90
10	16,84	154,26	147,83	90,20
15	10,72	164,98	157,73	96,20
22	6,12	171,10	163,88	100,00
28	0,16*	171,26	164,40	100,30

* : including the mean of the three CO2 absorber bottles after addition of 1 mL concentrated HCl to drive off inorganic carbonate

Table 4 : CO2 production and % biodegradation of the toxicity control

Day of the test	mg CO2 found	mg CO2 cum.	mg CO2 cum. netto	biodegradation %
0	0,00	0,00	0,00	0,00
1	1,71	1,71	0,43	0,10
2	35,04	36,75	34,23	10,40
3	24,06	60,81	57,72	17,50
5	38,70	99,51	95,90	29,00
7	30,55	130,06	125,28	37,90
10	29,22	159,28	152,85	46,20
15	19,69	178,97	171,72	52,00
22	10,05	189,02	181,80	55,00
28	1,97*	190,99	184,13	55,70

* : including the mean of the three CO2 absorber bottles after addition of 1 mL concentrated HCl to drive off inorganic carbonate

Table 5 : CO2 production and % biodegradation of the test item

Day of the test	Test substance - replicate 1
	mg CO2 found	mg CO2 cum.	mg CO2 cum. netto	biodegradation %
0	0,00	0,00	0,00	0,00
1	1,04	1,04	-0,24	-0,20
2	1,32	2,36	-0,16	-0,10
3	0,69	3,05	-0,04	0,00
5	5,39	8,44	4,83	2,90
7	21,58	30,02	25,24	15,30
10	21,17	51,19	44,76	27,20
15	10,37	61,56	54,31	33,00
22	5,16	66,72	59,50	36,10
28	0,97*	67,69	60,83	36,90
Day of the test	Test substance - replicate 2
	mg CO2 found	mg CO2 cum.	mg CO2 cum. netto	biodegradation %
0	0,00	0,00	0,00	0,00
1	1,30	1,30	0,02	0,00
2	1,44	2,74	0,22	0,10
3	0,70	3,44	0,35	0,20
5	1,90	5,34	1,73	1,10
7	12,13	17,47	12,69	7,70
10	20,36	37,83	31,40	19,00
15	16,88	54,71	47,46	28,70
22	14,64	69,35	62,13	37,60
28	4,59*	73,84	67,08	40,60

* : including the mean of the three CO2 absorber bottles after addition of 1 mL concentrated HCl to drive off inorganic carbonate

Table 6 : CO2 production production and % biodegradation of the test item : mean values of the 2 replicates

Day of the test	Mean of replicate 1 and 2 - Test substance
	mg CO2 found	mg CO2 cum.	mg CO2 cum. netto	biodegradation %
0	0,00	0,00	0,00	0,00
1	1,17	1,17	-0,11	-0,10
2	1,38	2,55	0,03	0,00
3	0,70	3,25	0,16	0,10
5	3,65	6,89	3,28	2,00
7	16,86	23,75	18,97	11,50
10	20,77	44,51	38,08	23,10
15	13,63	58,14	50,89	30,90
22	9,90	68,04	60,82	36,90
28	2,78	70,82	63,96	38,80

* : including the mean of the three CO2 absorber bottles after addition of 1 mL concentrated HCl to drive off inorganic carbonate

Validity criteria fulfilled:

yes

Remarks:

See "overall remarks".

Interpretation of results:

not readily biodegradable

Conclusions:

At the end of the 10-day window, biodegradation was under 60 %. Percentage biodegradation of the test substance after 28 days were 37 % for replicate 1 and 41 % for replicate 2, the mean being 39 % biodegradation. Consequently, the test substance was not considered to be readily biodegradable.

Executive summary:

In this study, the biodegradability of the registered substance was determined in an aerobic, inoculated aqueous medium, aerated with CO2 -free air at a controlled rate in the dark, according to the OECD guideline 301 B. The study was conducted with GLP compliance, and the validity criteria were fulfilled.

Degradation was followed over 28 days by determination of the CO2 production, in relation to the theoretical CO2 that could have been produced, based on the carbon content of the test item. The test substance had no inhibitory effect on micro-organisms in this test.

A concentation of 15 mg C/L was introduced into the system.

At the end of the 10-day window, biodegradation was under 60 %. Percentage biodegradation of the test substance after 28 days were 37 % for replicate 1 and 41 % for replicate 2, the mean being 39 % biodegradation.Consequently, the test substance was not considered to be readily biodegradable.

However, this study is considered not reliable due to potential of volatilisation. Indeed, with a Henry's Law Constant calculated at 1.24 Pa.m3/mol, the volatilisation becomes an important transfer mechanism, and an OECD Guideline 301B with aerated system is not acceptable for this substance.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 03 April 2019 to 22 May 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

This study was performed according to OECD Guideline 301F and EU Method C.4-D with GLP certificate. All validity criteria were fulfilled.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 21/08/2018; Date of issue: 19/11/2018

Specific details on test material used for the study:

- Water solubility: 490 mg/L at 25°C (iSafeRat v1.8 prediction)
- Vapour pressure: 3,46 Pa at 25°C (iSafeRat v1.3 prediction)
- Log Kow: 3,0 at 20°C (EEC A8, Shake-Flask Method, Phytosafe 2005)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

A mixed population of sewage treatment micro-organisms was obtained on 1 April 2019 from the final effluent stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, which treats predominantly domestic sewage.
The sample of effluent was filtered through coarse filter paper (first approximate 200 mL discarded) and maintained on aeration in a temperature controlled room at temperatures of between 19 and 21 °C prior to use.

Duration of test (contact time):

49 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

MINERAL MEDIUM:
The mineral medium used in this study was that recommended in the OECD Guidelines. The deionized reverse osmosis water used for the preparation of the mineral medium and the mineral medium used for the test contained less than 1 mg/L Total Organic Carbon (TOC).

TEST ITEM PREPARATION:
A nominal amount of test item (50 mg) was dispersed in mineral medium (350 mL) and subjected to ultrasonic disruption for 15 minutes prior to the addition of inoculum (5 mL) and adjusting to a final volume of 500 mL with mineral medium to give the test concentration of 100 mg/L. The inoculum control vessels were prepared in a similar manner without the addition of test item. However prior to the addition of the inoculum the pH of the mineral media in each inoculum control vessel was measured using a Hach HQ40d Flexi handheld meter. A test concentration of 100 mg/L was selected for use in the study following the recommendations of the Test Guidelines.

REFERENCE ITEM PREPARATION:
A reference item, aniline (C6H5NH2), was used to prepare the procedure control vessels. An initial stock solution of 1000 mg/L was prepared by dissolving a nominal amount of freshly distilled aniline, (500 mg), directly in mineral medium (500 mL) with the aid of ultrasonication for approximately 20 minutes. An aliquot (50 mL) of this stock solution was diluted with mineral medium (350 mL) prior to measurement of the pH value using a Hach HQ40d Flexi handheld meter and then addition of inoculum (5 mL) and adjusting to a final volume of 500 mL with mineral medium, to give the test concentration of 100 mg/L. The volumetric flask containing the stock solution was inverted several times to ensure homogeneity. The pH of the reference item stock solution was 7.4. The pH value was measured using a Hach HQ40d Flexi handheld meter.

TOXICITY CONTROL:
A toxicity control, containing the test item and aniline, was prepared in order to assess any toxic effects of the test item on the sewage treatment micro-organisms used in the test.
A nominal amount of test item (50 mg) was dispersed in mineral medium (350 mL) and subjected to ultrasonication for 15 minutes prior to the addition of an aliquot (50 mL) of the 1000 mg/L aniline stock solution. The inoculum (5 mL) was then added prior to adjusting to a final volume of 500 mL with mineral medium to give the test concentration of 100 mg test item/L and 100 mg aniline/L.

PREPARATION OF TEST SYSTEM:
The following test preparations were prepared and inoculated in 500 mL bottles:
a) Three replicate bottles containing inoculated mineral medium alone to act as the inoculum control.
b) Two replicate bottles containing inoculated mineral medium and the reference item, aniline, at a concentration of 100 mg/L to act as the procedure control.
c) Three replicate bottles containing inoculated mineral medium and the test item at a concentration of 100 mg/L.
d) Two replicate bottles containing the test item at a concentration of 100 mg/L in inoculated mineral medium plus the reference item, aniline, at a concentration of 100 mg/L to act as toxicity control vessels.
All vessels were inoculated with the prepared inoculum at a rate of 1% v/v.
On Day 0, the test and reference items were added and the pH of the inoculum control and procedure control vessels were measured using a Hach HQ40d Flexi handheld meter prior to the addition of the inoculum and the volume in all the vessels being adjusted to 500 mL by the addition of mineral medium. The pH of the contents of the test item and toxicity control vessels were not measured prior to the addition of the inoculum due to the risk of test item being lost from the test system by adherence to the pH probe as the test item was of an oily nature.
In order to confirm that the aniline stock solution was prepared correctly, a diluted 100 mg/L stock solution (in reverse osmosis water) was also sampled for Total Organic Carbon (TOC) analysis.
All remaining inoculum control, test item, procedure control and toxicity control vessels were placed in a CES Multi-Channel Aerobic Respirometer.
The system consists of a sample flask sealed by a sensor head/CO2 trap immersed in a temperature controlled water bath. The samples were stirred for the duration of the test with a magnetically coupled stirrer.
As biodegradation progresses, the micro-organisms convert oxygen to carbon dioxide which is absorbed into the ethanolamine solution (50% v/v) causing a net reduction in gas pressure within the sample flask. The pressure reduction triggers the electrolytic process, generating oxygen and restoring the pressure in the sample flask. The magnitude of the electrolyzing current and the duration of the current is proportional to the amount of oxygen supplied to the micro-organisms. The data generated from the respirometer’s own battery backed memory was collected on the hard disk drive of a non-dedicated computer.
The test was conducted in diffuse light at temperatures of between 21 and 22 °C.
On Day 49, two inoculum controls, one procedure control, two test item and one toxicity control vessel were sampled for pH analysis.
The remaining vessels which were not sampled were discarded and are not reported. Additional replicate vessels were prepared and incubated in order that in the event of a leak in the test system a replicate vessel could be discarded without jeopardizing the integrity of the test.

TEMPERATURE MEASUREMENTS:
The temperature of the water bath was recorded daily.

PH MEASUREMENTS:
In order to measure the pH of the inoculum control and procedure control preparations, the pH was measured using a Hach HQ40d Flexi handheld meter on Day 0 with the pH of all vessels being measured on Day 49. On Day 0 of the study, the pH of the contents of the test item and toxicity control vessels were not measured prior to the addition of the inoculum due to the risk of test item being lost from the test system by adherence to the pH probe as the test item was of an oily nature. On Day 49 the pH of two inoculum control, one procedure control, two test item and one toxicity control vessels were measured using a Hach HQ40d Flexi handheld meter.

Reference substance:

aniline

Preliminary study:

Information provided by the Sponsor indicated that the water solubility of the test item was 490 mg/L at 25 ºC (iSafeRate® v1.8 prediction). Therefore preliminary solubility/dispersibility work was performed in order to determine the most suitable method of preparation. From the preliminary solubility work and following the recommendations of the International Standards Organisation (ISO 10634, 1995) and in published literature (Handley et al, 2002) it was concluded that the best testable dispersion was found to be obtained when using the ultrasonication method of preparation.

Test performance:

The mean BOD of the inoculated mineral medium (control) was 25.97 mg O2/L after 28 days and therefore satisfied the validation criterion given in the OECD Test Guidelines.
The difference between extremes of replicate BOD values at the end of the test was less than 20% and therefore satisfied the validation criterion given in the OECD Test Guidelines.
The toxicity control attained 42% biodegradation after 14 days, 57% biodegradation after 28 days and 59% biodegradation after 49 days thereby confirming that the test item was not toxic to the sewage treatment micro-organisms used in the test.

Key result

Parameter:

% degradation (O2 consumption)

Value:

44

Sampling time:

28 d

Remarks on result:

other: Not readily biodegradable

Key result

Parameter:

% degradation (O2 consumption)

Value:

62

Sampling time:

49 d

Remarks on result:

other: not persistent (>60% biodegradation)

Details on results:

The test item attained 44% biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F. In the enhanced screening test, the test item attained 62% biodegradation after 49 days and therefore can be considered not persistent in the environment.
See biodegradation curve in "Illustration"

Results with reference substance:

Aniline (procedure control) attained 72% biodegradation after 14 days in a 10-Day Window and 76% biodegradation after 28 and 49 days thereby confirming the suitability of the inoculum and test conditions. TOC of the diluted aniline stock solution confirmed that it had been prepared correctly.

Tables for Biological Oxygen Demand (BOD) values, percentage biodegradation values, and pH values of the test preparations on days 0 and 49 are provided in "Attached background material".

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Remarks:

but not persistent in the environment.

Conclusions:

The test item attained 44% biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F. In the enhanced screening test, the test item attained 62% biodegradation after 49 days and therefore can be considered not persistent in the environment.

Executive summary:

The study was performed to assess the ready biodegradability of the test item in an aerobic aqueous media. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No. 301F, “Ready Biodegradability; Manometric Respirometry Test” referenced as method C.4-D of Commission Regulation (EC) No. 440/2008 and US EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph (q)).

The test item at a concentration of 100 mg/L was exposed to sewage treatment micro-organisms with mineral medium in sealed culture vessels in diffuse light at temperatures of between 21 and 22 ºC for 49 days. The biodegradation of the test item was assessed by the measurement of daily oxygen consumption values for 49 days. At the request of the Sponsor, the study was extended from 28 days to 49 days to provides proof of non-persistence. Control solutions with inoculum and the reference item, aniline, and a toxicity control were used for validation purposes.

The test item attained 44% biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F. However, the test item attained 62% biodegradation in the enhanced screening test, extended up to 49 days, and therefore can be considered not persistent in the environment.

Aniline (procedure control) attained 72% biodegradation after 14 days with greater than 60% degradation being attained in a 10-Day window. After 28 and 49 days 76% biodegradation was attained.

Description of key information

OECD Guideline 301F, EU Method C.4-D, GLP, key study, validity 1:

44% biodegradation after 28 days and 62% biodegradation after 49 days

The registered substance is not readily biodegradable but significant mineralisation occurred thus demonstating complete primary biodegradation, and based on the enhanced screening test, extended up to 49 days, the registered substance is not persistent in the environment.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Type of water:

freshwater

Additional information

Two experimental studies were performed on the registered substance, to assess the ready biodegradability of the substance in an aerobic aqueous media.

The first study (Covance, 2019), assessed as a reliable key study, was performed according to OECD Guideline 301F and EU Method C.4-D with GLP certificate. The substance at a concentration of 100 mg/L was exposed to sewage treatment micro-organisms with mineral medium in sealed culture vessels in diffuse light at temperatures of between 21 and 22 ºC for 49 days. The biodegradation of the substance was assessed by the measurement of daily oxygen consumption values for 49 days. The study was extended from 28 days to 49 days to provides proof of non-persistence. Based on the results of this study, the test item attained 44% biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F. However, the test item attained 62% biodegradation in the enhanced screening test, extended up to 49 days, and therefore can be considered not persistent in the environment.

The second study (LISEC, 2005), assessed as a non reliable supporting study, was performed according to OECD Guideline 301B with GLP certificate. The substance at a concentration of 15 mg C/L was exposed to activated sludge with mineral medium for 28 days, aerated with CO2 -free air at a controlled rate in the dark. The degradation was followed over 28 days by determination of the CO2 production, in relation to the theoretical CO2 that could have been produced, based on the carbon content of the test item. Based on the results of this study, the percentage biodegradation of the test substance after 28 days were 37 % for replicate 1 and 41 % for replicate 2, the mean being 39 % biodegradation. Consequently, the test substance was not considered to be readily biodegradable but significant mineralisation occurred thus demonstrating complete primary biodegradation.

Even if all validity criteria were fulfilled, this study is considered not reliable due to potential of volatilisation. Indeed, with a Henry's Law Constant calculated at 1.24 Pa.m3/mol, the volatilisation becomes an important transfer mechanism (Lyman et al., 1982), and an OECD Guideline 301B with aerated system is not acceptable for this substance.

In conclusion, the registered substance is not readily biodegradable but significant mineralisation occurred thus demonstating complete primary biodegradation, and based on the enhanced screening test, extended up to 49 days, the registered substance is not persistent in the environment.