Tris[2-[2-(2-methoxyethoxy)ethoxy]ethyl] orthoborate

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:

1999 (Study Plan 29.03.1999, Final Report 23.07.1999)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study was conducted according to OECD 301 A. The test selection (301 A) was appropriate with respect to relevant physical-chemical properties of the substance. Solubility in water at > 500 mg/L, Vapour pressure at 1.2 and 4.1 hPa (20 and 50°C respectively). Validity Criteria of the test were fullfilled: 1) Deviation of the degradation degree of the test substance in the plateau phase < 20% 2) Degradation degree of the reference substance > 70% after 14 days 3) Degradation degree in the inhibition control > 35% after 14 days

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: ISO 7827

Qualifier:

according to guideline

Guideline:

other: 92/69/EEC

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge : Laboratory waste water plants, fed with municipal and synthetic sewage
- The inoculum contained 6 g dry mass/L.

Duration of test (contact time):

>= 22 d

Initial conc.:

39 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: Deionized water 845 to 982 mL, inorganic medium A to D (13 mL)
- Additional substrate: Inoculum 30 mg dry matter per L test solution
- Solubilising agent (type and concentration if used): NA
- Test temperature: room temperature
- pH: 7.3 to 7.4
- pH adjusted: yes pre-adjustment value- CEC (meq/100 g): not provided

TEST SYSTEM
- Culturing apparatus: not provided (but most likely 1 L incubation vessels
- Number of culture flasks/concentration: Eight: two blank controls BC, one reference substance RS (aniline), one inhibition control IH (1 ml mercury per solution added on day 14 to the PC assay), one adsorption control (AC) and two test substance bottles TS.
- Method used to create aerobic conditions: aerobic conditions
- Method used to create anaerobic conditions: NA
- Measuring equipment: DOC analyser

SAMPLING
- Sampling frequency: 0,1,3,5,7,10,14,17,21,22 days after start of incubation
- Sampling method: Removal of aliquots

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, in duplicate (BC 1 and 2)
- Abiotic sterile control: yes (1 mL mercury chloride/L medium was added to the Positive control after 14 days)
- Toxicity control: yes (IH)
- Other: Adsorption control (AC) and Reference substance (RS)

STATISTICAL METHODS: NA

Reference substance:

aniline

Preliminary study:

NA

Test performance:

No deviations and amendments are reported which would jeopardize the validity of the results.

Parameter:

% degradation (DOC removal)

Value:

> 70

Sampling time:

10 d

Remarks on result:

other: The 10 day window was met

Details on results:

The degree of degradation of the test substance was > 70% within 22 days. The 10-day window was met

Results with reference substance:

Within 5 days, more than 70% of the initial amount of the reference test substance DOC was removed from the medium. Hence the test is considered valid.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The results indicate that the test substance is readily biodegradable.

Executive summary:

Methyltriglykol-o-Borat (CAS 30989 -05 -0), a borated glycol ester, was submitted to a DOC Die-Away Test according to OECD 301 A, ISO 7827 and 92/69 EEC. The OECD 301 A test was selected appropriately according to the physical-chemical properties of the test substance. The study was conducted under GLP, EN 45001 and ISO 9002. An activated, non-adapted sludge was used as obtained from laboratory waste water plants fed with municipal and synthetic sewage. The activated sludge contained approx 490 mg/g DOC, based on preliminary investigations.30 mg dry matter equivalents were added to 1 L medium, which was composed of 845 to 982 mL of deionized water and 13 mL of appropriate inorganic medium, numbere A to D in the report.

In total, 8 bottles were used to conduct the test:

Blanc Control - BC: two bottles

Reference Substance - RC: one bottle

Positive Control - PC (aniline), : one bottle

Inhibition control - IH (mercury chloride): one bottle

Adsorption control - AS: one bottle

Test substance - TS: two bottles

The concentration in inhibitory control, positive control, adsorption control and test substance test groups was 20 mg DOC/L.

The test vessels were incubated under aerobic (aeration) conditions for 22 days at ambient temperature. Samples were removed for DOC analysis on the following days: 0,1,3,5,7,10,14,17,21 and 22.

The following results were obtained (DOC decrease in percent):

Day	RS	IH	PC	AC	TS 1	TS 2	TS average
0	0	0	0	0	0	0	0
1	-5	0	-5	0	-7	-7	-7
3	8	9	5	0	6	6	6
5	95	45	-10		1	-5	-2
7	99	54	4		13	6	10
10	95	51	0		88	86	87
14	97	97	3		96	93	95
17	97	97	2		98	98	98
21	92	95	-4		100	98	99
22	100	97	-4		101	102	102

Notes: BC=blank control, RS=reference substance (aniline), IH=inhibition control, PC=abiotic control, AC=adsorption control, TS test substance. On day 14, 1 mL of mercury chloride was added to the PC assay.

Test results render the test as valid, since

1) The deviation of the degradation degree of the test substance in the plateau phase was < 20%

2) The degradation degree of the reference substance > 70% after 14 days

3) The degradation degree in the inhibition control > 35% after 14 days

4) Abiotic elimination was < 10% after 5 days.

The results obtained for the test substance indicate that the substance is readily biodegradable, since the degradation degree of the test substance was > 70% within 28 days and since the 10 -day time window criterion of the OECD guideline was met.

Description of key information

B-TEGME of 88% analytical purity was submitted to a DOC Die-Away Test according to OECD 301 A, ISO 7827 and 92/69 EEC (BASF 1999). The OECD 301 A test was selected appropriately according to relevant physical-chemical properties of the test substance. The study was conducted under GLP, EN 45001 and ISO 9002. It was valid according to the validity criteria of the test guidelines. The results show, that B-TEGME is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Four studies are available to address this endpoint. The key study (BASF 1999) is a valid study and was conducted with 88% pure B-TEGME, under GLP, and according to OECD 301A. It demonstrated that B-TEGME is readily biodegradable.

Shell 1999 used a mixture of Methyl Borated Esters as test material, which contained 22% B-TEGME, to conduct a valid GLP OECD 302 A study. The purpose was to investigate the inherent biodegradability of the test material. The results indicate that the test material was inherently biodegradable: 95% of the test material was degraded within 3 days after treatment. This supports the result of the key study.

Shell 1986 used a DOT 4 brake fluid to conduct ready biodegradation testing. This brake fluid is a mixture of Methyl and Butyl Borated Esters and contains 3% additives. B-TEGME contributes 17% to this brake fluid. The study was conducted non-GLP, with reference to internal SOPs. Two different test designs were used to assess ready biodegradation, i.e. the Closed Bottle Test and the Modified Sturm Test. Both tests fulfilled the validity criteria with respect to performance of the reference substance. The results show biodegradation within 28 days, however at low extent: Depending on the study design, average 8 and 24% of the test material were degraded, respectively. It is reported that degradation was still proceeding steadily at the end of the Modified Sturm Test. Degradation observed in these two tests may reflect partial or complete degradation of a number of components of brake fluid DOT4.