Methacrylic acid

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:

1991-01-03 to 1991-03-31

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Method in accordance with OECD Guideline, GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Guideline:

EU Method C.6 (Degradation: Chemical Oxygen Demand)

Version / remarks:

EEC Directive 67/548 Annex V C.6 as published in 84/449/EEC.

GLP compliance:

yes

Specific details on test material used for the study:

purity: > 98.5 %
Batch TD 90-133

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Aeration stage of the HRC Limited sewage treatment plant treating predominantly domestic sewage
Date of collection: 3 January 1991
Preparation: The sample was allowed to settle and the supernatant filtered through Whatman GF A tilter paper (first 250 ml discarded).

Duration of test (contact time):

28 d

Initial conc.:

3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

other: Percent biodegradation determined by comparing oxygen depletion value with the corresponding ThOD

Details on study design:

Sampling at 0, 5, 15 and 28 days
Temeprature: 20 +/-1°C

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

86

Sampling time:

28 d

Remarks on result:

other: 10 day window passed

Remarks:

Oxygen depletion = 4.325 mg O2/L; ThOD = 5.01 mg O2/L

Details on results:

Oxygen depletion in the inoculated and non-inoculated control series were within prescribed limits.
The substance passed the "time window" criterion (60% degradation within 10 days of attaining the 10% level)

Results with reference substance:

87% degradation within 28 days

Mean oxygen depletion and percentage biodegradation values

Culture medium	Day 5	Day 15	Day 28
(a) Dilution water without inoculum     02depletion (mgO2/I)	0.175	0.275	0.250
(b) Dilution water with inoculum     02depletion (mgO2/I)	0.100	0.300	0.375
(c) Test substance (3 mg/l)     02depletion (mgO2/I)     % degradation	3.050 61	3.000 60	4.325 86
(d) . Standard substance (3 mg/l)     02depletion (mgO2/I)     % degradation	3.275 65	3.450 69	4.375 87

t1/2: 10.3 days

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

In a valid guideline study, the substance was considered readily biodegradable (86% degradation within 28 days, 10 day window passed).

Executive summary:

In a valid guideline study acc. OECD 301 D (Readily Biodegradability: Closed Bottle Test) methacrylic acid attained 86 % biodegradation within 28 days. The"pass" level of 60 % was reached within 10 days of exceeding 10 % level. Therefore, methacrylic acid readily biodegradable.

Description of key information

In a valid guideline study acc. OECD 301 D (Readily Biodegradability: Closed Bottle Test) methacrylic acid attained 86 % biodegradation within 28 days. The"pass" level of 60 % was reached within 10 days of exceeding 10 % level. Therefore, methacrylic acid readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

For the evaluation of the biodegradability of methacrylic acid the following test result is considered:

Closed Bottle Test (OECD 301D): 86 % degradation after 28 days. (Douglas and Bell, 1992).

In the key study the criterion of the 10-day window was fulfilled.

The following information is taken into account for any hazard / risk / persistency assessment:

MAA, like all the other substances of the category, is readily biodegradable.

Based on the TGD the defaults for readily biodegradable substances the first order constants and half lives for biodegradation in surface water for all members of the category are as follows:

Rate constant (surface water) ksw = 0.047 d-1 (at 22/25 °C)

Half life (surface water ) [DT50] = 14 d (at 22/25 °C)