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DL-LACTONE CAS N°:79-50-5 - page 52 / 113

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OECD SIDS 3. ENVIRONMENTAL FATE AND PATHWAYS

DL-LACTONE

ID: 79-50-5 DATE: 18.01.2006

GLP: Test substance:

no as prescribed by 1.1 - 1.4

Method:

Result:

Test substance: Conclusion:

A standard inherent degradation test was performed with pure dl-lactone from lab production in a Sapromat respirometer in a test setup corresponding to OECD 302C, except that the sludge used as an inoculum was a 1:1 (dry weight) mixture of non-adapted activated sludge from one single small municipal sewage works and of activated sludge from the Roche in-house pilot sewage plant, which receives a flow-proprtional sample of the industrial wastewater. Test concentrations were 10, 100 and 1000 mg dl-lactone/l. Peptone/yeast extract was added to test cometabolic degradation. Degradation was followed by oxygen consumption in test substance vessels minus the oxygen consumption of a blank sludge vessel and compared to the COD for dl-lactone respectively the COD for dl-lactone plus peptone/yeast extract and calculated as percent degradation. Degradation for both 10, 100 and 1000 mg dl-lactone/l reached 99% in 21 days. There was no inhibition of peptone/yeast extract degradation in the presence of 10 or 100 mg dl-lactone/l; there was a slight inhibition (14%, borderline significance) of peptone/yeast extract co-metabolic degradation in the presence of 1000 mg dl-lactone/l. dl-Lactone from Roche, "pure", not otherwise characterised. dl-Lactone was well inherently biodegradable by non-adapted municipal sewage sludge at 10, 100 and 1000 mg/l. Further, it was not inhibitory on the biodegradation of a well degradable substrate, peptone/yeast extract, at 10 and 100 mg/l and it was only slightly inhibitory (14%, borderline significance) at

Reliability:

1000 (2)

mg/l. valid

with

restrictions

Biodegradability

and

inhibition

assessment

from

the

in-house

Flag: 10-MAR-2005

wastewater lab, not GLP professional laboratory Critical study for SIDS

but highly standardised test in with many years of experience. endpoint

a

(24)

Type: Inoculum: Concentration:

aerobic activated sludge 600 mg/l related to Test substance

Contact time: Degradation: Result: Control Subst.: Deg. product:

905 mg/l related to COD 7 day(s)

  • >

    95 % after 7 day(s)

inherently biodegradabl other: no data not measured

e

(Chemical Oxygen Demand)

Method:

Year: GLP: Test substance:

other: in-house biodegradation test with COD determination 1995 no as prescribed by 1.1 - 1.4

Method:

In a modification of a Zahn-Wellens test protocol, 1.2 g of test substance were dissolved in tap water; the solution was not neutralised. Then, mineral salts as per the Zahn-Wellens test method and rinsed activated sludge were added and the batch was supplemented with tap water to a total volume of 2 l. The final activated sludge concentration was approximately 1 g dry substance/l. The test flask or flasks (not stated whether one or two

52

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