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DL-LACTONE CAS N°:79-50-5 - page 9 / 113

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OECD SIDS

DL-LACTONE

2.2.5 Biodegradation

Modified Sturm Test

301B

Zahn-Wellens test (14 days)

302B

Zahn-Wellens test (21 days)

302B

Zahn-Wellens test (21 days)

302B

MITI test (13 days)

302C

MITI test (21 days)

302C

COD test (7 days)

-

76-82%

1

Desmares-Koopmans,

2004

98%

2

Gröner, 1983

80%

2

Gröner, 1983

97%

2

Gröner, 1985

Ca. 82%

2

Gröner, 1983

>98%

2

Gröner, 1983

>95%

2

Blechschmitt, 1995

Several tests for ready and inherent biodegradation indicate that DL-lactone is biodegradable (see table 2). In a Modified Sturm test the relative degradation values calculated in the 28-day test period were 82% and 76% degradation, for the duplicate bottles tested. Furthermore, more than 60% de- gradation of DL-Lactone was reached within a 10-day window. No inhibition of microbial activity, adsorption nor abiotic degradation occurred (Desmares-Koopmans, 2004). DL-Lactone was readily biodegradable under the conditions of the test.

Table 2 Type

Reference

Results from biodegradation studies OECD Guideline Degradation

Reliability code

2.2.6 Bioaccumulation

The potential of DL-lactone to bioaccumulate in fish and worms was investigated using various QSARs. Based on modelled bioconcentration factors, 0-3.2 for fish and 3.23 for worms, the substance is not expected to bioaccumulate (Uses 4.02, 2004; EPISuite 3.11, 2003; SciFinder, 2004; ChemSCORER; Veith, 1979).

2.2.7

Other information on Environmental Fate

Exposure of DL-lactone to the environment is expected to occur through sewage works into surface waters. In the specific case of the Dalry plant, the effluent from the plant sewage works goes into the municipal sewagw works of the town of Dalry, where further removal is expected (O’Leary 2001), before release into receiving waters. Based on the ready biodegradability attained in a test, the EU Technical Guidance Document (2003) suggests a surface-water half-life for biodegradation of 15 days.

In conclusion, based on partitioning properties, ready biodegradability, extrapolated hydrolysis and suggested surface-water degradation rate in water as well as calculated photodegradation in the at- mosphere, DL-lactone is not considered a persistent compound in the environment.

UNEP PUBLICATIONS

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