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DL-LACTONE CAS N°:79-50-5 - page 41 / 113

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OECD SIDS 3. ENVIRONMENTAL FATE AND PATHWAYS

DL-LACTONE

ID: 79-50-5 DATE: 18.01.2006

to the aquatic compartment.

Reliability:

(2)

valid

with

restrictions

Accepted

QSAR

model.

16-NOV-2005

(32)

Media:

Method: Year:

other: ai biota Calculati 2004

r - sediment - soil - water - suspended particles -

on according Mackay, Level II

Result:

Level III reaction constant ie, compl Compartme

Air Water

Model v2.70, Level II dynamic distribution with and advection (substance flux out of system), emission rate into system (compartment not specified, ete distribution) 1000 kg/h:

nt

Mass,

Percentage

Reaction,

Advection,

kg

kg/h

kg//h

70.1

3.03E5

0.023%

>99.9%

1.51

695

0.848

303

0.018%

0.053

0

4.02E-4%

0.001

2.43E-5

1.26E-5

-

-

1.02E-6

-

-

Soil

54.7

Sediment

1.22

Susp Fish ---

. particles 0.038 3.09E-3

Losses from system: Compartment Advection, % total losses

Water

30.3

Soil

-

Air

0.0701

Sediment 2.43E-6 Total losses, % 30.37

Reaction, % total losses

0.218 69.4

    • 5.27

      E-3

    • 1.17

      E-4

69.62

Reaction half-life, h 22.3 (1)

302

(2)

720

(3)

720

(3)

--- Overall residence time (system half-life), h Overall reaction time, h Overall advection time, h Total mass in system, kg --- Reaction half-life inputs:

303 435 998 30300

Conclusion:

  • (1)

    QSAR atmospheric half-life from chapter 3.1.1.

  • (2)

    Aquatic half-life derived by adding rate constants for surface water biodegradation (t½ = 15 d for readily biodegradable substances, TGD 2003, Part II, p. 54) and hydrolysis (see chapter 3.1.2) by using TGD 2003, Part II, equation 31, p. 57.

  • (3)

    Soil half-life for readily biodegradable substances according to TGD 2003, Part II, p. 56.

In a Level II dynamic distribution model with a constant emission rate into the system of 1000 kg/h, assuming complete fugacity-driven distribution, with reaction within and advection out of the system, dl-Lactone is predicted to partition virtually completely to the aquatic compartment, while partitioning into other compartments, specifically into biota, is very low. Water is also the most important

compartment for substance losses, both (accounting for 30.3% of total losses) biodegradation and hydrolysis (69.4%).

through advection and reaction by Losses in water add up

to 99.7% while losses in the atmosphere through OH-radical-mediated degradation account for 0.2%. The predicted overall average residence time in the system of

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