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DL-LACTONE CAS N°:79-50-5 - page 42 / 113

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OECD SIDS 3. ENVIRONMENTAL FATE AND PATHWAYS

DL-LACTONE

ID: 79-50-5 DATE: 18.01.2006

303 hours (12.6 d) suggests that dl-lactone

is

not

a

Reliability:

persistent

substance.

(2) valid

with restrictions

Accepted

QSAR

models

and

guidance

document.

24-AUG-2004

(20) (21) (32)

Media:

Method: Year:

other: air - sediment - soil - water - suspended particles - biota Calculation according Mackay, Level III 2004

Soil

0.0148

4.88E-3

1.43E-5

-

Sediment

0.436

0.144

4.20E-4

8.83E-6

Susp. particles

3.81E-5

1.25E-5

-

-

Fish

3.10E-6

1.02E-6

-

-

Compartment

Mass,

kg

Air Water

1.36E-4 303

Sediment 8.73E-4 Total losses, % 30.3

Reaction half-life, h 22.3 (1)

Result:

302

(2)

720

(3)

720

(3)

--- Losses from Compartment

Air Water Soil

system: Advection,

Reaction, % total losses

4.24E-4 69.6 1.43E-3 0.042 69.7

Level III Model v2.70, Level III dynamic distribution with reaction and advection (substance flux out of system), with a

Percentage, Reaction,

Advection,

% 4.49E-5 99.9

kg/h 4.24E-6 0.696

kg/h 1.36E-6 0.303

% total losses

1.36E-4 30.3 -

constant emission rate only into water of 1 kg/h, based on

actual production of dl-lactone:

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

304 436 1001 304

Conclusion:

  • (1)

    QSAR atmospheric half-life from chapter 3.1.1.

  • (2)

    Aquatic half-life derived by adding rate constants for surface water biodegradation (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 III dynamic distribution model with a constant emission rate into the system of 1 kg/h exclusively into the aquatic compartment, based on production information, 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 through advection (accounting for 30.3% of total losses) and reaction by biodegradation and hydrolysis (69.6%). Losses in water add up to 99.9% while losses in all other compartments account for less than 0.1%. The predicted overall average residence time in the system of

42

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