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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The adsorption/desorption of DTO as a whole substance is not scientifically necessary or meaningful for the purpose of environmental assessment. However, for risk characterisation, it is necessary to consider the properties of the individual constituents that determine their environmental fate. As a consequence, in this section, only data describing the adsorption/desorption of DTO constituents are considered.

Adsorption/desorption of DTO as a whole substance

In accordance with Section 1 of REACH Annex XI, the study does not need to be conducted because the adsorption/desorption of a UVCB substance of this nature should be evaluated on the basis of the properties of its constituents. A result for the whole substance is not meaningful scientifically for the purpose of assessment of exposure or risk. It is therefore not appropriate to conduct or propose a test for this endpoint. The needs associated with a sound understanding of adsorption/desorption are adequately met by the available data on constituents. Reliable adsorption/desorption data are characterised by quantitative structure activity relationships (QSARs) for constituents of the substance.

Adsorption/desorption of DTO constituents

No measured data are available for adsorption/desorption coefficient (Koc) of DTO constituents. Calculated values for the constituents of DTO were obtained using KOCWIN (PFA 2010b). Koc for each block is calculated from the weighted average for the constituents in the block, the adsorption of DTO constituent blocks is shown in Table 4.5.

Table 4.5: Adsorption/desorption for DTO constituent blocks

Block

Constituents

Adsorption (Koc)

1

Low boiling fatty acids

1.06E+03

2

C16 saturated - C18.3 unsaturated fatty acids

1.16E+04

3

C18 saturated - C24 saturated and unsaturated fatty acids

5.56E+04

4

Abietic acid

2.19E+04

5

Palustric acid

2.18E+04

6

Pimaric acid

2.08E+04

7

Sesquiterpene

1.20E+05

8

Abietol

-

9

Tetracosanol and dehydrated sterol

1.58E+07

10

Aldehydes

1.60E+04

11

Dimethoxystilbene

6.85E+03

12

Sitosterols and analoque

4.85E+06

13

Polymeric acids*

14

Polymeric neutrals*

*not assessed because they are high polymeric constituents

Key value for chemical safety assessment

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