Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Stability

Phototransformation in air

Stability of the substance in the atmosphere was calculated using the software AOPWIN (v 1.92). It is predicted that the substance will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals. The half-life for this reaction in air is estimated to be between 4.6 and 13.8hours, at different test conditions.The most conservative value was selected.

Hydrolysis

In accordance with REACH Regulation 1907/2006, Annex VIII, Column 2 hydrolysis as a function of pH does not need to be determined as the substance is readily biodegradable.

Stability of the substance against hydrolysis was calculated using the computer program HYDROWIN (v 2.00). A base-catalysed second-order hydrolysis rate constant of 0.03486L/mole-sec was estimated using a structure estimation method. This corresponds to half-lives of6.3 years at pH 7 and 230.2 days at pH 8.

 

Biodegradation

Ready biodegradability has been investigated in a modified Sturm test conducted according to OECD Test Guideline No. 301 B. 10% degradation (beginning of biodegradation) occurred after 9 -10 days and the 60% pass level was achieved within the 10 -day-window. The substance is thereforeregarded asreadily biodegradable.

A second test, conducted as a modified MITI Test reported in the literature describes the substance as being only inherently biodegradable.

 

Bioaccumulation

BCF has been calculated using the computer program BCFBAF (v3.01). It is predicted that the substance has BCF of 777 L/kg wet weight.It is therefore concluded that the potential for bioaccumulation of 1,2-Benzenedicarboxylic acid, di-C9-11-branched and linear alkyl esters (DIPLAST L 9 -11) is low.

 

A phthalate ester with branched (as opposed to linear alcohol chains) has undergone risk assessment (European Union Risk Assessment Report on 1,2-benzenedicarboxylic acid, di-C9-11-branched alkyl esters, C10-rich and di-“isodecyl” phthalate,Final Report, 2003).The report considers bioaccumulation in aquatic organisms and cites a single test where a BCF of < 14.4 was determined for fish (Cyprinus carpio) according to OECD test guideline No. 305C. In the same test system, a BCF of 1.3-29.7 was determined for DEHP. The authors comments that higher BCFs have been determined with DEHP in fish in other assays and that the only BCF result available for the substance with fish is very low compared with the results available for DEHP. As a result the BCF for fish of 840 retained for the risk assessment of DEHP was used for the assessment of the exposure of humans via the environment of the substance. This value is similar to that calculated for1,2-Benzenedicarboxylic acid, di-C9-11 -branched and linear alkyl esters and the calculated value may therefore be regarded as reasonable.

 

Transport and distribution

Adsorption / desorption

The adsorption coefficient (Koc) on soil and on sewage sludge using high performance liquid chromatography (HPLC) has been estimated for a phthalate ester with C-11 chain length. Adsorption coefficients were estimated to be log Koc soil = 21.41 and log Koc sewage sludge = 23.21.

 

The adsorption coefficient (Koc) on soil and on sewage sludge using high performance liquid chromatography (HPLC) has also been determined for a phthalate ester with C-6 to C-10 chain length. Adsorption coefficients were estimated to be log Koc soil = 5.55-10.37 and log Koc sewage sludge = 6.29-12.09.

 

In addition the adsorption coefficient (Koc) of the substance, a phthalate ester with chain length of C9 to C-11, has been estimated using calculation methods to yield a log Koc of 6.397. This value is lower than that obtained experimentally on two analogous substances and is likely to be an under-estimate.

 

In all cases, the McCall classification scheme classifies the substances as immobile in soil (Koc > 5000).

Henry's Law constant

The Henry's Law constant of 4.88 Pa-m3/mole indicates that the substance is moderately volatile from surface water.

Distribution modelling

Distribution in environmental compartments has been calculated using a Fugacity model according to Mackay, Level III. Distribution in various environmental compartments is estimated as:Air - 0.43%; Water - 3.5%; Soil - 27.2% and Sediment - 68.8%.

Sediment and soil were then found to be the major target compartments.