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Environmental fate & pathways

Endpoint summary

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Hydrolysis of a structural analogue of the substance, tetrahydromethylphthalic anhydride (MTHPA), has been investigated. The substance was found to hydrolyse rapidly, resulting in formation of the respective di-acid. The calculated half-lives at 20 degree C are, for all three pH values ( 4, 7 and 9) below 3.5 minutes (about 0.06 hours).



The hydrolysis product(s) of the substance are not readily biodegradable.

Half lifes in water, sediment and soil have beencalculated using a Fugacity model according to Mackay, Level III usingEPIWIN (v.4.0), giving values of 360 hours in water, 3240 hours in sediment and 720 hours in soil. Similar calculation has been undertaken on the hydrolysis product, the dicarboxylic acid, giving values of 208 hours in water, 1870 hours in sediment and 416 hours in soil.



The log Pow of 1.88 does not indicate thattetrahydro-4 -methylphthalic anhydride (4-MTHPA) might bioaccumulate.

The BCF of 4-MTHPA was, in addition, assessed in a weight of evidence approach by QSAR calculations and read across to related substances..

According to QSAR (BCFBAF ver.3.0), BCF of the test substance (4 -MTHPA) is 8.08 L/kg wet weight. As the substance is rapidly hydrolysed to the corresponding dicarboxylic acid, a QSAR calculation of the BCF of the hydrolysis product of 4 -MTHPA was conducted in addition, giving a value of 3.162 L/kg wet weight.

QSAR estimation of a structural analogue of the test substance, methyltetrahydrophthalic anhydride (MTHPA), results in a BCF in the range of 17.16 -20.9 while that of its hydrolysis product is calculated to be less than 3.2.

Bioaccumulation of the hydrolysis products of two structural analoges of 4 -MTHPA has yielded experimental values as follows:

4 -cyclohexene-1,2 -dicarboxylic acid. (CAS No. 88 -98 -2): < 0.2 (2 mg/l), < 2 (0.2 mg/l).

BCF of 4-methylcyclohexane-1,2-dicarboxylic acid (CAS No.57567 -84 -7): < 0.2 (0.5 mg/l), < 2.4 (0.05 mg/l).

It may therefore be concluded the potential of bioaccumulation of 4 -MTHPA is low.


Transport and distribution

The potential for adsoprtion is expected to be low, based on a low octanol water partition coefficient of 1.88.

The Henry's Law constant of 2.18 Pa-m3/mole indicates that the substance is not significantly volatile from surface water

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 – 0.462%; Water – 40.3%; Soil – 59.2% and Sediment - 0.0907%. Similar distribution modeling on the hydrolysis product of the substance indicated the following distribution: Air – 0.0000574%; Water – 19.9%; Soil - 0% and Sediment - 0.1179%