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PBT assessment

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PBT assessment: overall result

4-chloroformylphthalic anhydride
Type of composition:
boundary composition of the substance
State / form:
solid: bulk
Reference substance:
Composition 1
PBT status:
the substance is not PBT / vPvB

In determining the classification appropriate to trimellitic anhydride mono-chloride (TMAC), it is necessary to consider all available evidence concerning its persistence, potential to accumulate and predicted or observed environmental fate and behaviour that may present a long-term and/or delayed danger to the structure and/or functioning of aquatic ecosystems. These points are considered below.


Reliable studies are available to demonstrate that trimellitic anhydride mono-chloride (immediately hydrolysed to trimellitic acid under the test conditions) is readily biodegradable regarding results obtained on trimellitic anhydride (source substance).

Trimellitic anhydride mono-chloride may therefore be expected to degrade rapidly, and to be completely mineralised, i.e. converted to CO2and H2O without forming any recalcitrant metabolites. Trimellitic anhydride mono-chloride and its degradation intermediates are therefore non-persistent.


Log10 Kow values for trimellitic anhydride mono-chloride (QSAR prediction) and its hydrolysis product trimellitic acid (experimental value: log Kow=0.54) are all less than 3.0. The potential for trimellitic acid to bioaccumulate in the tissues of organisms that inhabit aquatic or terrestrial matrices contaminated with TMAC residues is therefore negligible. The risk that trimellitic anhydride mono-chloride or its derivatives may biomagnify through successive trophic levels of aquatic or terrestrial food chains is consequently also negligible. 


TMAC is a trimellitic anhydride mono-chloride. The first steps that may be predicted in its environmental fate, prior to biodegradation, are its immediate hydrolysis to trimellitic acid followed by conversion to trimellitate salts. Acute aquatic effects tests with fish, daphnids and algae showed no significant effects and LC50s were not established. Other than effects on algae, no long-term effects data are available on the substance itself. These studies demonstrate the low intrinsic toxicity of trimellitate to aquatic biota, and - taking into account its susceptibility to rapid biodegradation - provide assurance that trimellitic anhydride mono-chloride does not present a long-term and/or delayed danger to the structure and/or functioning of aquatic ecosystems. 

No classification is triggered based on available data, according to EEC Council Directive 79/831/EEC Annex VI, Part II (D) as described in Commission Directive 93/21/EEC or Regulation (EC) No 1272/2008.