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Ecotoxicological information

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Trimellitic anhydride mono-chloride (TMAC, target substance) is unstable in the presence of moisture and undergoes rapid hydrolysis to trimellitic acid (TMLA) (Lord and Cooper, 1992). The hydrolysis of TMAC was virtually instantaneous at 40°C and similarly fast hydrolysis of trimellitic anhydride (TMA) would also be anticipated in production and manufacturing waste waters, with complete conversion to trimellitic acid (TMLA) occurring even before reaching waste water treatment facilities.In view of its rapid hydrolysis, it is not technically possible to determine the aqueous solubility limit of the parent anhydride.

A number of reliable studies address the aquatic toxicity of trimellitic anhydride (TMA,source substance). In these studies (Knackeret al., 1992, 1993a & b; Lebertz, 1991a & b) trimellitic anhydride was first treated with aqueous NaOH solution,to convert the acid anhydride (TMA) to the sodium salt(s) of trimellitic acid (TMLA), and exposure in these studies was consequently to sodium trimellitate (following neutralisation of excess alkali).

No toxicity was observed under these conditions (trimellitic anhydride : TMA) :

Acute toxicity to fish - Golden orfe (L. idus melanotus) 96 hour LC0 (static):>957 mg TMA-equiv/L, 96 hour NOEC957 mg TMA-equiv/L;

Acute daphnia inhibition -D. magna 48 hour EC50 (static):>792 mg TMA-equiv/L, 48 hour NOEC792 mg TMA-equiv/L;

Algal growth inhibition -D. subspicatus 72 hour ErC50:>739 mg TMA-equiv/L, 72 hour NOEC739 mg TMA-equiv/L.

All these endpoints are mean measured values and represent the highest concentration applied.

Toxicity to aquatic microorganisms: 3 hour EC50, based on inhibition of respiration of activated sludge, was between 100 and 500 mg/L. Inhibition, relative to the untreated control, was observed at concentrations500 mg/L and the NOEC was 100 mg/L.

In conclusion, trimellitic anhydride mono-chloride (TMAC) exhibit very low toxicity to fish, aquatic invertebrates, unicellular algae and to aquatic microorganisms including biological waste water treatment processes based on results obtained on trimellitic anhydride (TMA) (and more environmentally relevant trimellitic acid, TMLA) using read across.

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