Benzene-1,2,4-tricarboxylic acid 1,2-anhydride

Endpoint summary

Description of key information

Trimellitic anhydride appears to be distributed to all tissues following inhalation exposure to rats. Elimination exhibited typical first order exponential kinetics with half-lives ranging from 3 to 46 days.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

The distribution, concentration and clearance of 14C-trimellitic anhydride and/or its metabolites in rats following a single inhalation exposure has been studied by Hatoum & Leach (1988). 28 Sprague-Dawley rats were exposed to trimellitic anhydride by inhalation at a concentration of 950µg/m³ during a 45 minute exposure period. The test animals were terminated at 3 hours and 1, 2, 4, 8, 16 and 32 days following the exposure period and the major tissues examined and analysed for 14C content. Peak 14C concentration was observed after 3 hours exposure with a rapid decrease observed in all tissues exponentially after 3 hours. Almost all tissues examined followed this pattern, with the possible exception of the lung associated lymph nodes. In this case, the14C content declined but then increased and reached a second maximum 8 days after exposure. This response was only evident in male rats. No deaths occurred during the study. Apparent elimination rate constants ranged from 0.015 in popliteal lymph nodes from female rats to 0.214 in faeces from female rats. In male rats, elimination rate constants (Ke) ranged from 0.030 in the heart and testes to 0.196 in faeces. Consequently biological half life values ranged from 3 to 46 days in females, and 4 to 23 days in males. Large differences in biological half-life values between male and female rats were calculated for the popliteal and lung-associated lymph nodes, bone marrow and heart. Other sex differences in biological half-lives were minimal. Trimellitic anhydride serum antibody levels remained at background levels through the first 4 days, with 2 rats developing significant antibody levels beginning at Day 8. Thus it appears that a single 45- minute inhalation exposure to trimellitic anhydride results in approximately 17% of the rats becoming sensitised.