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Key value for chemical safety assessment

Justification for classification or non-classification

No hyperplasia or necrosis was observed in groups of male and female rats exposed to isobutyric acid, monoester with 2,2,4 -trimethylpentane-1,3 -diol by the oral route at dose levels up to 1000 mg/kg bw/day for up to 51 days and all genotoxicity studies were negative both in the presence and absence of metabolic activation. Based on a weight-of-the evidence evaluation, isobutyric acid, monoester with 2,2,4 -trimethylpentane-1,3 -diol is unlikely to pose a significant risk for the development of any tumor type in humans exposed to this chemical and is not considered to be classified for Carcinogenicity according to EU CLP.

Additional information

There were no chronic repeat-exposure studies conducted with isobutyric acid, monoester with 2,2,4 -trimethylpentane-1,3 -diol available for review. However, results for a repeat-exposure study in which male and female rats were exposed to up to 1000 mg/kg bw/day of isobutyric acid, monoester with 2,2,4 -trimethylpentane-1,3 -diol for up to 51 days by oral gavage suggest that the test material is unlikely to pose a significant risk for the development of a carcinogenic effect. No necrosis or hyperplasia was observed in any organ at necropsy. Microscopic liver lesions found in both sexes were considered an adaptive metabolic rather than a toxic response. The only other adverse effect was an increase in chronic progressive nephropathy, a common spontaneous lesion in male rats and frequently exacerbated by chemical exposure. While very advanced chronic progressive nephropathy may be a risk factor for the spontaneous development of renal tumors in rats, chronic progressive nephropathy has not been observed in humans. 

In addition, no mutagenicity/genotoxicity was observed in a bacterial reverse mutation assay or an in vivo mammalian bone marrow mouse micronucleus assay. In addition, negative results were also observed in several in vitro mammalian mutagenicity/genotoxicity studies conducted with TXIB which shares a similar metabolic profile to isobutyric acid, monoester with 2,2,4 -trimethylpentane-1,3 -diol.

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