Toxicity major solvent groups

Evaporation rate 34 5.2.6 Toxicity of major solvent groups 89... 

Among the aldehydes and ketones tested acetone was least toxic, formaldehyde, butyraldehyde, and crotonaldehyde next, and mesityl oxide most toxic. In this group of compounds temperature was a major factor, both formaldehyde and mesityl oxide being much more toxic at 40 than at 25 C. None were outstanding as cholesterol solvents, but mesityl oxide was the best it penetrated nematodes the most easily and killed in the lowest concentrations. 

This section is intended to give a broad picture of the similarities and differences between the toxicity of solvents within and across the major chemical groups. It should not be taken as a comprehensive picture of the toxic effects of any specific solvent, for which reference should be made to one of the sources of information indicated in section 5.2.2. Where appropriate, the relevant UK occupational exposure limits (OESs or MELs) [9] are given in brackets after each individually named solvent. 

All the major solvents used in cosmetics and toiletry formulations are from the most benign group and have low toxicity. Ethanol, the most common solvent in this sector, has a low environmental impact and, in particular, is among the least potent of VOCs in forming tropospheric ozone. 

Other reactions must be mentioned beside the major reactions described above. These reactions may be responsible for the transformation of a toxic metabolite into the ultimate toxicant. Rearrangements and cyclizations are examples of reactions involved in these processes. In the case of the solvent hexane (Figure 33.19), the toxic metabolite, 2, 5-hexanedione, is formed by four successive oxidations of the molecule. The condensation of the -dicetone with the lysyl amino group of a neurofilament protein is followed by a Paal-Knorr cyclization reaction. This is the initial process that explains the hexane-induced neurotoxicity." A further auto-oxidation of the A-pyrrolyl derivatives leads to the cross-linking of the axonal intermediate filament proteins and the subsequent occurrence of peripheral neurotoxicity." ... 

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