Dermal toxicity Human skin, nature

Dermac SR-38 is one of a series of oxazolidinones, cyclic urethane compounds, evaluated as transdermal enhancers. The compound was designed to mimic natural skin lipids (such as ceramides), to be nonirritating, and to be rapidly cleared from the systemic circulation following absorption. In animal and human safety studies, Dermac SR-38 demonstrated a good skin tolerance (no observed irritancy or sensitization at levels of 1-10 wt% moderate to severe irritation in rabbit at 100%), and a low degree of acute toxicity (LD50(rat oral) > 5.0g/kg). The compound was evaluated for its ability to enhance the human skin permeation of diverse drugs from dermal and transdermal delivery systems. Data for minoxidil indicated an enhancer concentration-dependent effect for permeation enhancement. Dermac SR-38 was also found to enhance the skin retention of both retinoic acid when applied in Retin A cream, and dihydroxyacetone when applied in a hydrophilic cream. ... 

The observation that PAHs adversely affected the skin in both humans and animals is not surprising. The skin undergoes rapid cell turnover and is thus a likely target for PAH attack on DNA synthesis. Given the information discussed above, the ubiquitous nature of PAHs in the environment, and the susceptibility of the skin to PAH-induced toxicity, adverse skin effects may occur in individuals exposed to these chemicals by the dermal route. 

Toxicology. The nitroparaffins have minimal effects by way of actual contact. There were neither systemic effects nor irritation in dermal studies in rabbits. Human exposure of a prolonged or often-repeated nature has led to low grade irritation attributable to removal of oil from the skin, an effect produced by most organic solvents. Eye irritation potential of all four nitroparaffins has been deterrnined in rabbits. Other than a transient slight redness and some lachrymation, no effects were noted. The average Draize score was 0.0. The acute oral toxicity, LD q, of all four nitroparaffins has been deterrnined in the rat (Table 8). 

These substances in general exhibit low to intermediate order of toxicity in experimental animals. The severity of effects, however, depends on the nature of the species and also on the route of administration of the substance into the body. In humans, there is no reported case of poisoning. These substances have very low vapor pressure and are nonvolatile. The risk of inhalation is, therefore, very low. Also, any skin absorption or dermal route of entry of the pure material should be relatively insignificant. Accidental ingestion of a large dose, however, can be dangerous. 

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