Kotani, M., Masamoto, Y., and M. Watanabe. An Alternative Study of the Skin Irritant Effect of An Homologous Series of Surfactants. Toxic. in Vitro. 1994. 8(2): 229-233. [Reprinted with permission from Elsevier Science].

sodium n-butyl sulfate; sodium n-hexyl sulfate; sodium n-decyl sulfate; sodium n-hexadecyl sulfate; sodium n-octadecyl sulfate; sodium lauryl sulfate; sodium tetradecyl sulfate

An attempt has been made to differentiate between in vivo and in vitro skin reactions to a homologous series of surfactants (sodium alkyl sulfate, R-OSO3 Na) and to determine the usefulness of percutaneous absorption in vitro as an alternative test system. Sodium alkyl sulfate showed considerable biological activity by virtue of its polar head groups. The length of the lipophilic chain in the surfactants was an important factor in their overall activity. The following in vivo tests were performed: a primary skin irritation test in guinea pigs, a primary eye irritation test in rabbits and a closed patch test in humans. Peak skin irritation occurred with C10-C16 compounds. In the percutaneous absorption test in guinea pig skin, permeation was low for the C18 compound and high for the C4 compound. The results with the C18 compound suggest that differences between cell injury and skin irritation result from skin permeation. Although the C18 compound caused cell injury, membrane destruction and protein denaturation were more severely with the C10-C16 compounds, owing to their strong hemolytic and protein-denaturation action.