Skin irritancy of commercially available soap and detergent bars as measured by water vapour loss

The irritancy on human skin of 13 toilet soaps was assessed by means of water vapour loss measurements. The tests were performed on healthy skin of the volar side of the forearm in a panel of 33 subjects. The exposures were done using the Finn chamber method. Skin water vapour loss was measured by means of an "evaporimeter". All soaps--tested in 2 g/v% solutions--were found to lead to a statistically significant increase of water vapour loss as compared to the control sites. Synthetic detergents based on alkyl sulfates, particularly Lactacyd, generally had a relatively greater effect on skin vapour loss as compared with the other products. On the whole the differences between the products were small. It appears that every person probably has his own pattern of susceptibility to wash-active agents.