Speaking of 22-year-old research papers…

Here’s one that compared the reactions of patients in different subgroups to eight surfactants and distilled water. [Link][Pubmed Link]

Conclusion? “The subgroup of patients with atopic dermatitis reacted more severely than the subgroup of healthy controls with respect to synthetic detergents. The alkaline soaps were tolerated relatively well in this group.

Parenthetically, they also say “No significant differences in reaction upon the exposure of the surfactants could be noted between the subgroup of patients with irritant contact dermatitis and the subgroup of healthy controls” Note that appropriate irritants were not tested WITH detergent surfactants. The subgroup with irritant contact dermatitis would likely have reacted more to the combination of detergent and irritant than to the same level of irritant alone. (Detergents increase antigen penetration.)