It is commonly accepted that surfactants are not sensitising to the skin and do not cause allergic contact dermatitis. This is based on human experience gained by the industry over many years using surfactants in consumer products and clinical research conducted in Europe
However, while the results of well-established animal testing protocols (guinea pig test) support this view, the newly developed test method to evaluate the skin sensitising properties of chemicals, (local lymph node assay [LLNA]), frequently suggests that surfactants might have a sensitising effect. While the LLNA approach is favoured by many regulators, the results obtained are in contradiction to long-standing experience. An in-depth evaluation of the LLNA study and its mechanistic background was initiated to provide additional insight into the causes for these unexpected results.