A series of human studies have been conducted by Johnson & Johnson Consumer Companies, Inc. to test the allergic potential of skin care products with high content of pharmaceutical grade mineral oil (> 90 %; Johnson & Johnson Consumer Companies Inc). The tests included human repeated insult patch test (HRIPT) on a total of 1035 subjects, cumulative irritation test on 137 subjects, phototoxicity on 60 subjects, and photoallergy tests on 171 subjects. The results of these studies are summarized in Table 19.2. In all the tests there was no allergic, phototoxic, and photoallergic responses and in the case of the cumulative irritation tests the finding was negligible irritation potential.

Mineral oil has been suspected in popular press to cause blocking of skin pores, leading to acne and preventing toxins from escaping the body through the skin. However, recent studies using advanced measuring methods clearly demonstrated that the tested oils do not clog skin pores (Patzelt et al. 2012; Stamatas et al. 2008; DiNardo 2005). These studies concluded that mineral oil and vegetable oils used in skin care products form a protective layer on the skin, enhancing moisture retention, while allowing the skin to breathe without obstructing the pores. Wiechers et al. evaluated the effect of individual, blended, and formulated emollients on the mechanical properties of skin resulting in a defined tactile sensory perception (Wiechers 2008). The study recognized the existence of occlusion as a safe moisture-control mechanism, which depends principally on the choice of the emollients and by choosing the right emulsifier (Wiechers 2008; Caussin et al. 2007; Strübmann et al. 1993).