An evaluation of the allergic contact dermatitis potential of colloidal grain suspensions

Colloidal grain suspensions have been used for decades as adjuncts in the treatment of atopic dermatitis, especially in the US. In Italy, many young children have been exposed to colloidal grains. Recently, it was suggested that these bath therapies may induce allergic contact dermatitis in some young atopic children.

To evaluate the allergic skin reactions to topical oat and rice colloidal grain suspensions of normal and atopic children with and without previous exposure to colloidal grain suspensions.

A double-blind, randomized patch study. Two concentrations of oat and rice colloidal grains (0.007% and 0.7%) were applied occlusively to the backs of 65 children living in Italy, ages 6 months to 2 years (43 were atopic and 22 were normal).

There were neither immediate urticarial nor allergic reactions in any of the 65 study subjects, atopic or nonatopic; 5 of 43 (12%) atopic subjects developed irritant reactions to the test materials. Radioallergosorbent tests (RAST) tests were performed on 55 subjects. The negative RAST test results found in the nonatopic group correlated well with nonatopic status, but positive RAST tests were found in only 8 of 35 (23%) atopic dermatitis subjects. None of the sera from positive RAST scores corresponded to subjects with irritant patch reactions.

The data indicate that topical colloidal grains can be used as an adjunct in the management of mild atopic dermatitis in children under 2 years of age. There was no evidence of sensitization to topical colloidal grains in the group studied.