Benzisothiazolinone (BIT) is an organic compound with the formula C6H4SN(H)CO. A white solid, it is structurally related to isothiazole, and is part of a class of molecules called isothiazolinones.

[1] BIT's low molar mass allows for it to penetrate the epidermis and then react with the skin macromolecules, which causes the irritation.

"[10] The opinion further states: "There is no information on what may be safe levels of exposure to benzisothiazolinone in cosmetic products from the point of view of sensitisation.

The products under consideration were sunscreen, laundry detergent, dish soap, and spray cleaner; by way of calculation they derived BIT NESILs of 0.0075%, 0.035%, 0.035%, and 0.021%, respectively.

They then performed a pilot examination via bulk sample analysis of one representative product from each category labelled as containing BIT.