These are known in the art and may comprise the bariumcadmium salts of long-chain fatty acids, polyols such as pentaerythritol or alpha-methylglucoside, nitrogen compounds such as melamine or dicyandiamide, esters such as phenyl phthalate, phenyl benzoate, o-toluol benzoate, triethylene glycol salicylates, certain of the organic phosphates, and mixtures thereof.