Propoxur: A carbamate insecticide.Insecticides: Pesticides designed to control insects that are harmful to man. The insects may be directly harmful, as those acting as disease vectors, or indirectly harmful, as destroyers of crops, food products, or textile fabrics.Insecticide Resistance: The development by insects of resistance to insecticides.Dichlorvos: An organophosphorus insecticide that inhibits ACETYLCHOLINESTERASE.Blattellidae: A family of insects in the order Dictyoptera (COCKROACHES), including genera Blattella, Parcoblatta, and Symploce.Meconium: The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the INTESTINAL GLANDS; BILE PIGMENTS; FATTY ACIDS; AMNIOTIC FLUID; and intrauterine debris. It constitutes the first stools passed by a newborn.Malathion: A wide spectrum aliphatic organophosphate insecticide widely used for both domestic and commercial agricultural purposes.El SalvadorPesticide Residues: Pesticides or their breakdown products remaining in the environment following their normal use or accidental contamination.Carbamates: Derivatives of carbamic acid, H2NC(=O)OH. Included under this heading are N-substituted and O-substituted carbamic acids. In general carbamate esters are referred to as urethanes, and polymers that include repeating units of carbamate are referred to as POLYURETHANES. Note however that polyurethanes are derived from the polymerization of ISOCYANATES and the singular term URETHANE refers to the ethyl ester of carbamic acid.Cockroaches: Insects of the order Dictyoptera comprising several families including Blaberidae, BLATTELLIDAE, Blattidae (containing the American cockroach PERIPLANETA americana), Cryptocercidae, and Polyphagidae.