α-Naphthylthiourea

α-Naphthylthiourea (ANTU) is a rodenticide that is specifically used against Norway rats as bait (available as 10% active baits in suitable protein- or carbohydrate-rich materials and as a 20% tracking powder). However, it is futile against all other species of rodents because of its tendency to cause resistance and specificity. ANTU rapidly lost popularity and is no longer manufactured in the United States. Workers handling thiourea products showed ready penetration through skin, leading to destructive changes in the thyroid gland. ANTU is detectable in tissues only within 24h if the material was ingested in high doses, and its metabolites are primarily excreted in urine (>75%), pleural effusion, lung, skeletal muscles, and pancreas. Absorption of ANTU from the gut is rapid, especially in the presence of fat. Thiourea (TU) and its derivatives, phenylthiourea (PTU) and ANTU, have been employed in animal models as experimental tools to study characteristics of pulmonary edema common to a variety of drugs and toxic substances. The acute toxic signs associated with the administration of thiourea-like compounds are massive pulmonary edema, capillary hemorrhage, pleural effusion, and inflammation of the tracheobronchial tree. The mechanism whereby TU, PTU, and ANTU produce acute pulmonary edema is not clearly understood. A causative relationship between bradycardia and pulmonary edema has been demonstrated in the genesis of pulmonary edema. Repeat exposures can injure the thyroid and adrenals, producing hypothyroidism. Oral ingestion may cause vomiting, shortness of breath, and bluish discoloration of the skin. Large overdoses present with lassitude, anorexia, abdominal pain, hypoxia, cyanosis, dyspnea, pulmonary edema, tracheitis, and pneumonitis. Motor and sensory peripheral neuropathy, autonomic dysfunction, and central nervous system disorders have been reported. Acute inhalation of dust produces coughing, dyspnea, pulmonary edema, tracheitis, and pneumonitis. Dermal contact can cause skin and mucous membrane irritation. ANTU is not classifiable as a human carcinogen (Cat. 3).