Methemoglobin is an oxidized form of hemoglobin. Many oxidant chemicals and drugs are capable of inducing methemoglobinemia. Selected agents include nitrites and nitrates, bromates and chlorates, aniline derivatives, antimalarial agents, dapsone, propanil (an herbicide), sulfonamides, and local anesthetics (Table II–35). High-risk occupations include chemical and munitions work. An important environmental source for methemoglobinemia in infants is nitrate-contaminated well water. Amyl nitrite and butyl nitrite are abused for their alleged sexual enhancement properties. Oxides of nitrogen and other oxidant combustion products make smoke inhalation an important potential cause of methemoglobinemia.