East Africa that some 2% of patients were blinded via atrophy of the optic nerve. In Germany, Paul Ehrlich inferred Béchamp's report of Atoxyl's structure incorrect, and Ehrlich with his chief organic chemist Alfred Bertheim found its correct structure—aminophenyl arsenic acid or aminophenyl arsonic acid—which suggested possible derivatives. Ehrlich asked Bertheim to synthesize two types of Atoxyl derivatives: arsenoxides and arsenobenzenes. Ehrlich and Bertheim's 606th arsenobenzene, synthesized in 1907, was arsphenamine, found ineffective against trypanosomes, but found in 1909 by Ehrlich and bacteriologist Sahachiro Hata effective against the microorganism involved in syphilis, a disease roughly equivalent then to today's AIDS. The company Farbwerke Hoechst marketed arsphenamine as the drug Salvarsan, "the arsenic that saves". Its specificity of action fit Ehrlich's silver bullet or magic bullet paradigm of treatment, and Ehrlich won international fame while Salvarsan's success—the first particularly effective syphilis treatment—established the chemotherapy enterprise. In the late 1940s, Salvarsan was replaced in most regions by penicillin, yet organic arsenicals remained in use for trypanosomiasis. Contemporary usage Arsanilic acid gained use as a feed additive for poultry and swine to promote growth and prevent or treat dysentery. For poultry and swine, arsanilic acid was among four arsenical veterinary drugs, along with carbarsone, nitarsone, roxarsone, approved by the U.S. Food and Drug Administration (FDA). In 2013, the FDA denied petitions by the Center for Food Safety and by the Institute for Agriculture and Trade Policy seeking revocation of approvals of the arsenical animal drugs, but the drugs' sponsors voluntarily requested the FDA to withdraw approvals of three, including arsanilic acid, leaving only nitarsone approved. In 2015, the FDA withdrew nitarsone's approval. Arsanilic acid is still used in the laboratory, for instance in recent modification of nanoparticles. It is a reagent for the detection of nitrite in urinalysis dipsticks. Citations Anilines Arsonic acids