The Grade'A' Pasteurized Milk Ordinance (1965 Recommendations of the United States Public Health Service) requires that 'Samples shall be analyzed at an official or appropriate officially designated laboratory.' An official laboratory is a biological, chemical, or physical laboratory which is under the direct supervision of the State or a local health authority. An officially designated laboratory is a commercial laboratory authorized to do official work by the supervising agency, or a milk industry laboratory officially designated by the supervising agency for the examination of producer samples of Grade A raw milk for pasteurization. The state central milk loboratories listed have been certified by milk laboratory survey officials of the Public Health Service. The official, commercial, and dairy industry laboratories identified have been approved by a milk laboratory survey official of their state as being in substantial compliance with standard methods as evidenced by a survey at least biennially and acceptable analysis of split samples of milk sent by the state to each laboratory every 6 months.