By DAN SEWELL AP Business Writer CINCINNATI (AP) — The Procter & Gamble Co. says Susan Arnold is stepping down as president for global business units of the world's largest consumer products maker. P&G says Arnold will retire Sept. 1 after 29 years with the company. The announcement Monday said it has long been Arnold's intention to step down at age 55 — which she became on Sunday. She steps down as president effective Monday, and will report on special assignment to Chairman and CEO A.G. Lafley until retirement. Arnold has been the highest-ranking female executive at the Cincinnati-based company whose products include Tide detergent, Pampers diapers and Gillette shavers. She and Robert McDonald, chief operating officer, were promoted in 2007 in what some analysts perceived then as setting up a CEO succession.