Benjamin H. Kean, 81, tropical disease expert who reportedly advised President Jimmy Carter that the deposed Shah of Iran required medical treatment in New York. Carter’s decision to let the shah enter the United States in 1979 led to the storming of the U.S. Embassy in Tehran and the taking of 50 hostages by Muslim extremists. Kean flew to Mexico to examine the shah, but denied reports in the journal Science that he had said the shah was near death and must be permitted to go to New York. Kean sued Science for libel, and the journal stated in a settlement that he had acted professionally and ethically. Kean gained fame when he helped identify the E. coli bacteria as the cause of turista or traveler’s diarrhea in a study of American students visiting Mexico. On Friday in New York of cancer.