The Wyoming Department of Health and the Casper-Natrona County Health Department are warning Wyoming residents to avoid the use 0f ''spice'', or synthetic marijuana, due to potentially critical health effects. Spokeswoman Kim Deti says at least three Casper area residents who smoked or ingested "blueberry spice" in recent days have been hospitalized due to reported kidney failure. She says several other people have sought medical attention in connection with the drug's use. State  epidemiologist  Dr Tracy Murphy says the department is viewing use of the drug as "a potentially life-threatening situation".