A study by researchers at Stanford suggests that additional cancer-related deaths from radioactive materials released in last year’s accident at the Fukushima Daiichi plant could be as low as 15 cases and as high as 1,300 — a range that highlights the uncertainties associated with any attempts to predict the disaster’s health effects. Among the factors complicating an assessment: the government’s estimates of how much radioactive material leaked from the plant could change again. An earlier World Health Organization study said the amount of radiation exposure fell below what it said were cancer-causing levels. The latest study was conducted by the meteorologist John E. Ten Hoeve and the environmental engineering professor Mark Z. Jacobson, who said that deaths might have been higher if winds had not blown most of the radioactive material out to sea. The study’s best estimate was that the disaster would cause 130 additional cancer deaths among the public, almost all in Japan.