A group of scientists say they've connected last year's Fukushima accident to an increase in visible mutations affecting butterflies. Some of those mutations resulted in dented eyes and stunted wings. Here's an account from the Associated Press.

Scientists have also detected small amounts of radiation from the accident in people who were near the site. How this will affect their health remains unknown. I wrote a number of stories about the accident soon after it happened in March of 2011, and learned that we have limited data on the long-term risks of radiation:

"Where the experts do not agree is on how much cancer risk people are likely to face in nearby parts of Japan. Those exposures are significantly above the natural background but below levels where science has clear-cut data on cancer risk.
Some experts state emphatically that radiation is dangerous even in small amounts. Others say that at very low doses it is harmless or even beneficial.
More relevant to Americans is the profusion of CT scans, which can deliver many times the radiation dose of conventional X-rays. Several scientists have recently begun raising alarms that excess use of scans could be causing thousands of additional cancer cases each year, though that, too, is controversial.
As of late this week, scientists had measured elevated levels of radioactive iodine and cesium in air, and, more recently, radioactive iodine in tap water as far away as Tokyo, 150 miles away. They have also detected radioactive fallout on local spinach, cabbage, broccoli, and other vegetables."

From that story I learned that most of our data on the human health effects of radiation come from long-term studies of Hiroshima survivors. Monitoring of the atomic-bomb survivors began five years after the bombs were dropped and included more than 100,000 individuals. The results: Those who were most exposed suffered an increased risk of cancer ranging from 1 percent to 10 percent.