Radioactive iodine was first found in kelp off Santa Cruz in April of last year, a month after a massive earthquake and tsunami led to the Japanese nuclear reactor meltdown.
Scientists say the radiation didn't last very long and didn't appear to affect the kelp, but they're not sure what effect, if any, it had on fish that eat kelp. They say it's definitely not harmful to humans.
The study is published online in the journal "Environmental Science and Technology."
