The radioactive fallout from Japan’s Fukushima nuclear plant accident has spread as far as California waters, according to scientists from the University of California, Berkeley.

But although the level of radioactivity in the water was higher than normal, they said, it was still very low and not harmful to humans.

“The levels of fallout we have observed in San Francisco Bay area rain water pose[d] no health risk to the public,” wrote the study authors, led by Eric B. Norman of UC Berkeley’s Department of Nuclear Engineering.

The March earthquake and tsunami that rocked Japan compromised the nuclear plant, causing radioactive material to run into the surrounding waters.  Researchers subsequently found some of that same material in rainwater collected from the San Francisco Bay area. 

Samples gathered between March 16 and March 26 showed abnormally high levels of radioactive elements.   The levels were highest in samples collected on March 24, but after that the levels returned to normal.

“The levels in the rain water went down very quickly,” said Dr. Nagy Elsayyad, assistant professor of radiation oncology at the University of Miami’s Miller School of Medicine.  “Even the water with the highest levels would be safe. It’s impossible to ingest the amount of water it would take for the radioactivity to be harmful.” 

Additionally, he said, people don’t generally drink rain water.

Scientists also found radioactive material in samples of weeds, vegetables and milk sold in the area, but those levels were also very low.

While people have no reason to fear these findings, Elsayyad understands why people worry when they hear about elevated levels of radiation.   The health effects of being exposed to radiation can be very serious, and include organ damage and cancer. 

“It’s deeply ingrained in our culture that radiation is harmful,” he said.  ”I wouldn’t blame people for being worried, but it’s important to make it clear that these results show the water is safe.”