Radioactive elements from Japan’s Fukushima disaster were found in the ocean on the U.S. Pacific coast last week. Alarmist fringe sites were quick to herald everything up to an alleged collapse of the Pacific fishery as the result of this four-year, trans-ocean trek.

But Ken Buesseler, a senior scientist specializing in marine chemistry and geochemistry who has been tracking the radiation since the earthquake, says there isn’t much to worry about. At least for now.

Buesseler, who earned his Ph.D. studying the fallout of the A-Bomb tests from the ’60s, is no stranger to digging through radioactive data.

“I really didn’t expect the U.S. to have a strong response—[at least not] the public,” he explains from his office at the Woods Hole Oceanographic Institute. “Initially, yes. There was a right to be concerned those first few months. But about a year and a half ago, we saw more and more calls of people asking about swimming in Santa Cruz, and should they move their homes to be safe, because they had seen visually the debris show up.”

While the debris started showing up a while ago, the stuff that had the potential to be really sinister, such as radioactive element cesium-137, which was found last week off the coast of British Columbia, is just now arriving. The ocean around Fukushima was originally contaminated with 50 million times the normal amount of cesium-137. Yet when Buesseler arrived at the site with his research team two months after the initial meltdown, he found the ocean had diluted it to just 100,000 times the normal amount. While exposure to high concentrations of cesium-137 can increase cancer risks and even cause burns or death, it’s a number that sounds scarier than it actually is.

“At that point, it was certainly safe to be there,” he says, smiling slightly through a red beard that shows signs of graying. “You could swim in those waters, but you probably don’t want to eat the fish.”

The half-life, or amount of time for half of the radioactive element to decay, for cesium-137 is 30 years.

“That’s a long time,” Buesseler admits. “So you take a contaminated tuna, put it in a can, and it takes 30 years for half of that cesium to decay away per natural processes.”

Luckily, cesium is an electrolyte, and is water-soluble. Thus it moves through living organisms relatively quickly.

“It doesn’t have a target organ that it goes to, it just flushes through like a salt. So the good thing is one of the more serious contaminants for the ocean is lost quickly when it gets into the food chain.”

Unfortunately, it’s not all good news. “The bad news is, the Japanese found, through their own monitoring data, cesium levels weren’t going down in fish. That means they’re getting a source–they’re getting fed more cesium. There are still leaks at the site.”

There are millions and millions of gallons of contaminated water to be dealt with at the Fukushima site, a cleanup project that will take both decades and billions of dollars.

“There are 300 tons coming out a day of [contaminated] water,” Buesseler explains. “Well, that’s still not big compared to what happened four years ago. It’s maintaining levels that are high enough to keep fisheries closed, but I can go there and swim. People can surf in that area.”

And, even though it’s still gushing into the ocean in Japan, by the time that cesium-137 arrives on our own American shores Buesseler says it’s nothing to worry about.

“There are lower amounts of cesium the further you get from the source. Think about dropping dye into a bathtub. Eventually you don’t see it anymore.”

But just because you can’t see it, doesn’t mean it’s not there. Luckily, Buesseler can detect even the faintest trace of the element. It’s an expensive test, however, and there is no government support, or federal agency dedicated to doing their own monitoring.

So Buesseler decided to take the funding for sampling and testing to the people who were concerned. He set up ourradioactiveocean.org, a site dedicated to crowdfunding each analysis and a central point to display his findings.

“It’s not the best science plan, because we have a lot of people in LA and Vancouver who can afford to do it,” he admits. “It’s not a systematic sampling, but at these low levels you shouldn’t be worried about living along the coastline. Yet we can learn something scientifically from when these isotopes arrive across the ocean, and you engage people by having them taking their own samples.”

This hands-on experience gives even amateur scientists a sense of ownership in the process, and makes what can seem an arcane—and alarming—science that much more accessible.

“They want to know their results. As soon as we get them, it’s up online,“ says Buesseler. “It’s not published in a peer-reviewed paper six years later that no one even reads. We put it up, and talk about it.”

So, despite any alarmist talk, you don’t have to immediately pack up your house in California and make for the Midwest on account of radiation poisoning. But, where cesium-137 isn’t a current threat, there is another dark horse that has Buesseler more concerned.

“My latest concern is shifting, as the exposure for cesium has gone done 10,000 times, but it has stayed pretty constant for strontium-90.”

Strontium-90 is a byproduct of nuclear fission and behaves more like calcium than salt, embedding itself in bones, and can take two years rather than two months to pass through the body. While strontium isn’t currently heavily present in the ocean, there are thousands of tons of it in the contamination in the tanks at Fukushima, and it’s very, very hard to clean up.

“150 million gallons have been collected in tanks, and it’s all very, very high in strontium-90,” he says. “There’s a hundred times more in the tanks than was ever released. It’s more dangerous and there’s more of it there.”

For their part, the Japanese cleanup teams are working at containing it.

“They’re trying to clean it up,” Buesseler says, a little doubtful. “They have every intention of cleaning it up, but they haven’t proven they can do it on this scale. I can do it in the lab on a five-gallon scale. They’ve got to process 300 tons per day, and 150 million already collected. That will take a long time.”

And “any sort of new earthquakes or disasters,” Buesseler thinks, could spell trouble.

Here’s another thing that has him worried, and it’s not a chemical compound—it’s the lack of any government oversight whatsoever.

“The U.S. government has failed us because they don’t analyze ocean waters for radioactivity,” he says. “Once it gets salty, the ground water gets to the ocean, they don’t study it anymore. The EPA studies our drinking water and the air we breathe, but not ocean water. So I’m for crowdfunding because there’s no one to go to. It’s crazy. It’s in the U.S. national interest to have these types of measurements, and I’ve told them, but no agency is stepping up to the plate.”

Buesseler thinks he knows the answer: the Department of Energy.

“The Department of Energy used to study the fate of weapons testing fallout in the ocean. They still have responsibility for testing in the Marshall Islands. The DOE has a historical responsibility for this because they have the expertise. They have the tools to do this. They have very unique facilities. NOAA doesn’t have that. This is a DOE fit. They’ve shied away from the oceans for 20 to 30 years for political reasons.”

And for those quick to dismiss the importance of checking our oceans for radioactivity, remember this: Everything is radioactive. Everything.

“We live in a radioactive world. Some say we shouldn’t have cesium in the fish, but there’s already cesium in the fish,” he says, laughing. “How much more did Fukushima add? What other isotopes are already in the fish? Don’t worry about the cesium, because there are other things in much higher amounts.”

Other things, like polonium, a radioactive substance so lethal the KGN used it as a poison.

For now, Buesseler is just happy to have the opportunity to learn, even if that opportunity is afforded at such an unfortunate cost as Fukushima. In his line of work, studying radiation, there are very few positive situations that lend themselves to this level of research.

“Isotope variations can track things like Chernobyl and weapon testing,” he says. “We use these horrible disasters to see what the oceans do.”