Radioactive Fish?

We’ve all heard at one point or another about the risk of radioactive fish coming from Fukushima. I’m here to tell you not to be concerned. Seriously. Don’t worry.

Immediately after Fukushima, there were high levels of radiation detected in the immediate area but thanks to ocean currents, most of that radiation has been dispersed. If that sounds scary, it really shouldn’t. Think about labels that warn you that you shouldn’t do something in a poorly ventilated area. Carbon monoxide can be a deadly issue in a closed garage but it isn’t really if the garage is left open and air can flow out. The carbon monoxide that you let out of your garage isn’t going to kill your neighbor because it’s been dispersed by air currents and spread so thinly it’s not much of a risk to anyone.

Radiation in the ocean is much like opening the car garage. The area right next to your exhaust is probably not the best place to be but it shouldn’t cause any problems if you’re outside the garage door. Additionally, the half life of some of the elements is quite short. Iodine-131 has a half life of just 8 days.

One of the big radiation concerns was and still is the seafood in the area. Some fish, referred to as pelagic species, roam the open ocean and can travel across oceans. Tuna made the news when samples of tuna caught off southern California were found to contain radioactivity traceable to Fukushima. Scientists were excited about this – not because of concern about the radioactivity – but because the radioactivity demonstrated that bluefin tuna do routinely travel all the way across the Pacific Ocean. The amounts the fish carried were minuscule — far less, ounce for ounce, than the amount of naturally occurring radiation occurring in a banana— but enough for scientists to gain insight into animal migration.

Additionally, a study done by Oregon State University revealed traces of cesium in albacore tuna. However, “a year of eating albacore with these cesium traces is about the same dose of radiation as you get from spending 23 seconds in a stuffy basement from radon gas, or sleeping next to your spouse for 40 nights from the natural potassium-40 in their body," said Delvan Neville, a graduate research assistant in the Department of Nuclear Engineering and Radiation Health Physics at Oregon State University “It’s just not much at all.”

If you’re still concerned, know this: As of March 10, 2014, FDA has tested 1,345 import and domestic samples specifically to monitor for Fukushima contamination. Two hundred and twenty-five of these were seafood or seafood products.  Of the 1,345 samples, two were found to contain detectable levels of Cesium, but the levels were well below the established Derived Intervention Level (DIL) and posed no public health concern. 

Atmospheric Radiation Release from Fukushima

This post is in honor of the men and women that served on the USS Ronald Reagan in 2011 when Fukushima occurred. These men risked their lives and they’ve experienced the effects of large atmospheric releases first hand.

I figure we’ve all heard about Fukushima and the general events that happened there. What I’m specifically talking about is the atmospheric releases from the event.

First I’d like to start by sharing the image below with you.

I don’t know if you have all seen it but I personally seen it 100 times (not really I’m exaggerating) in connection with radiation released from Fukushima-Daiichi. I’m going to teach you a quick trick for checking how much images actually have to do with radiation, check the scale. The scale for this graph is in centimeters. What do centimeters have to do with radiation release? In this case, absolutely nothing! Especially because this is a map of how wave height was affected by the Tsunami.

This image is a much more accurate representation of the plume, or radiation cloud, that left Fukushima after their nuclear accident. And before you go getting scared on me, the radiation levels “reaching” the US are below 0.01 Bq/m^3. If you remember our conversation about Radon, anything below 4 pCi/L is totally fine. 4pCi/L translates to about 150 Bq/m^3 (which when you compare it with the dose from Fukushima makes the Fukushima dose basically insignificant). So basically you should still be more worried about what’s already in your home.

However, the crew of the USS Ronald Reagan was called in to assist Japan after the tsunami. Unfortunately, they got fully caught up in the plume coming from Fukushima. Radiation dust was being deposited on the decks, it was in their water supply. Most of the crew got some for of radiation poisoning, which meant a lot of puking and generally being ill. It also means that their future cancer risk is way high.

TL;DR : The men and women on the USS Ronald Reagan are heroes. Radiation from Fukushima isn’t going to kill you or cause your pets to mutate even if you live in California. You can also look at this site for more information. You should probably still consider a radon test (they’re only like $10 anyway). 

Regulating Atmospheric Emissions

On Wednesday, we talked about radiation protection standards and how much a nuclear site, whether medical or power producing, is allowed to release to the public. I emphasize the term nuclear plant because the reality is, if you’re not working with explicitly radioactive material, like those regulated by the Nuclear Regulatory Commission (NRC), the rules don’t really apply to you.

In theory, this makes sense. Why regulate if there’s no danger right? Wrong! The truth of the matter is that not just controlled materials produce radiation and without proper oversight, there are big industries that release radiation without ever being controlled. For example, fly ash, a product of coal fire plants, carries into the environment about 100 times as much radiation than a nuclear plant. If this sounds like an ad hominem argument, I don’t mean it to (well, maybe a little).

In fact what I mean to say is that the nuclear sector is thoroughly regulated, to the extent that two inspectors for the NRC are located at each power plant. Every move made at a nuclear plant has includes an insane amount of preparation. And more importantly, our operators are most definitely NOT Homer Simpson. Most plants even require a bachelor’s degree for operators, and that’s before the two to three years of training that precede actually being able to touch something.

Radiation releases are an important thing and preventing them, along with other releases to the public, is a big deal. Or maybe more industries should be as regulated as we are. That would prevent things like this plant in Texas that didn’t even have fire codes.

Radiation Protection Standards

At the start of the twentieth century it became clear that standards would have to be set in order to protect workers and patients from the negative effects of exposure to radiation. First attempts at protecting people created the concept of tolerable doses.  Tolerable doses are those below which no immediate effects occur. Though at first it seemed to do enough, in 1948 the National Council on Radiation Protection (NCRP) introduced permissible doses. These doses differed from tolerable doses in that they were not expected to cause harm during a person’s lifetime and not just the days following initial exposure.

Today, we understand that low-level radiation exposure can lead to stochastic effects, or effects that though they may be predicted statistically, occur spontaneously. Due to these stochastic effects, modern radiation standards are based on probabilistic assessments of radiation effects.

These modern standards are based on the idea that a high standard of safety for a work environment means that no more that 100 per million workers die in a year. To put it in perspective, in a workforce of 100 people, 1 person would die every 100 years. But, this was not considered safe enough so an acceptable risk of 50 deaths per million workers per year. This translates to 1 person every 200 years in a 100-person workforce.

After this definition of “safe” was set, statisticians did a whole bunch of math (that was overly safe and assumed people worked in the industry for 40 years and radiation effects built up and 10 percent of people would reach maximum dosage and blah blah blah) ultimately deciding that a “safe” whole-body dose-equivalent limit for stochastic effects was set for workers was set at 5 rem per year. Then, they released this limit to the industry, and the industry more or less uniformly decided that in order to stay super safe, they would use a limit far below that, and most companies set their own limit at 1 rem per year. The NCRP also calculated the dose limit to the individual members of the public, 0.5 rem per year. Once again, the industry set a standard below this to prevent crossing that line.

Again, these limits were set for stochastic effects so what they’re preventing is lifetime risk not just immediate harm. I guess what I’m saying is, the exposure limits are there to keep people super safe.

Radon: the thing you weren't looking for

One of the recognized naturally occurring radiation hazards to humans is radon. Radon is a radioactive gas that is released into the atmosphere from rocks, soils, and building materials.

The release of radon from rocks and soil is highly variable. Rain, snow, and freezing lower the rate at which radon is release. Decreased barometric pressure and increased wind speeds cause the rate of release for radon to increase. Despite the the high concentration of radon near mines, indoor concentrations of radon can prove a much higher issue. Radon can be released from building materials and unvented natural gas and can seep in from cracks in foundations and unventilated crawl spaces. Overall geographic variations contribute more to radon concentrations than other factors, meaning that it's a bigger concern if you live in a part of the country with a higher radon concentration than if your crawl space is unventilated.

Though radon is the cause of concern, it's only a minor hazard. The principle hazard is the short lived daughter particles created when radon undergoes radioactive decay. Radon's daughter particles are retained in the respiratory system tissues when inhaled. This retention means that as the daughter particles undergo their own radioactive decay, they release radiation into the surrounding tissue. The localized deposition of radiation leads to an increased risk of lung cancer. 

The expected increase in lifetime lung cancer risk varies with age at first exposure and number of years exposed. Smoking, however, increases the risk of radon induced lung cancer by a factor of ten. According to the National Academy of Sciences, the mean increase in radiogenic cancer risk for a non-smoker is 1.6% for men and 0.88% for women. For smokers, the increased risk is 16% for men and 8.1% for women. It can be postulated that this is due to the presence of radioactive particles in cigarettes which would increase of radiation deposition in the lungs.

If you're starting to worry, don't. The EPA only recommends action be taken when equilibrium concentrations for radon in a home exceed 4 pCi/L. Methods for remediation range from sealing cracks, increasing ventilation, and covering earth spaces to elaborate sub-foundation suction techniques. The recommendations of this writer are don't panic, find out whether you live in a radon rich area and consider installing radon detectors in your home like you would carbon monoxide detectors. And maybe, consider not smoking (those things are more likely to kill you than radon).

Why the Way We Calculate Cancer Risk Due to Radiation Makes No Sense

A large amount of evidence confirms that ionizing radiation (such as UV radiation, X-rays, and charged atomic particles), when delivered in high doses, increase the cancer risk in humans. Though radiation induced cancer looks no different than regular cancer, the connection is determined by the statistically higher cancer rates observed from people exposed to radiation than the expected natural occurrence for cancer. Though scientists have determined that high levels of radiation exposure and cancer are connected, they don’t fully understand how the two are connected, especially since cancer appears years after the initial exposure.

The way we calculate cancer risk due to low doses of radiation is perhaps more confusing than the odd but clear connection between high doses and cancer. Our knowledge about radiation-induced cancer is based mostly on studies from people who have received large doses, such as survivors of the attacks on Hiroshima and Nagasaki. However, these attacks released large neutron doses. Because neutrons have a large linear energy transfer (LET), they are relatively large in the scheme of ionizing radiation. Most of the radiation the average person is exposed to is low doses of low LET radiation. 

The lack of data about how low level doses affect cancer risk means that scientists calculate the risk from the high doses. This is like saying “if use a crane to drop a car on a house, we can determine how many tiles we’ll knock off if we place a tricycle on a different house”. If this sounds like it doesn’t really correlate, it’s because it doesn’t. This is referred to as the Linear No-Threshold Relationship (LNT). LNT states that any amount of radiation is bad. However, studies have shown that the absence of radiation is detrimental to organisms. This is especially significant when you consider the concept of radiation hormesis, which states that low levels of radiation, just above background levels, might be beneficial and help to stimulate the activation of mechanisms that help repair DNA.

Overall, though we can predict cancer for high level doses, the calculation of radiation-induced cancer risk are inefficient for low level doses. Until we determine better methods, it’s better to be safe than sorry.