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Radioactivity at the Grocery Store

Posted December 16, 2016 4:30 PM by lmno24

Most people shiver in fear when they hear the word radioactive. The fear of exposure, the long-term effects, the threat of a nuclear disaster, all comes to mind. To make matters worse, a new study found that avocados and bananas are both technically radioactive. But before you think eating guacamole or a smoothie will turn you into The Hulk, you should know it’s a minimal threat.

New research found that we interact with radioactivity daily, but at levels that are so minimal they likely won’t harm us. The North Carolina State University researchers said they wanted to complete the study to inform people and create a frame of reference for exposure to radiation and nuclear safety.

The radiation, measured in microgray per hour (μGy/hr), was tested using a portable gamma radiation meter and tested various fruits, vegetables, bricks and a few other items.

Avocados, for example, gave off 0.16 μGy/hr of gamma radiation – slightly less than the 0.17 μGy/hr emitted by a banana. Bricks gave off 0.15 μGy/hr, while smoke detectors (with their americium components) gave off 0.16. By way of comparison, natural uranium ore measured 1.57 μGy/hr.

By comparison, the regulatory level for workers – which is safe – is exposure to 50,000 μGy per year.

No matter where you are though, you’re likely to be exposed to low levels of radiation. In fact, our bodies give off a minimal amount too. Annually, we each receive a 40-millirem dose of radiation from our own bodies. That’s the same amount of radiation you’d be exposed to from having four chest X-rays. Your radiation dose level can go up by one or two millirem for every eight hours you spend sleeping next to a similarly radioactive person.

For reference, a rem is classified as a “large dose” of radiation, so a millirem is one one-thousandth of that. Just eating a banana or going to the dentist can increase your radiation dose level by a few millirem. Smoking cigarettes can increase it up to 16,000 millirem.

While the amounts are minimal – and seemingly harmless – this new research certainly has me looking at the produce section at the grocery store a little differently. How about you?

Sources:

http://phys.org/news/2016-10-dont-panic-avocado-radioactivestudy-eyes.html

https://news.ncsu.edu/2016/10/radioactive-avocado-2016/

http://journals.lww.com/health-physics/Abstract/2016/11003/Contributions_of_Various_Radiological_Sources_to.5.aspx

http://www.businessinsider.com/avocados-bananas-radioactive-food-2016-10

http://www.symmetrymagazine.org/article/the-particle-physics-of-you


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#1

Re: Radioactivity at the Grocery Store

12/16/2016 6:26 PM

And what better way to serve nukefruit than in a uranium-glass bowl?

Presentation is everything.

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#2

Re: Radioactivity at the Grocery Store

12/16/2016 6:43 PM

1 Gray = 1 Joule of energy absorbed in 1 kg of matter, and doesn't take into account what the absorber is and what damage the radiation causes.

1 gy = 1 m2/s2

https://en.wikipedia.org/wiki/Gray_(unit)

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#3

Re: Radioactivity at the Grocery Store

12/16/2016 8:49 PM
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#4

Re: Radioactivity at the Grocery Store

12/16/2016 11:17 PM

Sounds like you think the LNT (Linear, No Threshold) theory is valid. However, it is NOT. Tests long ago showed that LNT is not valid; in fact, low levels of radioactivity are good for us. We have lived with radioactivity (natural background, foods, etc, etc) since the beginning, and we benefit from low-level exposure.

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#7
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Re: Radioactivity at the Grocery Store

12/17/2016 10:07 PM

I think you are correct.

The LNT theory implies that there is no repair of damage due to radiation.Because there is repair of damage from radiation as well as other sources, then below some threshold the "maintenance crew" can keep up with the damage that occurs.

https://en.wikipedia.org/wiki/DNA_repair

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#14
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Re: Radioactivity at the Grocery Store

12/20/2016 2:23 PM

At least until the telomeres come unraveled....right?

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#5

Re: Radioactivity at the Grocery Store

12/17/2016 7:46 AM

This article makes me cringe at the absence of description of the measurement methodology.

What basis of measurement are they talking about? If its individual items, then if I work in a building near a brick wall having 1,000 bricks, my exposure would be 150uGy/hr (.15 x 1000) and thus 100 times natural uranium ore!!!

The poor shop staff in the fruit and veg store with 1000 avos and 2000 bananas must be copping a huge dose!

Given they are measuring gamma radiation, did they merely observe a background level of 0.16 +/1 0.01 for avocados, bananas, bricks, smoke detectors, ....... and a real reading for the uranium ore?

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#6
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Re: Radioactivity at the Grocery Store

12/17/2016 1:47 PM

Then we have the Banana Equivalent Dose or BED, directly traceable (in the U.S. at least) to the NIST Standard Banana maintained in an secure, undisclosed produce department somewhere in Washington, DC between the State Department's email servers and the FBI, though it seems a bit more apropos for Queensland to receive that honour given their agricultural propensities.

Not to be left out in the radiogenic cold, similar standards are currently under development for avos, brazil nuts, cinnamon bark, and kiwis, with NZ offering to host the latter standard in a temperature-and-humidity controlled, volcano-earthquake-and-tsunami-proof vault beneath Auckland. Christchurch also wants a piece of the action and have offered to host a completely different KED standard bearing no relationship to the first or to anything else really, but it sounded good on paper.

Where were we?

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#9
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Re: Radioactivity at the Grocery Store

12/18/2016 1:50 PM

You are right, the radiation hazard depends on inverse square of distance, the particular type of radiation (alpha, beta, gamma, neutrons, etc) and whatever shielding might be between the source and absorber. It's more complicated than just the amount of energy emitted by the radioactive material.

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#10
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Re: Radioactivity at the Grocery Store

12/18/2016 2:00 PM

Yep. It's not like the produce guy in one store is being irradiated by the competitor's produce down the road or even by the bananas on the far side of his own bin, especially where alpha radiation is concerned.

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#8

Re: Radioactivity at the Grocery Store

12/18/2016 12:32 PM

I thought all food had to be radioactive. Isn't this how the radioactive isotope 14C gets into all of our bodies for future carbon dating. (The isotope gnomes don't inject us a calibrated volume at the moment when we die.) Now certainly some foods will have more or less of some compounds, elements, isotopes, etc. depending on where it is grown and breeding. A green sweet pepper from an abandoned garden in Chernobyl will likely have more radioactive isotopes than any of my home grown Cayenne peppers. I'll let you guess which are hotter.

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#11

Re: Radioactivity at the Grocery Store

12/19/2016 3:14 AM

There's an awful lot of radioactivity in coal. So what?

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Re: Radioactivity at the Grocery Store

12/19/2016 9:52 AM

PWSlack: Yep! And it stays in the plume and the ash to be distributed in the environment. I have heard the figure 7 TONS of thorium and 5 TONS of uranium per year for a 1000 MW plant. That's just one of the reasons why I like fast nuclear reactor generating plants.

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#15
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Re: Radioactivity at the Grocery Store

12/20/2016 2:29 PM

Yes, American coals average around 1 mg/Kg coal as Uranium.

Not too many years ago, food preservation by irradiation was going to be the next big thing. Whatever happened to that? Did it only make it into MRE's?

Irradiation can preserve food better than some other means of sterilization against pathogenic organisms, molds, etc. It does not mean the food will glow in the dark, unless engineered to do so.

With 19th Century Uranium glass bowls around, who needs radioactive fruit cocktail?

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#13

Re: Radioactivity at the Grocery Store

12/19/2016 11:51 AM

Why are you worried about the fruit or veggies, just measure the granite counter top.

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