DISCLAIMER + [January 25, 2014: Important disclaimer added at the end of this blogpost + Important INTRODUCTION ADDED to differentiate between different types of doses more clearly. Please also note: this is a simplification; the complete picture is more complex.]
Kyoto, Japan – Monday November 25, 2013 — Shortlink: http://wp.me/puwO9-2iY
For an expert brief synopsis of the inverse square law, see NDT Resource Center.
Understanding the inverse square law for ionizing radiation is one of the keys to see through the most commonly used deception of the nuclear industry’s propaganda machine. The other aspect, covered in the introduction, is the different types of “dose”. This blog post is mainly about equivalent and absorbed doses (see intro for differentiation). Any time pro-nuclear apologists bring up ‘X-rays’ or ‘air plane flights’, when comparing to dose rates from radioactive fallout or food contamination, intentionally or not, you’re often dealing with crafty nuclear propaganda.
The issue, when there is one (it all depends upon the reporting), boils down to the intricacies surrounding the huge differences between external and internal radiation, and that reporting on the matter is sometimes done in deceptive and misleading ways. This blogpost goes into the very superficial basics of what is deceptive about some radiation reports that “compare doses”. For debunking the specific banana-comparison nonsense spewed by nuclear insiders, see Cs-137 versus K-40 in real life.
External radiation is radiation where the emitting radiation source is outside the body, such as the radiation coming from cosmic rays, or coming from nuclear waste through the sealed waste container, or from the radioactive particles flying around in the air, with the radiation but not the particles entering the body (superficially for alpha or beta, deeply for gamma).
Internal radiation happens if those particles are inhaled and broadcast their signature radiation from within the body upon and through various tissues. The most common natural internal radiation hazard is Radon-222, a gas commonly found in many unventilated basements. The most common natural internal radiation source in food is Potassium-40.
On the latter, because Potassium-40 is included in all Potassium, the harm of its radioactivity dwarfs in comparisson to the benefits of Potassium, something that can not be said about any of the main artificial radioactive fission products (such as Cesium-134, cesium-137, Iodine-131, Iodine-131, Strontium-90, Cobalt-60, Plutonium-239, etc.), see more about that, sorry for the repetition, at Cs-137 versus K-40.
Both mere ‘activity‘ (in the units Curie or Becquerel) and ‘dose rate’ (absorbed or equivalent dose per time unit, usually in SI units like µSv/hr (microSievert per hour), gray, mrem/hr, – see my RADIATION UNITS page for more) lend themselves exceptionally well to deceive. Effective dose comparisons can be helpful, but they are often brought up to compare between absorbed/equivalent and effective doses, which is extremely deceptive in its own ways (example below).
With this introduction and its examples and dozens of additional links added, this blogpost obviously became much longer, but perhaps… if you eat the whole sandwich and sip some links, I think you may get a much better understanding of common dose deceptions, and on what they depend.
First I need to start with the basics of the different types of “dose” concepts in reporting. The science is actually very clear on the issue. (By no means do I claim to fully understand all the science involved, though. See also my DISCLAIMER, if you still haven’t yet. This overview table summarizes the gist:
- The ABSORBED DOSE is defined as the mean energy imparted by ionizing radiation to matter of mass in a finite volume. The SI unit of absorbed dose is J/kg and its special name is the Gray (Gy).
- The EQUIVALENT DOSE is defined as the absorbed dose delivered by radiation type averaged over a tissue or organ; its SI unit is J/kg too, but its special name is the sievert (Sv).
- The EFFECTIVE DOSE is defined as the summation of tissue equivalent doses, each multiplied by the appropriate tissue weighting factor, to indicate the combination of different doses to several different tissues.
- There’s also “effective dose equivalent (EDE)”, but I’ll stick to these basics.
Source: Absorbed vs. Equivalent vs. Effective Dose [http://radonc.wikidot.com/absorbed-v-equivalent-v-effective-dose]
A word on how the EFFECTIVE DOSE of radiation in Sieverts is calculated:
In the calculation of ‘the effective dose’ (in Sievert), the type of radiation (alpha, beta, gamma, & respective decay energies), the distance of the source and its subsequent variety of intensities of the radiation at different distances, the type of the tissues involved (with differing radiation weighting factors depending on the tissue type (skin, bone, etc.), etc., all get factored in. The SI unit for ‘effective dose’ is the sievert (Sv) which is one joule/kilogram (J/kg). The effective dose in radiation is a measure of the cancer risk, solely due to all the radiation types and sources to a whole organism due to ionizing radiation delivered non-uniformly to part(s) of its body, while not per se factoring in other important (complex interactivity, chemical & biological factors, the latter of which is part of why cancer risks comparisons from fallout doses with Potassium are only theory, not reality-based).
For more details, see also these resources:
- University of Maryland – Environmental Safety: “Chapter IV Radiation Protection and Laboratory Techniques” [http://www.des.umd.edu/rs/material/tmsg/rs6.html]
- Idaho State University – Nuclear Physics -Radioactivity in Nature (activity and half-lives of common radioisotopes) [http://www.physics.isu.edu/radinf/natural.htm]
- Sample records for the topic icrp dosimetric methodology from Science.gov [http://www.science.gov/topicpages/i/icrp+dosimetric+methodology.html]
- United Nations Scientific Committee on the Effects of Atomic Radiation [http://www.unscear.org/docs/reports/2013/UNSCEAR2013Report_AnnexB_Children_13-87320_Ebook_web.pdf]
- US FDA’s “What are the Radiation Risks from CT?” includes other relevant information sources.
- If that doesn’t suffice, search internet for more on radiation dosimetry, a topic that fills tons of big books (that I have no intention of reading).
The science is clear, admits its known uncertainties, and keeps evolving, fine-tuning dosimetry as findings are incorporated. Problem (sometimes) is that some scientists, government officials, amateur radiation monitoring enthusiasts and especially unquestioning reporters mix up the various ways to look at radiation (activity, absorbed dose, equivalent dose, effective dose) and simplify comparisons (examples below). Nuclear physics + statistics + epidemiomoly + biology + medicine + nutrition covers véry vast complex fields of study, and adjustments to the multidisciplinary understanding continue to be made to aspects of internal radiation dosimetry to help theoretical risk estimates better match epidemiological impact evidence, most of which is gathered over years and decades. (See examples, for instance, of changes made to carcinogenic potencies or risk coefficients for Sr-90 and other radionuclides in this March 2006 – California government – Strontium document, or this critique of the IRCP in favor of a more epidemiological modeling approach. It easily gets murky in the reporting…
Couple examples of the range of confusion-causing reporting:
– Sometimes there’s exaggerating the effects of beta radiation:
As if the beta activity’s corresponding absorbed/equivalent dose were of gamma radiation, which would imply a much more severe effective dose. (See this New York Times example of such hyping up a (beta) surface hazard into a more lethal (gamma) hazard, well-debunked by Ex-SKF, here).
– Sometimes it is technically correct, but… it’s “cherry-picked” limited information, and what it actually means, especially in the bigger long-term health picture, is omitted, for instance:
National Geographic (NGO – August 7, 2013): “[…] Drinking water at 300 becquerels per liter would be approximately equivalent to one year’s exposure to natural background radiation, or 10 to 15 chest X-rays, according to the World Health Organization”, meaning that CANCER RISK (for which “effective dose” is meant to be an assessment aid) of drinking water (for 1 year) containing “310 Bq/l Cs-134 + 650 Bq/l Cs-137” = “one year’s exposure to natural background radiation“, or “10 to 15 chest-only X-rays“.
—> Couple things that are misleading about such a correct comparison of these 3 calculated effective doses for 1 year: the analystical approach doesn’t incorporate the longer-term cumulative impact of some radionuclides getting lodged in some tissues. For other isotopes than radiocesiums, and for specific organs (Strontium-90 lodged in bones, Plutonium-239 particles stuck in lungs, Iodine-131 & 132 concentrated in the Thyroid, etc.) the analytically derived ‘effective dose’ doesn’t always match the actual (more reality-based) biological and epidemiological evidence. For instance, tissue damage from radioactive Iodine may only show up as cancers 20 years later, long after nearly all radioactivity of the Iodine decayed away. Or, to steer my questioning in the other direction, one could point out that, “no statistically relevant increase of breast breast cancer could be found for multiple exposure to diagnostic X-rays for women under age 50“, and thus claim the above-used comparison implies that all-year consumption of 960 Bq/l radioCeciums-contaminated water would have the same statistically irrelevant effect.
And yet, it is well-known that at low doses, such as from normal average background radiation, our cells repair the damage rapidly. At higher doses, the cells might not be able to repair the damage, and the cells may either be changed permanently or die. Most cells that die are of little consequence, the body can just replace them. Cells changed permanently may go on to produce abnormal cells when they divide. In the right circumstance, these cells may become cancerous. This is the origin of our increased risk in cancer, as a result of radiation exposure. [Idaho State Univ.]. Thus the comparison to “just an extra background radiation added” is a deceptive use of dose comparisons, albeit seemingly only slightly so. Until we look at what fairly harmless “background radiation”, which in the US is estimated to add up to about “6200 microsieverts /year, (overall effective dose)”, actually means: If all of Tokyo (35 million people) drank such water, it would kill at least 6,000 people per year from cancers alone:
To pick something from “background radiation doses”, take just the effects of Radon gas, which comprises not even half of averaged-out “natural background radiation effective dose”, has been attributed for the cause of 21,000 annual lung cancer deaths in the US (just caused by that aspect of natural background alone – see US EPA Citizens Guide to Radon], which, for a US total population of 314 million is 6.6878 lung cancer deaths per 100,000 inhabitants. In other words, since “radon & thoron (background)” account for 37% [US EPA, Radiation: Facts, Risks and Realities], 100% of adding 1 additional “background radiation effective dose” to the existing background implies a quasi-certainty of killing (at the very least) 18 people per 100,000 inhabitants and causing an untold number of non-lethal cancers and unknown other health afflictions and complications. Morale of the story: don’t drink the groundwater near the Fukushima Daiichi nuclear power plant.
FYI: That was 2011, the 2011 groundwater contamination of 310 Bq/l Cs-134 + 650 Bq/l Cs-137 since increased to 750,000,000Bq/l Cs-134 + 1,600,000,000 Bq/l Cs-137 in July 2013. (They’re not suggesting you could practically drink it for a year anymore and be fine, “statistically speaking”, so now they’re back to comparing tiny doses of trace amounts in fish to bananas…). Anyways, that was an example of CORRECT dose comparisons.
– The most common misreporting usually comes in a variation of presenting some absorbed/equivalent dose (such as from geiger Counter measurements, often in picoCurie or microSievert per hour, or in “Counts per Minute (CPM)”, showing an absorbed or equivalent dose at the distance from external radiation sources, which is often a very complex mixture of absorbed/equivalent doses from external sources), with a variety of equivalent and/or effective doses, both from external, internal and well-calculated total effective doses. To make it even less clear to some readers, on top of that, the comparisons often mix doses that are “per exposure” with “annual” doses and dose rates in “per hour”). Classic example:
Take this piece of nuclear deception crap from PBS, “How much radiation is too much? A handy guide” (By Brianna Lee, March 22, 2011), which includes a commonly seen dose comparison overview table, supposed to put highly contaminated areas in the fallout zone of the Fukushima-Daiichi nuclear disaster region “in perspective”… (click on above article link to see the whole bs guide). I added some comments to a small selection of it:
PBS‘s own commentary is also packed with common nuclear deceptions. To pick just two more examples that stood out right away, in the text after the chart:
“A person living within 50 miles of a nuclear power plant absorbs 0.09 microsieverts of radiation per year, which is less than the amount absorbed by eating a banana.”
–> Nuclear power plant emissions include Tritium, and trace amounts of Cesium-137, Strontium-90, etc. Clues about the ACTUAL likely effect of living near a non-leaking normal nuclear power plant is hinted at in studies such as, “Childhood leukemia around French nuclear power plants – the Geocap study, 2002-2007.” and “Childhood Leukemia in Germany: Cluster Identified near Nuclear Power Plant” (After which of course government studies were done that found “no such evidence”…). More obviously exposing this particular deception is how the nuclear banana psycho-babble, contrasts with the net effect of an average 4.7 g of Potassium per day in your diet is ACTUALLY better health and less cancer.
“spending a day in a town near the Fukushima plant will expose a person to an extra 3.5 microsieverts of radiation – slightly less than that of a dental X-ray.”
—> 3.5 µSv/day = 0.1458 µSv/hr = absorbed/equivalent external radiation dose at the point of measurement, in this case in a context that includes wading through a fallout dust cloud that at that time contained considerable Iodine-131 and radioCesiums (deposition in the area was over 1,000,000 Bq/m^2 for each, near Fukushima City in March 2011, hazardous levels that were in fact designated ‘mandatory evacuation’ areas (!) near Chernobyl, Ukraine in 1986). Sure, “objectively”, utterly removed from an acutely relevant context, yes, a purely theoretical context-omitted “0.1458 µSv/hr equivalent dose” is very low as an equivalent dose, something one can incur from various natural external sources, including some x-rays, with negligible adverse health effects; that’s true. Yet merely stating some absorbed/equivalent dose (a la a Geiger Counter measurement) in a highly contaminated area, while not even mentioning the situational context, which comes with cumulative long-term health risks from sustained internal exposure to a large variety of manmade radionuclides (through both inhalation of contaminated air and through ingestion of contaminated food), is highly deceptive.
And the risks are known to be significantly higher for children as well. (See also Reuters, Oct 25, 2013, excerpt: “Children were found to be more sensitive than adults for the development of 25 percent of tumor types including leukemia, and thyroid, brain and breast cancer […] “The risk can be significantly higher, depending on circumstances,” the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) added in a statement.“)
Such comparisons of a simple absorbed/equivalent dose rate with an effective X-ray dose of only 1.0 µSv per exposure, while ignoring the hazardous fallout context one is actually referring to is, is an example of “dose deception.” (It is an aspect embedded in this particular type of deception that is further explained in the rest of this blogpost.)
The experts know the dose-type differences very well, which hints at either “nuclear experts” maybe not being what they claim to be, or the deception being intentional. (See also the book (free download), “The Primer in the Art of Deception: The Cult of Nuclearists, Uranium Weapons and Fraudulent Science.” by Paul Zimmerman.
NOTE: I mix up “absorbed” and “equivalent” doses myself sometimes, but when speaking about measured external doses for human beings, there’s no quantitative difference (both in Joule per kilogram, yet expressed as either Gray or Sievert). See more also on my Radiation Units & Conversions page. An “Absorbed Dose” is quantitatively the same as its “Equivalent Dose” when one is dealing with the same type of purely external radiation and for their impact on matter (human tissue), and AS SUCH absorbed dose and equivalent dose can be easily confused without actually causing problems. Geiger counters provide equivalent doses for external radiation on humans. Technically, ‘Effective Doses’ are the best to compare, but to calculate them many factors need to be known that aren’t always known.
Thus, to refer to the title of this blogpost, to say that 0.20 µSv/hr (from fallout) can be far more dangerous than 2.00 µSv/hr (from cosmic rays) would be incorrect IF, and only if, the comparison was between two doses of the same type.
As the examples have illustrated, what is actually ridiculous is comparing one type of “a dose” or dose rate (a Geiger Counter measurement is the perfect example), showing just an absorbed or equivalent dose, often stated as a dose rate (per hour usually)… with a very different type of “a dose“, not meaning an absorbed or equivalent dose, but an effective dose.
As such “the dose deception” I’m referring to enables pro-nuclear apologists to make people belief that some official monitor’s absorbed/equivalent dose 4 feet above extremely fallout-contaminated ground would somehow show what the actual effective dose might be for a baby born & raised in such a radioactively contaminated area. Absurd of course, but proving it would be difficult, ’cause such epidemiological data doesn’t exist (yet) (Japan’s “working on it…“), mainly ’cause generally people love their kids more than that they believe the see-through bullshit from pro-nuclear psychopaths, and flee. Anyways… (For evidence of what happens to people living in areas with a deposition of Cesium-137 @ 100,000 Bq/m^2, see this Post-Chernobyl Swedish Study)
[Jan 25, 2014 note: the rest of this blogpost was mostly left the same,
except for a few edits for increased clarity]
Disclaimer: I’m not an expert.
(Just educating myself and sharing.)
For starters, let’s have a look at a chart that mixes several different ways of getting exposed to radiation: from a distant source (radiation, but not the radiation-emitting source is moving through the body (airplane flight, CAT scan, living in a stone building, etc); an emitting radiation source is moving through the body (banana, smoking, inhaled or ingested fallout in food, water or air; radioisotope tracers for certain medical scans,…); and a combination is likely, but dose rates are a mixture of absorbed or equivalent, and some effective doses, generally for the externally received dose (time spent at nuclear contaminated zone (Chernobyl, Three Mile Island, Fukushima,…), living in some normal background radiation, etc; and possibly others, ignoring effects from inhaled or ingested fallout. I already pointed this out in 2011 (here, for example), without explaining the differences, they usually appear all combined on a chart like this:
- The INVERSE SQUARE LAW
Not limited to gravity. The below is an attempt to explain it for ionizing radiation.
I’m looking at an absorbed or equivalent dose rate, such as can be measured with a Geiger Counter: it is highly dependent on the distance from the emitting source.
Imagine a gamma radiation source in the starting point (top left, next image below); its intensity is of a certain value at a given distance (like a microsievert at a meter or yard or so): four times LESS intense at double that distance, and 9 times at 3 times, and 16 times less intense at 4 times that distance, and 25 times at 5 times… Or, moving towards the radiation source, let’s say from 10 inches to 1 inch, the radiation intensifies 100-fold.
It boils down to this: the intensity of the radiation you receive is much higher the closer you get to the emitting source, and logarithmically so, with the distance being squared in the equation. At double the distance, radiation is not half but four times as intense, and so on, as well as vice versa.
Theoretically, radiation intensity of the point at the point itself (distance = “0”, or rather an infinitely small fraction below 0) is (theoretically) infinitely intense, but the inverse square law only applies to point sources, and falls apart once the distance of measurement is
smaller than the size of the source. In any case, cells, or molecular DNA strands that come near such ionizing radiation emitting particles may sustain damage. The reason some amount of radioactive material in the environment is generally not a big deal is because, at least for normal natural background radiation (Earth surface, but not at a Uranium mine or so), our body has ways to constantly heal the constantly occurring damage.
Regarding the the most common source of internal radiation exposure, see also my (future) blogpost, Cs-137 versus K-40, which explains clearly why comparing fallout “to bananas” is utter nonsense. Some foods reportedly can help prevent radiation damage through boosting these self-healing ways, mainly by increasing anti-oxidant levels. For some suggestions on how to stay healthy in environments with elevated radioactive particle contents, see ‘What You Should Be Doing NOW to Protect Yourself from Radiation’, by Washington’ s Blog (November 10, 2013), and embedded links.
- Field example with calculations:
Let’s say we have a background radiation from primarily very distant sources (like, a combination of mainly cosmic rays bombarding the Earth from outer space), of 0.105 µSv/hr (microSievert per hour, see my Radiation Units page). (Not included in the calculation, but mentioned here for completeness: small amounts of various natural radioactive elements, such as carcinogenic Radon gas, may also contribute to a location’s natural “background radiation” dose rate.)
Now, add a package of Japanese Kelp, harvested far north of Fukushima on the Hokkaido coast; (in this example, the seaweed was bought in the city of Nara (Nara Prefecture), Japan, on November 22, 2013) up to the same measuring device, let’s say at 1 millimeter (it’s various distances, but then it gets too complicated for this purpose), and, “let’s say…”, this adds about 0.2 µSv/hr, then this new 0.305 µSv/hr is not about “3 times as bad” as the 0.105 µSv/hr. The dose may be about 3 times more, but that hides the fact that when one ingests such seaweed that some cells may get FAR more dangerous levels of (potentially harmful) radiation. Let’s see how much more… (VERY IMPORTANT added note: Although I have proven that the radiation from my Japanese seaweeds is due to exceptionally high natural and healthy potassium levels, which benefits out-do the harmful effects of the radiation from its inherent K-40 levels so much that the net result is actually cancer-fighting, something completely missed by mere dose comparisons as well. For this exercise, I assumed (erroneously, but that doesn’t change the illustration’s point) the radiation to be from man-made isotopes like Cesium-137.)
But first the reason I’m bringing this up in the first place. Watch Australia-ABC’s North Asia Correspondent Mark Willacy latest:
(Side-rant: pondering anecdotal evidence and limited statistical evidence: Related to this, consider the following: Why does child leukemia shows up in statistically relevant numbers near nuclear power plants? Most likely ’cause tiny minuscule amounts of radioactive dust’ is infrequently being released as part of routine operations. These releases are so small, however, they appear irrelevant on radiation monitors, as they can not even be differentiated from changes in cosmic rays, except in the rare case air filters in the area are lab-analyzed for radionuclides. And yet, in a couple miles radius around even “totally safe” and supposedly “not leaking” accident-free nuclear power plants, the incidence of leukemia has been found to be higher, statistically relevantly more, according to some studies. This is one of numerous examples that illustrate that the (old-school) analytical distant-source-based health effects model (ICRP), still used in the nulcear industry (in 2013 at least), is flawed.
See these studies from Germany and France (which I mentioned before, here) or the study I mentioned in my blogpost Visit to Fukushima, from the contamination effect’s seen along the Irish Sea in the UK. Now we’re dealing with radioactive particle releases that DO show up, very obviously and sometimes alarmingly, on radiation monitors. Even with a simple Geiger Counter, I was able to find ground hotspots measuring over 3.0 µSv/hr in unevacuated “nothing-happened” Iwaki, Fukushima Prefecture. They’re told that just ‘smiling’ renders radiation harmless…)
Okay, back to the calculation example to illustrate the INVERSE SQUARE LAW for ionizing radiation…
I’ll illustrate the example, see a calculation, further below.
Holding a MedCom Geiger Counter to a package of Kelp seaweed, the measurement jumped to more than double the store’s natural background gamma radiation (which ranged 0.037 µSv/hr to 0.163 µSv/hr, averaging around 0.100 µSv/hr – observed over 10 minutes of walking around). Store downtown Nara (east of Osaka, Japan), over 500 miles from Fukushima. The sale of similarly radioactive seaweed is WIDESPREAD
and appears to go unmonitored/unaddressed. (But, important notice: I had lab tests done and found out it is due to high potassium content, not due to Fukushima fallout!!!) Photo: Nara, Japan, November 22, 2013 by © Michaël Van Broekhoven, 2013.
You can easily get a much higher dose rate than 0.305 µSv/hr at higher altitude, from (distant) cosmic rays, and that would truly be nothing to worry about. That extra 0.2 µSv/hr from an absorbable/ingestable particle, however, is, in this example case, from a series of localized radioactive particles, that can make contact with the cells it passes by, or the tissue it may end up in. Depending on the particle’s decay, this can be no problem (as is the case with Potasium-40, to which the body is accustomed), or pose grave health risks, especially over a period of continued exposure (as is the case with Iodine-131, Cesium-137, Strontium-90, etc.).
There are (very complicated) formulas estimating the overall dose a body receives from such a tiny radioacive gamma-ray (or alpha or beta, or a combination thereof, depending on the radioactive isoptope) emitting source, how long how much of it is expected to remain in one’s body etc. The key piece is hidden in the explanation to the public, though: the closer to the emitting source, the more intense the radiation received right there. Calculating the overall risk (with various built-in assumptions based on observed or extrapolated likely effects of various types of radiation on tissues, etc.) to create some “dose” for the whole body, to be compared to other “doses”, from non-ingested/inhaled internal sources, simply isn’t honest as far as the actual health risks go. The examples in the introduction pointed that out already.
For the calculation example: We’re looking at Equivalent dose rates here, as measured with a Geiger Counter. Let’s say the extra 0.2 µSv/hr comes from 1 location in the seaweed, and from just 1 isotope, let’s say cesium-137 (cs-137 for short). It’s more likely to be a bit spread out throughout and a combination of isotopes, but for the point I’m making, this simplified example will do. So, example parameters: An amount (‘x’) of Cs-137 is measuring an hourly (equivalent) dose rate of 0.2 µSv/hr, at a distance 1 millimeter (0.1 cm or 0.0001 meter). I’ll use the Rad Pro Calculator included on my Radiation Units page:
This is for “in air”, so the actual radio-activity is likely slightly higher.
For future example calculations (below), I’ll round it up to “3 Bq of Cs-137” (for that part of the tested seaweed).
Given the contamination in the seaweeds is fairly consistent through the packages (when placing the Geiger Counter on different parts of the package, that is), let’s say that is per square centimeter, and a package is 10 cm by 10 cm (100 cm^2), then -if this assumption holds up – there would be some 3000 Bq of Cs-137 in such a package of seaweed, which weighs way less than a kilogram, say about 200 grams. IF SO (big if until tested in a lab), then the contamination level could be around 15,000 Bq/kg (of Cesium or combination of radioactive fission materials) Food maximum allowable level is 100 Bq for Cs-137. How much is ACTUALLY in such a package of Fukushima-contaminated seaweed? That would require lab tests.
So, the distance at which 3 Bq of Cs-137 would give a 0.2 µSv/hr dose rate is barely different than the 0.100 cm I started out with: 0.107 cm
At 1/10th of a millimeter (0.01 cm), the same 3 Bq of Cs-137 particles would measure a dose rate of 22.9 µSv/hr Screenshots from using the RadPro Calculator again:
And at a distance of a mere 1 micrometer (0.0001 cm), a distance in internal biology that could be considered “about upon contact“, the radiation dose rate (carcinogenic-potential ‘intensity’), right there, is (using this Scientific Notation To Decimal Notation Converter): 229,229.4 µSv/hr (equivalent dose at that distance).
NUANCE ADDED: The Inverse Square Law’s precise MATH is, however NOT useable to get precise quantifyable results for INTERNAL EXPOSURES. It gives an idea in principle, but due to the fact, pointed out at the beginning of this blog (and with some additional perspectives added in comments), the inverse square law only applies to point sources, and falls apart once the distance of measurement is smaller than the size of the source; as well as issues of shielding interfering with the math. !–> Therefor, these calculations are only suggestive, not to be taken for quantified precision.
So when you test food with a Geiger Counter, and you see it jump about 0.2 µSv/hr through the packaging, or a whopping 0.8 µSv/hr total from some seaweed sold in Iwaki, Fukushima Prefecture, you can’t actually honestly compare that to an X-ray (50 µSv/each or an airplane flight. In the case of those, the emitting source is distant, meaning there aren’t any cell walls or DNA that get far higher radiation levels than the Geiger Counter measurement suggests, bound to do cell damage, depending on the type of particle. Our bodies can repair much, but when the levels get too high all too often, as they are in fallout zones, it’s not surprising to see negative health effects already showing up. And if one were to compare the equivalent dose shown by a Geiger Counter with the equivalt dose of eating
IF the 0.8µSv/hr-measuring Kelp translates to “a local food-hotspot” of about 10 Bq of Cs-137, then that same 10 Bq would measure hundreds to many thousands of times more at just a micrometer distance. The concentration of the radioactive contamination could be well over 1000 Bq/kg. (NOTE: in case of the seaweeds I had tested, the radiation source turned out to be relatively harmless potassium, at thousands of Bq/kg, see Lab Results Summary; If the cause would have been from cesium and strontium, the example used would not have been fit for consumption.)
Our bodies are amazing that we can handle thousands of tiny radioactive particles flowing through us with very little health effects, constantly repairing damages. When we add a whole bunch of manmade radioactive fallout to our system, however… it gets harder and harder to keep up with the harm this does. Some estimates put the effects of Chernobyl at nearly a million premature deaths, mainly by cancers.
SUMMARY: Speaking in terms of equivalent doses, the radiation dose right by the radioactive particle(s), practically ‘on contact’, at 1 micrometer, would be a million times higher than at 1 millimeter. Thát is one of the main reasons fallout is WAY more dangerous than radiation from distant sources, like cosmic rays received in airplanes.
In addition, my impression (and at this point this is merely a suspicion) is that he long-term cumulative effect of ingested or inhaled fallout of a mixture of various manmade radionuclides is being downplayed in the modeling that underpin the effective dose calculation.
The conclusion is that nuclear accident reporting, with its typical comparisons of various types of doses, as found throughout the news media is often packed with nuclear industry deceptions. Reporters ought to use more discernment and expose the nuclear industry tricks instead of parroting its vileness.
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Jan. 8, 2014: Important disclaimer: The seaweed shown may be slightly radioactive due to naturally occurring radioisotopes. I have sent samples of similarly radioactive seaweeds to a lab for analysis to determine if the elevated levels are natural or from contamination. !–> Jan 20, 2014: It was almost entirely from natural and healthy high Potassium content. !!!–> See my own Lab data of “radioactive food” bought in Japan: not what I expected: Summary @ http://wp.me/puwO9-2rz