More Radiation Stuff - Hot Particles

I touched on hot particles previously. They are still somewhat in the news with the west coast of the US testing for up to 5 hot particles per day estimated per person.

A hot particle is a microscopic bit of a radioactive substance. The size of the particle can range from a few nanometers (a billionth of a meter) to a few micrometers (millionths of a meter). An atom of Cesium-137 has a diameter of about 0.4 nanometers. So a molecule of Cesium-137 oxide or whatever it happens to react with would be a little larger. For the sake of simplicity, let's say 1 nanometer since the particle may contain a little of something else.

Then a hot particle of Cesium-137 will contain anywhere from a few hundred Cesium-137 atoms to a few hundred thousand. For simplicity, let's say 100,000.

With a half life of 30 years, there would be 50,000 decays in 30 years, around 1700 decays per year, about 5 decays per day, per hot particle. With the bad luck of inhaling all 5 hot particles per day, that would be about 1 decay per hour. So if your bad luck continues, in sixty days you would add 60 decays per hour or 1/60 Becquerel to your radiation exposure. Becquerel is defined as decays per second.

Cesium-137 is convenient since it makes up the bulk of the radiation fallout. If the Hot Particle was Plutonium-239 with a half life of 24000 years, the decays would be 30/24,000 times 1 Becquerel. Roughly of course, since the diameters are a little different, but not much.

Based on food radiation limits, about 500 Becquerel per kilogram is safe, so to add the health impact of supposedly safe food day of meals, every sixty days you add one Becquerel so in 82 years you have accumulated 500 Becquerels of radiation from hot particles if you are unlucky enough to inhale all five hot particles per day of a Cesium-137 compound for 82 years.

Update: I used CPM instead of CPS, but you should still get the idea.

Wow! That sounds pretty dangerous to me! So if you plan on living to be 240, I would be scared shitless.

During the atmospheric nuclear testing age, there were a lot of hot particles. Chernobyl produced lots of hot particles. How much health impact have those hot particles had on cancer rates? Not a whole hellava lot since most folks don't live past 80 years. Do you think maybe that the hot particle press releases might be a little sensationalized?

More Biological Decay Chain

Besides the name sucking, the Radon Biological Decay Chain (RBDC), see I changed the name from Biological Half Life because that is confusing, has potential. The comparison of decay energy probability of known Radon, which we can't avoid, to other ionizing radioisotopes should be pretty easy to understand. Converting that to counts per minute is a little tricky.

Since we are comparing energy released over time for an isotope, a Radon atom will have one or two measurable counts in the decay chain, but the future counts have to be considered for biological impact. While Radon-222 has a lag of 22.3 years in the last half of the decay chain, the Pb-210 tends to stay in the body, so there is a high likelihood that the final energy in the decay chain will have a biological impact.

Since we are comparing decay energy, we compare to the probable decay energy of the other isotope, Uranium, Cesium, whatever, and few have the total biological decay chain of Radon. Radon has four alpha decays and five beta decays while most other isotopes will have one possibly two during a human life span. The RBDC ratio considers the decay energy, but the counts should be considered since that is the most common way of determining exposure. In the previous post I use the multiplier five. With one or two Radon counts out of nine probable being countable, 4.5 would be the worst case (9/2) with 9 being the best (9/1)case. Rounding to 5 should be reasonably conservative. The two multiplier just allows for normal biological tolerance and background fluctuations.

The 2 multiplier for comparing counts is most likely to be challenged. I include it because it allows for a multitude of uncertainty without pressing reasonable probability limits. One is the biological half life of the isotope. Another the the likelihood of absorption. To make the comparison more accurate, each could be considered resulting in a more complicated evaluation. The idea of the Radon Biological Decay Chain comparison is to simplify things. For the common isotopes that are likely to be fallout from a nuclear incident, it does the job.

Since Radon is naturally occurring and the leading cause of lung cancer in non-smokers, the RBDC ratio may not be all that comforting. The reality though is that life has risks and it is the magnitude of avoidable risk that is in question. Ten times the tested Radon count for most isotopes possibly causes the same risk of natural Radon exposure, remember, this is conservative. At this level other life choices cause more risk, over eating, alcohol, driving, sex you name it, all have equal or greater risk of shortening your life.

I will continue digging, but everything I have seen so far indicates that radiation risk is overly emphasized. Next I may tackle the risks in other forms of energy.

Biological Decay Chain - Understanding Ionizing Radiation

The Biological Decay Chain may be my own personal concept, but I doubt that. The biological damage caused by ionizing radiation should be proportional to the energy released by decay in the body. Isotopes that are likely to be active in an average lifetime less cancer growth time, about five years, have a ionizing biological impact. The isotopes may also have poisonous chemical impact, like heavy metal poisoning, but damage due to decay energy when isotopes give of alpha, beta or gamma radiation, (there are other forms, but let's stick to the basics), cause the most negative health impact.

In the photo from Wikipedia above, you can see that a lot of stuff happens after Thorium-232 decays to radium-228. In this chain, once Thorium-232 decays, the entire resulting decay process takes less than eight years to complete, resulting in stable lead-208. To simplify the biological impact, assume that each alpha decay is five and each beta decay is one. This chain has a BHL of 32 or approximately 32,000 KeV. You will notice that there is a branch near the end of the chain. There is a little difference in energy depending on the path, but not much if you consider the whole chain.

I have written about Radon-222 before and its impact. Behind smoking, Radon is the main cause of lung cancer. It is naturally occurring and it is the greatest ionizing radiation risk. Radon-224 is more harmful because the time to stable lead is much shorter.

This is the Uranium-238/Radium-226 decay chain commonly called the Radium Chain. Things really start happening at Radium which is probably the reason. Starting at Radium, this chain has a BHL of 30 with alternate paths, it can increase to 32, though the time to stable is about four times longer, 22.5 years with a less likely start at Radium.

These are the two main decay chains since the Neptunium chain is considered extinct and the Uranium-235 chain start with a rare isotope. For the U-235 chain, the Radium 225 to stable lead is very close to the other more common chains.

Since Radon gas is more commonly inhaled, we can reduce the BHL radium energy by one alpha decay to give us a basic Radon BHL unit of 25 to compare to other isotopes. So the danger is greater if another isotope released more energy in a life time of say 70 years.

There is one thing that complicates things a little, Spontaneous Fission. Isotopes with an atomic weight of 230 and over have the possibility of under going fission which releases much more energy. Plutonium-240 is likely to under go fission outside of a reactor, but luckily Pu-240 is rare outside of a reactor.

Plutonium-240 is formed when Pu-239 absorbs a neutron. That is extremely improbable outside of a reactor but not impossible. Pu-239 can also spontaneous fission with little probability. The odds are pretty remote, but a spontaneous fission cannot be ruled out. Pu-240 has a half life of 6569 years and the probability of fission during a decay is 5 time 10^-8 or 1/500000000, that is a low probability which I consider negligible.

Note: For the nuclear purists, spontaneous fission is negligible as a biological factor. If you are trying to build a bomb, don't neglect it or your bomb will fizzle like North Korea's. Weapons grade Plutonium has less than 7% Pu-240 and the complex geometry of Plutonium based bombs is due to billions of Pu-240 atoms that are to expensive to remove. I may have to do a post on commercial nuclear waste and how it doesn't make good bombs.

To compare the relative dangers you have to consider two things, the energy and the probability that the energy will be released inside of the body in a normal human lifetime. The main consideration is the half life and quantity, to determine the probability of decay energy.

Plutonium-239 has a half life of about 24,000 years with one alpha decay of any significant probability since it decays to Uranium-235 with a half life of 700 million years. Since Radon WILL decay to stable in a human lifetime if ingested early in life and Pu-239 has a probability of 0.3 percent of decaying in a human lifetime (70/24,000) with 1/5 the energy (5 versus 25), Pu-239 is 0.06 percent as likely to cause biological damage as Radon.

For Strontium-90 with a half life of 29 years and two beta decays to stable Zirconium-90, compared to radon it is 2/25 or 8 percent as likely to cause biological damage.

Iodine-131 with a half life of 8 days and one beta decay to stable Xenon-131, it is also 8 percent as likely to cause biological damage as radon.

Note that in the comparisons, if the half life of the isotope is less than 70 years, average human life time, the ratio of the energy determines the comparable risk.

Just to round things off assume the comparison is ten percent instead of eight percent, then ten times more of Strontium-90 or Iodine-131 ingested than normal Radon ingested from background would give you the same cancer risk. The types of cancer would be different, Strontium-90 is likely to cause bone cancer or leukemia, Iodine-131 thyroid cancer and Radon lung cancer, but the chance of cancer would be close using the Radon BHL.

Note: Just to make this perfectly clear, ten times is on an atom to atom basis, counts is a different issue.

Plutonium-239 at 0.06 percent as likely as radon to cause harm, is barely statistically significant on an atom to atom basis. Radionuclides with half lives greater than 24,000 years would produce insignificant risk in small quantities compared to radon.

The amount of these longer lived radionuclides is then the issue. This is where the dose meters come in with a little qualification. Dose meters record what your body is exposed to not what is ingested. For this purpose ingestion would be by consumption, inhalation or direct absorption into the blood stream. Inhalation and direct absorption more directly compare. With consumption, only a percentage consumed makes it into the blood stream. Food limits then have a built in safety factor since they do not consider the percentage absorbed. Strontium-90 when consumed in food is 20 percent absorbed, Plutonium between 1 and 5 percent absorbed. Inhalation is the greatest likely danger and most directly comparable to Radon which is primarily inhaled.

Cesium-137 is a common fallout isotope with a half life of 30 years and a beta decay to stable Barium-137. There are a couple routes to stable Barium with a comparison energy of about 1.25. 1.25/25 equals 5 percent as likely as Radon at the same quantity. Cesium is more likely absorbed into the blood stream through consumption, so there is not extra safety factor.

So how well does this radon biological half life factor work? If you consider Strontium and Iodine, ten times the quantity produces equal risk, so ten times normal Radon is the cancer threshold where you would be equally likely to develop cancer. Ten times background is the prudent limit for normal safety. At this ten times limit the counts per minute or second would be roughly equal to background, so twice background would be the possible statistically significant threshold if measuring absorbed radiation.

Measuring absorbed radiation is complicated. Only some of the Radon would be measured, about a fifth because of the delay in the chain, so exposed radiation, the real counts that can be measured, would result in five times two or ten times normal background in counts to meet the threshold.

If measuring food, the normal background is approximately 100 Becquerel per kilogram. Ten times normal is 1000Bq/kg would be the implied limit by the radon BHL, which compares will with most national standards which are less than or equal to 1000 Bq/kg. For exposure limits, ten times background would be 1 Microsievert per hour in Japan or about 9 milliSieverts per year.

So the Radon biological half life standard does not change any limits, it only offers a better indication on the amounts of different radionuclides based on half life and energy required to add significant risk.

I need to double check my math, but this may give a better perspective of radiation risk than the banana dose.

For a double check, the radon decay energy to stable lead is close enough. While Radon-222 takes over 22 years to decay, the 25 is reasonable as a basic reference. To compare with another radionuclide, determine the probable decays in 70 years, that does not have to be exact. Then divide that energy (as an integer)by 25 to get a raw percentage. If the half life of the radionuclide is much greater than 70 years, divide 70 by the half life and multiply that by the probable energy in integer form divided by 25. That gives a fair conservative estimate of the relative harm of that radionuclide compared to common radon.

This may seem incorrect because of the horror stories. For example Uranium miners may have a higher cancer risk, but that is more likely due to the variety of radionuclides in the ore or pitch blend, which includes a good deal of radium. Radium alpha decays to radon so a comparison to Radium-226 with a half life of 1600 years would be (70/1600)times (30/25) yields 0.043 times 1.2 equals 0.0525 or 5.25 percent. With Radium-223, which has a very short half life, that comparison would be 30/25 or 20 percent greater chance than radon. Radium-224 would also be 20 percent greater as an estimate. Radium-228 would be 35/25 or 140 or 40 percent greater risk. Brazil nuts contain Radium-226 and are not considered a cancer risk in reasonable quantities. If they contained significant amounts of Radium-228,-224 or -223, they would be.

The decay chains with half life and energy are available online in several places. For this post I used Wikipedia Decay Chain.

As far as the ten time natural background for Cesium, Strontium and Iodine radionuclides, the ingested should be reasonably conservative. The external exposure relationship may be debatable, but should be conservative because those radionuclides are beta emitters.

Another thing that makes the Radon Biological half life comparison conservative it that Cesium-137 for example has an actual biological half life of under 120 days.

I may try and make a comparison chart, but the isotopes covered should give you an idea of how to make your own rough estimate of risk.

Name That Decay Chain!

There are a lot of studies comparing different energy sources and risk. A lot of the risk is more political than real. Popular opinion means a lot to politicians. Actual risk seems to get lost in the politics.

One comment I saw today was based on a coal versus nuclear study. A large part of the study was a pole of people living near nuclear or coal power plants. That is a big part of the decision of course, what will people vote for, but education of the real risks involve is not as big a deal as I think it should be.

A coal power plant emits a lot of stuff if not scrubbed and filtered. Then if it is scrubbed and filtered, the ash and particulates contain stuff that can be nasty. Heavy metals are a big concern, with radiation a little bit of a concern that looks to be over emphasized.

Coal contains traces of Uranium and Thorium, plus other natural radioactive isotopes. Natural isotopes are generally very long lived, but a there are a few short lived isotopes in the natural decay chains.

For some odd reason, long lived isotopes have a bad reputation. Statistically, it is the short lived ones that are nasty. The short lived are more likely to decay releasing ionizing energy. Uranium-238 has a half life of 4.5 billion years. So a few atoms of Uranium-238 are essentially stable in a biological environment. You would have to ingest a fairly large amount of Uranium-238 to have any radiation harm. It would likely be more harmful as a poisonous heavy metal than a radiation hazard. Think about it. It takes 4.5 billion years for half of the ingested amount to decay. If you ingested 4.5 billion atoms of U-238, 2.25 billion would decay in 4.5 billion years, so only 2.25 would decay per year in your body. Compare 2.25 per year to 4400 per second beta decays normal for a 160 pound (about 75 kilo)person, and that ain't a lot, even if U-238 is 60 times more harmful than K-40. Plutonium-239 is only supposed to be 100 times more harmful than potassium 40, so that makes sense.

I need to build a biological decay table to make it easier for people to compare radiation risk by isotope. Then maybe people can start focusing more on the real risks. A biological decay table would b e the probability of harmful decay energy per microgram of isotope. Then everyone could compare fallout danger to the banana dose or Brazil nut dose.

Fukushima Fallout Continues

The world is full of well intentioned people with not grasp of statistical probabilities. The Fukushima radiation fallout will continue because statistically misguided, but well intentioned people seem to have to repeat poorly contemplated probabilities. It is not just radiation, it is every part of our lives that statistics are involved that suffer.

On CCN, a well educated professor spoke on the risk of minute levels of radiation causing health problems. He could not say that there is zero probability of one or two cases in millions that MAY result because of Fukushima fallout, because there is always a CHANCE. How do you quantify the chance for the population to understand?

In the professor's case, Fukushima Iodine 131 fallout in the United States as of the first of April 2011 could cause a person on the west coast to absorb 3 to 5 decays or counts per day. Five counts per day is equivalent to 0.000058 Becquerel or counts per second. Compare that to an average background radiation of 12 counts per minute or 720 counts per second and you have a 0.000% chance of any health impact. What? Not enough decimal places? How about 0.00000806 percent chance of cancer risk over the normal background? If that percent risk frightens you, play the local lottery. Someone has to win right?

Even that estimate, 0.00000806 percent is high. It is only the percent increase in radiation. The radiation threshold is approximately 500 times normal background, with 100 times normal background showing no increase cancer risk. So the risk is verging on astronomically small. There is a chance though.

In Japan, the risks are much higher. Still, the risk is very low if the cause were anything but radiation. The 500 times normal background threshold is a conservative estimate. Studies for individual radioisotopes place limits in the range of 1000 times before there is any statistically significant (i.e. possible) chance of cancer. Those studies generally use linear no threshold (LNT) methods to determine risk. LNT in itself is overly conservative as it does not consider nonlinear factors and can confuse other risks with radiation levels. So the gray area can be 50 times greater. So being 20 pounds over weight has roughly 60 times more risk that having radiation levels 100 times normal and about 20 times the risk of radiation levels of 500 times normal. There is still a risk.

What is acceptable risk? That is the question of the millennium. There will never be zero.

For the Tokyo Radiation Levels Gang

Citizens testing radiation levels is both good and bad. It is good because more people will become familiar with the normal radiation everyone in the world lives with daily. Bad because some will jump to conclusions that may frighten others.

Setting basic standards for testing will help increase the good and decrease the bad. The various detectors that are purchased by private citizens vary greatly. The main differences between detectors will be the biological impact readings. These are generally given in MicroSieverts or Roetgens Equivalent Man (REM). Biological impact depends on the type of radio isotope, whether its radiation is internal or external, how easily the isotope is inhaled or ingest. For example, Uranium 238 is pretty common, is an alpha particle emitter and is not very harmful unless ingested or inhaled. Alpha particles have high energy, but they can be stopped by a sheet of paper, the human skin, even air restricts the distance it can travel significantly. A dose meter would assign a fairly high microSievert reading to a sample of Uranium, but really it would have virtually no biological impact.

Iodine 131 is a beta/gamma emitter with a short half life that can be very harmful, so a microsievert setting for Uranium would underestimate the biological impact. Since radio Iodine is so harmful, dose meters may be calibrated for that harm, so they would over estimate the harm of uranium. Most dose meters are calibrated for Cesium 137 as a compromise, but may have settings for other isotopes like Iodine 131. Without knowing the calibration and calculations used, the microsievert reading is nearly useless. If calibration and calculation are known, it can be invaluable for determining the potential harm of known isotopes.

For the amateur, The counts per minutes is much more useful. To get the most use, you should have a standard method for testing and recording your data. For instance a common natural radiation in the background is Radon gas. Radon has a half life of four days. It can react in rain to form compounds that are solids, so it can be rinsed out of the air and collect in drainage ditch, culverts, and soil. With a half life of only four days, a Citizen Radiation Patrol (CRP) participant can measure a level after a rain at actually determine if the radiation is due to Radon by measuring the same spot over a number of days the same way. This would be a reasonably scientific method of testing.

To make it better, record the type of meter, background level of the area, time of day, weather conditions and an average of more than one test per day of the site in question. Three five minute tests should be enough to determine a reasonable average in counts per minute or second. Recording the microsievert reading as well could provide more information on how conservative you detector is. It should be conservative, read higher, because it is a safety device. Repeating the tests in the same manner over a number of days may give you an indication of the types of radioisotopes present. Radon222 and Iodine131 should be the easiest to isolate since they have half lives of 4 and 8 days respectively. Other isotopes with longer half lives would require more complex test equipment, but the CRP can gather pretty good information if they use a standardized test method.

Food testing can also be done with reasonable accuracy, provided natural levels in food are considered. I found a couple of good references for natural radiation in foods, but to simplify, 125 Becquerel per kilogram is good average to expect. Since the average radiation detector cannot test the whole one kilogram mass, a small amount, approximate 1 gram can be tested which should produce 125/1000 (0.125)becquerel or counts per second. Since there is normal background radiation in the air, your meter may measure virtually nothing in the food sample. Then again it may show a few counts above background for perfectly normal food. A much higher reading is what to expect if the food is contaminated. Since 10 to 15 counts per minute is a typical background level, food with more than 30 counts per minute (0.5 counts per second)may be suspect, but over 60 counts per minute ( 1 counts per second)would indicate significant contamination. That does not mean the food would exceed safe limits, only that it has more than just natural radiation. It takes a very strict method to produce repeatable results. Considering the numbers and limitations, four times normal background is a good indication of other than natural radiation, anything less is a maybe.

With high quality equipment and proper test procedure, one gram of a food item with the 500 Becquerel per kilogram upper limit would measure 0.5 counts per second or 30 counts per minute. Natural radiation levels would produce about 7.5 counts per minute. With normal background which should be subtracted, 17.5 to 20 counts per minute may be perfectly normal.

With background measurement the same should apply. Twice normal background is not unusual, four time normal background is an indication of significant contamination.

Even with readings that indicate significant contamination, that does not mean unsafe conditions. Japan like most countries has areas with higher natural radiation. There are natural springs high in radiation. So there may be other areas with higher than normal background levels. This leads to a good deal of confusion. Man made radioisotopes are assumed to be more dangerous. Some are and some are not. Radon, which is a decay product of radium is the prime example.

"222Rn belongs to the radium and uranium-238 decay chain, and has a half-life of 3.8235 days. Its four first products (excluding marginal decay schemes) are very short-lived, meaning that the corresponding disintegrations are indicative of the initial radon distribution. Its decay goes through the following sequence:[20]

218Po, 3.10 minutes, alpha decaying to...
214Pb, 26.8 minutes, beta decaying to...
214Bi, 19.9 minutes, beta decaying to...
214Po, 0.1643 ms, alpha decaying to...

At the next step, 214Po decays to 210Pb, which has a much longer half-life of 22.3 years. Its progenies are:

210Bi, 5.013 days, beta decaying to...
210Po, 138.376 days, alpha decaying to...
206Pb, stable."

From Wikipedia, Radon has a 50% chance of decaying to 210Pb (unstable lead) in the sequence above in 4 days. Then alpha decays, where the atomic weight drops by 4, have an average energy of 5,000 KeV (thousand electron Volts) and the beta decays (elemental change with the same weight) release an average energy of roughly 1,000 KeV. So the total energy from 222Radon is about 8,000 KeV. From Radium the total energy would be about 13,000 KeV, (I had a typo in the Plutonium post). With a possibility of another 11,000 KeV to stable 206Pb from 214Pb with a 22.3 year half life.

Plutonium 239 for example, considered the most dangerous man made isotope, has about a 24,000 year have life and alpha decays to Uranium 235 which has a half life of 700 million years. Energy wise, radon 222 is just as harmful if not more so.

Do double check my numbers, but I think you will find radiation deserves respect but not fear. Everything I have read supports the limits imposed by different countries for safety with a few overly conservation limits that could be relaxed.

Japan's Citizen Radiation Patrol - The Geiger Counter Explosion

With all the purchases of Geiger counters and dose meters I wrote a post a while back about testing your food. It is not all that easy to take an off the shelf Geiger counter and accurately test stuff on your own. You can get an initial range or baseline to compare things, but accurate readings that can compare to another reading with another counter is difficult. There can be a wide range of counts per minute or second. The REM or Sievert readings are even more difficult to compare from one unit to another. So I recommended sticking to counts per second which is the same as Becquerels.

There are now radiation clubs posting results online. I found one group on Facebook thanks to Japan Probe. In the video, one Citizen Radiation Patrol member, measures a fairly high Sievert level in a street drain. Street drains should be higher than normal because radiation in the air can be rinsed out by rain and collect in the water run off. Remember that there is often natural Radon 222 that adds to the counts for a few days following rain.

The reading obtain is a little humorous. The little dp802i dosemeter sounds the alarm for high radiation. The Sievert reading hits 5.77 microsieverts per hour compared to the initial background reading of 0.11 Microsieverts per hour. So is this a danger signal that should be heeded?

First, isolated patches of higher levels are not uncommon. A 25% increase following rain is not uncommon, but should drop in four days if the extra radiation is due to Radon 222 washing out of the air. If you plan on living in the drain, that may be a indication that that is not a great idea.

Second, the Sievert readings on most dosemeters are very sensitive. It is after all suppose to warn you of potential danger. The counts per second readings are what the overall dose is based on, or at least that should be the plan.

In the video, the Sievert reading is in the middle of the display in the largest font. Below that is the counts in what appears to be per minute (could be counts per hour, hard to see the decimal placement). The 11.4 Counts per minute is pretty normal as I stated in my previous post.

A second video linked by the Japan Probe post shows a variety of counters or dose meters being compared when using a slightly radioactive lantern mantle or a test sample. One of those happens to be a model dp802i.



The dp802i is on the left.

In the test, you can see the Sievert reading fluctuate wildly and the counts gradually change up dating every 15 seconds or so.

The Japan Probe poster believes that the dp80i is either wildly inaccurate or requires a longer time to obtain a reliable reading. He(she) is right that it does take a longer time. As far as accuracy, the dp801i appears to be pretty good, it is just the sievert readings sensitivity is very sensitive. This is not a sign of inaccuracy, more of a safety feature. It warns of a increase, but it takes time to determine the energy which is needed to determine the actual potential harm. So I would say that the dp802i is not a bad dose meter, just that it is not the final word on radiation evaluation, which it is not designed to be.

The Tokyo Radiation Levels Facebook page is dedicated to locals learning about radiation detection. If you are interested, you can follow their efforts a learn along with them. There are and will be plenty of high sievert readings that seem scary, but once you learn that Sieverts are very inaccurate until properly calculated, you will be amused. Dose meters should read well on the high side for safety. Then the high quality equipment can be brought in to provide the needed accuracy. It is not a conspiracy, just the nature of the beast. The dp802I is on the overly sensitive side, but if you consider the counts, not too bad of an inexpensive dose meter.

Sensitivity To Radiation - Things We Find When We Look For Them

One of the fall outs of Three Mile islands was there is more radiation in our lives than we ever knew. Radiation understandably freaks people out. So when things like TMI, Chernobyl and now Fukushima happen, everyone starts checking things to see if they have anything to worry about. Nothing particularly unusual about that, it is human nature.

Since most of us don't walk around with Geiger counters most of the time, it is a little bit of a shock to see how much radiation is around us. Following TMI, abnormally high levels of Radon gas were found. They were abnormally high, because we had never really tested for them. That sparked a massive Radon testing program, mitigation programs and played hell on property values for a while. Many people were freaked out that their homes had, at the time, high levels of radiation.

In some cases the high levels were a real problem. New energy efficient homes are tighter. That means they are better insulated and had fewer drafts. Vapor barriers were installed to keep condition air in, but they kept other things in too, like radiation, mold, carbon dioxide, formaldehyde, all sorts of stuff that were always there, just not captured so well by home construction improvements before.

Thanks to energy efficient building designs, energy inefficient remedies had to be designed to protect ourselves often from ourselves. It was frustrating for me at the time because I had to test buildings and adjust systems to prevent what was called "tight building syndrome".

It was frustrating because the cures often led to more problems. There were new control devices at the time to monitor the concentrations of gases. With those, it was fairly simple to open or close air dampers (like a valve for air) to purge the bad stuff when needed and to save energy when purging was not needed. Unfortunately the control monitors were expensive, so the simplest solution was to just let the buildings breath more. That didn't fly with most building owners and architects. They wanted everything perfect in our imperfect world. So instead of installing an inexpensive attic fan or roof turbine, they wanted the air forced in and measured. Mold was a particularly bad problem. A small water leak in a tight building caused mold to grow which could not naturally dilute itself because the building was tight.

It is not surprising to me, that asthsma cases have been steadily rising since all the wonderful energy saving building designs have taken off. Anytime man tries to create a more sealed bio-verse for himself, he screws up. It is all a learning experience. Unfortunately, people die from well intentioned actions.

There are quite a few studies (I'll let you Google your pet issue), were overly protective parents have children that are more susceptible to different diseases. Common measles is one that hits the news from time to time. In the bad old days, kids caught the measles and other childhood diseases in school or daycare or on the playground, suffered through it and then were immune for the rest of their lives. Parents, wanting only the best for their kids, forced them to lead more sterile lives. Childhood vaccinations were developed, but with anything, there is always a small chance of complications. So a fairly large number of parents avoided the vaccinations, purely because they wanted only the best for their kids.

The problem is that, the viruses that caused childhood diseases still existed. There were much fewer cases, because of the vaccination programs, so some kids started getting the measles at older ages. Younger children, with their developing immune systems, are better able to develop the antibodies needed to protect them than older kids. So while there are fewer cases of childhood diseases, the cases started to have more complications.

There are a lot of things little kids do that just plain gross parents out. They eat dirt, stick every damn thing they find in their mouths, even pet poop. Well, there have been studies that have found that eating dirt may help infants and toddlers develop antibodies. I think I would do my best to stop them from tasting the cat poop, but who knows. The dirt eating thing is interesting. Dirt has all kinds of microbes. Tiny traces of bacteria and fungus are kind of like natural inoculations. Dirt even has radiation in it.

You can Google the things I have typed so far, but this is my own thought. Small amounts of radiation exposure in childhood is probably a good thing. That small amount is probably more than most would think. While there are still plenty of ongoing studies, "normal" background radiation is not really that normal. There are huge variations from place to place and diet to diet. The confounding thing in doing radiation studies is that huge variation. Overly protected children may be much more likely to have adverse reactions to radiation than the average public schooled, dirt eating toddler living in a house which by most standards does not have a floor you can eat off of. A little parenting sloth, may not be a bad thing.

Don't take my word for it, do your own research. It is in my mind better to be truly informed, than just getting your parenting education from the tube and trendy books. Still, until more research is available, try to keep them out of the cat poop.