How to interpret raw data from Gross ALPHA/BETA Test results by grass roots farmers in Northern California.

We are a family farm. We sampled our surface water and soil and had a gross alpha beta test run by FGL. Below are the results, our questions are...

What does it mean that we have 8.16 pCi/g of beta radiation in our soil?
Is this dangerous?
Does this mean that there is Fukushima landing on California?

Thanks in advance for any educated help!
Wolf Mountain Farms

Constituent Result ± Error
Gross Alpha 2.41 ± 2.58 pCi/g
Gross Beta 8.16 ± 2.58 pCi/g

Constituent Result ± Error
Gross Alpha 0.000 ± 0.919 pCi/L
Gross Beta 0.000 ± 0.919 pCi/L

Gross alpha and beta of our soil measurements

I have been able to look at the natural isotopes in our soil samples, and I thought a little of this data would help understand the gross alpha and beta measurements of the OP's and Paul's soil.

The upshot is that if we had our soil measurements tested in the same way, the range of gross alpha should be about 1–10 pCi/g and the range of gross beta about 4–22 pCi/g. The two private tests that have been posted in this thread are consistent with these ranges (actually, Paul's gross beta is lower than our samples). There is no way to tell how much if any radioactive cesium is present in soil from gross alpha or beta testing. In fact, our highest measurement of Cs-137 would add only 2.5 Bq/kg (0.07 pCi/g) to the gross beta, which is much smaller than the total gross beta. Variations in gross beta have more to do with potassium content of the soil than anything else since K-40 is by far the largest contributor to the gross beta.

Here is a list of the naturally-occurring isotopes with the strongest gamma-ray lines, along with the average values and range of values from all of our soil measurements:

IsotopeDecay chainBranching RatioAverage Activity (Bq/kg)Activity Range (Bq/kg)

Even though we don't measure every isotope in each decay chain (e.g., we cannot observe alphas), we know that those other isotopes must be present because the activities of the isotopes that we can observe agree very well with each other. This is because natural decay chains are usually in what is called secular equilibrium, which means that each isotope in the chain decays at exactly the same rate. For example, the activities of Ac-228 and Bi-212 (both in the Th-232 series) are almost exactly the same even though they aren't adjacent in the decay chain. Here's what I get when I use the previous data to calculate the equilibrium activity of each decay chain:

Decay chainAverage Activity of Chain (Bq/kg)Activity Range of Chain (Bq/kg)

Each decay chain may have a series of alpha decays. Here is what those activities are when multiplied by the number of alpha decays in the chain:

Decay chainAlpha decays in ChainAverage Alpha Activity (Bq/kg)Alpha Activity Range (Bq/kg)
Total gross alpha170 Bq/kg50–370 Bq/kg
(4.6 pCi/g)(1.4–10 pCi/g)

Likewise, each decay chain may have a series of beta decays:

Decay chainBeta decays in ChainAverage Beta Activity (Bq/kg)Beta Activity Range (Bq/kg)
Total gross beta460 Bq/kg150–830 Bq/kg
(12.4 pCi/g)(4.1–22 pCi/g)
These ranges should point out the difficulty of inferring anything from gross alpha or beta measurements. I should also reiterate that our highest measurement of Cs-137 would add only 2.5 Bq/kg (0.07 pCi/g) to the gross beta. Mark [BRAWM Team Member]

Gross alpha and beta test

I live on Long Island and I had my vegetable garden soil tested because radiation was discovered beneath the farm where I get my compost. The readings for the gardens were as follows:

Result Error LLD Units
Gross Alpha 09/12/11 12:00 4.1 1.1 0.47 pCi/g
Gross Beta 09/12/11 12:00 3.4 0.75 0.86 pCi/g

Result Error LLD Units
Gross Alpha 09/12/11 12:01 3.9 1 0.43 pCi/g
Gross Beta 09/12/11 12:01 2.9 0.78 0.85 pCi/g

These samples were take from the surface of the gardens which are box gardens 18 inches deep.

Should I be eating the vegetables?

Should I have the samples tested for more detail?

Does Long Island have background levels of radiation being a glacial sand deposit?


Nothing to worry about

Hi Paul, I just posted a calculation of the gross alpha and gross beta implied by our measurements of several soil samples. Your numbers are not abnormal — if anything, your gross beta is on the low side. The gross beta is dominated by a radioactive isotope of potassium (K-40), and the potassium content of soil can vary a large amount. Let me also just rewrite your results for easier reading:
SampleQuantityResultErrorMinimum Detectable Concentration
FrontGross Alpha4.1 pCi/g1.1 pCi/g0.47 pCi/g
FrontGross Beta3.4 pCi/g0.75 pCi/g0.86 pCi/g
BackGross Alpha3.9 pCi/g1 pCi/g0.43 pCi/g
BackGross Beta2.9 pCi/g0.78 pCi/g0.85 pCi/g
Mark [BRAWM Team Member]

Soil contamination


One more question:

Though levels of each seem to be normal, what about the combined effect? In the front garden, that would be 7.5 pCi/g of combined alpha and beta and in the back garden, 6.8 pCi/g of combined radiation?


Combined activity not very useful

Hi Paul,

The alpha and beta activities should be kept separate for at least two major reasons: (1) in general, they result from the decays of different radioactive isotopes and (2) the particles have very different effects on surrounding material (alphas stop immediately, while betas can travel a few mm or cm). Summing the two activities isn't particularly useful, and it takes away some information about the soil.

Also, the sum also falls into the combined range for natural radioactivities in our measurements: 5.5–32 pCi/g, with an average of 17 pCi/g.

I hope this helps.

Mark [BRAWM Team Member]

Nothing to worry about.

Thank you, Mark. The information you have provided is very much appreciated - a big relief.


No, that does not mean that fallout is in your soil. Here is what these data mean:

Gross Alpha 2.41 ± 2.58 pCi/g

The alpha testing that they performed yielded no detection. Their detection limits are approximately twice the error bars, or 5.16 pCi/g (or less than 191 decays per second per kilogram using the units we use in BRAWM). If there were alpha-emitting nuclides that emitted more than about 191 decays per second per kilogram of soil, then they would have found them.

Even if this had been a detection, there are actually many naturally-occurring alpha-emitting nuclides, such as Uranium-238, Thorium-232, and Radium-226, that are found in small quantities in soil.

Gross Beta 8.16 ± 2.58 pCi/g

The beta testing they performed yielded a significant detection of beta-emitting nuclides. This amounts to 302±95 beta decays per second per kilogram.

There are many naturally-occurring beta-emitting nuclides. As BC pointed out, Potassium-40 is a major one, and your measurement is within the range of typical values.

As BC also pointed out below, our soil measurements of the beta-emitting nuclides Cesium-134 and Cesium-137 total to approximately 2 decays per second per kilogram. This is both far below the detection limits of the testing that was done, and indistinguishable from Potassium-40 in a gross beta test. We can only tell the difference here at BRAWM because we perform gamma spectroscopy, in which each isotope gives out a distinct signature. So there is definitely nothing out of the ordinary here.

Do you have any idea what your soil chemistry is like? If you could give a number on the potassium content in parts-per-million or something, then I could tell you if these numbers can be explained by Potassium-40 alone. For example, potassium content of 10000±3000 parts per million by mass could account for the beta activity detected in your soil.

Mark [BRAWM Team Member]

Thanks Mark.


I understand your point and aim to get our soil composition tested.

Any Chance of the BRAWN team running our Northern California soil through there gamma spectroscopy machine?? If not , i will attempt to get the ppm Potassium-40 checked asap.

The anonymous poster below yours had some scary numbers he threw out...any chance you can confirm or deny what he/she said?
""302 Bq/kg x 1000 kg/m3 x 1 = 302,000 Bq/m2""
and saying that this is close to Chernobyl most contaminated area.

I just want to do what is best for my wife and future family, it is hard to produce food for your community if you think it might Poisson them.

Thank you so much for shedding your light on this topic!

There is no way that the

There is no way that the fallout has contaminated Northern California as much as the worst-hit areas around Chernobyl. We are measuring radioactive cesium at the rate of approximately 2 decays per second per kilogram (=2 Bq/kg), which is a tiny fraction of those Chernobyl numbers. I'm still working on the exact conversion to Bq per area, but it's tiny in comparison.

Our detector is still swamped here with samples, so we probably cannot fit yours in to our queue. However, your soil is probably very similar to the soil we tested in the Bay Area, so you can look at that to get a sense for how much fallout from Fukushima would be in your soil. It is only a tiny fraction of the natural radioactive elements in the soil (primarily potassium-40). You can also see some produce we have tested, and we give conversions for how many kilograms you would have to eat to receive a small dose.

So my advice is to relax and not worry since the levels are so small!

Mark [BRAWM Team Member]

Mark, I am looking for

I am looking for confirmation of conversion formula of Bq/kg to Bq/m2 of soil. In June you said you were "still working on the exact conversion to Bq per area". Can you recommend a reliable formula? And can you elaborate on how important the sample depth is in the calculation of bq/m2?
Thanks so much!

First of all, the gross

First of all, the gross alpha of 2.41 is below the error amount of 2.58. Usually, this is expressed in terms of a 95% confidence interval. So a level of 2.41 would yield roughly a 90% confidence of detection. You can decide for yourself whether this is a detection or not, but keep in mind that alpha-emitting radionuclides include dangerous isotopes like uranium-238 and plutonium-239.

Second, the town of Eureka, California experienced 53 times more gross beta radiation in the second half of March than the corresponding period in 2010, according to EPA Radnet air concentrations. This cannot be due to natural background radiation, and it must be due to Fukushima. Consult the natural radiation background map at . Northern California has low natural background radiation.

Your gross beta of 8.16 picocuries per gram translates into 302 becquerels per gram ( ) or 302 Bq/kg. Assuming a soil density of 1 gram per cubic centimeter ( ), or 1,000,000 g/cubic meter, and also assuming that the sample was dug to a depth of 1 meter, we can use the formula at ( ) to estimate the concentration of gross beta in square meters. This formula is:

Radioactivity (Bq/kg) x Soil density (kg/m3)x sample depth (m)
= Surface contamination (Bq/m2)

302 Bq/kg x 1000 kg/m3 x 1 = 302,000 Bq/m2

If you go to the Poland section at you will find the some of the most highly contaminated areas near Krakow after Chernobyl had levels of 360,000 Bq/m2. Now if the depth of the sample dug was 30 cm, we would have:

302 x 1000 x .3 = 90,600 Bq /m2

This is comparable to more typical areas of southern Poland. You can plug whatever multiplier corresponds to the depth of the soil sample.

The contamination of your soil is significant. You should have another analysis done, and measure the amounts of iodine, cesium, and strontium isotopes, and also plutonium if possible.

Adam - This poster is high

Adam -

This poster is high on doom. In my part of the country, they would say that they are trying to "dazzle you with Bu-shee".

I will post further, if someone smarter than me does not destroy this beforehand. Meantime, this is full of crap. Taking M3 and making it M2. Imagine, amount of sugar in a cake, and then, make it the amount in the piece of waxed paper underneath and infer that these levels are the same. While referring very bad waxed paper results,

Will contact you further tommorrow.


Wow, That seems scary.

Are you sure about the conversions? The soil was surface soil taken from 30 spots around our food production zone.

302 Bq/kg x 1000 kg/m3 x 1 = 302,000 Bq/m2 seems super scary. How could we be close to Chernobyl levels?

Any Idea where to send samples to get retested? Forum folks seem to be suspicious of the lab we used.

surface soil

If you took the sample from the top of the surface, say 5 cm, the formula would be:

302 Bq/kq x 1000 kg/m3 x .05 = 15,100 Bq/m2

Still enough to be concerned, but not Poland after Chernobyl.

Don't believe the potassium nonsense around here, this is actually straightforward.

Not scary

Hi Adam, please read my comment above. I disagree with the interpretations of that poster, and most of this is explained in my comment. The presence of naturally-occurring radioactive potassium in the soil can easily account for the beta counts. If you are in Northern California, the levels of radioactive cesium in your soil are probably very close to our soil measurements, which come to about 2 decays per second per kilogram — a very tiny amount of radioactivity.

Mark [BRAWM Team Member]

Comparission of bay area TO TRINITY County

I appreciate that Mark.

I am not sure that the bay area folk have been watching the weather as closely as we have. It has been unusually rainy spring, and just stopped a week ago. I think this might open us up for more fallout.

I am hoping that it is potassium giving us this reading. Amazing how hard it is to locate someone to test the soil with the equipment sensitive enough for our needs.

OK, thanks for the attention and knowledge!

Adam and Melissa- Please see

Adam and Melissa-

Please see my post re: Boise ID.

This place had by far the most recorded "fallout". The numbers are quite low, I mean, really low. Follow the math if you can, work it through.

Also, regarding lots of rain, rain is only a problem if there is crap in the air for it to bring down. I would wager that there has been very little of that since say 4/20. All the rain after that is washing some of it away into low spots and dispersing the stuff on the surface into the ground, which for the small amount we got is a good thing.

You might also check out the new EPA drinking water tests, all non detect, seems to indicate that there is less of this crap out there since around 4/20.

Hopefully situation holds. For now, I think we are OK by quite a margin.

Soil Testing

Hi Adam. Where'd you get your soil tested? Have you figured out what the test results mean? We run an organic vegetable farm in southern Oregon and are interested in getting our soil tested. Let me know if you got clarification and if you have resources....Thanks! -Melissa

a few things...

It's the weekend - you might get a few more of the science guys and gals with input during the week.

There is a search box in the upper right hand corner of the page, but you have to be able to find a unique keyword to use it, otherwise it will brings up a whole bunch of threads to wade through.

Sure hope that your numbers don't mean anything bad.

I reckon Mark or Tim can

I reckon Mark or Tim can help, but please clarify - the soil measurements, are they in grams of kilograms?

Big difference.

The report says the soil

The report says the soil showed 8.16 pCi/g of gross beta.

We are novice at this but have been educating ourselves as best we can.

Would 8.16 pCi/g of BETA be dangerous to grow organic vegetables in?

Could the particles emitting the radiation be kicked up and inhaled/ingested?

We really appreciate some perspective on this fallout and the work that Berkeley and the students are doing!


Waiting myself...

Hi , I am also anxiously awaiting the answer to Adam's inquiry. I live on the Central Coast of California, and I have a commercial crop of organic avocados that I want to test---along with the soil and water.

So, I am extremely interesting in everyone's private testing results!

GrassRoots testing, DIY...How to interpret.

Hello, after much searching, we found 'Fruit Growers Labs' to test our h2o and soil. We sent the samples to the...
...Santa Paula Office Phone: (805)392-2000.

Michelle, the Lab manager tried to quell my fears about having 8.1pCi/g of Beta Radiation in the top soil. The samples were taken from inside our vegi garden, @ 3000' elevation in Trinity County.

I am having a hard time assessing if it is healthy for our family to be living/working/growing food in our dirt and dust.

Should we worry?

Peace yall,



Constituent Result ± Error
Gross Alpha 2.41 ± 2.58 pCi/g
Gross Beta 8.16 ± 2.58 pCi/g"

First thing, I do not see how the margin of error can be greater than the measurement for the alpha.

Second, to put some context on the beta, to convert pCi to becquerels (the measurement BRAWM is using) just multiply .037. So 8.16 X .037 = .302 bq/gram. Multiply by a thousand to to get it in kilos and you're looking at 302bq/kg.

Okay, so if you look at BRAWMs recent topsoil measurements, the Ce-134/137 has been close to 2 bq/kg . Now that is just Ce, and I am sure that if you were to add potassium isotopes and such that number would be somewhat higher. But to me, a novice, 300bq/kilo is sounding pretty damned high. I do not mean to worry you, in fact, I'm guessing that something is screwy with these measurements.

And my disclaimer - I have learned everything I know about this in the last couple of months, and AM NOT and expert.


BC - thanks for the response.

Where did you get the conversion info for pCi/g to bq/kg?

If this number is high...why are the educated scientist speaking up about Americas food basket getting radiated?

What is the 'not to worry' amount?

Is any one on here that can give us a relative comparison on what 8.13pCi/g looks like?

Searching for answers,

The lab...hmmm....

Hi Adam,

I am the lady with the avocados (see my entry above). The lab that you used is within an easy drive of where I am and, when I asked around, it was the lab that many recommended. So, I called and spoke to the radio chemist on the staff, with the intention of using that lab.

However, her responses to my questions gave me serious pause. In fact, since I am not a scientist, but having learned the little that I did know from this site, I actually asked the BRAWN team to comment, without naming the lab, as a "sanity check." Their response convinced me that I should indeed find a different lab.

(I just tried going back to find my questions and their responses--but, so much to wade through now! But, if I find it, I will identify the topic for you.)

So, although I feel awkward naming names, I just had to pass this along since it appears that the test results that you were given should, at the very least, be confirmed by a second lab. Which, all in all, is likely a good idea in any event.

BTW, I have not yet tested my produce, soil or water. But, I will surely post when I do.


Hi Avo Lady!

What did the lab tech say that put you off to there test?

do you have a lead on another lab that will test for these radioactive particles?

how does BRAWN test there samples?


My concerns about the lab...

Hi Adam,

Okay, I found the old post and it is now posted where you can easily see it. See the posted topic: "Radiation iodine confusion after speaking with certified lab."

In addition, I was told that their germanium detector was broken, and they were debating if they should replace it. So.....

I have been investigating other labs, but the ones that I am considering appear to be really booked up. In any event, I would divide whatever sample I have and send it to two different labs. In addition, I would confirm that they are using the same protocol...just in case.
(Avo Lady)

Oppppsss...Meant to type "RADIOACTIVE iodine..."


Past topic...

See Topic, "Radioactive iodine confusion after speaking with certified lab."

Adam- I am not a real


I am not a real scientist, but I did dig up some more info that should make you feel much better. First all conversion factors can be done at

Second, I'll bet that you have a decent amount of Potassium-40 in your dirt. This stuff is completely normal, and Mark from BRAWM did an awesome post on how many becquerels per liter of K40- are in a liter of milk (~45 or so).

Third, even if you don't care to fiddle with the conversions, look at the bottom line on the chart below and notice that K40 naturally occurs at levels between 1-30 picograms/g (and your sample is 8.6 pCi/g). K40 emits beta radiation, so I'm near certain that almost all of the beta activity in your soil is naturally occurring stuff.

Fourth, I think that the alpha is really a non-detect. Like I said, if the margin of error is higher than the level detected, that says to me non-detect. The real scientists can no doubt expand:).

Fifth, one issue with these "gross beta" , "gross alpha" tests is that they just tell you how much of a given type of radiation is coming from your sample, but they can't tell you exactly what from. The type of testing that BRAWM is doing is way more in depth and can separate out the individual isotopes responsible (most the time anyhoo).

Long and short, think you've got a decent potassium level :)

Sorry if I spooked you, told you I was NOT an expert, but I'm pretty sure I got her now. I wouldn't worry too much.



also, reference -

"Primordial nuclides
Nuclide Symbol Half-life Natural Activity
Uranium 235 235U 7.04 x 108 yr 0.72% of all natural uranium
Uranium 238 238U 4.47 x 109 yr 99.2745% of all natural uranium; 0.5 to 4.7 ppm total uranium in the common rock types
Thorium 232 232Th 1.41 x 1010 yr 1.6 to 20 ppm in the common rock types with a crustal average of 10.7 ppm
Radium 226 226Ra 1.60 x 103 yr 0.42 pCi/g (16 Bq/kg) in limestone and 1.3 pCi/g (48 Bq/kg) in igneous rock
Radon 222 222Rn 3.82 days Noble Gas; annual average air concentrations range in the US from 0.016 pCi/L (0.6 Bq/m3) to 0.75 pCi/L (28 Bq/m3)
Potassium 40 40K 1.28 x 109 yr soil - 1-30 pCi/g (0.037-1.1 Bq/g)"


Thanks for the time and energy you have been spending educating yourself and others. We have been students ever since the lids blew off the plants. As long as the other 50 reactors in Japan dont blow, I think we will remain residence of California.

It is hard to judge damage control. I think that I fall into the "Caldecott Camp" on the topic of "there is no safe amount of man-made radioactivity" that we should ingest.

I do understand the naturally occurring radiation that our human organism has evolved to live with.

Even though we may not be experts, I bet you and I know more than we did pre-fukushima.

Thanks for your response.
I am looking for another lab to test for redundancy, if you know of one.

Peace to you and the Brawn Family.

Adam- You are welcome for


You are welcome for whatever small contribution I make here, if any.

I will tell you this - Things are Ok for now, but sketchy. If you see an SFP go up, get out of Dodge. So be cool, and hope that the progress in FK continues. There is progress, even if it is hard to call it that

And you are correct about our knowledge level now vs then. I learn every day, some good, some bad, some I do not know. The last two months have nearly destroyed me mentally. Thank goodness that this thing has not been as bad as it could be for the US, and also that we have some level of knowledge of what is going on and what it may mean from prior events.

BTW, every day, I wish I was a farmer, full respect to you. And if you get your normal potassium level measured, and baseline it to the level of naturally occurring K40, I would bet that over 90% of the beta is from the potassium after what I've read this afternoon.

Best to you.

What is SFP?

What is SFP?

Master BC,

Master BC,
Thank you for your diligence. I feel you on the "Mental Destruction" tip. I have been up and down and think that this event is helping to solidify the good practice of positive thought combined with dutiful action. Strong Minds and bodies and spirits are called for now and always.

Question, What is "SFP"?
I would be interested in talking with you further. For an exchange of information, and also as a "support group" of sorts.

my email is if you would like to correspond.

Peace and good health to you and yours,

Spent fuel pool = spf I

Spent fuel pool = spf

I think