My Opinion and Statement on Using Geiger Counters for Food Testing
—–Nan Bhajani Tierra
This my opinion and personal statement regarding using geiger counters for food testing. I am primarily referring here to the high-end meters with pancake geiger mueller tubes (Inspectors, Mazur PRM 9000) and the ability to do long timed counts. The less expensive meters (Soeks, etc) can be very hard to use to tease out subtle increases in radiation because of the lack of sensitivity and narrower range of the cylindrical geiger mueller tubes, and their inability to do the long timed counts that contribute to quality data sets.
In water dense foods (produce, meats, dairy) meters will primarily pick up on what’s on the surface of the food but alpha that is not on the immediate surface, and probably part of the lower energy beta will be blocked by the density / water content of those foods. In dry foods – nuts, dehydrated foods, grains, etc – the lower water content makes measurement somewhat less of a problem, however alpha radiation will still be largely blocked except for what is on the surface of food.
All that said, geiger counters certainly *do* pick up on radioactivity in and on food, as many of us have abundantly demonstrated with our meters. But they are unlikely to paint the full picture, and probably are missing significant amounts of the radiation for the reasons I noted above, in addition to the fact that some isotopes are missed by most / all geiger counters because those isotopes are outside the sensitivity range of the meter. However, if you are picking up elevated radiation readings on foods you can pretty safely assume that there is more radiation present that you are not detecting with your meter – either because it is blocked by the density of the food, or because it is outside the range of the capacity of your geiger counter to detect.
On another note, my understanding is that the ports in the United States use Inspector geiger counters to scan foods incoming from overseas, so unless what I have read is incorrect our own government uses them for gross (big picture) food testing.
I *will not* stop using my geiger counter for food testing, nor will I stop suggesting that folks who own geiger counters check everything in their environment for radiation – that is how we learn, and gain experience and skill – by using our meters. Certainly if my bag of California pistachios are elevated 20% above background on a long timed count that is of concern. Trying to discredit the use of the meters that we hold in our hands for food testing I believe is unwise, and frankly ridiculous. However using a geiger counter to test food should come with the caveat and warning that your meter is likely missing quite a bit of the radiation that is present because of the blockage of *some* of the radiation by the density of food, and the limitations posed by the sensitivity range of the meter. Again, alpha radiation may be largely blocked except for what is on the surface of the food – because a simple piece of paper will block alpha – it is very easy to block and exclude from readings. Most of the beta and gamma radiation, within the range of the meter, will be measured.
A geiger counter will not provide the full picture – it obviously won’t tell you what isotopes are present – it is not the tool for that, and it will miss a proportion of the total radiation for the reasons noted above – but it will certainly give you an indication regarding foods that are significantly elevated in many instances. I have thrown out MANY foods after testing with my Inspector. I use a threshold of 10-15% elevation above background as my trigger figure in deciding whether to toss food out – that is just my comfort zone, others may feel differently…
I have a hard time with the claim that we “can’t” detect radiation with a high-end geiger counter using good scientific process and long timed counts. Why would we *not* test our foods if we are sharing our lives with a high end meter? Most of us, sooner or later, end up testing pretty much everything in our homes and then continue on to carry our meters everywhere with us. Why would we test our surroundings but not the food we put into our bodies? We will never, ever have a spectrometer in every house – so it is foolish IMO not to use our geiger counters as a basic screening tool, particularly if you have a meter that can do long timed counts.
I counsel the use of no less than a 100 minute timed count to tease out a mildly elevated food / household items. There is easily a 10-15% variation in background readings on 10 minute timed counts – they are simply not long enough to really tell what’s going on unless the item is significantly elevated.
Also – and this is very important – in order to really know what’s going on, particularly if there is a subtle elevation, you need to know your background in the environment where you are testing, and you need to know if your testing surface and location, as well as nearby objects, are elevated. Really what you want to know is whether the food or item tests out at above your stable background reading, so you need to have a controlled setting for testing.
Consistent testing processes are extremely important. Testing in the same location as where you check your background, testing any plate / bowl that you are using for your sample, and testing nearby objects is critical – otherwise you may think that you have something “hot” when really it’s the tile, or the ceramic bowl that you have your sample placed in, or the table that you are testing on, or whatever – you need to know all factors that may influence your readings – I can not emphasize this enough – this is citizen science and it is meaningless without good process. ~ Nan