Take a look at the Soeks ecotester.
A Russian device that measures radiation (alpha, beta, gamma) and can test the nitrate levels in foods and liquids. Nitrates are a good indicator that various toxins (pestercides, fertilisers, etc) have been used in the food production. Hence this value can help you pick out the good from the bad.
It has a pre-set range of nitrate levels for basic foods using Russian standards (stricter than the EU). However it will give the nitrate reading on any food or liquid. What is important is the total level of nitrate you are taking in per day;
- 200 – 300 mg per day is ok
- 600 – 700 mg per day is a toxic dose
So after a while you’ll get to know how much you are absorbing per day, and which foods to leave on the shelf
Concerning background radiation 0 – 0.2 mcSv/h is acceptable (in Russia the norm is 0.05 to 0.2 mcSv/h). If you read 0.4 mcSv/h or more then the reason for the radiation needs to be found and eliminated. Values above 1.2 mcSv/h mean that the area is very danderous!
I personally find this device a useful tool to test foods and check radiation levels of the house, region, foods, objects, etc.
One line of defence that is reasonably priced (about €220 in Germany).