MODEL RELEASED. Radiation levels in food. Researcher preparing food samples to be tested for their radioactivity. Here, the samples are being freeze-dried to form a powder for analysis. The food is mixed in a food processor to make a homogenous (uniform) sample before it is freeze- dried. Diet samples are taken to monitor the dietary intakes of nutrients and contaminants for large groups of the population. Radioactive contamination may arise from nearby nuclear power stations or natural sources, which can cause serious health problems.