Quality control methods for

Interpretation of results 
No spots corresponding to aflatoxin should be obtained from any of the sample 
residues. If any such spot is obtained, compare its position with the spots 
obtained from the aflatoxin mixture to identify the type of aflatoxin present. An 
approximate estimation of the concentration of aflatoxin in the sample may be 
obtained by comparing the intensity of the spots with those of the aflatoxin 
mixtures. 

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Quality control methods for medicinal plant materials 
19. Radioactive contamination 
A certain amount of exposure to ionizing radiation cannot be avoided since 
there are many sources, including radionuclides occurring naturally in the 
ground and the atmosphere. These sources are described extensively in the 
booklet Facts about low-level radiation (13). 
Dangerous contamination may be the consequence of a nuclear accident. The 
World Health Organization, in close collaboration with several other 
international organizations, has developed guidelines for use in the event of 
widespread contamination by radionuclides resulting from a major nuclear 
accident (14). This publication emphasizes that the health risks from food 
accidentally contaminated by radionuclides depend not only on the specific 
radionuclide and the level of contamination but also on the quantity of food 
consumed. 
The range of radionuclides that may be released into the environment as the 
result of a nuclear accident might include long-lived and short-lived fission 
products, actinides, and activation products. The nature and the intensity of 
radionuclides released may differ markedly and depend on the source (reactor, 
reprocessing plant, fuel fabrication plant, isotope production unit, etc.). 
The amount of exposure to radiation depends on the intake of radionuclides and 
other variables such as age, metabolic kinetics, and weight of the individual 
(also known as the dose conversion factor). 
Even at maximum observed levels of radioactive contamination with the more 
dangerous radionuclides, significant risk is associated only with consumption of 
quantities of over 20 kg of plant material per year so that a risk to health is most 
unlikely to be encountered given the amount of medicinal plant materials that 
would need to be ingested. Additionally, the level of contamination might be 
reduced during the manufacturing process. Therefore, no limits for radioactive 
contamination are proposed.