This International Standard applies to portable instruments used for measuring the specific or volumic activity of gamma-emitting radionuclides in food/foodstuffs intended for operation under field conditions, particularly in case of a post-accidental situation. It does not apply to low background laboratory instrumentation requiring highly skilled personnel. The instruments designed for measurement of gamma contamination in foodstuffs under field conditions should not require special sample preparation other than machining (cutting, grinding, etc.). These instruments may be used, in principle, to measure the gamma emitting surface contamination and other radiation measurements as well, but these applications are outside the scope of this standard. The same instruments intended for measuring foodstuffs can also be used for the measurement of environmental samples, such as soil, sewage, plant and animal life, etc. These instruments can be used to estimate specific gamma activity for a wide variety of samples according to this standard.