The Selenium test using an Atomic Absorption Spectrophotometer (AAS) with flame and GFA modes is a laboratory test designed to measure the concentration of selenium in environmental or biological samples. Selenium is an essential nutrient that plays an important role in many vital functions, including antioxidant activity and immune system support. This test is based on measuring the amount of light absorbed by selenium atoms in the sample at a specific wavelength. It can be used to evaluate selenium levels in blood, urine, or tissues, helping to identify excessive exposure or deficiency of this element. The results are important in public health, as the test helps guide nutritional strategies and assess health risks associated with selenium deficiency or excess. It is also used in environmental studies to determine the effects of pollution or exposure to heavy metals.