Anthropogenic (⁹⁰Sr, ¹³⁷Cs and ¹³⁴Cs) and primordial (⁴⁰K, ²²⁶Ra and ²³²Th) radionuclides are available in diverse environments such oceans, rivers, streams, soils, rocks, vegetable, animals and human body [1] . As a result, human being are constantly bombarding by radiation [2] due to human activities such as use of phosphate fertilizer in cultivation, burning of fossil fuels to generate heat and electricity, mining, milling operations and building materials [2] [3] . Food is one of the sources by which man is exposed to radiation. Therefore, radioactivity measurements in food stuffs (especially mushrooms) have widely reported in literature [3] - [11] .

Mushrooms are known to accumulate radionuclides efficiently [12] . However, there are no studies that determine primordial and anthropogenic radionuclides composition in edible mushrooms in Nigeria, therefore dearth of record abound. Mushrooms are highly rich in fiber, proteins, vitamins and minerals such as potassium, phosphorus, iron and sodium and are widely consumed in Ekiti State. As a result 95% of families in Ekiti and its environs consume up to 4 kg∙y⁻¹. Mushrooms are commonly found in cocoa plantation and thick forest. Samples are as seen in Figure 1 and Figure 2. Farmers in Ekiti usually use chemicals and herbicides to control weeds, pests and fungi. It is imperative to ascertain the level of radionuclides in these mushrooms that could absorb them in the atmosphere though their surface cells of from soil through their roots.

Edible mushrooms were obtained from different towns and villages in the state. Ten samples of each species were collected. The species are Termitomyces striatus, Psathyrella atroumbonata, Termitomcyes robustus, Pleurotus tuber-regium and Pleurotus squarrosulus. Fifty samples were collected in all. Samples were washed, cleaned and dried in air. They were then oven-dried at 80˚C for 16 hrs to remove the moisture content [13] . Dried samples of the same species were grounded together using a domestic blender. Thirty (30 g) of each dried mushrooms were placed in polyethylene beakers previously cleaned with 10% nitric acid. The beakers were then sealed and allowed to stand for at least 4 weeks so that the ²²⁶Ra series was able to reach radioactive secular equilibrium. The activity concentrations of natural radionuclides ⁴⁰K, ²²⁶Ra and ²³²Th in the samples were determined using a NaI (Tl) γ-ray spectrometer system. The ²²⁶Ra activity determination was based on 1.76 MeV gamma rays from ²¹⁴Bi. The activity of ²³²Th was determined through its 2.62 MeV gamma rays from ²⁰⁸Tl. The activity of ⁴⁰K (non-series) radionuclides was determined through its 1.46 MeV gamma rays. In situ measurement was carried out at the point of obtaining mushroom samples and after laboratory exposure using gamma scout detector that is calibrated across a wide scale (0.01 to 50 μSv∙hr⁻¹). This was done to ensure safety at point of collection and laboratory. The values obtained are presented as shown in Table 1.