keywords: Background gamma radiation, dose levels, exposure rate, rice farm
In-situ assessment of background gamma radiation exposure rates and dose levels were carried out on Nkalagu-Ezillo rice farms during and after planting to ascertain the level of the radiological contamination of the farmland. The radiation exposure rates were measured using GQ GMC-320 Plus nuclear radiation meter at an elevation of 1.0 m above ground level with a GPS for geographical location. The results reveal that the exposure rates after planting are slightly higher than that during planting. Mean exposure rates of 0.014±0.002 mRh-1 and 0.015±0.002 mRh-1 were observed in farm 1 and farm 2, respectively. These values were found to be above the international recommended limit of 0.013 mRh-1 for normal environment. The evaluated mean equivalent dose and absorbed dose rates exceed their respective safe limits of 1.00 mSvy-1 and 84.0 nGyh-1 while the annual effective dose equivalent is in tandem with safe limit of 1.00 mSvy-1. The study has thus revealed that the rice farms show an area of relatively high background gamma radiation exposure and dose levels. However, the contamination and the radiation levels at the present rates do not constitute any immediate health effect on the farmers and general public, but there exist the potential for long-term health hazards such as cancer due to accumulated doses.