Jibiri N N, Farai I P, Alausa S K
Radiation and Health Physics Research Laboratory, Department of Physics, University of Ibadan, Ibadan, Nigeria.
Radiat Environ Biophys. 2007 Mar;46(1):53-9. doi: 10.1007/s00411-006-0085-9. Epub 2007 Jan 9.
One of the three goals of the United Nations for sustainable food security is to ensure that all people have access to sufficient, nutritionally adequate, and safe food. Decades of tin mining in the Bitsichi area of the Jos Plateau, Nigeria, have left a legacy of polluted water supplies, impoverished agricultural land, and soil containing abnormally high levels of naturally occurring radioactive elements. In order to ascertain the radiological food safety of the population, different crops that constitute the major food nutritive requirements were collected directly across farmlands in the area. The activity concentrations of (226)Ra, (228)Th, and (40)K were determined in the food and soil samples using gamma-ray spectrometry. Additionally, in situ gamma dose rate measurements were performed on the farms using a pre-calibrated survey meter. The corresponding activity concentrations in the food crops ranged from below detection limit (BDL) to 684.5 Bq kg(-1) for (40)K, from BDL to 83.5 Bq kg(-1) for (226)Ra, and from BDL to 89.8 Bq kg(-1) for (228)Th. Activity concentrations of these radionuclides were found to be lower in cereals than in tubers and vegetables. As for the soil samples, activity concentrations of these radionuclides varied from BDL to 166.4 Bq kg(-1), from 10.9 to 470.6 Bq kg(-1), and from 122.7 to 2,189.5 Bq kg(-1) for (40)K, (226)Ra, and (228)Th, respectively. Average external gamma dose rates were found to vary across the farms from 0.50 +/- 0.01 to 1.47 +/- 0.04 microSv h(-1). Due to past mining activities, the soil radioactivity in the area has been modified and the concentration level of the investigated natural radionuclides in the food crops has also been enhanced. However, the values obtained suggest that the dose from intake of these radionuclides by the food crops is low and that harmful health effects are not expected.
联合国可持续粮食安全的三大目标之一是确保所有人都能获得充足、营养丰富且安全的食物。在尼日利亚乔斯高原的比齐奇地区，数十年的锡矿开采遗留了水污染、农田贫瘠以及土壤中天然放射性元素含量异常高的问题。为了确定当地居民的放射性食品安全状况，直接从该地区的农田中采集了构成主要食物营养需求的不同作物。使用伽马射线能谱法测定了食物和土壤样本中镭 - 226、钍 - 228 和钾 - 40 的活度浓度。此外，使用预先校准的测量仪在农场进行了现场伽马剂量率测量。粮食作物中相应的活度浓度范围为：钾 - 40 从低于检测限（BDL）到 684.5 Bq kg⁻¹，镭 - 226 从 BDL 到 83.5 Bq kg⁻¹，钍 - 228 从 BDL 到 89.8 Bq kg⁻¹。发现这些放射性核素在谷物中的活度浓度低于块茎类作物和蔬菜。至于土壤样本，这些放射性核素的活度浓度分别为：钾 - 40 从 BDL 到 166.4 Bq kg⁻¹，镭 - 226 从 10.9 到 470.6 Bq kg⁻¹，钍 - 228 从 122.7 到 2189.5 Bq kg⁻¹。发现各农场的平均外部伽马剂量率在 0.50 ± 0.01 至 1.47 ± 0.04 μSv h⁻¹ 之间变化。由于过去的采矿活动，该地区的土壤放射性已发生改变，粮食作物中所研究的天然放射性核素的浓度水平也有所提高。然而，所获得的值表明，通过粮食作物摄入这些放射性核素的剂量较低，预计不会对健康产生有害影响。
