Radiological Assessment of Soils on the Waysides of the Road Underconstruction in Ijebu-Ode, Ogun State, Southwestern Nigeria

The ongoing road construction and rehabilitation of major highways in Ijebu-Ode involved the grading, refilling of the roads with different types of soils and the use of various materials that may be radioactive. Therefore the construction and the rehabilitation of the roads may lead to enhancement of the natural radioactivity levels in the area. Soil samples were collected from the sideways of the roads and analysed using a single crystal 0.51cm x 0.51cm NaI (Tl) detector, manufactured by Scintitech Instrument, USA, is coupled through a Hamamatsa (R1306NSV3068) photomultiplier tube to a Multichannel Analyser, MCA (2100R:01) manufactured by Price gamma Technology, USA. The activity concentrations in the entire area of study were 396.1±70.9 Bqkg-1, 17.7±4.6 Bqkg-1, and 33.9±6.7 Bqkg-1 for 40K, 226Ra and 232Th respectively. The absorbed dose rate and the outdoor effective dose rate were 27.6±5.5 nGyh-1and 33.9±6.7µSvy-1 respectively. The collective health detriment was 1.1 x 10-4. The radiological health effect on the populace in the area were insignificant as the results showed very low radioactivity levels and collective health detriment indicated that 11 out of 100,000 people were vulnerable to any type of cancer. Keywords: Impact assessment, natural radioactivity, road constructions, health detriment, Nigeri

Radiological Impact Assessment of Farm Soils and Ofada rice (Oryza sativa japonica) from Three Areas in Nigeria

            يزرع الارز الاسيوي والمسمى ب (ارز اوفادا )في مجتمعات المسماة (أراموكو ، وأباكاليكي وأوفادا) ويستهلكها كل من الفقراء والأغنياء في نيجيريا على حد سواء . تم تحديد ما مجموعه عشرين مزرعة من أراضي الأرز في كل منطقة من مناطق الدراسة ، وتم جمع عينات من الأرز بشكل عشوائي ، وتم خلطها بشكل دقيق لتقديم عينة من كل أرض زراعية. تم جمع عينات التربة في كل مزرعة على عمق 5-15 سم من ثماني نقاط مختلفة على الأقل وتم خلطها معًا لتشكيل العينة. تم التحليل الطيفي لهذه العينات. تم استخدام كاشف أشعة كاما NaI (Tl) ذو معايرة جيدة في التحليل الطيفي للعينات واستخدمت الإحصاءات الوصفية لتحليل النتائج.لقد كان متوسط التركيز الاشعاعي للعناصر  40K,232Th,238U , هو 261.8±52.5Bq/kg      و   9.6±1.2Bq/kg و 8.7±1.0Bq/kg (أوفادا)،257.3±39.0Bq/kg،9.3±1.1Bq/kg و 7.8±1.8Bq/kg (أباكاليكي) و 248.2±54.8Bq/kg،9.3±0.9Bq/kg،7.6±1.5Bq/kg (أراموكو) على التوالي اما تراكيز النشاط الاشعاعي في التربة للعناصر  40K,232Th,238U ,كانت 333.9±62.8Bq/kg،11.1±1.1Bq/kg و 11.0±1.4Bq/kg (اوفادا) ،306.8±36.0Bq/kg،10.7±0.8Bq/kg و 9.4±1.8 Bq/kg (أباكاليكي) و 321.8±42.4Bq/kg،10.9±0.5Bq/kg و9.5±0.6Bq/kg (أراموكو). تم تسجيل أعلى متوسط جرعة 106.0±8.0µSv/y والجرعة الفعالة في الهواء الطلق البالغة32.4±3.40µSv/y في  Ofada. وان أعلى معدل لخطر الاصابة بسرطان قدره (0.33±0.004) x10-3 تم تسجيله في (أراموكو). أشارت النتائج إلى أن جرعة  النويدات المشعة أقل بكثير من الحد العالمي البالغ   290µSv/y  ومخاطر انخفاض السرطان عن الحد الذي أوصى به UNSCEAR وهو 0.29x10-3 ، وبالتالي فإن استهلاك الأرز ofada من المناطق قد لا يشكل أي تأثير صحي خطير.Oryza sativa japonica (ofada rice) is largely grown in Aramoko, Abakaliki and Ofada are communities and consumed by both the poor and rich in Nigeria. A total of twenty ofada rice farmlands were identified in each study area and rice samples were randomly collected, thoroughly mixed to make a representative sample from each farmland. Soil samples were collected in each farm to a depth of 5-15cm from at least eight different points and thoroughly mixed together to form a representative sample. The samples were thereafter taken to the laboratory for preparation and spectroscopic analysis. A well-calibrated NaI(Tl) gamma-ray detector was used in spectrometric analysis of the samples and descriptive statistics was used to analyze the results. The respective mean 40K, 238U and 232Th activity concentrations in the rice were 261.8±52.5Bq/kg, 9.6±1.2Bq/kg and 8.7±1.0Bq/kg (Ofada); 257.3±39.0Bq/kg, 9.3±1.1Bq/kg and 7.8±1.8Bq/kg (Abakaliki); and 248.2±54.8Bq/kg, 9.3±0.9Bq/kg and 7.6±1.5Bq/kg (Aramoko). The respective mean 40K, 238U and 232Th activity concentrations in the soils were 333.9±62.8Bq/kg, 11.1±1.1Bq/kg and 11.0±1.4Bq/kg (Ofada); 306.8±36.0Bq/kg, 10.7±0.8Bq/kg and 9.4±1.8 Bq/kg (Abakaliki) and 321.8±42.4Bq/kg, 10.9±0.5Bq/kg and 9.5±0.6Bq/kg (Aramoko). The highest mean ingestion dose of 106.0±8.0µSv/y and outdoor effective dose of 32.4±3.40µSv/y were recorded in Ofada community. The highest mean ingestion cancer risk of (0.33±0.004) x10-3was recorded in Aramoko. The results indicated significantly lower radionuclide ingestion dose than the world limit value of 290µSv/y and lower cancer risks than the UNSCEAR recommended limit of 0.29x10-3, therefore consumption of ofada rice from the areas may not pose any serious health impact