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ABSTRACT
Background
People may be exposed to ionizing radiation due to naturally occurring radionuclides through consumption vegetables. Estimation of radionuclides vegetables is critical for public health protection. This study estimated natural radioactivity (40K, 232Th, and 226Ra) concentrations in vegetables (spinach, onion, potatoes, chili, tomatoes and beetroot) from two selected farms in South Africa.
Method
Thirteen vegetable samples were collected from each of the two selected farms in South Africa and coded differently to allow easy identification. Samples were dried in an oven over two days and then grounded. A gamma-ray spectroscopy connected with a scintillation detector crystallized with thallium-activated sodium iodide NaI (TI) was used to measure the natural radioactivity (40K, 232Th, and 226Ra) concentrations in the samples.
Result
The activity concentration levels in onions, beetroots, potatoes, chili, tomatoes and spinach from farm A were 30.81, 129.40, 97.83, 112.20, 112.90 and 44.40 Bq/kg respectively for 226Ra, while the corresponding 232Th concentrations were 106.60, 109.40, 110.20,143.10,121.20 and 115.30 Bq/kg and for 40K the corresponding concentrations were 1460.00; 1655.00; 1491.00; 1542.00; 1592.00; and 15776.00 Bk/kg. For farm B, the mean radioactivity concentration levels for 226Ra were 105.10; 91.43; 106.40; 96.37;37.79 and 102.60 Bq/kg. The corresponding 232Th concentrations were 117.00; 105.30; 117.20; 124.40, 108.70 and 115.90 Bq/kg while the corresponding 40K concentrations were 1532.00; 1628.00; 1606.00; 1463.00; 1563.00; and 1625.00. The mean of the annual effective dose equivalent due to intake of crops was 1.86 mS/year form A and 1.87 mSv/year which is higher than the 1 mSv/year annual limit recommended by the International Commission on Radiological Protection.
Conclusion
Vegetables cultivated in both farm A and B expose the population to high radiation which may be detrimental to their health.