210Pb, 210Po, 226Ra, U and Th in Arable Crops and Ovine Liver: Variations in Concentrations in the United Kingdom and Resultant Doses

Abstract

Concentrations of a range of naturally occurring radionuclides have been determined in the same crops grown at two sites in the UK. Ovine liver has also been studied. One site was in an area where concentrations in soil are typical of the UK (the 'control' site) and the other in an area where levels were well above average (the 'test' site). For an average adult consumer of all of the foodstuffs studied, the doses from consumption for the test site were about 4 times higher than those for the control site. However, the differences were small compared with the variability in overall doses from natural background across the UK. 210Pb and 210Po were important contributors to doses for both sites, but at the test site the contribution from 226Ra was also significant. Of the foodstuffs studied, consumption of leafy vegetables and liver gave the highest doses. The doses from leafy vegetables were sensitive to the weather conditions prior to harvesting. Consequently, rigorous monitoring programmes should be based on several samples collected throughout the year; extrapolations based on a single annual sample are unlikely to be reliable.

Proposal for new best estimates of the soil-to-plant transfer factor of U, Th, Ra, Pb and Po

“…For Cereals, Root crops, and Tubers, TFs were comparable. This is confirmed by observations by Ham et al (2001). Furthermore, these authors suggested that translocation from shoots to roots was negligible.…”

“…in the vicinity of metal smelters (Pettersson et al, 1988;Ham et al, 2001;PietrzakFlis and Skowrofiska, 1995). The relative importance of these two pathways depends upon the concentration of the radionuclides in the soil, the soil-plant TF, and the rate of deposition onto the aboveground plant parts.…”

A first order assessment of the potential radiological impact of foodstuffs grown in a catchment area influenced by mining and mineral processing industries

“…In general, the observed concentrations of the nuclides were in the range of worldwide values [1][2][3][4][5][6][7], although higher than reference concentrations of natural radionuclides in foods assumed by UNSCEAR [13] which range from less than 0.001 to about 0.2 Bq/kg (see Table 1). Individual samples with high activity concentration (oats and rye) should be considered as special cases and the reason for the high values further investigated.…”

“…Compared to the annual effective dose of no more than 200 Sv/a from natural radionuclides in food as assessed by UNSCEAR [13] this does not imply an unacceptable level of exposure. For comparative purposes the average annual effective dose from ingestion of natural radionuclides in Sv/a is estimated as 14.5 in Brazil [6], 23.9 in Nigeria [2], 83.9 in the UK [5], 110 in Korea [3] and 69-280 in Hong Kong [7].…”

“…Intake of these radionuclides may vary considerably because of differences among classes of food in the diet. Comprehensive studies on the concentration of natural radionuclides in foodstuffs and the dose due to intake of these radionuclides through the diet have been carried out in various part of the world [1][2][3][4][5][6][7]. Information on the dietary intake of natural radionuclides in South Africa is relatively scarce.…”