Recent Developments

1. Selenium and Human Health - Summary
2. Selenium and Human Health - Latest Studies
3. Selenium in Food: Studies on Grains and Fish
4. Studies on Selenium in China

 

3. SELENIUM IN FOOD: STUDIES ON GRAINS AND FISH

1. Fan, M.-S, et al., "Historical changes in the concentrations of selenium in soil and wheat grain from the Broadbalk experiment over the last 160 years", Science of the Total Environment, Volume 389(2-3), January 2008.

Selenium intake has decreased substantially in the UK population since 1970s. To investigate whether selenium concentration in wheat grain has changed as a result of yield improvement or environmental changes, we analyzed archived what grain from the Broadbalk Wheat Experiment at Rothamsted, England, which as been run continuously for over 160 years. Soil selenium concentrations showed an increasing trend in all plots over 160 years. The unfertilized control plots had higher selenium concentrations (maximum: 0.236 micrograms per gram (part per million)) in the wheat grain samples than the fertilized or manured plots. The results show that the selenium concentration of wheat grain was influenced (decreased) by sulphur inputs from fertilizers and atmospheric deposition, and that improving grain yield through plant breeding was not the cause of the decrease in grain selenium in the fertilized plots.

2. Williams, P.N., et al., "Market basket survey shows elevated levels of As in South Central U.S. processed rice compared to California: Consequences for human dietary exposure", Environmental Science and Technology, Volume 41(7), April 2007.

The findings show differences in transitional metal levels between polished and unpolished rice and geographical variation in arsenic and selenium between rice processed in California and the South Central US. The difference between the two regions was found to be significant for arsenic and selenium . No statistically significant differences were observed in arsenic or selenium levels between polished and unpolished rice. No significant differences in grain levels of manganese, cobalt, copper, or zinc were observed between California and South Central US. Maximum daily intakes of arsenic and selenium may be potentially exceeded if drinking water concentrations and intakes are considered.

GRAIN SOURCE	Arsenic	Selenium
South Central US Mean (N=107)	0.30 ug As/g	0.19 ug Se/g
California Mean (N=27)	0.17 ug As/g	0.08 ug Se/g

3. Terry, N., et al., " Selenium in higher plants", Annual Review of Plant Biology, Volume 151, 2000.

Plants vary considerably in their physiological response to selenium . Some plant species growing on seleni ferous soils are selenium tolerant and accumulate very high concentrations of selenium . But most plants are selenium non-accumulators and are selenium sensitive. Recent advances in our understanding of the plant's ability to metabolize selenium into volatile forms are discussed, along with the application of phytoremediation for the cleanup of selenium contaminated environments.

4. Mercury Information Clearinghouse , "Quarter 9 Mercury Information Clearinghouse Final Report", Prepared by: Canadian Electricity Association, Energy and Environmental Research Center (EERC, North Dakota), Center for Air Toxic Metals (CATM), USA Department of Energy (DOE) National Energy Technology Laboratory (NETL), December 2005.

The role of selenium in reducing bioaccumulation of mercury in fish has been reported and inverse relationships between fish tissue mercury and the abundance of selenium present in the ecosystem have been noted. Selenium supplementation of lake waters in Sweden resulted in a 75%-85% reduction in mercury levels of fish over a 3 year period, and loss of selenium can have the opposite effect. When selenium -rich discharges of fly ash to an artificial lake were removed, researchers noted a steady increase in mercury concentrations. Studies such as these, indicate the importance of selenium dependent mercury retirement in aquatic ecosystems, possibly through formation of insoluble mercury- selenium complexes that deposit in sediments. Several studies of the relationships between Hg and Se are currently ongoing in Canada and elsewhere in the world.

 

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