Biomonitoring Equivalents for selenium
- DOI
- Language of the publication
- English
- Date
- 2014-07-25
- Type
- Article
- Author(s)
- Hays, Sean M.
- Macey, Kristin
- Nong, Andy
- Aylward, Lesa L.
- Publisher
- Elsevier
Abstract
Selenium is an essential nutrient for human health with a narrow range between essentiality and toxicity. Selenium is incorporated into several proteins that perform important functions in the body. With insufficient selenium intake, the most notable effect is Keshan disease, an endemic cardiomyopathy in children. Conversely, excessive selenium intake can result in selenosis, manifested as brittle nails and hair and gastro-intestinal disorders. As such, guidance values have been established to protect against both insufficient and excessive selenium exposures. Dietary Reference Intakes (DRIs) have been established as standard reference values for nutritional adequacy in North America. To protect against selenosis resulting from exposure to excessive amounts of selenium, several government and non-governmental agencies have established a range of guidance values. Exposure to selenium is primarily through the diet, but monitoring selenium intake is difficult. Biomonitoring is a useful means of assessing and monitoring selenium status for both insufficient and excessive exposures. However, to be able to interpret selenium biomonitoring data, levels associated with both DRIs and toxicity guidance values are required. Biomonitoring Equivalents (BEs) were developed for selenium in whole blood, plasma and urine. The BEs associated with assuring adequate selenium intake (Estimated Average Requirements – EAR) are 100, 80 and 10 μg/L in whole blood, plasma and urine, respectively. The BEs associated with protection against selenosis range from 400 to 480 μg/L in whole blood, 180–230 μg/L in plasma, and 90–110 μg/L in urine. These BE values can be used by both regulatory agencies and public health officials to interpret selenium biomonitoring data in a health risk context.
Plain language summary
Biomonitoring efforts have produced continually expanding databases of the levels of chemicals that have been measured in the blood and/or urine of Canadians. Such biomonitoring surveys provide a wealth of information on the levels of chemicals that are found within the general population; however, the presence of a chemical within the body does not necessarily indicate there is the potential for harm. A concept known as Biomonitoring Equivalents (BE) has been developed to aid in interpreting and communicating biomonitoring results in the context of potential risks to health. A BE is defined as the concentration of a chemical in blood or urine that corresponds to an exposure guidance value, such as a reference dose (RfD) or tolerable daily intake (TDI). By comparing biomonitoring data for a chemical with its BE, one can assess whether population exposures to the chemical are below or above a level that is not considered to be harmful. In order to inform Health Canada’s selenium-containing substances risk assessment, this study reviewed several available health-based exposure guidance values for selenium and calculated a BE in blood and urine from each of those values. Selenium is an essential nutrient with a narrow range between the low levels required for regular healthy body functions and an excess amount that leads to toxicity. As such, guidance values from government and non-governmental health authorities have been established as an information tool, helping people avoid either insufficient or excessive selenium exposure. Blood and urine BE concentrations were calculated using equations describing the relationship between tissue levels and average daily requirements for selenium. The BEs associated with nutritional requirements (Estimated Average Requirements) are 100 µg/L , 80 µg/L and 10 µg/L selenium in whole blood, plasma and urine, respectively. The BEs associated with selenium toxicity range from 400 to 480 µg/L in whole blood, 180 to 230 µg/L in plasma, and 90 to 110 µg/L in urine. The outcome of this work will allow Health Canada to place the results of selenium biomonitoring studies into a public health risk context and will assist in the prioritization of any further risk assessment or management follow-up actions. This study was conducted in collaboration with Summit Toxicology, LLP.
Subject
- Health,
- Health and safety