Laboratory issues: use of nutritional biomarkers.

Biomarkers of nutritional status provide alternative measures of dietary intake. Like the error and variation associated with dietary intake measures, the magnitude and impact of both biological (preanalytical) and laboratory (analytical) variability need to be considered when one is using biomarkers. When choosing a biomarker, it is important to understand how it relates to nutritional intake and the specific time frame of exposure it reflects as well as how it is affected by sampling and laboratory procedures. Biological sources of variation that arise from genetic and disease states of an individual affect biomarkers, but they are also affected by nonbiological sources of variation arising from specimen collection and storage, seasonality, time of day, contamination, stability and laboratory quality assurance. When choosing a laboratory for biomarker assessment, researchers should try to make sure random and systematic error is minimized by inclusion of certain techniques such as blinding of laboratory staff to disease status and including external pooled standards to which laboratory staff are blinded. In addition analytic quality control should be ensured by use of internal standards or certified materials over the entire range of possible values to control method accuracy. One must consider the effect of random laboratory error on measurement precision and also understand the method's limit of detection and the laboratory cutpoints. Choosing appropriate cutpoints and reducing error is extremely important in nutritional epidemiology where weak associations are frequent. As part of this review, serum lipids are included as an example of a biomarker whereby collaborative efforts have been put forth to both understand biological sources of variation and standardize laboratory results.

Chernobyl and iodine deficiency in the Russian Federation: an environmental disaster leading to a public health opportunity.

The Chernobyl nuclear disaster of April 26, 1986, triggered a chain of devastating events that later included an unexpected increase in childhood thyroid cancer and evidence of iodine deficiency (ID) in Russia. For the Russian people the Chernobyl event had profound psychological impacts, provoking anxiety about nuclear technology and mistrust of governmental control efforts. Frequently in public health a crisis is required to create the political will to manage longstanding problems, and public health officials must rapidly mobilize to take advantage of the opportunity. In this case, ID, previously not seen as a problem in Russia, was recognized to be potentially serious, and the Russian Federation, assisted by the catalytic bi-national effort of the U.S.-Russian Joint Commission on Economic and Technological Cooperation (Gore-Chernomyrdin Commission (GCC)) established a model salt iodization policy, developed a planning process, and implemented a program to prevent ID through a systematic approach that included the people, government, and private groups using open communication, dissemination of the findings, and action plans. By 1999, political will had been mobilized and over 20% of the nation's salt was being iodized, up from about 1% in 1996. Universal iodization of salt was not a specific objective of the GCC; however, the increasing availability of iodized salt is leading to the elimination of ID, which is now a political goal in Russia. The full realization of this goal will require more time for education, marketing, and possibly legislative action.