Trace element toxicity, factors affecting

There are numerous variables that can affect trace element determinations before the analysis of the sample is undertaken and these require careful control. Guidelines giving details of sample collection procedures, and procedures for limitation of contamination in a range of sample types, are available for essential and toxic trace elements. Age, sex, ethnic origin, time of sampling in relation to food intake, time of day and year, history of medication, tobacco usage, and other factors should be recorded when establishing reference intervals from healthy control populations. 

When trace elements are analyzed in living subjects, the specimens that are available are limited. Usually only blood, urine, faeces or hair are available. Thus the tissues or organs of most interest, e.g. target organs for a toxic effect, may not be directly sampled and analyzed. The physiological factors that affect the relationship between the concentrations of a trace element in the target tissues and in the body fluids are thus very important. 

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