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Despite many major and minor problems with interpretation of analytical data, chemical analyses of human hair have some potential value. Extensive research will be necessary to define this value, including correlation of hair concentrations of specific elements with those in other tissues and metabolic pools and definition of normal physiological concentration ranges. Many factors that may compromise the correct interpretation of analytical data require detailed evaluation for each specific element. Meanwhile, hair analyses are of some value in the comparison of different populations and, for example, in public health community surveys of environmental exposure to heavy metals. On an individual basis, their established usefulness is much more restricted and the limitations are especially notable for evaluation of mineral nutritional status. There is a wide gulf between the limited and mainly tentative scientific justification for their use on an individual basis and the current exploitation of multielement chemical analyses of human hair.

Low income diets provide relatively little zinc. This study was designed to evaluate the zinc nutritional states of 74 low income preschool children enrolled in the Denver Head Start Program. Zinc is necessary for normal growth, hence children were selected on the bases of low height percentiles. The mean (+/- SE) hair zinc concentration was 87.0 +/- 5.9 mug/g, and the mean plasma zinc concentration was 74.5 +/- 1.5 mug/100 ml. These levels were both lower (P is less than 0.005) than those of middle income children of similar age. Sixty-eight percent of the study group had a hair zinc concentration less than 70 mug/g and/or a plasma zinc concentration less than 68 mug/100 ml. These results indicate that inadequate zinc nutrition may be common among preschool children with low growth percentiles from low income families.