FIG. 1.

(a) Hair iodine frequency distribution. Common median for both ♂ (n=270) and ♀ (n=600); M₀=0.499 μg/g. #, Individual subject number (subjects 1–870 are numbered sequentially depending upon the increasing iodine concentration). Abscissa A scale, iodine (μg/g). Exponential equation (Abscissa B scale, M₀–M₁₀) y=492.8 e^−0.537x, R²=0.963. ANO Center for Biotic Medicine hair iodine reference values (μg/g): ♀ 0.65–8.00, ♂ 0.65–9.00. (b) Box and whisker plot of the hair iodine log concentrations. –, min/max; ×, 1%/99% percentile; □, mean; ♦, outliers; top whiskers=maximum, greatest value excluding outliers; bottom whiskers=minimum, least value excluding outliers. Box: bottom line=lower quartile, 25% of data less than this value; top line=upper quartile, 25% of data greater than this value; middle line=median. (c) Mirror-image model of the hair iodine median derivatives for assessing the tentative level of what would be environmental “background” iodine concentration today. See Appendix for model and Table 1 for model input values. ♂, men; ♀, women; M₀, median; D₁–D₇, ♂+♀ common downward (descending) median derivatives; U₁, ♂+♀ common upward (ascending) median derivative.