FIG. 2.

(a) Hair iodine logistic sigmoid function curve. The difference between the hair iodine median derivatives of men (n=270; □) and women (n=600; ○) combined. ——, logistic function: A₂+(A₁ – A₂)/[1+(x/x₀)^p]; ---, 0.95 confidence interval; …, 0.95 prediction limit. ♂: y=0.978+(−0.015−0.978)/[1+(x/0.456)^1.624]; ♀: y=0.995+(−0.011– 0.995)/[1+(x/0.499)^1.532]. (b) Iodine linear saturation range for (♂+♀) (log conc). (c) Iodine linear saturation range separate for ♂ and ♀ (log conc). See Appendix for model and Table 1 for input values. D (♂) and d (♀), downward median derivatives; U (♂) and u (♀), upward median derivatives.