Figure 1: Tibia lead–blood pressure relationship and cocaine addiction severity as modifier of the relationship. Main effect of (log₂-transformed) lifetime lead exposure on blood pressure levels and modifying effect of cocaine addiction severity on the relationship between bone lead (log₂-transformed μg/g bone) and blood pressure levels. Cocaine addiction severity categories include all participants (All: main effect); nonusers (C0, reference), <44% lifetime use years (C1), >44% lifetime use (C2: square). 95% CI: 95% confidence interval; *P for interaction <0.05