~21 million Americans died early because of lead.

Lead is the most under-recognized cardiovascular risk factor in the United States. The 2018 Lancet Public Health paper by Lanphear and colleagues estimated that low-level lead exposure contributes to over 250,000 cardiovascular deaths per year in the US alone.

Run those hazard ratios backward against the actual blood-lead distributions NHANES measured in each era, and you get the wave.

How lead kills the heart

Lead damages the kidney's ability to manage sodium. It triggers oxidative stress in blood-vessel walls. It raises blood pressure quietly, for decades. The end of that road is hypertension, heart attack, and stroke.

For the 1950s and 1960s American adult, those mechanisms were running at peak intensity through their entire working life.

The wave was widest in the 1970s

Look at the top panel. The red wave (lead-attributable deaths) inside the gray band (total CVD deaths) is widest in the 1970s and 1980s, exactly when peak-exposure cohorts were in middle age and the cumulative burden caught up with them.

PAF goes from 91% of CVD deaths attributable to lead in 1960, to 13% today. That sounds like a victory. The 13% is still tens of thousands of preventable deaths a year.

The cohort survival panel is the human-scale view

Bottom-left. The solid red line is the 1955 birth cohort with lead exposure modeled at NHANES II adult levels. The gray dashed line is the no-lead-effect counterfactual. The gap at age 70 is roughly 12 percentage points. That is about half a million people from a single birth year who would have been alive at 70 if not for childhood lead.