Lead

What it isA toxic heavy metal with no known biological role. Lead enters the body through old paint, plumbing, contaminated water, leaded gasoline residue, certain spices and cookware, and some occupational sources. It stores in bone for decades and re-mobilizes during pregnancy, lactation, and bone loss.

DoesDisrupts enzymes that depend on zinc and calcium, impairs heme synthesis, damages neurons, and stiffens arteries.

GoodA near-undetectable lead level signals minimal cumulative exposure and protects cognition, blood pressure, and kidney over decades.

BadEven low chronic exposure raises blood pressure, accelerates kidney decline, lowers IQ in children, and increases cardiovascular mortality. There is no safe threshold — risk rises continuously from zero.