Neurodevelopmental harm in children (no safe level): Blood lead below 5 mcg/dL associated with reduced IQ, academic achievement, and attention. Each 10 mcg/dL increase associated with 3.9-point IQ decline. Effects are permanent and irreversible. Steeper harm at lower doses.
Behavioral effects: Prenatal and early childhood exposure associated with ADHD, impulsivity, aggression, and conduct disorders in longitudinal studies.
Kidney damage: Chronic lead exposure causes tubular dysfunction and progressive nephropathy. Lead accumulates in bone and soft tissue with a half-life of years to decades.
Cardiovascular effects: Lead exposure associated with hypertension and cardiovascular disease in adults. Even low-level exposure elevates blood pressure.
Reproductive harm: Prop 65 listed as reproductive toxicant. Associated with reduced fertility in both men and women, increased miscarriage risk, and adverse pregnancy outcomes.
Cancer: IARC Group 2B (possibly carcinogenic to humans). Inorganic lead compounds associated with kidney, brain, and lung cancers in occupational studies.