Lead is unequivocally bad for you. There is no safe level of exposure. Unlike many substances that are harmful only in large doses, lead causes measurable damage to the brain, heart, kidneys, and reproductive system at concentrations so low they produce no obvious symptoms. The CDC currently uses a blood lead reference value of 3.5 micrograms per deciliter (µg/dL) to flag children with elevated levels, but health effects have been documented well below that number.
Why Lead Is Uniquely Toxic
Lead’s danger comes from a molecular trick: it mimics calcium, one of the most important signaling minerals in your body. Lead ions are similar enough to calcium ions that they slip through calcium channels in your cells and then compete with calcium for binding spots on proteins. This disrupts nearly every process that depends on calcium, which includes nerve signaling, muscle contraction, and the release of chemical messengers between brain cells.
In the brain, lead blocks calcium channels at the junctions between nerve cells, preventing neurotransmitters from being released normally. It also interferes with the proteins that help package and deliver those neurotransmitters. The result is a kind of widespread communication breakdown across the nervous system, one that is especially devastating during the years when a child’s brain is still forming connections.
How Lead Affects Children
Children absorb lead far more efficiently than adults and are more vulnerable to its effects because their brains and organs are still developing. The consequences are not subtle. A meta-analysis of case-control studies involving over 3,300 children found that those with blood lead levels above 10 µg/dL scored significantly lower on IQ tests. Children exposed for longer than 4.5 years showed an average IQ difference of nearly 23 points compared to less-exposed peers. Even shorter exposure periods produced a measurable drop of about 3.5 IQ points.
A study in Massachusetts found that children with blood lead levels between 5 and 10 µg/dL scored 7.8 IQ points lower than the control group. Below 2 µg/dL, no difference was observed, which helps illustrate that the damage scales with exposure but begins at very low levels. Beyond IQ, lead exposure in children is linked to shortened attention spans, increased antisocial behavior, learning difficulties, hearing loss, and developmental delays.
Symptoms in children can be hard to spot because they overlap with many common childhood issues: irritability, fatigue, loss of appetite, stomach pain, constipation, and weight loss. Seizures occur at very high levels. Many children with moderately elevated lead show no obvious symptoms at all, which is why screening through blood tests is the only reliable way to catch it.
Risks for Adults
In adults, the most well-documented harm from lead is cardiovascular. The evidence linking lead exposure to high blood pressure is strong enough that researchers consider the relationship causal, not just a correlation. Lead appears to damage the kidneys in ways that reduce their filtering capacity, which in turn drives blood pressure up. This kidney effect has been observed at blood lead levels below 5 µg/dL.
The cardiovascular risks go beyond blood pressure. Data from the National Health and Nutrition Examination Survey found that adults with blood lead levels at or above 3.63 µg/dL had roughly 1.9 times the risk of coronary heart disease and 2.5 times the risk of stroke compared to those with the lowest levels. Peripheral arterial disease risk nearly doubled at levels above 2.47 µg/dL. Even as average lead levels in the U.S. population have dropped significantly over the decades, the statistical relationship between lead and cardiovascular death remains consistent.
Adults with lead exposure may also experience joint and muscle pain, headaches, memory and concentration problems, mood changes, and abdominal pain. In men, lead reduces sperm count and causes abnormal sperm. In women, it increases the risk of miscarriage, stillbirth, and premature birth.
Lead Crosses the Placenta
Lead in a pregnant person’s blood passes directly to the developing baby. This exposure can cause premature birth, low birth weight, and damage to the baby’s brain, kidneys, and nervous system. Children exposed to lead before birth are more likely to have learning and behavioral problems later in life.
What makes pregnancy especially risky is that lead stored in bones can re-enter the bloodstream during pregnancy and breastfeeding. The body increases its calcium mobilization to support the growing baby, and because lead is stored alongside calcium in bone, it gets pulled back into circulation at the same time. A woman who was exposed to lead years or even decades earlier can unknowingly expose her child.
Lead Stays in Your Body for Decades
Lead in the bloodstream has a half-life of about 28 to 36 days, meaning it clears relatively quickly from circulation. But the body doesn’t eliminate it. Instead, about 94% of the lead an adult absorbs gets deposited into bone, where it can remain for decades in an inert storage pool.
That stored lead becomes a problem whenever the body breaks down bone faster than usual. Pregnancy, breastfeeding, menopause, advanced age, broken bones, thyroid disorders, kidney disease, prolonged bed rest, and periods of physical stress all increase the rate at which lead moves from bone back into blood. Calcium deficiency makes this worse in every case. This means a single significant exposure earlier in life can produce health effects that resurface years later, long after the original source is gone.
Where People Are Still Exposed
Lead paint in homes built before 1978 remains the most common source of childhood lead exposure in the United States, particularly when old paint deteriorates into dust or chips. But there are less obvious sources that catch many people off guard.
Drinking water is a significant route. Lead leaches into water from old pipes, solder, and service lines connecting homes to water mains. The EPA’s action level for lead in drinking water is 15 parts per billion. A 2024 rule update requires water systems to better identify and eventually replace lead service lines, but millions of older homes still have them.
Imported spices from countries including Vietnam, India, and Syria have tested positive for lead contamination. Certain traditional medicines and remedies are extremely high in lead. Greta and Azarcon, used in some Hispanic communities for stomach problems and teething pain, contain lead concentrations as high as 90%. A Thai digestive aid called Daw Tway has tested at 970 parts per million of lead. Sindoor, a product used in some South Asian religious and cosmetic practices, has been found with lead levels as high as 87%. Kohl and kajal, traditional eye products used in parts of Africa and the Middle East, can also contain significant lead.
Older ceramic dishes with lead-based glazes, certain imported toys, and some occupational settings (battery manufacturing, construction, shooting ranges) are additional sources.
What Happens if Levels Are High
There is no way to reverse the neurological damage lead causes in children. For ongoing exposure, the most important step is always identifying and removing the source. In cases where blood lead levels are very high, medical treatment with chelation therapy can help pull lead out of the body. For children 10 and under, chelation is recommended when blood lead reaches 45 µg/dL or higher. For adults and adolescents, chelation is typically considered at 45 µg/dL when symptoms are present, and more urgently recommended above 70 µg/dL. Lead encephalopathy, a life-threatening swelling of the brain, requires emergency treatment regardless of the specific blood level.
For the vast majority of people whose exposure is low-level and chronic, the practical approach is reducing exposure and ensuring adequate calcium and iron intake, since deficiencies in those minerals cause the body to absorb more lead. Maintaining good nutrition won’t undo past exposure, but it limits how much additional lead the body takes in and how much stored lead gets released from bone.