Lead poisoning happens when lead builds up in the body, and health agencies agree there is no known safe amount. The CDC says no safe blood lead level in children has been identified, and the World Health Organization says no level of lead exposure is known to be without harmful effects. This page explains, in plain words, what those agencies say lead does to the body, who is most at risk, where exposure usually comes from, and when to talk to a doctor.
In short: lead can harm the brain, nervous system, kidneys and blood, and young children and pregnancy are the most sensitive times. Most children with lead in their blood have no obvious symptoms, so the CDC calls a blood lead test the best way to know. The CDC uses a blood lead reference value of 3.5 micrograms per deciliter (µg/dL) to flag children with higher levels than most US children. If you are worried, talk to your doctor or your local health department. For a possible poisoning, call Poison Control at 1-800-222-1222.
This page is general information from public health agencies. It is not medical advice and does not replace a doctor. LeadDetector does not diagnose or suggest any treatment.
What lead does to the body
Lead gets into the body when it is swallowed or breathed in, most often as dust. According to the WHO, it builds up over time in the bones and teeth. That storage matters later, because lead held in bone can move back into the blood, for example during pregnancy.
The WHO says lead can affect many organ systems, including the brain, kidneys, liver and bones, and that in adults it contributes to high blood pressure, heart and blood vessel problems and kidney damage. The National Institute of Environmental Health Sciences (NIEHS) lists effects on the heart and blood vessels, nerves, kidneys and fertility in adults, and says even blood lead levels below 5 µg/dL may lower kidney function in adults. CDC’s workplace safety institute, NIOSH, notes that high exposure in adults can cause anemia, kidney damage, brain and nerve damage and infertility in both men and women.
For children, the CDC says lead can damage the brain and nervous system, slow growth and development, and cause problems with learning, behavior, hearing and speech. These can show up as lower IQ, a shorter attention span and poorer results at school. The CDC adds that the effects of lead poisoning can be permanent. You can read more about how these effects show up in our guide to lead poisoning symptoms.
| Who | What health agencies describe | Source |
|---|---|---|
| Young children | Damage to brain and nervous system, slowed growth, learning, behavior, hearing and speech problems | CDC |
| Pregnancy | Higher risk of miscarriage; baby born too early or too small; harm to the baby’s brain, kidneys and nervous system | CDC |
| Adults | Higher blood pressure, heart and kidney effects, nerve disorders, fertility problems | WHO, NIEHS, NIOSH |
| Everyone | Lead builds up in bones and teeth over time | WHO |
There is no safe blood lead level
This is the single most important point on the topic. The CDC states plainly that no safe blood lead level in children has been identified, and that even low levels are linked to developmental delays, difficulty learning and behavior problems. The WHO takes the same position for everyone. In practice it means public health advice focuses on finding and removing sources of lead before anyone is exposed, not on waiting for a number to look high.
The CDC blood lead reference value: 3.5 µg/dL
Blood lead is measured in micrograms of lead per deciliter of blood (µg/dL). The CDC currently uses a blood lead reference value (BLRV) of 3.5 µg/dL. The CDC lowered it from 5 µg/dL to 3.5 µg/dL on October 28, 2021, after its advisory committee recommended the change.
It helps to know what this number is, and what it is not:
- It is based on the 97.5th percentile of blood lead levels in US children, so children at or above it are in the top 2.5%.
- The CDC calls it a screening tool to identify children with higher levels than most children.
- The CDC says it is not health-based and not a regulatory standard. A result below 3.5 µg/dL does not mean “safe.”
- States set their own action levels, so what happens after a test can differ from state to state.
- The CDC reviews blood lead data every four years to decide whether the value should change.
Our guides to the blood lead test and to lead and children explain how testing is done and what the CDC says about results. Your child’s doctor is the person to explain your own family’s results.
Who is most at risk
Young children
The CDC says children younger than 6 are more likely to be exposed because of their hand-to-mouth behavior, and more vulnerable because their bodies are developing quickly. The WHO adds that young children can absorb more lead than adults from the same amount. The CDC names children living in homes built before 1978, children from low-income households, and immigrant and refugee children, including recently adopted children, as groups at greater risk.
Pregnancy
The CDC explains that lead stored in an adult’s bones can be released into the blood during pregnancy, and that if a pregnant woman is exposed, the developing baby can be exposed too. According to the CDC, lead in the blood during pregnancy can increase the risk of miscarriage, cause the baby to be born too early or too small, and hurt the baby’s brain, kidneys and nervous system. The CDC also notes that breastfeeding and formula mixed with contaminated water can expose infants. If you are pregnant and think you may have been exposed, the CDC’s advice is to talk to your healthcare provider.
Workers and their families
NIEHS says most adults with high blood lead levels were exposed at work, for example in mining, construction, welding and battery making. NIOSH warns that workers can carry lead dust home on clothes, shoes and hair, and that children have been poisoned this way. Some hobbies, such as stained glass, can do the same.
Common sources of lead exposure
Knowing the source is what makes prevention possible. The CDC and NIEHS name these as the main ones in the US:
- Old paint and the dust it makes. Homes built before 1978 probably contain lead-based paint. NIEHS calls lead dust the most common way people in the US are exposed. See lead paint testing and lead dust and soil testing.
- Drinking water from lead pipes, solder or fittings. NIEHS notes testing is the only way to know. See lead water testing.
- Soil near old houses, busy roads, airports or factories.
- Some imported products: certain spices, candies, traditional medicines, cosmetics such as kohl, toys, jewelry and cookware. See lead in household items.
- Jobs and hobbies that use lead.
When to talk to a doctor
The CDC says most children with lead exposure have no obvious immediate symptoms, which is why it does not recommend waiting for signs. Health agencies point to a conversation with a doctor in situations like these:
- Your child lives in, or often visits, a home built before 1978, especially one with peeling paint or recent renovation work.
- Your home has lead pipes or water testing found lead.
- Your family used a product named in an FDA or CPSC lead alert, such as recalled cinnamon or kohl.
- You are pregnant or breastfeeding and think you may have been exposed.
- Someone in the household works with lead.
- A home test, inspector or landlord has found lead hazards where children live.
The CDC says children enrolled in Medicaid are required to be tested at 12 and 24 months, and children aged 24 to 72 months with no record of a test must also be tested. Your child’s doctor can tell you whether a test makes sense for your child.
Who to call
- Poison Control: 1-800-222-1222. The Poison Help line connects you with a poison center, with expert advice 24/7 at no cost. Call right away if you think someone swallowed something containing lead. In an emergency, call 911.
- Your doctor or your child’s pediatrician for questions about testing and results.
- Your local health department. Most can run blood lead tests or point you to one, and many have lead programs that help families find sources at home. You can look yours up in NACCHO’s directory of local health departments.
- EPA’s National Lead Information Center: 1-800-424-LEAD (5323) for help finding a lead risk assessor or an accredited lab.
Finding the source at home
A blood test shows exposure, not where it came from. Finding the source is a job for testing: paint, dust, water, soil and household items each need their own method, and a test for one tells you nothing about the others. Start with our testing hubs, and if your home was built before 1978 or a child has a high result, consider a certified lead risk assessor. Our page on how to find a lead professional explains who does what.
Testing for lead poisoning
A blood lead test is the only way to know whether a person has lead in their body. Our testing guides explain every step:
- How to test for lead poisoning: every option, from a doctor’s blood test to what home kits can and can’t tell you.
- Blood lead test: how the test is done, finger-stick vs venous.
- Blood lead levels: what a normal or elevated result means, with the official charts.
- Lead screening for children: the ages and rules for testing kids.
- Lead testing for adults: work, hobbies and pregnancy.
- Heavy metal test: blood, urine and hair tests, and which ones to trust.
Frequently asked questions
What is a safe blood lead level?
None has been identified. The CDC says no safe blood lead level in children has been identified, and the WHO says no level of exposure is known to be without harmful effects.
What is the CDC blood lead reference value?
3.5 micrograms per deciliter (µg/dL). It marks the top 2.5% of blood lead levels among US children. The CDC says it is a screening tool, not a health-based or regulatory standard.
Can you tell if a child has lead poisoning by looking?
Usually not. The CDC says most children have no obvious immediate symptoms and calls a blood lead test the best way to know. Ask your child’s doctor.
Can adults get lead poisoning?
Yes. NIEHS says most adults with high levels were exposed at work, and links adult exposure to blood pressure, kidney, nerve and fertility effects. Talk to your doctor if you work with lead.
Does a home test kit tell me if my child is poisoned?
No. Home kits test paint, water or dust, not people. Only a blood test, ordered through a doctor or health department, measures lead in the body.