To screen for possible excessive exposure to lead, especially in children
As indicated by a child lead screening program or physician preference, such as at 1 and 2 years of age; children considered to be at risk may need additional testing from 18 months to 6 years of age; when your occupation or hobby may expose you or your family to lead; when you have symptoms suggesting lead poisoning
Blood is drawn from a vein in the arm. Sometimes, blood is collected by fingerstick (or heelstick for infants). If test results from a fingerstick are abnormal, a second test should be done on blood drawn from a vein to confirm the results.
Lead is a soft metal present in the environment that is highly poisonous when absorbed into the body, affecting almost every organ. This test measures the current lead level in the blood. Approximately 1% of lead is found free in blood, so the blood lead level (BLL) may not reflect actual lead levels.
You can be exposed to lead by breathing in or ingesting lead dust or by absorbing it through your skin to a lesser degree. In adults, most lead is absorbed via inhalation, but in children most absorption occurs through the digestive tract. Once absorbed, lead is distributed to blood, soft tissues, and bone. Lead can cause damage to the brain, organs, and nervous system.
Even with long-term exposure of low levels, lead can cause irreversible damage without associated physical symptoms. In an infant, lead can cause permanent cognitive impairment, behavioral disorders, and developmental delays. Symptoms of lead toxicity are different depending on whether the exposure to lead was acute or chronic. Acute lead exposure can cause constipation, loss of appetite, abdominal pain, joint/muscle aches, headache, depression, and decreased sex drive. At blood lead levels greater than 150 micrograms per deciliter (mcg/dL), brain damage may occur, resulting in coma, seizure, or death. Chronic, low level exposure can cause depression, anxiety, decreased neuromotor function, anemia, and kidney damage. Chronic lead exposure has also been linked to hypertension, but the degree of association is not well established. Lead can be passed from mothers to their unborn children and can cause miscarriages and premature births.
In the past, lead was used in paints, gasoline, water pipes, and other household products, such as the solder used in canned food. Although these uses have been limited in the U.S., lead is still used in many products and industrial processes both in the U.S. and around the world. Housing built prior to 1978 may contain lead-based paint and lead-contaminated household dust. Soil surrounding these houses may also be contaminated with lead. In addition, approximately 10 million people receive their water from pipes that are at least partially lead.
Children under 3 years of age are the most susceptible to lead exposure and poisoning. Increased risk of lead toxic effects are due to an incomplete blood brain barrier, higher tendency for iron deficiency, and because children often put their hands in their mouths, accidentally ingesting lead dust or paint chips. They can also inhale lead dust and mouth or chew lead-contaminated items. Adult lead exposure is usually related to occupational or recreational (hobby) exposure. Children of those who work with lead may also become exposed when lead contamination is brought home on the work clothes of their parents.
For additional information, read the article on Lead Poisoning.
How is the test used?
The lead test is used to determine the concentration of lead in the blood at the time the sample was collected. The blood lead test is used to screen for exposure to lead. It may also be ordered to monitor the effectiveness of treatment and to confirm that lead levels are decreasing over time.
Lead concentrations are monitored at the local level following state and national standards. The Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics (AAP), and a variety of other organizations make recommendations regarding screening children for lead exposure.
Blood lead is monitored in workers whose environment contains lead. It is used to evaluate chronic lead exposure and recent lead exposure. Sometimes, a zinc protoporphyrin (ZPP) test is also ordered. The ZPP is increased when lead begins to affect red blood cell production. It is not sensitive enough to use as a screening tool for children, but it may be ordered to help evaluate average lead exposure in adults over the last several weeks. ZPP may also be ordered when a person shows signs of lead toxicity, but their BLL is not increased to a level to account for these symptoms.
When is it ordered?
For screening children:
The American Academy of Pediatrics (AAP) recommends that a risk assessment be performed for lead exposure at well-child visits at 6 months, 9 months, 12 months, 18 months, 24 months, and at 3, 4, 5, and 6 years of age. A blood lead level test should be done only if the risk assessment comes back positive. According to the AAP and the U.S. Centers for Disease Control and Prevention (CDC), universal screening or blood lead level tests are no longer recommended, except for children in high prevalence areas where more than 12% of children between 1-2 years of age have an elevated blood lead level, or where more than 27% of housing was built before the 1950s.
Pediatricians may also offer screening to:
- Medicaid-eligible children at age 1 and again at 2 years of age
- Children of all ages who are recent immigrants, refugees, or adoptees at the earliest opportunity
- A child whose parent, guardian, or provider requests blood lead testing due to suspected exposure
People should check with their healthcare practitioner and/or local health department regarding lead screening guidelines specific to the risks in their area.
Managing children with elevated blood levels:
Since fingerstick samples can be contaminated during collection of the specimen, an initial elevated result obtained by a fingerstick sample should be repeated with testing on a blood sample drawn from a vein in the arm for confirmation, and time to repeat varies based on the blood lead level measured. Follow-up testing is then used to monitor the persistence of an elevated blood lead test and is recommended whenever a child's blood lead level is higher than 5 mcg/dL.
For screening adults:
- Blood lead tests may be ordered to screen adults in the workplace when lead contamination is a possibility. Family members also may be screened because lead can be carried home on clothing. This testing conforms to federal and state laws for occupational exposure.
- Adults who have hobbies that involve lead-based paints, ceramics, or gasoline also should be tested. For a list of hobbies that may expose someone to potentially high levels of lead, see the article on Lead Poisoning.
- Pregnant women and mothers who are breastfeeding may be screened if they are at increased risk of lead exposure.
For both children and adults, lead testing may be ordered when signs and symptoms suggest potential lead poisoning. These symptoms are non-specific and may include:
- Changes in mood
- Nausea, prolonged stomach distress
- Weight loss
- Peripheral neuropathy
- Encephalopathy, memory loss, seizures, coma
Many children have no physical symptoms at the time of the exposure, but potentially permanent damage can still be occurring. Testing for lead exposure should be considered in children who grow slower than children the same age or who have anemia, sleep problems, hearing loss, or speech, language or attention deficits.
What does the test result mean?
The higher the test result, the more lead there is in the blood. However, the amount of lead in the blood does not necessarily reflect the total amount of lead in the body. This is because most lead is stored in bones and teeth. The danger that a particular lead level represents depends on the age and health of the person, the amount of lead they are exposed to, and the amount of time that they are exposed to elevated lead levels.
Exposure to lead is not healthy for anyone, but children are more vulnerable to its effects. The CDC uses a blood lead reference value (BLL) of 5 mcg/dL (five micrograms per deciliter) to identify children with lead levels much higher than most children. Children with elevated blood lead levels should prompt responses that include environmental assessments to determine the source of lead source exposure, educating family members about lead poisoning, and instituting follow-up testing to monitor the condition. Children should also be assessed for iron deficiency and general nutrition consistent with AAP guidelines. Blood lead levels will need to be monitored over time until the environmental investigations and subsequent responses are complete.
Children with blood lead levels greater than 45 mcg/dL need evaluation and chelation treatment (chelation). Chelation treatment consists of giving a medication orally that binds lead and eliminates it through the urine. Some children may not be able to take this medication and will require treatment with calcium disodium ethylenediaminetetraacetic acid (EDTA) via injection. Children with an initial blood lead level greater than 70 mcg/dL will typically require hospitalization and immediate intervention.
In 2015, the National Institute of Occupational Safety and Health (NIOSH) designated 5 mcg/dL or above as an elevated blood lead level in adults. The U.S. Department of Health and Human Services recommends that blood lead levels among all adults be reduced to less than 10 mcg/dL.
Because lead will pass through the blood to an unborn child, pregnant women need to limit their exposure to lead to maintain a low blood level and as close to zero as possible to protect the developing fetus.
Any lead level greater than 70 mcg/dL should be considered a medical emergency.
Is there anything else I should know?
Lead interferes with the absorption of iron. Children with raised blood lead concentrations should be tested for iron deficiency.
Each person eliminates lead differently. Thus, laboratory tests are just one part of the picture in lead poisoning cases. Careful monitoring with medical examinations is needed. Patients with altered kidney function may not eliminate lead as quickly.
Healthcare practitioners should be aware that cultural practices and folk remedies, including soil ingestion, can increase the risk of lead exposure. Folk remedies prepared by newly immigrated populations from Southeast Asia are particularly known as possible sources of lead. Other potential lead sources include imported foods, candy, cosmetics, costume jewelry, brass keys, and toys or household items containing or painted with lead.
What products in the U.S. still contain lead, besides paint and ceramics?
How do people get exposed? Is touching these products enough to raise my blood lead level?
Just holding a lead object in your hands won’t poison you. Most lead is present as an inorganic compound and does not move well through the skin. Breathing in or swallowing lead-laden dust may poison you, however. Situations that could lead to lead poisoning would be:
- Touching surfaces covered with lead dust and then transferring the dust to your mouth with fingers, food, or toys
- A toddler touching the windowsills in a pre-1978 house with their mouth or fingers and then swallowing lead dust or lead chips
- Inhaling dust during a home renovation project on a house built before 1978, especially when using power sanders or other work practices that generate lead-contaminated dust
- Ingesting lead through gardening in contaminated soil around the foundation of an older house or garage, or in soil contaminated with leaded gas along older highways, or abandoned industrial settings
- Drinking water through lead pipes – nearly 10 million Americans get drinking water from pipes that are partially lead. In addition, high levels of lead are found in drinking water throughout the U.S., most particularly in Flint, MI.
- Swallowing lead shot (shotgun ammunition), a curtain weight, or a lead toy and not passing it through your system
- Inhaling fumes from burning lead-painted wood or battery casings in home fireplaces
- Consumer products:
- Baby bibs, electrical cords, purses, garden hoses
- Toys, art supplies, imitation leather, jewelry, hair dyes
- Brass faucets, fishery sinkers, curtain weights
What occupations might result in lead exposure?
Some occupations that put people and their families at risk for lead exposure include:
- Lead smelting
- Steel welding
- Bridge reconstruction
- Firing range instruction and cleaners
- Remodeling and refinishing older homes
- Foundry work
- Scrap metal recycling
- Stained glass making
- Using lead glazes in ceramics
- Painting metal
- Auto repair work
- Electrician work
- Cable splicing
Are there ways to protect myself and my family from lead exposure?
Yes. If your home was built before 1978:
- Assume that you may have lead in the house, or get the house and the soil that surrounds it checked by a professional
- Use cold water for drinking
- Damp mop smooth floors and surfaces frequently to control dust
- Vacuum carpets and upholstery to remove dust – use a HEPA vacuum filter if possible
- Do a monthly check to look for chipping, peeling, or other damaged surfaces, especially in window areas and porches; repair any chipping, peeling, or damaged paint or surface as soon as it is observed, then thoroughly clean the area to remove lead dust
- Learn how to do renovation and repair projects using lead-safe work practices to avoid creating more lead dust or contamination
For your child:
- Frequently wash your child’s hands and toys to reduce lead dust contamination
- Avoid using home remedies that contain lead
- Keep your children (and pregnant women) away from lead hazards and out of the area during renovation or repair projects
- Don’t let children put objects in their mouths that were not made to be used as a child’s toy, including keys, jewelry, or dirt
- Get your child tested for lead at least at 1 and 2 years of age; contact your local health department to learn more about screening recommendations for your area
- Eat a well-balanced diet with adequate calcium, iron, and vitamin C
Are there ways to protect myself and my family if I have a job where I may be exposed to lead?
Yes. If you are working in a job with potential exposure to lead dust or fumes:
- Wash your hands before you eat, drink, or smoke
- Eat, drink, and smoke in areas that are free from lead dust and fumes
- Wear a properly fitted respirator with a HEPA filter (N-100 rating); shave your face to get the best fit
- Keep your street clothes in a clean place; change into different clothes and shoes before you work with lead
- Shower immediately after working with lead, before you go home
- Launder your work clothes at the work place or separately from other family members’ clothes