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To screen for possible excessive exposure to lead
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
A blood sample taken from a vein in your arm or by fingerstick or heelstick (for infants)
Lead is a soft metal present in the environment. When it is inhaled or ingested, lead can cause damage to the brain, organs, and nervous system. This test measures the current lead level in the blood.
Even at low levels, lead can cause irreversible damage without causing physical symptoms. In an infant, lead can cause permanent cognitive impairment, behavioral disorders, and developmental delays. Lead exposure can cause weakness, anemia, nausea, weight loss, fatigue, headaches, stomach pain, and kidney, nervous system, and reproductive dysfunction. 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.
Children under 6 years of age are the most likely to be exposed to lead because they 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.
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 venous blood draw should be ordered to confirm the results.
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. Testing recommendations and the definition of what is an abnormal blood lead level have changed significantly over the past 45 years.
The CDC uses a threshold blood lead level (BLL) of 5 mcg/dL to identify children living in environments that expose them to lead hazards. Children with elevated blood lead levels should prompt responses that include environmental assessments to determine lead sources, 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. BLLs will need to be monitored over time until the environmental investigations and subsequent responses are complete. Children with BLLs greater than 45 mcg/dL need evaluation and treatment (chelation).
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.
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 with increased risk factors.
Pediatricians may also offer screening to:
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, usually within a week to a month after the first test. 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. Those with persistent lead levels above 5-19 mcg/dL (remain elevated for 3 months or more) and those with initial tests greater than 20 mcg/dL should have their home surroundings evaluated to determine the source of the lead exposure.
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.
There is not yet a national guideline for blood lead screening in adults as there is for children. The clinical cut-off values for elevated blood lead currently vary from state to state. According to the CDC's Adult Blood Lead Surveillance program (ABLES), a national health objective is to reduce all blood levels in adults to less than or equal to 5 mcg/dL in 2015.
Adults who work in industries known for lead exposure, such as smelter facilities, lead plating, auto repair, and construction, should be screened for lead 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.
The Occupational Safety and Health Administration (OSHA) has developed rules for monitoring for lead in the workplace. OSHA requires that employee blood monitoring programs be triggered by the results found in an initial air monitoring program. If a worker has an initial blood lead test result of more than 40 mcg/dL, for example, testing should be done every two months until two consecutive lead tests show a blood lead level below 40 mcg/dL. Higher levels call for closer monitoring.
For both children and adults, lead testing may be ordered when a person's symptoms suggest potential lead poisoning. These symptoms are non-specific and may include fatigue, changes in mood, nausea, prolonged stomach distress, headache, tremors, weight loss, peripheral neuropathy, anemia, reproductive failure, encephalopathy, memory loss, seizures, and 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 presenting with growth failure, anemia, sleep problems, hearing loss, or speech, language or attention deficits.
The higher the test result, the more lead 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 lead travels from the lungs and intestinal tract to the blood and organs, and then is gradually removed from the blood and organs and stored in tissues such as 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 threshold blood lead level (BLL) of 5 mcg/dL (five micrograms per deciliter) to identify children living in environments that expose them to lead hazards. Any test results above this level should trigger lead management and monitoring. Any child who has an elevated blood lead level needs to have his or her home or other environment evaluated. Other people at the residence should be tested as well. Without the elimination or reduction of the source of the exposure - a lead hazard in the environment - the elevated lead level will likely recur.
In 2015, the National Institute of Occupational Safety and Health (NIOSH) designated 5 mcg/dL 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. The U.S. Occupational Safety and Health Administration (OSHA) Lead Standards require workers to be removed from lead exposure when BLLs are greater than or equal to 50 mcg/dL (construction industry) or greater than or equal to 60 mcg/dL in general industry, and allow workers to return to work when their BLL is less than 40 mcg/dL. Removal may also be recommended if the person is symptomatic at any level below 70 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.
Most experts agree that a child with a lead level greater than 45 mcg/dL should be treated with succimer/chelator in the hospital unless he or she is encephalopathic. Any lead level greater than 70 mcg/dL, whether in a child or an adult, should be considered a medical emergency.
Poisoning with lead is more harmful for children, whose brains and other organs are still developing. Adults tend to recover from lead ingestion better than children. Children who may be at risk should be screened as soon as possible.
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.
Healthcare practitioners should be aware that cultural practices and folk remedies, including soil ingestion, can increase a person's 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.
Some products that still contain lead include car batteries, solder, some pipes, ammunition, roofing, industrial paints, job sites, hobby areas, electronics, batteries, scrap metal recycling, some PVC, vinyl and plastics, brass objects including keys, costume jewelry, and X-ray shield materials.
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:
Some occupations that put people and their families at risk for lead exposure include:
Yes. If your home was built before 1978:
For your child:
Yes. If you are working in a potentially harmful environment with exposure to lead dust or fumes:
For more information about lead poisoning and workplace safety, visit the National Center for Environmental Health online at http://www.cdc.gov/nceh. For state and local health department assistance, you can contact CDC Emergency Response (24-hr. assistance during emergencies only) at 770-488-7100.
Sources Used in Current Review
2016 review by Irene Shu, PhD, DABCC, Assistant Laboratory Director, USDTL.
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