Do you remember in the old western movies we watched as kids, the outlaws, ie. the “bad guys,” always died from “lead poisoning?” That’s right! When the bad guy finally “met his maker” it was because the sheriff, or some good guy on a white horse, shot him full of bullets. Symbolically, he was dying of “lead poisoning” but only because the bullets were made of lead. It wasn’t the lead that killed him, but the bullet!
Lead poisoning, in the non-western-movie sense, is a real entity, however. It doesn’t kill but when it occurs it has long term, irreversible consequences. Lead poisoning is far less a problem now than it was before 1978 when the federal government outlawed the manufactured of lead-based paint and introduced unleaded gasoline for automobiles. This eliminated the most common sources of, and means by which, children and adults got lead poisoning. Those were by ingestion or inhalation. In recent studies, lead has been found in widespread areas in drinking water and consumer products, once again drawing attention to the problems it can cause.
Bottled water has been considered safe from lead exposure, but some amounts of lead are still detectable. The Food and Drug Administration (FDA) has set limits for the amount of lead permissible giving some leeway, but The American Academy of Pediatrics has stated that “no amount of lead in drinking water is considered safe.”
Lead toxicity from inhalation could be classified with industrial lung diseases, but it is not because it bypasses the lungs and ends up affecting the blood, the skeletal system (the bones), and soft tissues. The kidneys, bone marrow, and nervous system are the “soft tissue” organ systems affected by lead poisoning that have the most serious negative consequences.
Most adult lead poisoning comes from “workplace” exposure. Those who labor in “smelting, battery making, ship burning, soldering, stained glass manufacture, brass foundry work, construction, and structural demolition” are at risk. “Particularly severe exposures have occurred in construction workers involved in the demolition and renovation of painted steel structures such as bridges and elevated highways,” and older homes and buildings, as well. Lead is also a problem when it is “in the air, dust, soil, and drinking water.” People inhale lead from their surroundings or from residue on their clothing or ingest it from unwashed hands.
Lead exposure in children is most often by ingestion. Lead-based paint on cribs, furniture, or woodwork, and “paint chips” from those areas, is the principal source. We all know how kids love to put anything in their mouths and chew away. Contaminated dust and soil are concerns, as well. Every child likes to play in the dirt and then put their hands in their mouth. Drinking water is a common source especially if it is “contaminated by passing through lead pipes or coming in contact with lead solder.” Lead pipes are not used in homes today so newer construction poses less of a risk. Folk medicines, herbal remedies, imported goods such as candies, spices, and pottery are sources, too.
When lead is ingested or inhaled, it doesn’t disperse evenly throughout the body. The “toxic effects are principally in three organ systems: the blood, the nervous system (both central and peripheral), and the kidneys.” Additionally, it deposits in the bone marrow. In the nervous system, lead destroys the axon, the part of the nerve that distributes nerve impulses, it slows nerve impulse conduction, and destroys the protective sheath covering nerve fibers. These result in neurologic problems with the hands and feet. Cognitive and behavioral changes occur also. “Diminished intelligence, shortened attention span, and slowed reaction time” and even worse, delirium and coma, can occur. In the kidneys, lead damages the filtering tubules and reduces kidney function.
Once lead has entered the body, about 1% of it finds its way into the blood, most of it depositing in the red blood cells (RBC’s—basophilic stippling). By so doing, it can destroy RBC’s and cause anemia. The remainder of the lead, the vast majority, finds a home in the skeletal system where it remains stored. Lead poisoning is often asymptomatic, but it can cause non-specific symptoms like headache, abdominal pain, constipation, and loss of appetite. The major concerns with lead poisoning, however, are the neurologic abnormalities from long term exposure to the nervous system.
It is recommended that children at risk of lead exposure have a blood test for lead at ages 12 and 24 months for Medicaid patients. Otherwise, children between ages 3 and 6 years should be screened at least once. Being “at risk” means the following:
Does the child live in, or regularly visit, a house built before 1978?
Is the child from a low-income family?
Is the child an immigrant, refugee, or recently adopted from an underdeveloped country?
Does the child live with someone who works with lead or has a hobby exposing them to
lead?
Has a family member been observed to have or treated for lead poisoning?
Does the child live near a smelter, battery recycling plant, or other industry likely to release
lead?
Screening is done by a finger-stick or heel-stick blood sample, and if positive, must be confirmed and verified by additional testing. Definitive testing gives the doctor an actual blood level of lead which determines if treatment is needed. Chelation therapy is the treatment of choice. In chelation therapy, a chemical is given IV that chelates, or attracts and absorbs, the lead out of the blood stream. It works quite effectively.
As with a lot of medical problems, primary prevention is the most effective deterrent. Avoiding lead exposure in the home, at the workplace, and the drinking water is the best policy. Hand washing, unleaded gasoline, lead-free paint, and good personal hygeine are just a few of the important preventive measures.
During my years of practice, 1974-2014, I recall, perhaps, one child whose heel-stick lead screen test was positive for lead. Follow-up with venous blood sampling, however, was negative. I also recall a situation where the lab reported “basophilic stippling” in a child’s blood sample. Basophilic stippling is the presence of blue particles in the RBC’s when observed by a microscope. This most often occurs in lead poisoning. Testing the child, retrospectively, for lead proved negative. The cause of basophilic stippling was never determined.
Lead poisoning was a bigger problem in the past. It occurs today only in low income or migrant families, old construction housing, or workplace exposure. Much has been done to eliminated lead from our environment with successful results, but a significant number of children are still found to have concentrations of lead above safe levels. Any detectable level of lead is abnormal so awareness and testing are still warranted.
References: Mayans L. Lead Poisoning in Children Am Fam Phys 2019 July 19;100(1):24-30.
Landrigan PJ, Todd AC. Lead Poisoning West J Med 1994;161:153-159.
Thomas A. Lead has not gone away—What should Pediatric clinicians do? Medscape Medical News 2024 Apr 5.
