What is lead poisoning?
Lead poisoning is a preventable condition that results from environmental exposure to lead. This exposure, indicated by elevated blood lead levels, can result in permanent health damage, especially among children. According to the Centers for Disease Control and Prevention (CDC), about 250,000 children in the United States between the ages of 1 and 5 years have blood lead levels that are higher than 10 micrograms per deciliter (mcg/dL), the concentration at which the CDC, until recently, had recommended public health measures be taken. This number will rise to 450,000 children as a result of the 2012 recommendation of the CDC's Advisory Committee on Childhood Lead Poisoning Prevention (ACCLPP) to lower the blood lead level threshold to 5 mcg/dL, which the CDC accepted in May 2012. The recommendation was based on accumulating evidence of the detrimental health effects of even minute amounts of lead. It is hoped that lowering the threshold will impact efforts to address this public health problem, improving detection so that actions can be taken sooner.
Lead is a soft, corrosion-resistant metal that is present in small quantities throughout the environment. Prior to 1978, it was a major ingredient in household paints and gasoline, used in water pipes, used to solder canned foods, and put into pesticides that were used in orchards. While these uses have been banned in the United States and lead is much more carefully controlled, it is still used in more than 100 industries and a variety of hobbies.
Small particles of lead enter the body primarily through inhalation or ingestion of lead-laden dust. From the lungs or intestinal tract, the lead travels to the bloodstream and to organs throughout the body. The body then gradually moves lead from the blood and organs to the bones and teeth, where it may be stored for decades. About 94% of the lead in adults and 73% of that in children is eventually stored in the bones. To rid itself of lead, the body slowly takes it back out of the bones and excretes it in the urine and stool. Lead can also sometimes re-mobilize, moving back into the blood and organs when a bone is broken or during pregnancy. It can be passed from a mother to her unborn child and to an infant during breastfeeding. Women whose fetuses are exposed to lead may miscarry or have a premature delivery.
Lead poisoning can affect almost all parts of the body, but its effects are most pronounced on the central nervous system and kidneys. Lead can impair cognitive development, which can lead to learning disabilities and behavioral problems. Acute lead exposure can cause encephalopathy, severe abdominal pain, vomiting, diarrhea, coma, seizures, and in some cases death. Chronic exposure can cause weakness, prolonged abdominal pain, anemia, nausea, weight loss, fatigue, headache, and loss of cognitive function. Chronic, low-level lead exposure can be asymptomatic until kidney function starts to deteriorate.
The degree to which a person experiences lead poisoning depends on their age, the amount they are exposed to, the time period they are exposed to excessive amounts, and their own health and nutritional state. Those who are iron deficient or malnourished, for instance, are more vulnerable to increased lead absorption.
Housing built prior to 1978 is likely to contain lead-based paint and lead-contaminated household dust, especially if the house was built prior to 1950. Soil surrounding these houses may also be contaminated with lead and be a source of exposure. According to the CDC, about 24 million housing units in the United States have leaded paint and lead-contaminated house dust. Of these, about 4 million homes have one or more young children living in them.
Children less than 6 years of age are the most likely to be exposed to lead because of their increased hand-to-mouth behavior and high absorption rates. The lead gets into their bodies by their ingesting lead dust or paint chips, inhaling dust, mouthing or chewing items that contain lead or have been contaminated by lead, and/or by eating contaminated food or water.
Adult lead exposure is usually related to occupational or recreational (hobby) exposure. Children and spouses of those who work with lead may become exposed when lead contamination is brought home on the work clothes of the employee.
Work settings where lead exposure is possible
- Lead smelting
- Construction work
- Steel welding
- Bridge reconstruction
- Firing range instruction and cleaners
- Remodeling and refinishing
- Foundry work
- Scrap metal recycling
- Auto repair work
- Cable splicing
Hobbies where lead exposure is possible
- Casting bullets or fishing sinkers
- Remodeling a home built before 1978
- Target shooting at firing ranges
- Lead soldering
- Auto repair work
- Stained glass work
- Glazed pottery work
- Painting with artistic pigments
Some folk remedies, health foods, nutritional supplements, cosmetics, costume jewelry, toys, and canned foods imported from other countries may contain lead. Doctors should consider screening people, especially children, who are immigrants, refugees, or who are adopted from other countries as they are at an increased risk for excessive lead exposure.