What Is Lead Poisoning?
Lead poisoning is the accumulation of lead in the body which usually develops over the course of months or years
Lead is a naturally occurring metal with no benefit to the body.
Toxic exposure can affect the brain and other vital organs, causing neurological and behavioral changes, gastrointestinal illness, kidney impairment, and developmental delays.
At very high levels, it can be fatal.
A poisoning can be diagnosed with blood and imaging tests.
If metal concentrations are high, treatment may involve the use of chelating drugs that bind to lead so that it can be eliminated from the body.
Lead Poisoning Symptoms
While the poisoning can cause injury to almost every organ of the body, the brain, and gastrointestinal tract are usually where the first signs of disease appear.
The symptoms of poisoning are often subtle and difficult to spot.
In some people, there may be no symptoms.
The most commonly seen include:
- Loss of concentration
- Deficits in short-term memory
- Dizziness and loss of coordination
- Unusual taste in the mouth
- A blue line along the gum (known as the Burton line)
- Tingling or numb sensations (neuropathy)
- Abdominal pain
- Decreased appetite
- Nausea and vomiting
- Diarrhea or constipation
- Slurred speech
Unlike adults, children may exhibit extreme behavioral changes (including hyperactivity, apathy, and aggressiveness) and will often fall developmentally behind other kids of the same age.
Permanent intellectual disability can sometimes occur.
Complications of lead poisoning may include kidney damage, hypertension, hearing loss, cataracts, male infertility, miscarriage, and preterm birth.
If lead levels increase to over 100 μg/dL, brain inflammation (encephalopathy) may occur, resulting in seizures, coma, and even death.
Children are at especially high risk, due in part to their small body mass and relative level of exposure.
They also tend to absorb lead more readily in tissues of the brain and exhibit hand-to-mouth behaviors that promote exposure.
Other typical causes of lead exposure include:
- Water, mainly due to older lead pipes and the use of lead solder
- Soil that has been contaminated with leaded paint or gasoline
- Occupational exposure in mines, smelting plants, or manufacturing facilities where lead is involved
- Imported pottery and ceramics used for dinnerware
- Leaded crystal used for decanted fluids or food storage
- Ayurvedic and folk medications, some of which contain lead for “curative” benefits and others of which are tainted during manufacture
- Imported toys, cosmetics, candy, and household products manufactured in countries with no lead restrictions
A poisoning can also occur during pregnancy, caused when transient bone loss leaches lead into the system and exposes the unborn baby to high levels of toxicity.
Lead toxicity can be diagnosed through a variety of lab and imaging tests.
The main test, called the blood lead level (BLL), can tell us how much lead there is in your blood.
In an ideal situation, there should be no lead, but even low levels may be considered acceptable.
The blood lead concentration is measured in terms micrograms (μg) per deciliter (dL) of blood.
The current acceptable range is:
- Less than 5 μg/dL for adults
- No acceptable level has been identified for children
While the BLL can give a clear picture of your current status, it cannot tell us the cumulative effect that lead has had on your body.
For this, the doctor may order non-invasive X-ray fluorescence (XRF), essentially a high-energy form of X-ray which can assess how much lead there is in your bones and reveal areas of calcification indicative of long-term exposure.
Other tests may include blood film examination to look for changes in red blood cells and erythrocyte protoporphyrin (EP) which can give us a clue as to how long the exposure has been going on.
This main form of treatment for a poisoning is called chelation therapy.
It involves the use of chelating agents that actively bind to metal and form a non-toxic compound that can readily be excreted in urine.
Chelation therapy is indicated in people with severe poisoning or signs of encephalopathy.
It may be considered for anyone whose BLL is above 45 μg/dL.
Chelation therapy has less value in chronic cases below this value.
Therapy may be delivered either orally or intravenously.
The most commonly prescribed agents include:
- Bal in oil (dimercaprol)
- Calcium disodium
- Chemet (dimercaptosuccinic acid)
- EDTA (ethylene diamine tetra-acetic acid)
Side effects may include headaches, fever, chills, nausea, vomiting, diarrhea, shortness of breath, irregular heartbeat, and chest tightness.
On rare occasions, seizure, respiratory failure, kidney failure, or liver damage has been known to occur.