Lead is a heavy metal and a strong poison. It can accumulate in the body if it enters the mouth or is inhaled. It can also enter through splits in the skin or through mucous membranes.
It can damage all of the body systems, including the heart, bones, kidneys, teeth, intestines, reproductive organs, and the nervous and immune systems.
Young children, especially before the age of 6 years, are particularly sensitive to lead poisoning. It can irreversibly damage mental and physical development.
Around half a million children in the United States between the ages of 1 and 5 years are believed to have lead levels in their blood that put them at risk of lead poisoning.
The most common sources are lead-based paint and water pipes in older buildings, lead-based dust, and contaminated water, air, or soil. Particles of lead can collect in household dust and garden soil. Cigarette smoke may also contribute.
- Lead is a naturally occurring heavy metal that can damage all human body systems.
- Children and unborn children are particularly susceptible.
- Some 24 million American homes are thought to contain unsafe quantities of lead paint or dust.
- The production of lead-based paint was banned in America in 1978.
- Symptoms of poisoning include nausea, dizziness, reduced brain volume, and a strange taste in the mouth.
- Some traditional medicines contain lead.
Lead is poisonous to all body functions, especially in children.
The symptoms of lead poisoning typically appear when a dangerous amount of lead is already in the body.
Occasionally, it can occur from a single high dose, but more often it is a gradual build-up.
Symptoms vary across age groups.
Children are more at risk from lead poisoning for a number of reasons:
- They are more likely to pick up lead contamination from the soil and to then consume it.
- They are also closer to ground level more frequently and, therefore, more at risk of breathing in dust from the floor.
Signs and symptoms of acute lead poisoning include:
- abdominal pain and vomiting
- black diarrhea
- encephalopathy, which affects the brain and can lead to seizures, coma, and death
However, symptoms are more likely to appear over time. This is known as chronic poisoning.
- slowed body growth
- reduced IQ
- loss of appetite and weight loss
- constipation and mild abdominal pain
- general fatigue
- blue tinge around the gums
- hearing loss and reduction in other senses
- neurological weakness, in the later stages
Young children absorb lead 4 to 5 times more readily than adults and, because their bodies are still developing, the risks are further increased.
Lead poisoning can cause hallucinations.
The following are symptoms of lead poisoning in adults:
- abdominal pain is usually the first sign if a high dose of lead is ingested
- raised blood pressure
- joint and muscle pain
- tingling, pain, and numbness in the extremities
- memory loss and decline in mental functions
- unusual taste in the mouth, often described as metallic
- difficulty sleeping
- mood disorders
- reduction in sperm volume and quality
- loss of pregnancy or preterm birth
- foot or ankle drop, in the later stages
Those who work in jobs that involve lead have a higher risk than those in other occupations.
Examples include auto repair shops and home improvements, especially if the home was built before lead-based paint was banned in 1978.
Lead is a natural element found in the earth's crust. Human activity — such as mining, burning fossil fuels, and manufacturing — has made it more widespread and accessible. Where lead is in the air as a pollutant, it can be present in dust.
It is no longer used in paint or fuel in the US, but it is still present in batteries, pottery, pipes, solder, some cosmetics, and jewelry.
Lead as a constituent in paint was banned in 1978, but it may still be present in some older residences. The majority of lead poisoning cases in children are due to eating old lead-based paint chips.
Brass plumbing fixtures and pipes made or soldered using lead and can release lead into tap water. Lead solder used in the manufacture of food cans is banned in the U.S., but is still used in some countries.
Traces of lead in the soil can remain for long periods of time.
- Soil: Lead that has arrived in the soil from lead-based gasoline or paint can survive for many years. Areas next to old walls or by the sides of roads can be particularly affected.
- Dust: Paint chips or contaminated soil can form dust particles.
- Toys: Old toys might have been colored with lead-based paint. Although this is illegal in the US, toys from other countries may still use lead-based paints.
- Traditional cosmetics: Kohl, used as an eyeliner, has been found to contain high levels of lead.
- Stained glass: Making stained glass involves using lead solder.
- Pottery: Some ceramic glazes contain lead.
- Tobacco smoking: Active and passive smoking have been linked to higher lead levels in the blood.
Other, less common sources of lead include some traditional medicines:
- Daw tway: This digestive aid, used in Thailand, contains high levels of lead and arsenic.
- Ghasard: This is an Indian tonic and digestive aid.
- Ba-baw-san: A Chinese herbal remedy that is used for colic in babies.
- Litargirio: This peach-colored powder is used as a deodorant, particularly in the Dominican Republic.
- Greta (also called azarcon): This is a Hispanic powdered remedy for upset stomachs. It is also used to soothe teething babies. Some preparations contain 90 percent lead.
Lead damages every system in the body that it encounters. Two of its most damaging interactions are with the enzymes and the nervous system.
Much of the damage lead produces is due to an interruption in the work of enzymes. These are proteins that carry out multiple functions within the human body.
Like other metals present in the body, lead binds to enzymes that non-lead co-factors bind to. These are sometimes called "helper molecules."
But, while other metals and substances carry out necessary roles, being a co-factor for switching enzymes off or on, lead binds to co-enzymes without causing the appropriate enzyme action to occur. This impedes the enzymes from carrying out their work.
Lead negatively impacts delta-aminolevulinic acid dehydratase (ALAD) and ferrochelatase. These enzymes are needed to help form a vital component of blood called heme.
On the nervous system
The organ most severely affected by lead poisoning is often the brain.
The brain is one of the organs most affected by lead, and particularly the prefrontal cortex and anterior cingulate cortex. These areas are responsible for high-level functions, mood regulation, and decision-making.
The barrier between the blood supply and the brain, known as the blood-brain barrier, protects the brain from many toxins. However, lead passes easily through this protective layer.
Once in the brain, lead interferes with the development of synapses, the production of neurotransmitters, and the structure of ion channels.
Lead also disprupts the myelin coating on nerves. This insulating layer is essential for the successful transmission of messages.
Many neurotransmitters are hindered by lead, including glutamate in the hippocampus. Glutamate is vital for learning and laying down memories.
Lead has been found to trigger programmed cell death (PCD, also called apoptosis) in the central nervous system, including the brain.
PCD is usually a normal function of the human body. It helps clear away old and broken cells. However, if PCD gets out of hand, it can wrongly destroy fully functioning cells. Depending on the type, these cells may not be replaced.
Anyone who is concerned that their child may be affected by lead can request a blood test. This involves a simple prick of the finger or vein puncture.
Testing the blood for the presence of lead is a relatively simple procedure.
The CDC recommend starting to take preventive action when that a blood lead levels reach 5 micrograms per deciliter (µg/dL). Around half a million children are currently thought to have lead above this level in their blood in the U.S.
The CDC aim to see all lead levels in children reduced to 10 µg/dL or less by 2020.
In adults, 10 µg/DL is considered the safe upper level.
In adults, gastrointestinal symptoms are usually seen at 45 μg/dL or higher.
In most adults with levels of 25 µg/DL, this is due to workplace exposure.
There are no safe levels of lead in the body. In other words, any presence of lead in the body can cause harm.
Other tests for lead poisoning include:
- bone marrow biopsy
- erythrocyte protoporphyrin level (a test for iron deficiency)
- iron level
- complete blood cell count and coagulation tests
- x-ray of long bones and abdomen.
As with most types of poisoning, the first step is to identify and remove the source of the poison.
If the problem is old paint, it may be best to seal in the paint rather than to chip it, sand it or burn it off, which could increase the quantities of lead in the air.
If removing the source does not reduce blood levels, the following may be necessary:
- Chelation therapy: This involves medication that binds with the lead and allows it to be passed in the urine or feces.
Additionally, if there are concerns that someone has eaten a life-threatening amount of lead in one dose, the following procedures might be needed:
- Bowel irrigation: Flushing out the entire gastrointestinal tract with large volumes of polyethylene glycol solution
- Gastric lavage: Also called gastric suction or stomach pumping, this involves washing out the stomach via a tube and saline irrigation inserted into the throat.
Intravenous fluid administration may be necessary.
If lead is present in the pipework, run the tap for 1 minute before use.
Measures that can help reduce the risk of lead poisoning include:
- Running water: In older properties with lead pipes or fittings, run the cold water for at least 1 minute before use. Do not use the hot water tap for cooking or drinking.
- Avoiding soil: Prevent children from playing in the soil. Perhaps provide a sandbox and plant grass to cover patches of bare soil.
- Following a healthful diet: a diet that is rich in calcium and iron can help lower lead absorption.
- Installing a filter: if water tests high for lead, consider installing an effective water filtering device, or switch to bottled water.
- Washing: Wash children's hands regularly to lower the risk of swallowing fragments of lead from soil and dust.
- Cleaning: Keep the environment as free from dust as possible. Wipe floors with a damp mop and clean surfaces with a damp cloth. This keeps the dust from lifting back into the air and being breathed in.
- Containers: Do not store wine, vinegar-based dressings, or spirits in lead crystal decanters for long periods of time, as lead can leach into the liquid.
- Canned foods: Avoid imported canned foods, as some countries have not yet banned lead from manufacturing processes.
Adults who have experienced relatively minor lead poisoning may recover completely. As children are still developing, they may not fully recover. There may be permanent IQ and attention deficits.
Other body systems, such as the kidneys and nerves, might also sustain permanent damage. Depending on severity, recovery can take months or years.
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