What is it?
Lead poisoning occurs when lead builds up in the body, often over a period of months or years. Even small amounts of lead can cause serious health problems. Children under the age of 6 are especially vulnerable to lead poisoning, which can severely affect mental and physical development. At very high levels, lead poisoning can be fatal.
Lead-based paint and lead-contaminated dust in older buildings are the most common sources of lead poisoning in children. Other sources of lead poisoning include contaminated air, water, soil, and some toys and cosmetics. Although lead is still found widely in the environment, you can take a number of steps to help protect yourself and your family.
Initially, lead poisoning can be hard to detect — even people who seem healthy can have high blood levels of lead. Signs and symptoms usually don't appear until dangerous amounts have accumulated.
Although lead can affect almost every part of your body, it usually targets the oxygen-carrying protein in red blood cells (haemoglobin) first. In time, it attacks your nervous system.
Symptoms in children
The signs and symptoms of lead poisoning in children may include:
- Loss of appetite
- Weight loss
- Sluggishness and fatigue
- Abdominal pain
- Unusual paleness from anaemia
- Learning difficulties
Symptoms in newborns
Babies in the womb who are exposed to lead through their mothers may have:
- Learning difficulties
- Slowed growth
In some cases, these problems may persist beyond childhood.
Symptoms in adults
Although children are primarily at risk, lead poisoning is also dangerous for adults. Even exposure to amounts of lead too low to cause symptoms in the short term may increase the risk of high blood pressure and mental decline in the future. Symptoms in adults may include:
- Pain, numbness or tingling of the extremities
- Muscular weakness
- Abdominal pain
- Memory loss
- Mood disorders
- Reduced sperm count, abnormal sperm
- Miscarriage or premature birth in pregnant women
Lead is a metal that occurs naturally in the earth's crust, but human activity — mining, burning fossil fuels and manufacturing — has caused it to become more widespread. Lead was also once a key ingredient in paint and gasoline and is still used in batteries, solder, pipes, pottery, roofing materials and some cosmetics.
Sources of lead contamination include:
- Soil. Lead particles that settle on the soil from gasoline or paint can last for years. Lead-contaminated soil is still a major problem around highways and in some urban settings.
- Water. Lead pipes, brass plumbing fixtures and copper pipes soldered with lead can release lead particles into tap water.
- Lead paint. The use of lead-based paints for homes, children's toys and household furniture has been banned in the United States since 1978. But lead-based paint is still on walls and woodwork in many older homes and apartments. Most lead poisoning in children results from eating lead-based paint chips. Glazes found on ceramics, china and porcelain also can contain lead that leaches into food. Lead may be found in toys and other products produced abroad.
- Household dust. Household dust can contain lead from paint chips or soil brought in from outside.
- Some imported canned food. Although lead solder in food cans is banned in the United States, it's still used in some countries.
- Traditional remedies and cosmetics. Some cases of lead poisoning have been traced to the use of certain traditional medicines from India and other South Asian countries. Litargirio, a peach-colored powder popularly used in the Dominican Republic, contains very high levels of lead and should not be used. Kohl is a traditional cosmetic, often used as eyeliner. Testing of various samples of kohl has revealed high levels of lead.
People most at risk of harmful effects from lead in their body include:
- Babies and children under 6 years of age. Infants and young children are more likely to be exposed to lead than are older children. They may chew paint chips, and their hands may be contaminated with lead dust. Young children also absorb lead more easily and sustain more harm from it than do adults and older children.
- Children living in older homes. Although the use of lead-based paints has been banned since the 1970s, older homes and buildings often retain remnants of this paint.
- Children living below the poverty level. Although any child can be exposed to lead, children from low-income families are disproportionately affected, often because they live in older or unrenovated housing. Nonwhite children tend to have higher rates of lead poisoning.
- People with lead amalgams in their teeth. Although lead is no longer used to fill cavities in children's teeth, some adults may still have these fillings.
- Pregnant women. Because lead can harm an unborn child, pregnant women or women likely to become pregnant are especially at risk.
- Certain adults. Adults who breathe in lead dust while remodelling a home, making stained glass or refinishing furniture are also at risk.
Exposure to even low levels of lead — 10 micrograms (a microgram is one-millionth of a gram) in a deciliter (1/2 cup) of blood — can cause damage over time, especially in children. The greatest risk is to brain development, where irreversible damage may occur. Higher levels — 25 micrograms per deciliter of blood — can damage the kidneys and nervous system in both children and adults. Very high lead levels may cause seizures, unconsciousness and possibly death.
Complications in children
Health problems in children caused by elevated blood lead levels may include:
- Decreased muscle and bone growth
- Hearing damage
- Learning disabilities
- Nervous system and kidney damage
- Poor muscle coordination
- Speech, language and behavior problems
Complications in adults
High levels of lead in adults may lead to:
- Damage to reproductive organs in men
- Digestive problems
- High blood pressure
- Memory and concentration problems
- Muscle and joint pain
- Nerve disorders
- Pregnancy complications, including miscarriage, preterm delivery and stillbirth
Doctors usually use a simple blood test to detect lead poisoning. A small blood sample is taken from a finger prick or from a vein. Lead levels in the blood are measured in micrograms per deciliter (mcg/dL). An unsafe level is 10 mcg/dL or higher.