Lead has many industrial uses, some of which have dispersed this element throughout the environment. Once lead is dispersed, it can have negative health effects. What is the connection between lead, children, and migratory birds?

Composer Ludwig van Beethoven suffered from ceaseless abdominal pain, nausea, irritability, and depression in the years leading up to his death in 1827. He consulted with dozens of doctors, none of whom could diagnose the problem. As early as 1802, Beethoven asked his brothers to have the cause of his illness determined after his death.

Almost two centuries later, a doctor has indeed discovered the cause. Analyzing a strand of Beethoven's hair that survived for many generations, Dr. William Walsh of the Health Research Institute in Naperville, Illinois, recently identified levels of lead that were 100 times what is now common in humans. Walsh determined that Beethoven had lead poisoning, which would explain the various symptoms from which the composer suffered. Walsh thinks that it is unlikely that the lead poisoning caused Beethoven's deafness, which developed gradually over a 20-year period and became total in 1819.

It is unclear what the source of Beethoven's lead poisoning was—it could have been his drinking water, his food, or the utensils with which he ate. What seems certain is that other residents of the area were not sickened by lead, at least not to the same degree that Beethoven was.

• Read more about Walsh's diagnosis in the CNN.com article, "Lead poisoning seen as probable cause of Beethoven illnesses."

Lead poisoning continues to be a problem even today. According to the Centers for Disease Control and Prevention (CDC), nearly 1 million children in the United States have lead levels in their blood that are high enough to cause irreversible damage to their health.

Lead is a heavy metal once used widely in many products, such as paint, gasoline, and food containers. As a natural element, lead does not break down in the environment. Once it has been dispersed, it remains in the environment until humans intervene to remove or at least contain it.

Lead most often enters the human body by being swallowed. In cases of extreme exposure to lead-contaminated dust, the lead can enter the body through the respiratory system. Lead poisoning can only be diagnosed with a blood test. The CDC defines a blood level of 10 µg/dl (micrograms per deciliter) as a lead level requiring intervention to reduce lead exposure. Many pediatricians now test for lead levels during routine checkups for young children.

The most common sources of lead poisoning are:

• lead-based paints. Lead-based paints, the major source of lead exposure, cause lead-contaminated dust, especially in older homes. The dust settles on children's hands and toys. Then through normal hand-to-mouth activity, the children swallow the leaded dust. Remodeling a home can send large quantities of lead-contaminated dust into the house.
  
  
• drinking water. Most of the lead in drinking water comes from household plumbing, not from the local water supply. Homes in which water is delivered in lead pipes or in copper pipes with lead solder are at highest risk. The lead level can only be determined by a certified laboratory.
  
  
• ambient air, soil, and dust. The outside vicinity of a house can be contaminated by flaking lead-based paints or old deposits of leaded gasoline, for example, from gasoline-powered lawn mowers. Children can ingest the contaminated soil while playing outside, and people unknowingly carry the soil into the house on the soles of their shoes.
  
  
• food. Food can become contaminated either from dust or from being stored in containers containing lead. Such containers include those made of leaded crystal, soldered cans, and lead-glazed ceramics.
  
  
• work-related sources. Adults who work in construction, demolition, painting, radiator repair shops, lead factories, or with batteries, are exposed to lead. They can carry lead dust home on their clothing, shoes, and hair. This transported lead can expose family members.

There is currently no cure for lead poisoning. In severe cases medical treatment may reduce the blood levels, but there is no way to completely eliminate the lead from the bloodstream. Therefore, prevention is the most effective course of action.

• A substance that is swallowed into a person's digestive system can enter the bloodstream and be carried to all major organs. Learn about the pathways and functions of the human circulatory system in the Biology Gateways activity, Functions of the Circulatory System. (Requires Logal Express. Get a free trial subscription.)

The U.S. government has taken steps over the past 20 years to limit lead in consumer products, and the results are significant. According to the National Health and Nutrition Examination Survey (NHANES), the percentage of American children with elevated blood lead levels dropped from 88.2% in the late 1970s to 4.4% in the early 1990s.

The following changes helped achieve this reduction:

• By the 1950s, a voluntary standard called for manufacturers to limit lead content in paints to 1%. The limit became mandatory in 1972. In 1978, lead was banned altogether from residential paints.
  
  
• All new gasoline-powered cars sold in the United States since 1974 have had to use unleaded gasoline.
  
  
• In most residential plumbing, copper pipes have replaced lead pipes, although lead solder is still widely used with the copper pipes. Lead-contaminated water remains a problem in houses that are very old and more likely to have lead pipes, and in very new houses where the pipes have not yet "mellowed."

While the level of lead being introduced into the environment has decreased, removing existing lead remains a problem. Some of the responsibility for preventing lead poisoning remains with individuals. Families, particularly those living in homes built before 1978, should take the following precautions:

• Mop and wipe hard surfaces with a high phosphate solution at least once a week. Do not vacuum hard surfaces, because vacuuming can disperse lead-contaminated dust. Do vacuum rugs.
  
  
• All family members, especially small children, should wash their hands and face before eating.
  
  
• Wash toys frequently.
  
  
• Plant grass or ground cover near the house, especially if an exterior lead paint was used.
  
  
• If your household plumbing is a source of lead contamination, run the cold water for several minutes to flush the pipes before using the water for cooking or drinking. Only use the cold water tap for these purposes; heat causes more lead to enter the water.
  
  
• Do not store food in open cans, especially if they are imported. Some countries do not restrict the use of lead in cans.
  
  

Not Just Humans

Humans are not the only ones to suffer from lead poisoning. Lead also poisons wildlife, especially birds.

Hunters of waterfowl and small game have traditionally used lead bullets. The bullets that miss their mark often end up in the food supply of migratory birds, including waterbirds such as ducks, geese, swans; raptors such as eagles; shorebirds; and upland game birds such as pheasants, quail, and doves. When the birds accidentally eat the bullets—either directly or by preying on a creature that has swallowed one—they can die of lead poisoning.

The list of species affected by lead poisoning is a long one. Lead is thought to account for half the deaths among the common loon populations in New England and around the Great Lakes. In 1999, thousands of pintails and mallards died of lead poisoning at Catahoula Lake in Louisiana. The California condor's slide toward extinction is partly attributed to lead poisoning.

In 1991 the U.S. Fish and Wildlife Service (USFWS) initiated a ban on lead bullets in hunting waterfowl. Researchers examining ducks on the Mississippi River Flyway have determined that 1.4 million ducks were saved from lead-induced death as a result of the ban. At present the ban does not extend to hunting for big game, but the USFWS is monitoring the situation and may propose such a ban in the future.

Another source of lead poisoning among birds comes from fishing. Anglers often use sinkers and jigs containing lead. Birds ingest these fishing devices together with the small stones and grit they swallow to aid digestion, and then die of lead poisoning. The USFWS is trying to educate anglers about the benefits of nontoxic sinkers and jigs for wildlife. In 1999 it introduced a plan to establish lead-free fishing areas in selected national wildlife refugees.

Learn More

• Study the properties of lead (Pb) using the Periodic Table Tool.
  
  Can you see a property that contributes to lead's popularity as a solder? (Hint: View the periodic table "by Property" and see where lead falls in relation to the other elements for each property. Consider what the characteristics of a good solder are.)

More Links

• Learn more about childhood lead poisoning at the site of the Alliance to End Childhood Lead Poisoning.
  
  
• The CDC offers extensive information about the effects of lead poisoning on human health: CDC Childhood Lead Poisoning Prevention Program.