Lead Exposure Can Result in Serious Health, Learning Problems
Maintaining Your Health on Mackinac
By Yvan Silva, M.D.

The human body requires several elements in the diet, such as iron, chromium, copper, cobalt, and zinc to provide for physiological interactions conducive to the normal state. Lead is atomic number 82 in more than 110 elements defined in the periodic table of elements. From what is known, humans do not require any lead to survive - the universal minimum daily requirement is zero. In fact, care must be used in handling lead because it is a cumulative poison. For humans, especially infants and young children, consumption of even moderate amounts can result in serious consequences. Lead is toxic to many tissues.

Lead is a bluish white metal of bright luster. The price of lead on global markets has risen sevenfold in the last six years, because of rising demands from countries like China and India. Seventy-five percent of lead ends up in batteries. It is also used in computer and mobile phone networks, bullets, cable, hobby materials, and paints. In recent years, the use of lead in paints has been drastically curtailed to eliminate health hazards. Prior to that, lead was ubiquitous in paints, because paint pigment made from white lead had the desirable quality of exceptional brightness. Painters lauded its covering power, and noted that it clung to wood the best. Today, lead paint continues to cover many structures, and shedding and removal of the paint can pose health hazards. Similarly, environmental concerns with lead poisoning have led to a national program to eliminate lead in gasoline.

The recent spate of imports from China of millions of leadpainted toys has caused serious concerns that an entire generation of children who might be exposed may suffer the consequences of impairment of their neurological development, in addition to other morbidities.

Lead poisoning results from exposure to lead in the environment. The presence of elevated levels of lead in the blood is diagnostic. It is estimated that about 2% of children younger than the age of six years in the United States have elevated blood lead levels. Lead enters the body through the lungs, from breathing lead-contaminated air, and the digestive system, from eating contaminated substances. Lead is particularly toxic to the central nervous system, the brain and spinal cord, and the red blood cells that carry oxygen to the tissues. Lead is toxic to adults and children, but especially to children younger than age six years, because their nervous system is still developing. Death by lead poisoning is uncommon, but children can have serious health problems, including lower intelligence and poor school performance. Even slightly increased blood levels of lead may cause toxicity, and therefore it is important to be tested, if there is the possibility of risk of contamination.

There are several sources of lead exposure: Paint dust and chips from lead-based paint, used commonly before 1978; water that has passed through lead pipes - in the 1980s legislation restricted the use of lead in public water systems; food stored in lead-glazed earthenware, or in imported cans soldered with lead - lead solder to seal food cans was banned in 1995 in the United States; contaminated soil - lead particles from paint and gasoline used years ago can still be found around major highways, old homes, and urban settings. Some hobby materials such as stained-glass and fishing weights, toys, and jewelry, contain lead. Some traditional remedies in certain ayurvedic medicines from India and other Asian countries may contain lead, and some cosmetics have been shown to contain lead. Kohl, a traditional cosmetic used in eyeliner, has been shown, in some tested samples, to contain high levels of lead, often more than half the sample weight.

Lead is not biodegradable, and can continue to remain a health threat, if not properly removed or contained.

Lead poisoning may be hard to detect. The accumulation of lead in the body is usually gradual, and children can have high levels of lead and yet appear healthy, until symptoms and signs appear when levels can be dangerously high. Children may exhibit sluggishness, loss of appetite, weight loss, or failure to thrive; abdominal pain, vomiting, and constipation; pallor owing to anemia, and learning difficulties. Adults are affected less frequently, but when they are, they exhibit pain, numbness and tingling of the extremities, muscular weakness, headaches and abdominal pain; memory loss and mood disorders, and reduced sperm counts have also been noted.

There is a well described protocol for screening and diagnosis for children. Parents are asked to complete a risk questionnaire for lead exposure, and those children identified at risk are tested. The Centers for Disease Control recommend that children be tested at six months, and then yearly if the home contains lead paint, or if family members are exposed to lead at work or use lead as a hobby. Lead levels in the blood are measured in micrograms per deciliter (mcg/dl). Blood is obtained by finger prick or from a vein. An unsafe level is 10 micrograms or above. Levels are stratified into Classes I through V, according to the levels, and Class V is the most severe at 70 or greater, to be treated emergently.

Children with abnormal lead levels are susceptible to nervous system and kidney damage, learning disabilities, speech and language and behavior problems, poor muscle coordination, and impaired muscle and bone growth. Adults also suffer high blood pressure, early cataracts, nerve disorders, memory and concentration problems, complicated pregnancy in women, and damage to sperm in men.

The initial step in treatment is to stop the exposure. If lead cannot be removed, there may be alternatives. It might be better to seal in, rather than remove, old lead paint. Local health departments are able to recommend the identification and reduction of lead in the home.

In earlier cases, stopping exposure to lead, and retesting after a month, may suffice. For more severe cases, chelation therapy is instituted. Lead levels greater than 45 micrograms per deciliter, which fall into Class IV or V, are treated intravenously with a chelating agent (a binding agent) that removes the lead and excretes it in the urine. The drug used is EDTA, ethylenediaminetetraacetic acid, which may be combined with another agent called dimercaprol (BAL). The therapy may not reverse damage that has already occurred in cases of severe lead poisoning. Iron deficiency may also be discovered, and the anemia requires treatment.

Precautions including lead inspection and risk assessment are required in the home. Everyday activities for children should be carefully assessed in the context of lead hazards. Home renovation projects involving lead-based paint are best done with these factors in mind.

Dr. Silva is a professor of surgery at Wayne State University and a resident of Woodbluff on Mackinac Island.