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LEAD POISONING

By Donald B. Louria, M.D

(March 2001)

Lead poisoning is still an important problem in the United States. Prior to the 1970s, the definition of an abnormal and unacceptable level was a blood concentration of 40 micrograms per deciliter. Young children with high blood lead concentrations suffered from severe and obvious forms of poisoning characterized by lethargy, vomiting, convulsions, and sometimes death. Those who recovered after treatment with effective, but toxic, drugs were often left with permanent brain damage.

Since the 1970s, as we learned more about the damaging effects of lead on the brain, the definition of excessive lead burdens has progressively been lowered.

At the same time, we phased out leaded gasoline and cleaned up a large number of homes built before 1950 that used leaded paints on the interior.

Whenever we have established a new lower definition of what constitutes lead poisoning, it turned out to still be too high. That is because we have learned that children who absorb too much lead, but have no obvious evidence of poisoning, still suffer long-term reduction in intelligence, educational underachievement, increased school drop-out rates, lessened attention spans, and slower responses to various stimuli. Additionally, there is growing evidence that adolescents and young adults who have higher lead levels are more likely to be involved in antisocial, even violent, behaviors.

The current dividing line between acceptable lead blood levels and concentrations considered too high is 10 micrograms. An estimated one million American children have blood levels of 10 or above. In some inner cities, where the population is largely African-American or Hispanic, 30 to 60 percent of 1- to 8-year-old children have blood concentrations above 10, putting their brains at risk of permanent damage.

A new study by an experienced group of investigators now claims that learning and thinking deficits can be detected in young children with blood concentrations as low as 2.5 micrograms per deciliter. If that study is confirmed, it puts 13 million American children at risk - a risk that can result in damaged brains, educational underachievement, and delinquent behavior. This much is clear:

1. We as a society have made enormous strides in the last thirty years in reducing the amount of environmental lead and the amount of lead poisoning. Only rarely do we now see the dramatic convulsions and coma.

2. We still have a long way to go to protect our children from the more subtle damage inflicted by excessive lead absorption.

3. Lead is so widely dispersed in our environment that additional cleanup can help, but will not solve the problem.

4. We have no drugs that are safe and effective and can be given by mouth that will prevent buildup of lead levels to 10 or more micrograms.

What can be done to prevent excessive lead burdens? The answer is probably to be found in the diet. The time of greatest danger for young children is ages 1 to 8 years. That is when there is greatest absorption of lead from their intestinal tracts. In experimental animal studies, if the animal is given lead and the dietary calcium is increased, lead absorption is decreased. Even if lead is given and absorbed and then the dietary calcium is increased, tissue levels of lead are decreased - probably because the calcium keeps the lead in bones where it cannot do much harm. Several studies in people have shown that there is an inverse relation between dietary calcium intake and blood lead levels - the higher the calcium intake, the lower the blood lead concentrations.

A large percentage of children and adults in the United States do not get enough calcium in their diet. A recent study in Newark, New Jersey found that 50 percent of 1- to 8-year-old children had inadequate calcium intake.

It would appear the best approach to the prevention of lead poisoning is to make sure every 1- to 8-year-old child in the United States gets enough calcium in the diets. Calcium provides other benefits. It is needed to build strong bones. In older adults, an adequate calcium intake is helpful in preventing osteoporosis.

The State of New Jersey is taking the initiative in regard to lead poisoning prevention through a campaign focused on 1- to 8-year-old children titled "Calcium in, lead out". It will start in Newark, the city with the greatest problem, and then be expanded to cover the entire State.

Parents should be sure their young children get enough calcium in their diet. An adequate calcium intake is advisable for everyone at every age.

CLICK HERE FOR A LIST OF CALCIUM-RICH FOODS AND BEVERAGES

Remember:

Calcium helps build strong bones;

Calcium helps prevent osteoporosis (bone thinning);

In young children, calcium can help prevent the excessive lead burdens that can permanently damage young brains - so, get calcium in, keep lead out.