Epidemiologic studies of children show that those exposed to lead, even low levels of lead, may have a lower IQ, learning disabilities, behavioral abnormalities and kidney damage. Cognitive and growth defects also may occur in infants whose mothers are exposed to lead during pregnancy. Lead intoxication is a widespread problem. One of every nine children under six years of age has blood lead levels high enough to be at risk. In 1970, an estimated 3 million children aged less than 6 years had blood lead levels associated with adverse health events. Children in older, inner-city neighborhoods are more likely to be affected, but children in suburban and rural areas are at risk too.
There is currently no lead level believed to be safe for infants and young children. The Centers for Disease Control (CDC) define blood lead levels of 10 mcg/dL as toxic. The previous level, set in 1985, was 25 mcg/dL. The new federal definition was established in 1991 as evidence accumulated indicating that serious consequences occur in infants and young children at levels greater than 10 mcg/dL. In lead poisoning, there is a silent progression of nonspecific symptoms which makes it difficult to detect. Irritability, stomachache, diarrhea, colic, distractibility and lethargy are all symptoms of progressive lead accumulation. Higher levels or chronic exposure results in more severe symptoms such as kidney and nervous system damage.
Although lead-containing paint was banned for residential use in the United States in 1978, residual paint on older buildings is the most frequent source of lead exposure in young children. But, a variety of other substances contribute to lead poisoning. Paints used in industry or on equipment or in playgrounds or parks may still contain lead. Tap water can be contaminated by lead pipes, copper pipes with lead solder or bronze and brass faucets containing lead. Automobile exhaust from leaded gasoline, factory emissions and pesticides contribute to both air and soil lead pollution. Lead exposure can also result from lead crystal and poorly glazed ceramic dishware. The Food and Drug Administration (FDA) sets strict limits for the lead content on products made or sold in the United States, but other countries may have higher limits or no limits at all. Ceramic dishware produced outside the United States, china and lead crystal can leach dangerous amounts of lead into food. Occasional servings of food from these products is acceptable; food storage is unsafe. Food can also be contaminated with lead when it is grown in soil with a high lead content or when plants are sprayed with insecticides containing lead.
Proper nutrition is important in the prevention of lead poisoning, especially in young children. A balanced diet of grains, fruits, vegetables, dairy products and selections from meat, poultry, fish, dry beans, nuts or eggs can help decrease susceptibility to lead intoxication. It is particularly important to include adequate amounts of calcium and iron.
Anemia, a decrease in the quantity or quality of red blood cells, occurs most frequently due to a deficiency of iron. Iron deficiency results in a decrease in the normal quantity of hemoglobin, the protein which carries oxygen in the blood. Lead poisoning can mimic iron deficiency. In fact, lead intoxication can also cause anemia. The occurence of iron deficiency and lead poisoning simulataneously can be synergistic and devastating. Anemia is more severe in these children and up to 50 percent more lead may be absorbed in children with an iron deficiency than in those with normal hemoglobin levels. Children who are most likely to be exposed to lead are likely to have other risk factors, such as a poor diet, which can contribute to iron deficiency.
The Recommended Dietary Allowance (RDA) for iron for children from age 6 months to 10 years is 10 mg per day. Substantial amounts of iron are found in fortified cereals, meat, legumes, prunes, raisins and green leafy vegetables. The following table lists the iron content of some representative foods. The absorption of iron in foods will be enhanced when iron-rich foods are consumed with foods high in vitamin C.
|Food||Serving Size||Iron (mg)|
|ground beef, lean, baked||3.5 oz||2.09|
|ham, lean, roasted||3.5 oz||1.48|
|chicken, roasted, no skin||3.5 oz||1.21|
|kidney beans, boiled||1 cup||5.20|
|spinach, boiled||1 cup||5.20|
|broccoli, raw||1 cup||0.78|
|carrots, raw||1 medium||0.36|
|whole wheat bread||1 slice||0.86|
|oatmeal, instant||1 pkt (3/4 c, cooked)||4.50|
|Cheerios||1 and 1/4 cup||4.45|
|Captain Crunch||3/4 cup||4.50|
|Fruit Loops||1 cup||4.50|
Green leafy vegetables may absorb lead from soil where exposure is high, such as near freeways or main roads and near lead smelting plants. Contaminated dirt from the garden can add to lead in the diet if vegetables are not well washed before consumption. If a home garden is desired and the property is in or near an area of high exposure, soil should be tested before planting.
An adequate calcium intake can protect against lead poisoning. It has been observed in animals and humans that both the absorption and retention of lead decreases as calcium intake increases. Many children at risk for exposure to excess lead are also those who live at the poverty level, and may consume a diet with insufficient calcium. Therefore, increasing consumption of low-cost calcium rich foods can reduce the severity of the effects of lead exposure.
The RDA for calcium for children ages 1 to 10 is 800 mg per day. Calcium rich foods include milk, cheese, yogurt, leafy green vegetables, beets, broccoli, and legumes. Suggested amounts of some foods which would provide the RDA for calcium are listed in the following table.
|Food||Serving size to = 800 mg milk 2.5 cups|
|swiss cheese||3 ounces|
|american cheese||4.5 ounces|
|cheddar cheese||4 ounces|
|spinach, cooked||3.25 cups|
|turnip greens, cooked||4 cups|
Growing children need adequate amounts of energy and nutrients to support growth. Dietary fat is an important source of kilocalories for this age group. But, fat should be consumed in moderation because of the potential contribution of excess dietary fat to long-term health concerns. It also has been suggested from animal studies that excess dietary fat may enhance lead absorption.
Following the new food pyramid will provide a child with a well balanced diet which includes sufficient fat to support growth without supplying an excess. Children should be offered fruits and vegetable sticks with peanut butter, iron fortified breads and cereals, pudding or cheese instead of chips and candy for snacks.
The risk of ingesting excess lead intoxication from tap water can be reduced by running the COLD water faucet for at least one minute before using it for drinking, cooking or cleaning food. This should be done whenever the faucet has not been used for several hours. The water from the one minute flushing can be used for watering plants or washing dishes. Taking this precaution can significantly reduce exposure in infants who are bottle fed formula mixed with water.
For more information on lead, see HYG Fact Sheets #1149-93, "Lead in the Garden" and #5537-93, "Lead in the Home."
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
TDD No. 800-589-8292 (Ohio only) or 614-292-6181