Within the body, lead is absorbed through the gut and enters the bloodstream, where it can enter most organs. Eventually, most of the lead is taken up into the structure of the bones, where it can slowly leech out over many years. Children whose diets are deficient in calcium or iron absorb the lead that reaches their guts even more readily than those with sufficient diets, again, putting poor, under-nourished children at higher risk.
Studies have linked high lead levels to many impairments, from compromised intelligence to compromised height, to hearing and possible balance or behavioral problems. In general, the higher the lead level, the more damage is done. At lead levels above 50 mcg/dL (and even as low as 25mcg/dL) many children experience gastrointestinal symptoms such as loss of appetite, nausea, vomiting, abdominal pain and/or constipation. Above 100mcg/dL, lead is extremely dangerous, leading to such effects on the brain as confusion, poor balance, seizures, coma and possibly death. Many who have survived such poisoning are left permanently paralyzed or mentally retarded.
For children with lead levels above 45 mcg/dL a therapy called chelation is available. Chelating agents work by binding to the lead molecule and allowing the chelator-lead combination to be excreted in urine. But because most of the lead in the body is sequestered within bone, even with chelation, lead is difficult to remove.
The best intervention is prevention. For prevention to work, we need to find those children at high risk, then work to clean the environment around them, maximize their diets and educate their caretakers as to which behaviors put them at high risk. For years, a universal screening policy was in place that mandated that all children get lead level tests. In 1997, acknowledging the large reduction in lead-poisoned children and the difficulty of testing them all, those recommendations were modified. A screening questionnaire designed for parents of one- and two-year-olds is used to ferret out at-risk children. The questionnaire identifies the risk factors of older housing, a child's tendency to chew on surfaces and mouth non-food items, and proximity to factories or plants that use lead. These higher risk children are then screened with blood lead levels at one year, two years and, if not already tested, some time between three and six years.
Children who live in high-risk communities that have more than 26 percent of houses built before 1959 or more than 11 percent of their children with lead levels above 10mcg/dL are all screened despite their individual risk assessments. If risk factors aren't known or can't be determined, a blood level is drawn.
The next step depends upon the lead level. The higher the result, the more aggressive the approach. All children with lead levels above 10mcg/dL should receive an environmental assessment by a public health official to determine the lead source and risk. Trained professionals using sophisticated techniques can evaluate a home, or parents can send paint or dirt samples to special labs for analysis. To reduce the chance of absorbing lead already in the gut, calcium and iron intake should be maximized.
If a home is found to contain lead, remediation work should begin immediately. Two options are available. Complete lead removal is more expensive, must be done by trained professionals, and often exposes more lead during the removal, but is a permanent solution. Families must sometimes find somewhere else to live during the process. The other option aims not to make a home lead-free, but lead-safe, by covering surfaces with sealants. Though toddlers can't be stopped from normal exploring behaviors, efforts to vacuum dust and wash hands often can reduce the amount of lead presented to a toddler's body.
Despite the successes of the past two decades at curbing 'new' sources of lead contamination, existing lead already surrounds us and is here to stay. As a nation and as individuals, we must continue to be vigilant at protecting our children from lead poisoning.
What Can Parents Do?
Contact your state and local health departments' lead poisoning prevention programs or the housing authorities for more information. They can tell you about testing labs and contractors who can safely remove lead-based paint. Or contact the National Lead Information Clearinghouse at 1-800-424-LEAD.