Roughly 200,000 houses in St. Louis might as well have the cross-stitched phrase "Home, sweet (and toxic), home" hanging in a frame on their living room wall, according to a University of Missouri-Rolla researcher.
Lead-based paint, which tastes sweet like sugar, was banned for household use in 1978 but can be found in thousands of housing units in St. Louis and an estimated 57 million homes across the country.
Children are at a higher risk for lead poisoning than adults, says Paula Lutz, dean of the College of Arts and Sciences at UMR and a professor of biological sciences. Lutz has been researching the effects of lead exposure on children’s immune systems for the past decade. She began the first phase of her work in Springfield, Mo., but has partnered with the St. Louis city health department for the second phase.
"Any toxin that children take in seems to be much more dangerous than it is in adults just because we’re more rapidly growing and still developing as children," Lutz explains. "Also as we get older, we learn to wash our hands and not put our hands in our mouth so we’re a little less likely to be exposed in that way."
Although kids age 18 months to three years are in the highest risk group, Lutz includes children from 13 months to six years in her study.
"At that age, kids are doing what we call normal ‘mouthing’ activities," Lutz explains. "In other words, they put everything in their mouths. They drop their pacifiers; they pick them up and put them in their mouths. They may chew on their blanket, which they drop in the dust next to the wall where there’s lead-based paint." Some children even start peeling and eating the paint chips because they like the sweet taste, Lutz adds.
Research on the effects on environmental lead on the human central nervous system is widely publicized, but no one looked at lead’s effects on a child’s immune system until Lutz started her work.
"Your immune system is like Star Wars; it’s your strategic defense initiative," Lutz explains. "It’s here to protect you from all the nasty infectious organisms like viruses and bacteria. Our immune system has to be up and running and doing a good job if we are to stay healthy."
Lutz spends every Tuesday in St. Louis working on her research in a clinic, where families bring their children for interviews and have a blood sample taken.
Each child receives $15 for participating in the study, which is sponsored by the National Institutes of Health. They can take part in the project once or they can be in the longitudinal study where they come back every six months for at least two years and give several samples. "That way we can watch the child’s immune system over a period of time," Lutz adds.
Once ingested, the lead follows calcium to bones and nervous tissue, as well as to many other tissues, creating a residual repository of lead.
"Our preliminary data has found a correlation between elevations of blood lead and a type of protein that your immune system produces, an antibody called IGE that’s associated with allergies and asthma," Lutz says. "Of course a correlation does not necessarily mean that it’s the direct cause, so we have to look for any other contributing factors that might be present. When you work with people, it’s a real challenge."
Blood lead levels of more than 10 mg/dl (micrograms per deciliter) are cause for concern, Lutz says. "If a child is found to be elevated, the health department in St. Louis will actually go to the house and do an environmental survey," she says. "Using X-ray fluorescent technique, they can discover through the layers of paint if there is lead-based paint underneath."
Because it can cost around $10,000 to fully clean up one housing unit, other techniques are often used before renovation is possible. Special soaps, along with a damp cloth, can be used to grab the paint’s chalky dust and prevent it from being released into the air. Another cost-effective option is encapsulation, a technique that bonds materials to the existing painted surface.
"You can also counteract a little bit of the absorption of lead if the child has a diet rich in calcium, iron, and other divalent cations (ions with a +2 charge) because they’re using the same pathways to get in," Lutz explains.
If a child’s blood lead level is 30-35 mg/dl, chelating agents, organic compounds that bond well to metals, may be used to "grab up" lead and remove it, Lutz says. "Then the body equilibrates again, pulling more of the lead out of the bone and tissue," Lutz explains. "You have to do that technique several times, usually under a physician’s care."
Limited federal funds are available for St. Louis residents who need to have lead-based paint removed from their home, Lutz says. "There was a time early in the Bush administration where there were several hundred million dollars put aside for lead abatement," Lutz says. "But that wouldn’t even do the entire city of St. Louis. The problem is being taken care of but not very quickly."