The pigs' diet includes a clump of food that looks a little like cookie dough, Casteel says, with a small sample from the site embedded inside. It doesn't hurt the pigs, because they don't get enough lead to be toxic, he says.
The primary concern over lead is its impact on children. Lead is similar to calcium, and young children need a lot of calcium for their growing skeletons. The lead literally mimics the role of calcium, so if children ingest lead, more of it will end up in their bones. That can lead to brittle bones, growth deformities, and most unfortunately, irreversible brain damage.
The concern over children is the reason Casteel uses immature pigs in his research. Like children, they have a preference for lead.
The pigs have also confirmed something that many scientists suspected. The soil that contains the lead at a hazardous site can be amended to lower the absorption rate.
An old lead smelter in Jasper County, Mo., left the land so contaminated that the EPA is faced with cleaning up 2,700 different properties, Doolan says. Scientists there, under a program sponsored by the Missouri Department of Natural Resources, applied phosphorus to the land, theorizing that it could reduce the "bioavailability," or the absorption rate, of the lead.
Sorting Good Lead From Bad
Samples from the site were then fed to Casteel's pigs with encouraging results. The pigs absorbed less than half as much lead as they had before the application of phosphorus, a common ingredient in most lawn and garden fertilizers.
What that means, Doolan says, is the soil can be treated in place instead of dug up and hauled away, reducing the cleanup cost by around 75 percent.
That means more money can be allotted to areas that resist on-site treatment. It also means there's something the rest of us can do if we suspect our area may have contaminated soils. Casteel says the most important thing is to insure that children do not come in direct contact with the soil.
He recommends planting a lawn and treating it with fertilizer that has heavy phosphorus content.
Many areas, of course, are so contaminated that there's no other way than to spend hundreds of millions of dollars to get rid of the problem. But thanks to Casteel's pigs, at least we're better equipped now to figure out which areas need the most attention.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.