That will be a big help to future regulators and communities who want to look beyond chemical measures to see exactly what impact human activities may have on aquatic ecosystems down the road. At this point only a few states require use of biological indicators in environmental regulation. But Gernes says indices of biotic integrity are gaining acceptance. Subsequent investigation determined that children from a nearby school routinely used the property as a makeshift playground. The discovery led to an all-out effort by the MPCA, MDH, the railroad and the community to clean up a site many people believed hosted only weeds and jackrabbits.
Most people know that children and lead are a bad combination.
A child's developing nervous system can be adversely affected by lead poisoning, leading to learning, behavior and health problems. That's why the regulatory goals set by the MDH and used by the MPCA take a conservative stance toward human exposure. Levels of air, water or soil contamination considered acceptable for humans may vary, depending on the populations likely to be exposed. After the discovery that children played on the property, a soil cleanup standard of 400 ppm pertained. For surface soil alone, state law requires a cleanup level of 100 ppm in residential areas when a child with an elevated blood lead level is living on the property.