High concentrations of lead in the city's soil have previously been reported by others, but lead generally remains embedded in the soil and does not easily come in contact with people unless disturbed, says study leader Steven M. Presley, Ph.D., an environmental toxicologist at Texas Tech in Lubbock. He says that severe flooding may have loosened large amounts of embedded lead and caused it to be deposited on soil surfaces, where exposure to lead particles is more likely, either through skin contact or the inhalation of aerosolized particles. Lead exposure is a particular health concern among children because it can impair the nervous system and cause developmental problems.
Although lead is the biggest health concern, the scientists also found concentrations of aldrin (an insecticide), arsenic, and seven semivolatile organic compounds that exceeded EPA Region VI safe levels and are on EPA's list of known or suspected human carcinogens. In all, the researchers analyzed the sediment and soil samples for 26 metals and more than 90 semi-volatile compounds.
In addition to sediment and soil samples, the researchers also tested water and animal tissues following the flood. Other contaminants found among samples include high levels of iron, several banned pesticides and pathogenic bacteria, but the researchers say that concentrations of most of these contaminants were unlikely to pose an immediate human health threat. Th