Ecological receptors could become exposed to site contaminants through direct contact with soils contaminated by off-site deposited sediments; ingestion of soils contaminated by off-site deposited sediments; and ingestion of contaminated food (e.g., sediment- or soil-dwelling insects, vegetation).

Analytical results described above indicate that hazardous substances, as defined by CERCLA Section 101(14), pollutants, and contaminants are present at the Site, and represent an actual or potential exposure threat to nearby animal populations.  Concentrations of DDT exceed the PRG (5 mg/kg).  An initial PRG range of 2-9 mg/kg total DDT in soil for robin reproduction is based on a high quality laboratory toxicological study (performed with Japanese quail showing decreased post-hatch chick survival) and a robin exposure model based on site-specific data on soil-earthworm bioaccumulation. A laboratory study of ring doves performed with a single exposure treatment at a dose intermediate to the ones bracketing adverse effects in the Japanese quail study also showed decreased post-hatch chick survival.  The soil PRG for Velsicol conditions derived from this study is 5.6 mg/kg.  Selection of this PRG decreases the likelihood of encountering the possible developmental effects indicated by the aforementioned studies. A spatially-averaged 5 mg/kg total DDT soil concentration is recommended for a preliminary remedial goal (PRG) for acceptable robin reproduction and development of offspring.

The Site is located behind the Pine River Elementary School in a residential neighborhood and includes a baseball field, softball field, track and practice football field, and open play fields associated with the St. Louis High School.  The Site is bordered on the south by the Pine River and by additional adjacent residential houses and properties to the north within 100 feet of the Site.

According to the Agency for Toxic Substances and Disease Registry (ATSDR), DDT (dichlorodiphenyltrichloroethane) is a pesticide once widely used to control insects in agriculture and insects that carry diseases such as malaria. DDT is a white, crystalline solid with no odor or taste. Its use in the U.S. was banned in 1972 because of damage to wildlife, but is still used in some countries.

DDT affects the nervous system. People who accidentally swallowed large amounts of DDT became excitable and had tremors and seizures. These effects went away after the exposure stopped. No effects were seen in people who took small daily doses of DDT by capsule for 18 months. A study in humans showed that women who had high amounts of a form of DDE in their breast milk were unable to breast feed their babies for as long as women who had little DDT in the breast milk. Another study in humans showed that women who had high amounts of DDT in the blood had an increased chance of having premature babies. In animals, short-term exposure to large amounts of DDT in food affected the nervous system, while long-term exposure to smaller amounts affected the liver. Also in animals, short-term oral exposure to small amounts of DDT or its breakdown products may also have harmful effects on reproduction.