Historical profiles of toxic chemicals in urban and rural Louisiana lake sediments: epidemiological significance.

Sediment cores collected from lakes in rural and urban/industrial areas of Louisiana were dated using 137Cs, sectioned, and analyzed for a wide range of pollutant chemicals deposited during the period 1950 to 1991. Mutagenicity testing also was performed on extracts from the cores. Statistical and other comparisons of chemical data indicated that annual loadings of polycyclic aromatic hydrocarbons (PAHs), chlorinated chemicals, and toxic trace metals were not significantly different in the urban lake versus the rural lake over the historical period compared. Mutagenic activity was detected in both lakes, primarily in sediments deposited between 1955 and 1980, with minimal activity before and after that period. This was a time of widespread industrial and agricultural activity in Louisiana, before restrictions on chemical releases to the environment were instituted and enforced.