Galveston Bay pesticide study: water and oyster sample analyzed for pesticide residues following mosquito control program.

The purpose of this study was to determine the effect of increased pesticide applications in the Houston area on shellfish and shellfish-growing waters of Galveston Bay. The study was conducted during the fall of 1964 following a large-scale mosquito control program in the Houston area. Water and oyster samples were collected in Sept. and Oct. 1964, during and after the mosquito control operations. Oyster samples collected in this study were compared to samples collected from April to July 1964, prior to the mosquito operations. Analyses included determination of levels of BHC-lindane, DDE, DDT, dieldrin, endrin, heptachlor, aldrin, chlordane heptachlor epoxide, methoxychlor, toxaphene, and Trithion. Pesticide levels were determined by the use of electron capture gas-liquid chromatography, with thin layer chromatography for confirmation. Pesticide levels in both water and oysters were low at all times. The data indicate little or no increase in levels due to the control program in Houston.