It is likely that the US government, or the Texas state government will have collected some data on this. Naturally, you will find that most Texas universities will also have collected data on this subject. Here and some papers on the impact of DDT:
Aktar, Md. Wasim, Dwaipayan Sengupta, and Ashim Chowdhury. “Impact of Pesticides Use in Agriculture: Their Benefits and Hazards.” Interdisciplinary Toxicology 2.1 (2009): 1–12. PMC. Web. 4 Sept. 2016;
Forrester MB et al. Epidemiology of lindane exposures for pediculosis reported to poison centers in Texas, 1998–2002. J Toxicol - Clin Toxicol, 2004, 42:55;
Kutz, Frederick W., and Ann E. Carey. "Pesticides and toxic substances in the environment." Journal of arboriculture (USA) (1986).
I have also added a list of interesting web pages and pdf downloads of papers and reports on the subject to get you started.