INTEGRATION OF GEOCHEMISTRY, TOXICOLOGY, AND EPIDEMIOLOGY TO EVALUATE THE LIGNITE-WATER HYPOTHESIS IN THE UNITED STATES GULF COAST REGION

Abstract

Many Gulf Coast states including Arkansas, Texas and Louisiana rely on groundwater from aquifers that contain low-rank coal called lignite. These lignite seams may be a source of dissolved organic matter, and continuous consumption of organic matter in drinking water over time may increase the risk of kidney disease. The fundamental research questions are: what are the geochemical characteristics of organic matter that can leach into the groundwater, and is it dangerous? Are there higher rates of kidney disease associated with lignite-containing aquifers in the Gulf Coast region? Laboratory leaching experiments were performed to produce the water-soluble fraction from several Gulf Coast lignite samples, and the leachates were characterized using a variety of geochemical methods. Lignin degradation products and microbial signatures identified as phenols and aliphatic acids dominate the coal extracts. A fraction of the water-soluble leachates were also exposed to human kidney cells to quantify the toxicity of the extract, which showed comparable toxicity to other organic nephrotoxins. The relationship between lignite deposits and incident rates of end-stage renal disease (ESRD) in Texas, Arkansas and Louisiana was also investigated. Rates of ESRD were spatially correlated with areas that rely on lignite-containing aquifers for water needs, even after considering confounding factors like race, ethnicity, and poverty. Together, the research presented here provides evidence in support of links between lignite-derived organic material and kidney disease.