Amyotrophic Lateral Sclerosis (ALS) Admission Rates and Metals Detected in Private Drinking Water Wells in Texas
Mitchell S Wachtel, Bradley B Miller. Texas Tech University Health Sciences Center, Lubbock, TX
Background: The etiology of ALS remains obscure. Reports of geographic pockets of ALS suggest certain metal exposures may be a trigger in some cases. Texas (TX) has a combination of extensive agriculture and widespread use of private drinking water-wells; we hypothesized that evaluating ALS admissions by region and proportions of wells with detectable metals might produce evidence warranting further investigation of these contaminants.
Design: ALS admissions by quarter were obtained from the TX Hospital Discharge Inpatient Database; annual populations and proportions of populations older than 64 y, from the US Census; boundaries of TX regions and well water test results, from TX Ground Water Database. ALS admission rates were expressed by region as admissions per 100,000 person years for each of the quarters of 2004-2009. Number of wells tested positive metals was divided by total number of wells in each region.
Above are medians (interquartile ranges) of admission rates for the 12 regions. The highest median, 4.9, is nearly four-fold that of the lowest median, 1.4; the wide range raises the possibility that regional differences in exposure to metals via ground water might be of importance.
Log negative binomial regression produced the above results, adjusted for proportions of persons over 64 y, the year, and the quarter of the year. The roughly 25% increases in admission rates associated with increased proportions of wells with thallium (P=0.003) and aluminum (P=0.04) were not explicable by chance; a similar effect observed for manganese (P=0.05) might have been due to chance.
Conclusions: Proportions of wells with detectable thallium and aluminum are positively correlated with ALS admission rates, providing evidence these metals might play a role in ALS pathogenesis. The safety of thallium as an insecticide should be explored.
Wednesday, March 6, 2013 1:00 PM
Poster Session VI # 256, Wednesday Afternoon