An ecological study examining the correlation of end-stage renal disease and ground water heavy metal content in Texas counties

Abstract

An ecological study was conducted to examine the correlation of end-stage renal disease (ESRD) and the ground water heavy metal level of lead, arsenic, cadmium, mercury and the cumulative level of all four metals in Texas counties. The heavy meal dab was collected from the United States Geologic Survey (USGS) measurement and covered the twenty-one year span 1970- 1990. The ESRD data was gathered from the Texas Department of Health Kidney Program ESRD Registry for the five-year span 1988-1992. This registry included more than 99% of incident ESRD cases over the same time period. The 1990 U.S. Census data was used to estimate county population by age, race and sex. Exposure was defined as residence in a county with ground water measurements that fell in the highest quartile for each metal (mercury 0.297ug/, arsenic 3.216ug/l, lead 4.685ug/l, cadmium 1.423ug/l, cumulative metal level 8.911ug/l). Outcome was defined as an incident case of ESRD between the years 1988-1992 and examined as five-year incidence of ESRD per 10,000 persons. Among 254 Texas counties, 52 had at least 7 years of metal measurements for lead and cadmium, 51 counties had at least 7 years of metal measurements for arsenic and mercury and 50 counties had 7 years of measurements for all four metals. Linear and logistic regression procedures were carried out to examine the relationship between heavy metal ground water levels and incidence of ESRD. None of the metals demonstrated a statistically significant positive relationship with five-year incidence of ESRD per 10,000 persons. Counties with high levels of heavy metals did not indicate an increased odds of having a five-year ESRD incidence per 10,000 persons above the 1988-1992 state average. The percentage of Black or Hispanic persons in a county was a positive predictor of increased five-year incidence of ESRD per 10,000 persons.