Investigating an Epidemic of Chronic Kidney Disease in Western Nicaragua

EPA Grant Number: F13D10721
Title: Investigating an Epidemic of Chronic Kidney Disease in Western Nicaragua
Investigators: Laws, Rebecca L
Institution: Boston University
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2014 through September 1, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Epidemiology

Objective:

The objectives of this project are to (1) evaluate repeated measures of biomarkers of kidney injury and CKD among sugarcane workers by investigating differences by job task; (2) determine whether there is evidence of kidney injury and CKD among miners, construction workers and stevedores who have never worked in the sugar cane industry; and (3) characterize biomarkers of exposure to nephrotoxic heavy metals (i.e., cadmium, lead, uranium, arsenic) and examine the association with biomarkers of kidney damage.

Approach:

A cohort of Nicaraguan workers in the sugarcane, mining, stevedoring and construction industries was previously recruited and sampled for blood and urine. Sugarcane workers representing seven different job categories were sampled twice, before and at the end of the 6-month harvest season; workers in other industries were sampled once. Exposure will be assessed in two different, but complementary, ways. First, because the causal agent is unknown, job category will be used as a surrogate for exposure. Various job categories in the sugarcane industry are quite different in terms of potential exposure to hypothesized causal agents (i.e., heat stress, agrichemicals), so identifying which jobs have the greatest risk of kidney injury during the harvest season will provide information about which occupational factors may be important. Second, biomarkers will be used to quantify exposure to nephrotoxic heavy metals (lead, cadmium, arsenic, uranium). Kidney damage will be assessed by analyzing serum samples for creatinine (used to estimate glomerular filtration rate) and by analyzing urine samples for creatinine, albumin, neutrophil gelatinase-associated lipocalin (NGAL) and interleukin-18 (IL-18). The urine analytes NGAL and IL-18 are considered novel markers of tubular injury. Linear regression models will be used to evaluate predictors of kidney injury, estimated glomerular filtration rate and metals exposure. All data will be analyzed using SAS statistical software.

Expected Results:

Among sugarcane workers, biomarkers of kidney damage are expected to increase during the harvest season and to be different by job category, suggesting an occupational component to the disease. Workers in other industries also are likely to have elevated biomarkers of kidney injury, indicating that CKD is affecting nonagricultural workers in the region. Exposure to heavy metals is predicted to be different by job category and positively associated with biomarkers of kidney damage. Finally, low proteinuria and high tubular marker levels area expected, indicating that the kidney disease is tubulointerstitial and not glomerular in nature.

Potential to Further Environmental/Human Health Protection

The epidemic of CKD in Central America is a severe public health crisis. The very limited access to renal replacement therapy in the region means that the majority of people diagnosed with CKD will die. This research will provide valuable information about the type of kidney damage and the potential causes of the CKD epidemic, with public health implications that will likely extend to other affected regions outside of Nicaragua.

Supplemental Keywords:

chronic kidney disease, metal contamination, Mesoamerican nephropathy

Progress and Final Reports:

  • 2015
  • Final