Superfund Research Program
Epidemiology, Biomarkers and Exposure Assessment of Metals
Project Leader: Margaret R. Karagas
Grant Number: P42ES007373
Funding Period: 1995-2021
Final Progress Reports
The goal of this project is to conduct a case-control epidemiological study examining the relationship between arsenic exposure and incidence of skin and bladder cancer in New Hampshire. The study involves extensive collaboration between epidemiologists, biostatisticians, pathologists, chemists and geologists. It also relies on the cooperation of physicians, pathology laboratories and hospitals through NH and bordering areas. One of the major accomplishments of the study during the past year was demonstrating the feasibility of studying low levels of arsenic exposure in relation to cancer risk in a U.S. population. Second, after repeating the initial pilot study of toenail arsenic on 20 individuals in over 200 randomly selected individuals, the researchers verified that toenail measurement of arsenic is an individual biomarker of arsenic exposure. Third, household water samples from over 1,000 individuals residing throughout the state were tested. These results were used in several manuscripts including a study on the geographic distribution and potential sources of arsenic in NH drinking water. The project investigators are completing interviews on about 450 bladder cancer cases diagnosed between July 1994 and June 1998 and about 130 controls age- and sex- matched to bladder cancer cases diagnosed from July 1995 to June 1997. The remaining diagnostic periods overlap with a concurrent NCI-funded skin cancer study (CA5794). Therefore, for efficiency, this project is sharing a control group for this period. Researchers have tested for arsenic in over 1,000 household water samples from bladder and skin cancer cases and controls. Procedures for case and control sampling and for subject contact have worked smoothly. Physician cooperation is nearly 100%. Of the 626 individuals successfully contacted, 87% have agreed to take part. The remaining interviews are to be completed by December 2000. Toenail clippings have been obtained from 94% of interview subjects, household water samples from 95% and blood samples from 80%. An experienced phlebotomist is currently following up on difficult blood draws, so this percentage is expected to be higher by the end of the study. An added component of the study is success in obtaining cases' permission to request their pathology records and specimens. Access to pathology specimens permits diagnostic verification and studies of molecular/genetic markers of arsenic-induced malignancies being conducted by Dr. Karl Kelsey and colleagues of the Harvard Superfund Program.