Mercury and Other Toxicants from Mine Waste and Immune System Health Effects: The Cheyenne River Sioux Tribe's Concerns

Abstract

Over 900 silver and gold mines were in operation in the Black Hills area of South Dakota for almost 100 years. Extraction released mercury to the environment and it is up-taken by various fresh water fish. Fishing is vital part of Lakota life that supports subsistence and provides recreation along the Cheyenne River. CRST communities sought academic partnership as early as 2000 trying to address concerns of immunotoxicity associated with metals originated from the drinking water.Our team recruited 225 adults (53% males, 47% females; mean age: 42.9 years (range: 18-77 yrs) regularly fish along CRST waters. Hg considered ubiquitous on the land and arsenic exposures were also estimated via fishing survey. Smoking and various land use activities were assessed using questionnaires. Blood and urine samples were collected for biomonitoring. Indirect immunofluorescence and in-house ELISA techniques were used for serum autoimmunity marker determinations and multiplexing assays were applied to determine serum cytokines and immunoglobulins, components of the human immune response. Percentages of blood lymphocytes were also measured by flow cytometry. Serum cotinine concentrations validated self-reported smoking.Multivariate statistical modeling ascertained that current cigarette smoking and fish consumption were significant predictor variables of increased cytokine productions resulting in an activation of cellular and mucosal immune reactivity (GM-CSF, p= 0.015; IL-2, p= 0.008; IL-8, p= 0.049). Increased prevalence of antinuclear autoimmunity (36% ANA positivity, score >2+) was identified compared to the US national average (13.8%) and showed negative associations with serum cotinine concentrations. These results suggest that environmental toxicants can have complex, both pro- and anti-inflammatory influence. Immune response inhibition via toxicant exposures might play crucial role in chronic disease development in exposed Indigenous communities.