Water Concentrations, Bioaccumulation, and Human Health Implications of Heavy Metals in Lake Chapala

Abstract

Inorganic contaminants in Lake Chapala may pose risks to human health through exposure routes such as drinking water, recreation, and fish consumption. Accurately assessing these risks is difficult, as the fate and transport of metals in surface waters is governed by multiple processes. In this chapter, data for metals in Lake Chapala water, plants, and fish are reviewed, and risks to human health due to fish consumption and drinking water are evaluated. At times during the year, the concentrations of Cd and Pb were above USEPA Maximum Contaminant Levels for safe drinking water, indicating a need for monitoring. Levels of dissolved arsenic in water were consistently above recommended guidelines for safe consumption of water. Data on metal concentrations in fish point to a need for monitoring mercury in all edible species of fish from Lake Chapala, and suggest elevated Cu and Pb levels in fish tissue as well. Suspended clay particles have been shown to be important in metal accumulation in Lake Chapala, due to their high affinity for metals. To more accurately characterize the Lake, we need a more comprehensive monitoring program for toxic metals in the sediments, the water column (dissolved and particulate) and within the biota, and an assessment of population exposures.