A Preliminary Exposure Assessment of Microcystins from Consumption of Drinking Water in the United States (Journal Article)
Cyanotoxins can cause adverse human and ecological health effects. Large quantities of cyanotoxins can be released into water bodies during or immediately following freshwater cyanobacteria blooms, also known as harmful algal blooms (HABs). HABs exhibit complicated temporal and spatial patterns of formation as well as largely unexplained mechanisms of progression. Understanding the multiple factors that affect HABS and the relationships among them is important for determining high-end concentrations of cyanotoxins and devising appropriate risk management actions. This paper presents a preliminary exposure assessment based on reported microcystin concentrations measured in a study of U.S. and Canadian drinking water utilities. We describe the gaps and limitations in the data needed to assess these exposures. Given these limitations, our results suggest that most individuals are exposed to microcystin levels in finished drinking water that are considerable lower than the World Health Organization’s (WHO) provisional guideline level of 1 μg/L. For most members of the population, consumption of MC at levels measured in U.S. treated drinking waters are significantly lower than provisional WHO tolerable daily intake level of 0.04 μg/kg-day.