Inorganic mercury is toxic when humans or wildlife are exposed to high levels for a short peri- od of time. Organic methylmercury has a greater tendency to accumulate in the body over time, eventually causing harm, even in small amounts. Methylmercury has the three properties that make substances particularly harmful to humans and other organisms — it persists, it bioaccumulates, and it is toxic to most life forms. The health effects of mercury are described in more detail in the next chapter of this primer. The terms “biological uptake” and “bioaccumu- lation” describe the processes whereby methylmer- cury can enter the food chain — either directly from the water or through the consumption of small.
