The information in this section of our web site offers general guidance on how to initiate a program and technical guidance for implementing the program. There are both inorganic forms and organic forms of mercury. Many of the forms of mercury circulate in the environment, moving from land or water to air and back again, and the forms of mercury may change from one to another as they circulate. Human activities significantly redistribute mercury and release it into the environment. In the water or soil, microorganisms can convert inorganic mercury into a more toxic organic form, methylmercury.
Fish take in methylmercury from their diet and from water passing over their gills.
They bioaccumulate the methylmercury in their bodies because the rate of intake of methylmercury is much greater than its elimination. Methylmercury bioaccumulates in the tissues of a fish throughout its lifetime. Fish with high levels of methylmercury may be caught and consumed by humans, waterfowl or other wildlife. All forms of mercury are toxic to humans, but the various forms of organic and inorganic mercury have different toxicity. Generally, organic forms are much more toxic than inorganic forms.