Knowing the evolutionary relationships among species allows scientists to choose appropriate organisms for the study of diseases, such as HIV. Scientists are even using the principles of natural selection to identify new drugs for detecting and treating diseases such as cancer. Environmental change and isolation of groups of organisms play an important role in evolution. Environmental change is any change in an environment to which an organism must adapt. Change can be gradual, such as when mountains or deserts form, other species die out, or new species evolve.
Chelation therapy is a method for removing heavy metals, such as mercury or lead, from blood. It's one of the standard treatments for many types of metal poisoning. Hope this helped :)