Metal ions play a role in numerous biological and biochemical processes, and among these processes genetic regulation is of great importance. Metal ions are required for all aspects of genetic information transfer. These essential metal ions are acquired by biological organisms, including man, from the environment. These metal ions can sometimes accumulate in various tissues and organs in abnormal concentrations, and under such conditions lead to harmful effects. Metal ions with no known benefits and only potentially harmful consequence to the body can also accumulate in this way.