Exposure to mercury can cause symptoms which include insomnia, nervousness, tremors, muscle twitches, mood swings and deficits on cognitive tests. At higher amounts, it may affect the respiratory system and the kidneys and could result in death. In fetuses, infants and children, it can cause neurological problems. Exposure in the womb can affect the developing nervous system and brain. Therefore, children are most vulnerable. Arsenic exposure has been associated with certain types of skin cancer. Studies show a possible link with lung, bladder, liver, colon, and kidney cancers. Tremors, headaches and numbness as well as stomach upsets, diabetes and blood pressure can all be affected. If children are exposed, they have a risk later in life of developing respiratory diseases, lung cancer and it may adversely affect their I.Q.'s.