Hello! Thank you for writing! I think that the best thing is to rule it out. You aren t sure if your grandson has swollen some, so better go to the ER. Swolling mercury it s dangerous Mercury poisoning is a type of metal poisoning, due to mercury exposure. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashes, anxiety, memory problems, trouble speaking, trouble hearing, or trouble seeing. High level exposure to methylmercury is known as Minamata disease. Methylmercury exposure in children may result in acrodynia (pink s disease) in which the skin becomes pink and peels. Long term complications may include kidney problems and decreased intelligence. The effects of long term low-dose exposure to methylmercury. Tests of the blood, urine, and hair for mercury are available but do not relate well to the amount in the body. Wish your grandson good health. Thank you.