Chronic Exposure:Prolonged contact with Wood's Metal or its fumes may lead to some degree of heavy metal poisoning, especially the accumulation of lead in the body. Lead is a cumulative poison and exposure even to small amounts can raise the body's content to toxic levels. Muscle weakness and central nervous system irregularities may be noted. Chronic exposure to cadmium, even at relatively low concentrations, may result in kidney damage and an increased risk of cancer of the lung and of the prostate. Decrease in bone density, renal stones, and other evidence of disturbed calcium metabolism may be observed. Prolonged inhalation of tin dust or fumes may result in a benign pneumoconiosis, producing distinctive changes in the lungs with no apparent disability or complications. Repeated or prolonged ingestion of bismuth may cause black spots on the gums, foul breath, and salivation. Chronic exposure may affect kidneys and liver.