Argyria
Not all body-changing conditions are caused by genetic disorders. Some can be explained by exposure to certain substances. Out of the latter, argyria is surely one of the most outstanding. People with argyria display an unmistakable dark grey skin tone; this rare disorder is irreversible, but what is it that causes it?
Believe it or not, the ingestion of approximately six grams of silver nitrate (either due to industrial exposure or medicine consumption) is all it takes for one’s face to change color indefinitely. Side effects include kidney problems and headaches.