Selenium poisoning: Selenium posioning may be acute (short-term) or chronic (long-term). The effects of acute selenium poisoning depend upon the route of exposure.
Acute inhalation exposure to selenium (usually in the form of selenium dioxide or hydrogen selenide) primarily results in respiratory effects with irritation of the mucous membranes in the nose and throat, producing coughing, nosebleeds, dyspnea (difficulty breathing), bronchial spasms, bronchitis, and chemical pneumonia. There may also be gastrointestinal effects including vomiting and nausea; cardiovascular effects; neurological effects such as headaches and malaise; and irritation of the eyes.
Acute oral exposure to selenium compounds results in pulmonary edema and lesions of the lung; cardiovascular effects such as tachycardia; gastrointestinal effects including nausea, vomiting, diarrhea, and abdominal pain; effects on the liver; and neurological effects such as aches, irritability, chills, and tremors.
Chronic (long-term) exposure to high levels of selenium in food and water results in discoloration of the skin, deformation and loss of nails, reversible loss of hair (baldness), excessive tooth decay and discoloration, a garlic odor to the breath, weakness, lack of mental alertness, and listlessness.