Poisoning caused by the ingestion or inhalation of arsenic, an ingredient in some pesticides, dyes, and medicinal products. Small amounts absorbed over a long period may cause headache, nausea, coloring of the skin, and the appearance of white lines on the nails. Ingestion of large amounts leads to severe gastrointestinal problems, swelling of the arms and legs, and possibly renal failure, shock, and death.