Mercuric chloride (HgCl2)

Mercuric chloride (CAS# 7487-94-7) is used in photographical processes, wood preservatives, disinfectants, fungicides, and some pharmaceutical products. Mercury chloride is one of the most toxic salts of mercury, and it is poisonous if absorbed by inhalation, ingestion, and skin contact. In humans, the gastrointestinal absorption of metallic mercury is generally low. However, ingested metallic mercury is oxidized in the gastrointestinal tract to mercury salts such as mercury chloride, thus increasing the uptake in the central circulation. Central nervous system, gastrointestinal tract, and especially the kidneys are most vulnerable to its toxic effects. Mercuric chloride is primarily a skin and mucous membrane irritant. Acute poisoning by ingestion or inhalation may cause respiratory insufficiency, gastrointestinal disturbances (nausea, vomiting), and renal damage. As little as 0.1 g is enough to cause damage to body tissues, and 1–4 g ingestion may be fatal. As regards chronic exposure, the main target of toxicity is the kidney, but other symptoms may include increased salivation, inflammation of the gums and black lines on the teeth. Although mercuric chloride showed carcinogenic effects in some animal models, evidence in humans are scarce, and therefore it is considered a Group 3 carcinogen.