Chronic Arsenical Poisoning occurs when small quantities of arsenic are absorbed over long periods. The gastrointestinal symptoms may be slight, but other symptoms such as skin rashes and pigmentation, conjunctivitis, become manifest.
In suspected arsenical poisoning the diagnosis can be made certain by analysis of the vomit, urine and faeces in acute cases. In chronic cases additional information may be obtained by analysis of the hair and nails.
Antimony is an irritant poison like arsenic. Tartar emetic or potassium antimony tartrate is one of the most commonly used compounds. It has on several occasions been used for homicidal purposes owing to the possibility of its being administered with out detection by taste or smell.
Metallic Poisons if taken by the mouth give rise to irritant poisoning. Examples are : Lead.—The common salts of lead will in large doses cause gastrointestinal irritation. Acute poisoning by lead is rare. Chronic lead poisoning is caused by the continued absorption of small quantities of lead and is a dangerous condition owing to the causation of disease of the kidneys, blood vessels, heart and nervous system. Lead-tetra-ethyl is a very poisonous organic compound of lead. It has been recently used commercially as a constituent of ethyl petrol, which is claimed to be superior in some respects to ordinary petrol as a fuel for motor engines. In Great Britain the possible dangers from its use have led to a special Government enquiry.
Copper.—The sulphate of copper (blue vitriol) and other cop per compounds are irritant poisons. The use of copper salts as a
colouring matter of foodstuffs such as preserved green vegetables is reprehensible, and has often led to legal action.
Zinc Salts are irritant poisons. The sulphate of zinc (white vitriol) occurs in crystals like Epsom salts for which it has been taken in mistake. Zinc chloride has a corrosive as well as an irritant action.
Barium Salts.—Except the quite insoluble sulphate these are irritant poisons and may also act on the nervous system.
Cliromates especially potassium bichromate are powerful irri tant poisons.
Phosphorus.—The yellow variety is intensely poisonous and used to be used largely in the manufacture of matches. Owing to its dangerous properties its use for this purpose has been abandoned. Yellow phosphorus is used as a constituent of some rat poisons. The substance, in addition to being a gastrointestinal irritant, is a deadly poison to the liver and kidneys.
Mercury.—Acute mercurial poisoning usually arises from the taking of mercuric chloride (corrosive sublimate) or from the biniodide of mercury, both of which are extensively used as dis infectants for medical purposes. The immediate symptoms are those of acute gastrointestinal irritation (vomiting, abdominal pain and diarrhoea) but they are generally followed by sup pression of urine and symptoms of acute ulcerative colitis which latter symptoms are commonly fatal. Chronic Mercurial Poison ing is characterised by inflammation of the mouth and gums.