Re: How long does arsenic poison stay in the system? Anti-dote? Deliberate pois

The toxicity of arsenic is relative to the type of arsenic compound used. 
Arsenic in the forms in which it ordinarily occurs in foods, including the 
organically bound arsenic of shrimp, is well absorbed and rapidly 
eliminated in the urine. The more toxic trivalent compounds, including 
arsenic trioxide, is well absorbed and excreted rather slowly. 

The symptoms of acute arsenic poisoning are nausea, vomiting, diarrhea, 
burning of the mouth and throat, and severe abdominal pain. Chronic 
exposure to smaller, perhaps continued doses, results in weakness, 
prostration, muscular aching, skin abnormalities, peripheral neuropathy, 
and pigmentation within the fingernails.The antidote  (for the acute 
condition) is BAL that protects enzymes containing active thiol groups. 
This usually is given in a hospital seting quickly after exposure. 

Retained arsenic (as from arsenic troxide) is concentrated in hair and 
fingernails. Hair samples, even some time after exposure, can be analyzed 
for arsenic. Hair containing over 2 parts per million can engender 
suspicion of arsenic poisoning. One should go to a medical doctor and give 
him/her a health history including possible symptoms of chronic arsenic 
poisoning and request that a laboratory perform arsenic analysis on hair 
samples. The laboratory will take the hair in a proper sampling manner. The 
laboratory must have sensitive instruments to detect small concentrations 
of arsenic in the hair, e.g., neutron activation technique is one example 
of sensitive instrumentation. There are others. It is very difficult to 
predict if an increased arsenic hair concentration,after many months after   
possible arsenic chronic poisoning exposure, can still be observed.