In chronic arsenic poisoning the following samples can be sent for laboratory examination, except:

D i.e. Blood sample Arsenic is rapidly cleared from the blood and is distributed to various organs & tissues, where it is detectable for prolonged periods. Blood sample is thus of use only in a case of acute poisoning, but not in chronic poisoning. In chronic poisoning arsenic is found in hair, nails, bones, skin etc and its detection is possible when any of these structures is available - Parikh