NEGATIVE RESULTS DO NOT EXCLUDE ARSENIC POISONING

> Dear Mahasiswa,

> > > You would have heard that the samples that the UKM sent were negative > for arsenic. The BN is going to try and use this to discredit the > opposition. Some points from a medical perspective.

> > 1) It is important to know what samples were sent and how they were > collected -- nail clippings are from that part of the nail that was > formed 3 to 4 months before. Arsenic ingestion 1 to 2.5 months ago will > not show up in these clippings. So absence of arsenic in nail clippings > just means that at the time this bit of nail was formed, there was no > arsenic ingested. It does not exclude arsenic ingestion before or after > that period of time.

> > 2) Similarly, deposition of arsenic in hair is also time specific. Hair > grows at about 1.5 cm per month. So the first 1.5 cm closest to the > scalp is the most recently grown hair and arsenic in this part of the > hair would indicate arsenic ingestion in the previous month. The second > 0.5 cm will reflect arsenic ingestion in the month before.

> > It is therefore important to know how hair samples were collected -- > were the entire hair collected, or merely more distal locks sampled. If > the second scenario, they would be hair that grew some 4 months ago, and > their being negative does not rule out arsenic poisoning that took place > more recently.

> > 3) Urine arsenic levels would be very high in the first 24 hrs after > ingestion of arsenic. The levels would decay very rapidly if arsenic > intake is ceased -- perhaps by as much as 50% every 24 hrs -- it is not > certain how rapidly but one would have to check this with a pharmacist.

> > So negative results do not completely exclude arsenic poisoning -- a lot > depends on how the samples were collected.

> > Views of a Medical Doctor >