Don,
It isn't a method I use on a regular basis. I have used it and survived. KMnO4 is a powerful oxidant, the stuff you take anti-oxidants to get rid of so its a toss-up. I did some research on KMnO4 toxicity and there have been a few cases of people taking lethal doses or near lethal doses in suicide attempts. In each case they were talking high concentrations of the stuff. I'll try to find the research. The tiny amounts we're talking about come nowhere near a lethal dose but the stuff is scary potent. Mac
ETA - I edited the above post to correct my recollections as i found the info i had saved
KmnO4 Toxicity
IPA COPYRIGHT: ASHP A case of corrosive burns to the mouth, esophagus and trachea in a 3-yr-old boy who ingested 5-10 g of potassium permanganate (I) is presented. The mouth was washed repeatedly with water. He was given 2 glasses of milk. Laryngoscopy revealed edema of his upper airway. He was intubated to prevent upper airway obstruction secondary to progression of the edema. The child received an intravenous administration every 6 h of ampicillin 50 mg/kg and hydrocortisone 4 mg/kg. The laryngeal edema resolved and he was extubated 3 days later. A follow up esophagoscopy at 7 days showed normal mucosa and he was discharged. A plasma manganese level performed on day 4 was 4.1 mcg/l, one month later this had fallen to 1.5 mcg/l.
The pathogenesis of the systematic toxic effects of potassium-permanganate (7722647) (KMnO4) was examined, based on the case history of a suicidal ingestion. The patient was admitted to the hospital 1 hour after ingestion of about 5 to 10 grams of KMnO4 crystals, with hands, lips and oropharynx stained dark brown. She was treated with activated charcoal and antibiotics. Alanine-amino-transferase (ALT) and lactate-dehydrogenase (LD) levels increased significantly by day two. Acute hepatic necrosis and progressive cardiovascular failure developed. N-acetyl-cysteine was administered 48 hours after ingestion. ALT and LD levels peaked at day three. On day six she died of complications arising from hepatic, renal, cardiovascular, and respiratory failures. Postmortem examinations revealed significantly higher whole blood and tissue manganese (7439965) concentrations, relative to a control autopsy. The authors conclude that oxidizing free radicals generated by the permanganate ion are predominantly toxic to the liver and kidneys, perhaps due to the high blood flow through these organs. They recommend that N-acetyl-cysteine, a reducing agent, be administered as soon as possible after KMnO4 ingestion.
IPA COPYRIGHT: ASHP A case of a 66-yr-old man who ingested 125 ml of an 8% solution of potassium permanganate (10 gm) over a 4 wk period is reported. Neurological and gastrointestinal symptoms are discussed. Treatment with pentetate calcium trisodium decreased serum levels and increased urine excretion of manganese. Nine months after poisoning, the first sign of progressive Parkinson disease become evident.
The dose we are talking about for water purification is a very small fraction of a gram. Seriously, you would have to have a very sensitive scale to even weigh it. Ordinary iodine crystals would probably have a similar toxicity if large doses were ingested. Remember, iodine, chlorine and potassium permanganate disinfect water because they are lethal to living organisms. The concentration needed to kill a single celled organism is far below what you can safely tolerate as a large primate. Mac
From Wiki - Elemental iodine (I2) is poisonous if taken orally in larger amounts; 2–3 grams of it are a lethal dose for an adult human.
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