The most difficult toxins riddles

The manchineel tree is native to tropical southern North America and northern South America. All parts of the tree contain strong toxins and even the merest contact with human skin causes a breakout of blisters, and blindness can occur if it touches a person's eyes. In some parts of its range, many trees carry a warning sign, while others are marked with a red "X" on the trunk to indicate danger.

Methanol has a much weaker sedative effect than ethanol, which leads the victim to drink more than it would normally do with ethanol. Methanol is oxidized to formaldehyde and then to the poisonous formic acid in the liver.

Amanita muscaria contains several biologically active agents, at least one of which, muscimol, is known to be psychoactive. Ibotenic acid, a neurotoxin, serves as a prodrug to muscimol, with approximately 10–20% converting to muscimol after ingestion. An active dose in adults is approximately 6 mg muscimol or 30 to 60 mg ibotenic acid; this is typically about the amount found in one cap of Amanita muscaria. Spring and summer mushrooms have been reported to contain up to 10 times more ibotenic acid and muscimol than autumn fruitings.

The value of LD50 for a substance is the dose required to kill half the members of a tested population after a specified test duration. Botox is the most acutely lethal toxin known, with an estimated human LD50 of 1.3–2.1 ng/kg intravenously or intramuscularly and 10–13 ng/kg when inhaled.

An effective treatment to prevent toxicity after methanol or ethylene glycol ingestion is to administer ethanol. Alcohol dehydrogenase has a higher affinity for ethanol, thus preventing methanol from binding and acting as a substrate. Any remaining methanol will then have time to be excreted through the kidneys.