Question

Why is milk used as a first-aid remedy for someone who has swallowed a heavy-metal poison?

Answer 1

Answer:

Heavy metal poison specifically due to lead are removed by intake of milk (as it is a source of calcium)

Explanation:

Toxicity produced by heavy metal specifically lead can be removed by intake of calcium metal which is predominantly found in milk. The interaction between lead-calcium subsides the toxicity of lead.  

Both calcium and lead ion i.e Pb(2+) and Ca2+ compete with each other for transportation at the plasma membrane but due to the presence of Ca2+ channels, and the Ca2+ pumps, calcium get preference over lead and hence it is removed from the nervous system.

Answer 2

Human trials have indicated an inverse relationship between blood lead level and calcium intake. While milk isn’t an antidote to let’s say, lead poisoning, the dietary calcium inhibits the lead absorption. This sort of poisoning is incredibly dangerous to the systems of the human body, and the ingredients within the milk help to defend against it. The purpose of the milk is to dilute the ingested poison.