Ranked by the numbers

Ranked by the lowest reported oral LD50, preferring the rat and then the mouse so the numbers compare like with like. Every row names its route and species. A molecule measured only by injection is not listed here, because an injected dose is not a swallowed one. Animal data shown as neutral science: an estimate, never a threshold to act on.

Ranked by sweetness relative to table sugar (sucrose = 1×).

Ranked by Scoville heat units, the pungency of the pure compound: from resiniferatoxin and the capsaicinoids that make chili peppers burn, down to the milder bite of ginger and black pepper. Values outside the capsaicinoids are comparative estimates, since the Scoville scale is defined for capsaicin-like compounds.

The stinkiest molecules, ranked by odor detection threshold in air: the tinier the concentration a person can smell, the higher the rank. Sulfur compounds and the fecal, fishy, and sweaty notes top the list. Air-panel thresholds (Nagata 2003); values vary between studies, so these are representative published figures.

Ranked by molecular weight: the heaviest molecules in the canon.

Ranked by molecular weight, smallest first: the simplest molecules in the canon, the gases and small acids most of everyday chemistry is built out of.

The Deadliest board read the other way: ranked by the HIGHEST reported oral LD50, so the molecules that take the largest dose per kilogram of body weight to do harm come first. Same oral-only rule and the same route and species on every row. A high LD50 means an animal study found a large dose tolerable, nothing more: it is not a safety rating and not advice.

The most famous molecules in the canon, ranked by average monthly views of their English Wikipedia article. This measures attention, not importance: it is an honest popularity board, and the one place on the site where the ranking says something about people rather than about molecules.