The combination of arecoline, the lime, and the betel leaf is strongly associated with oral submucous fibrosis — a precancerous condition in which scar tissue progressively restricts the opening of the mouth.

It is associated with dramatically elevated rates of oral cancer, esophageal cancer, and pharyngeal cancer.

It causes progressive staining and destruction of the teeth.

It is physically addictive.

In the countries where betel quid use is most prevalent, oral cancer rates are far higher than in countries where it is not used.

The World Health Organization classifies betel nut (areca nut) as a Group 1 carcinogen — the same category as tobacco and alcohol — based on sufficient evidence of carcinogenicity in humans.

This is the substance that someone on Sulawesi was using between 16,000 and 25,000 years ago.