Mineral Oil
In plain terms
A clear, petroleum-derived oil that sits on skin to seal in moisture. Two worries follow it around, that it clogs pores and that it is a toxic petroleum product, and the refined grade used in cosmetics earns neither.
What the evidence shows
Mineral oil carries two reputations it has largely outlived. The first is that it clogs pores; in modern testing it scores at or near zero for that, and dermatologists use it and its cousin petrolatum in wound care and on newborn skin, about the most demanding safety test there is. The second is that, being from petroleum, it must be a carcinogen. This is where grade is everything. Untreated industrial mineral oils do carry cancer-causing aromatic compounds and are classed as known carcinogens, but the cosmetic and pharmaceutical grade is refined specifically to strip those out, and review bodies in Germany, Canada, and beyond have looked and concluded that properly refined cosmetic mineral oil poses no carcinogenic risk. On skin it barely absorbs, under half a percent, and does not sensitize. The honest footnotes are small: the saturated hydrocarbons can accumulate slightly in body tissue, and because lip products are partly swallowed, those are held to a stricter food-grade purity for the aromatic fraction. None of that overturns the basic picture for skin use, where refined mineral oil is one of the most tested and most inert moisturizers there is.
On the label
Listed as mineral oil or paraffinum liquidum. Cosmetic and pharmaceutical grades are the refined kind; the carcinogen label you may have read about belongs to untreated industrial oils, which are not what goes in skincare.