There seem to be serious risks in some food oils that are commonly considered healthy. This report says:
hexane processing strips the remaining nutrients from the oil, and turns a significant quantity of polyunsaturated fats into inflammatory, artery-clogging trans fats!
Hexane processing is apparently common for Canola oil, soybean oil, and other plant-based oils (but not olive oil). Trans-fat levels have been measured at 0.56 to 4.2 percent in commercial oils.
Since FDA-regulated labels are only accurate to about 0.5 grams, and oils are often labeled for 14g serving sizes, a 1 or 2 percent trans-fat content would apparently show up as zero. I suspect those levels are more harmful than most additives that the FDA has banned from foods.
The bottled Canola oil I buy from Trader Joe’s says it’s expeller pressed – no solvents used, so I’m still guessing it’s healthy, but I’ll try harder to avoid processed foods containing plant oils. (There a lot of misleading arguments against Canola oil that should be ignored).