All processed oils contain trans fats. The more solid the oil the higher the trans fat level. Liquid vegetable oils contain up to 6% trans fats and margarines and shortening up to 58%. You can identify trans fats in other foods by looking for the word "hydrogenated" or "partially hydrogenated" in the ingredients list. You will find these words on the labels of many breads, candies, baked goods, chocolate, frozen dinners, and processed meat products. If you want the best of health, don't eat them.
The worst aspect of this trans fat nightmare is the FDA, who is suppose to protect our food, remain 20 years behind the times. I read an old article dated back in 94' last week from the Center for Science in Public Health Interest. They asked the FDA why the regulations did not enable consumers to find out the level of trans fats in foods, the official replied, "We're exhausted from the rule writing." That's the sort of health protection that has made America sick over the years.
The whole of Europe has had mandates against trans fats for some years. Many European foods now state specifically on the labels that they are made with cis fats, the healthy kind, even margarines. Buy and use organic flax seed oil, it will go a long way to protect your health.