Total U.S. estimated use of TCE exceeded 200 million pounds in 1990. All 200 million pounds entered the general environment sooner or later. When it gets loose, TCE has a strong tendency to enter the atmosphere. In other words, the whole atmosphere is contaminated with TCE at low concentrations. Any particular molecule of TCE only remains in the atmosphere a few days.
Rain brings TCE back to the ground where it then moves into streams, rivers, lakes, and oceans.
Once it enters water, much of it moves back into the atmosphere quickly, but some of it enters plants, then small animals, then fish. Fish from various waterways contain TCE in the range of 10 to 100 ppb. Fresh bread contains 7 ppb, various brands of margarine contain 440 to 3600 ppb. These are not national averages, so the foodstuffs in your refrigerator may contain less or more than these values. In sum, we industrial humans have managed to spread TCE everywhere.