Is the ethylene gas that is used to ripen tomatoes quickly in supermarkets safe?
Ethylene gas is produced naturally by most fruits, such as tomatoes, bananas, peaches, and avocados, and it promotes ripening. Most tomatoes today are picked green and transported unripe to protect them from bruising and spoilage. The green tomatoes are then ripened somewhat artificially by exposing them to ethylene gas. This is generally not done in the supermarket but at the produce distributors that supply local markets.
The early picking, transport and rapid ripening results in the inferior, mealy tomatoes that we have in our grocery stores today. In many cases you are better off using canned tomatoes for cooking than fresh.
It doesn't appear that there is a danger. Keep in mind that the tomatoes naturally produce ethylene gas and are doing so there in the grocery (and on your kitchen counter). Interestingly, ethylene gas was once used as an anesthetic. Long term exposure to lab animals by ethylene gas did show some increase in risk of cancer, but studies of workers that are involved in professions using the gas do not.
It is very likely that it is just as safe for you to eat tomatoes that have been "gassed" as those that "gas themselves" with ethylene gas.
Thanks for writing,
Timothy S. Harlan, M.D.