How Dangerous is Ethylene Gas for Human Consumption?

Ethylene gas is a naturally produced chemical or plant hormone created during the ripening process of many vegetables and fruits such as bananas and apples, and is considered a ripening agent and a growth regulator and is an ordinary occurrence. Naturally forming ethylene gas is why your grandmother would place a few green tomatoes in a bag with either an apple or banana to ripen them over a period of a few days through the interaction of the released chemical.

Manufacturers have tried to make ethylene gas in bulk using organic substances by artificially heating large amounts of this biomass material. However, this method of obtaining ethylene gas has not been conducive to commercial production due to the high volume of heat needed to convert natural greenstuffs into a useable commercial product, thus making the process cost prohibitive. Instead, most ethylene gas today is created out of petroleum products such as natural gas liquids or crude oil by the use of heat, nitrogen, and steam that is converted into a liquid gas, and then stored in metal containers used for dispersing on food crops.

Unfortunately, ethylene gas in the form of a liquid is most dangerous to humans who are applying the gas to crops or in fruit or vegetable ripening rooms because it can be very flammable and explosive. If a person is contaminated by ethylene gas by inhalation, it can cause dizziness, nausea, and even suffocation or asphyxia (through lack of oxygen).

When used safely, it is incorporated by many large scale farms to artificially accelerate the natural ripening process of physiologically mature bananas, pears, mangoes, peaches, honeydew melons, tomatoes, avocados, citrus fruits (and which also degreens most citrus), bean spouts, and to make pineapple plants flower at a uniform rate and to make the fruit itself more consistent in size. It is not good for other fruits and vegetables such as lettuce, broccoli, cauliflower, and most flowers.

One of the most well known examples of ethylene gas used for human consumption is the tomato normally purchased in stores when local sun-ripened tomatoes are "out of season". Almost everyone loves a sun-ripened, juicy red tomato right out of the garden and, in fact, the majority of all vitamins consumed by people are from tomato consumption. Even so, while shopping for food, one of the most popular items bought year round is a tomato; however, most tomatoes purchased in a grocery store are anything but sun-ripened and, technically, may not be quite ripe at all.

So, exactly why is that tomato red if it did not ripen on the vine? In order to have red tomatoes available year round, most tomatoes today are picked green, and then shipped to markets all over the world. For you to be able to select that red tomato, it is normally "gassed" during shipment with ethylene gas (also called ethene, elayl, or olefiant gas) which starts the natural process of ripening through normal chemical changes that would typically occur in the field - only at a faster or accelerated pace. The important end result is that these tomatoes will ripen, turn a familiar red, and resemble any other ripe tomato, and the residue left by ethylene gas is negligible and safe. These tomatoes are not dangerous to eat and can be used for sandwiches, soups, stews, sauces, and chili. Another good result is that the nutrients in the tomato are not harmed and there is less chance of loss because the tomatoes will reach the dinner table sooner because of the ethylene gassing.

Despite that, the term "ripen" may be a somewhat misleading word because a majority of gassed tomatoes are hard, mealy textured, and with little to no "real" tomato flavor. Some growers claim this is from bad shipping practices with too cool storage temperatures, the variety of tomato, damaged or inferior produce, and the maturity of the crop when harvested.

Therefore, how dangerous is ethylene gas for human consumption? Ethylene gas is safe when used for readying produce for market because it is already a naturally occurring gas created by the growth and maturation of fruits, vegetables, and some microorganisms on their own. No link has been discovered that cites ethylene gas as being harmful or carcinogenic and it is environmentally safe since it is naturally found in soil and plants. Nevertheless, while these commercially ethylene induced red tomatoes are safe for human consumption, they will never replace those naturally sun-ripened red fruits from your garden.