Acetylene is not especially toxic, but when generated from calcium carbide, it can contain toxic impurities such as traces of phosphine and arsine, which give it a distinct garlic-like smell. It is also highly flammable, as are most light hydrocarbons, hence its use in welding. Feb 27, 2018 · Ethylene gas can be used to de-green citrus and other crops (e.g., pineapples). For these particular fruits, ethylene gas only alters their appearance and does not aid in their ripening process. Ethylene gas works to remove the overlying chlorophyll (green color) to unmask the color underneath. Sep 24, 2018 · Arne Dedert/Getty Images If you've ever tried to ripen a piece of fruit by sticking it in a bag with a banana, you've harnessed the power of ethylene. Ethylene is an important plant hormone. In .