Calcium carbide is used industrially as a welding agent due to the liberation of flammable acetylene gas on contact with moisture. It is included in the Toxic Substances Control Act (TSCA) Chemical Substance Inventory of the Environmental Protection Agency (EPA). Industrial acetylene gas behaves as a simple asphyxiant which affects the neurological system by causing prolonged hypoxia. In developing countries, calcium carbide is illegally used as an artificial ripening agent as the acetylene gas is an ethylene analogue which is a naturally occurring ripening agent produced by fruits. What other potential toxicities may be involved in this process?
Despite its ban by the South Asian Association for Regional Co-operation (SAARC), there is no policy/guideline on fruit agriculture in developing countries. Calcium carbide manufacturing can often get contaminated with heavy metals such as arsenic and phosphorous which can result in liberation of arsine and phosphine gas. These impurities can be removed by driving acetylene gas through acidified copper sulfate solution, unfortunately, in under-resourced settings, this step is ignored. Fruits ripened with calcium carbide exhibit the least organoleptic quality compared to naturally ripened fruits. The fruit may develop an attractive surface color but the tissue inside may be unripe. A very raw fruit would require greater amounts of calcium carbide making it highly toxic. Consumers should thoroughly wash and peel off the fruits so that surface chemicals are removed.
Contributor: Muhammad Akbar Baig, MD, Northshore University Medical Toxicology Fellowship
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