Zero Toxics Knowledge Base
STEEL, by definition, is made primarily from iron. Iron is a naturally occurring metallic element. It is rarely found on the surface of the earth because it oxidizes readily in the presence of oxygen and moisture, and disintegrates into rust. The iron used in products, such as cast iron, is made from the iron ore hematite, from which oxygen has been removed by heating to high temperatures. So when a product is made primarily from iron, it will naturally rust.
Pure single crystals of iron are very soft, so other metals are added to strengthen it. These are called “alloys”. Alloying iron with small amounts of other metals and carbon produces steel, which can be 1,000 times harder than pure iron.
There are two basic types of steel: carbon steel and stainless steel.
The type of steel used to make mattress springs, auto bodies, cans, cutlery, and woks is plain carbon steel, produced by the Basic Oxygen Furnace process. You can easily tell that it is carbon steel because it turns black over time and easily rusts when exposed to air and moisture. Carbon steel is mostly iron, with less than 2% carbon, 1% manganese, and small amounts of silicon, phosphorus, sulfur and oxygen. It can be recycled and often contains a minimum of 25 percent recycled content whether it is so labeled or not. The Electric Arc Furnace process, which is used to produce steel shapes such as railroad ties and bridge spans, uses virtually 100 percent recycled steel.
Most consumer products made from steel, however, such as cookware and bakeware, cooking utensils, and flatware, are made from stainless steel, which has a special ability to resist stains and corrosion (so it doesn’t rust or turn black). The average stainless steel object is made of about 60% recycled material of which about 40% originates from products consumers have recycled and 60% comes from manufacturing processes. (The Recycling of Stainless Steel” International Stainless Steel Forum. 2006).
Steel is not toxic for most uses and exposures. It does not emit toxic pollutants into the air. Stainless steel is often used for jewelry as an alternative to nickel because it doesn’t react to the skin, However, there is some evidence that stainless steel will leach heavy metals into foods and beverages during cooking or storage, so there is some concern about using stainless steel for food storage or cookware. I personally no longer use stainless steel in my kitchen except for utensils, where the food is in contact with the steel for only moments.
Stainless Steel Leaching Into Food and Beverages
For a lot more information about stainless steel see my post from Toxic-Free Q&A Stainless Steel Leaching into Food and Beverages.
ZERO TOXICS IS LIKE A PUZZLE
In this Knowledge Base, i'm gathering together bits and pieces of information about materials used to make products, and bringing some order to them so we can all better understand what's in our products. So many pages will be incomplete as I go through this process. When I feel I've put together a fairly complete picture of the material, I'll take down this notice from this page.
ZERO TOXICS is rooted in my forty years of research and experience living toxic-free. I'm gathering and organizing the data I have to make this knowledge available to everyone. Feel free to ask questions, share data, and join in the discussion in the comments section below.
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