Bay Area Medical Information
What are Dioxins?

Dioxin and related compounds (PCBs), sometimes referred to "as the most toxic compounds made by mankind"1, were first found in Agent Orange, an herbicide widely used during the Vietnam War. Dioxins were originally thought to solely be a by-producut of many industrial processes involving chlorine, specifically waste incineration, chemical and pesticide manufacturing and pulp and paper bleaching. More recently the origins of dioxins has been further clarified by researchers, and it is now generally accepted that a principal source of dioxins are various combustion processes, including natural events such as wild fires and even volcanic eruptions.

"Today, the critical issue is the incineration of waste, particularly the incineration of hospital waste, which contains a great deal of polyvinyl chloride plastics and aromatic compounds that can serve as dioxin precursors. One study examined the burning of household trash in drums in the backyard. It turns out that these small burnings of debris can put out as much or more dioxins as a full-sized incinerator burning hundreds of tons of refuse per day. The incinerators are equipped with state-of-the-art emission controls that limit dioxin formation and their release into the environment, but the backyard trash burning does not."1 Dioxin and related compounds unintentionally get released into the environment where they not only persist, but ultimately build up in the food chain. Humans are then exposed to dioxins mostly by eating animal fat from beef, pork, fish, and dairy products, although significant occupational or accidental exposure occurs as well.

"Efforts to reduce dioxin and related compounds in the environment in recent years have resulted in lower concentrations of the chemicals in humans."2 Dioxin levels in the environment have been declining since the early seventies and have been the subject of a number of clean-up actions, as well as federal and state legislation; however, current exposure levels continue to remain a concern.3

Are Dioxins Harmful?

Dioxins have been widely dispersed throughout the environment in low concentrations. Through our consumption of animal fat they have accumulated in the tissues of our bodies. In fact, most people today have detectable levels of dioxins in their tissues. These levels, in the low parts per trillion, have accumulated over a lifetime and will persist for years, even if no additional exposure were to occur. This low exposure level is likely to result in an increased risk of cancer or liver damage and is uncomfortably close to levels that can cause subtle adverse non-cancer effects in animals and humans. These effects include changes in hormone systems, alterations in fetal development, reduced reproductive capacity, and immunosuppression. At high doses, dioxins can cause a serious skin disease called chloracne.

Lower your exposure--limit the dietary animal fat (saturated fats)

Although dioxins are an environmental contaminant, exposure most often occurs through the food chain by eating animal fat (saturated fat). For most people, following existing Federal Dietary Guidelines significantly reduces fat consumption and, thus, reduces dioxin exposure. The dietary guidelines outline a diet based on moderate amounts of fats. Eliminating all fats is not healthy. Whereas saturated fats come from animal sources, unsaturated fats are found in products derived from plant sources. Unsaturated fats are found in vegetable oils, nuts, and seeds.  There are 2 main categories of unsaturated fats: polyunsaturated fats & monounsaturated fats.  Both are liquid at room temperature--polyunsaturated fats are also liquid in the refrigerator, but monounsaturated fats start to solidify at refrigerator temperatures. These fats are considered healthy fats. Our body needs these fats, and consuming them will help lower the risk of heart attack and stroke.

Overall, the best strategy for lowering the risk of dioxins while maintaining the benefits of a good diet is to follow the recommendations in the Federal Dietary Guidelines to choose fish, lean meat, poultry, and low or fat free (skim) dairy products and to increase the amount of fruits, vegetables and whole grain products in the diet. Lean meat includes meats that are naturally lower in fat, and meat where visible fat has been trimmed. For fish and poultry you can reduce fat by removing the skin. Reducing the amount of butter or lard used in the preparation of foods and cooking methods that reduce fat (such as oven broiling) will also lower the risk of exposure to dioxin.

Always read food labels when available. In general, try to limit saturated fat to 15 to 20 gms/day. (For people with diabetes or heart disease, limit saturated fat to <10 grams/day. For people with elevated LDL-cholesterol, limit to 15 gms/day.)3 Saturated fats are usually a bigger problem than the cholesterol we consume.  These fats are mainly animal fats and are found in meat, lard, butter, whole milk dairy products (cheese, milk and ice cream) egg yolks, tropical oils-coconut, palm, and palm kernel oil.  Saturated fats are usually solid at room temperature.

These strategies help lower the intake of saturated fats, which will lower the risk of heart disease and stroke, as well as reduce the risk of exposure to dioxins.

Can dioxins be released into the food by cooking in plastic?

Yes. Only use plastic cookware and utensils that are specifically meant for cooking. Inert containers are best, for example heat-resistant glass, ceramics and stainless steel.1 According to Rolf Halden, PhD, from Johns Hopkins, "In general, whenever you heat something you increase the likelihood of pulling chemicals out. Chemicals can be released from plastic packaging materials like the kinds used in some microwave meals. Some drinking straws say on the label “not for hot beverages.” Most people think the warning is because someone might be burned. If you put that straw into a boiling cup of hot coffee, you basically have a hot water extraction going on, where the chemicals in the straw are being extracted into your nice cup of coffee. We use the same process in the lab to extract chemicals from materials we want to analyze."1

Tips from the USDA:9

  • Only use cookware that is specially manufactured for use in the microwave oven. Glass, ceramic containers, and all plastics should be labeled for microwave oven use.
  • Plastic storage containers such as margarine tubs, take-out containers, whipped topping bowls, and other one-time use containers should not be used in microwave ovens. These containers can warp or melt, possibly causing harmful chemicals to migrate into the food.
  • Microwave plastic wraps, wax paper, cooking bags, parchment paper, and white microwave-safe paper towels should be safe to use. Do not let plastic wrap touch foods during microwaving.
  • Never use thin plastic storage bags, brown paper or plastic grocery bags, newspapers, or aluminum foil in the microwave oven.
Can dioxins can be released by freezing water in plastic bottles?
No. This is an urban legend. According to a leading Johns Hopkins researcher, "There are no dioxins in plastics. In addition, freezing actually works against the release of chemicals. Chemicals do not diffuse as readily in cold temperatures, which would limit chemical release if there were dioxins in plastic, and we don’t think there are." Many email warnings have circulated on the internet to avoid freezing water in plastic bottles so as not to get exposed to carcinogenic dioxins. This is not true.

(1) Researcher Dispels Myth of Dioxins and Plastic Water Bottles from Johns Hopkins University
(2) EPA Assessment of Dioxin from the National Academies
(3) Dioxins and Furans from the EPA, April 30, 2007
(4) Cholesterol Control from the US National Library of Medicine & Nat'l Institute of Health
(5) PBTs and You (PBT=Persistent Bioaccumulative and Toxic) may be affecting your health and the health of your community. If you have specific questions or need information about PBTs in your state or community, this page can offer you several sources of information.
(6) Air Quality Animated Map of Florida from the Florida Dept of Environmental Protection
(7) Florida's Air Quality Monitors Map from the Florida Dept of Environmental Protection
(8) ToxMap Environmental Health eMaps from the U.S. National Library of Medicine
(9) Cooking Safely in the Microwave Oven from the USDA

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