What are dioxins?
The term “dioxins” refers to a family of chemical compounds that share several common characteristics. They are colorless, odorless organic compounds containing carbon, hydrogen, oxygen and chlorine. Dioxins occur as natural byproducts from volcanoes and forest fires, and are produced from man-made processes such as manufacturing, incineration, paper and pulp bleaching and exhaust emissions. Burning household trash and/or fuels like coal, wood or oil also forms dioxins.
Dioxins are measured in parts per trillion (ppt). (A part per trillion is roughly equivalent to a drop of ink in an Olympic-size swimming pool.) In the United States, industrial sources of dioxins released into the environment have decreased significantly over the past 20 years. Today, studies indicate that the largest sources of these chemicals in the U.S. are backyard trash burning and forest fires.
Should consumers be concerned about dioxins?
In the past, unusually high levels of dioxin exposure, such as workplace and accidental exposures, have caused adverse health effects but today’s environmental levels are well below international guidelines for safe exposure.
Because there are natural sources of dioxins, including forest fires and volcanoes, dioxins are prevalent throughout the environment at very low concentrations. As such, virtually every living creature has been exposed to dioxins.
However, the July 2005 report from the U.S. Centers for Disease Control and Prevention, Third National Report on Human Exposure to Environmental Chemicals, states that “…human blood levels of dioxins (in the U.S.) have decreased by more than 80 percent since the 1980s.”
How are humans exposed to dioxin?
Dioxins are ubiquitous in the environment. They are found throughout the world in air, water and soil. Although dioxin exposure can come through industrial exposure by contact with the skin or inhalation, overall, this represents very small sources of dioxin exposure.
Dioxins may enter the food chain. They can be deposited on plants and taken up by animals and fish as they feed. Dioxins have a high affinity for fatty substances and are found in fat tissue of both plants and animals. We as humans are exposed to dioxin by our diet. It is estimated that 95 percent of human exposure to dioxins comes from the diet through food, meat, milk and poultry and through human breast milk.
What are the health effects of dioxin exposure?
There are no clearly established health effects associated with exposure to current, low background levels of dioxins. High levels of dioxin—hundreds of times greater than background levels—are known to cause a reversible skin condition known as chloracne. Chloracne has been documented in people (a) accidentally exposed in industrial settings, and (b) intentionally poisoned.
Some studies of industrial worker groups have suggested a small increase in cancer rates in persons subjected to unusually high dioxin exposures. Studies of high level exposure also indicate that some biochemical changes, such as enzyme and hormone levels, may be induced by such exposures.
What has been done to control dioxin releases into the environment?
Over the last 30 years, through regulatory and voluntary efforts, industrial sources of dioxins in the United States have decreased significantly. According to data from the U.S. Environmental Protection Agency (EPA), there has been a reduction in dioxin emissions of more than 90% since 1987. Major coordinated efforts and regulation by federal, state and local government agencies and industry have successfully reduced levels of dioxin released into the environment through industrial and community sources (e.g., trash incinerators). Collectively, these actions have resulted in stricter controls of all of the known major industrial sources of dioxins.. Studies continue to demonstrate falling dioxin levels in humans, food, soils and sediments.
The EPA is working to discourage the practice of backyard trash burning, currently estimated by the EPA to be the single largest source of dioxins to the environment. Information about the hazards of open trash burning and alternative methods for trash disposal are available in a series of brochures produced by the EPA.
How do dioxins get into the food chain?
Dioxins can enter the food chain through a number of different routes: in fish, the primary route of exposure is through water; plants are exposed to dioxins primarily through particulate matter in the air; animals are exposed through airborne dioxin particles that settle on forage or feed, which is then eaten by animals. Dioxins can concentrate in the fatty tissues of beef and dairy cattle, poultry, pork or seafood and therefore create human exposure through the diet. However, dioxin particles that settle on fruits and vegetables as a result of airborne exposure are not absorbed into the plant and can be removed through washing.
What is the federal government doing to ensure that dioxin levels in foods are minimized?
In addition to actions the EPA has taken to reduce environmental levels of dioxins, the U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA) both monitor the levels of dioxins in food and animal feeds, and conduct investigations when particularly high dioxin levels (above the background levels) are detected in food or animal feeds.
For example, in 1999, the FDA began annual monitoring for dioxins in foods as part of its Total Diet Study (TDS), a yearly program that determines levels of various contaminants and nutrients in food. TDS analysis results are used to determine human exposure levels. If the investigation determines a specific source of increased dioxins, the FDA takes action to remove that source.
According to the TDS, dietary intake levels of dioxin-like compounds are 90% lower than those of the 1970s, and a further 50% reduced from the mid-1990s. The FDA estimated intakes for every age group from infants to 70-year-olds and found that exposures were below World Health Organization tolerable limits. The TDS report can be accessed at: http://www.cfsan.fda.gov/~lrd/dioxdata.html.
In May 2000, FDA's Center for Veterinary Medicine initiated a preliminary national survey to determine background levels of dioxin-like compounds in fats and other feed ingredients commonly used in animal feeds. In addition, the FDA is continuing its research efforts to better understand how dioxins get into the food supply and to identify ways for further reducing the level of dioxins in food.
The USDA’s Food Safety and Inspection Service periodically monitors levels of dioxin-like compounds in various livestock. Levels of these compounds have declined in all livestock surveyed. Average declines between the survey periods 1994 – 1996 and 2002 – 2003 range from 33% (steers and heifers) to 81% (market hogs). A June 2005 report announcing that data can be accessed at: http://www.fsis.usda.gov/PDF/Dioxin_Report_0605.pdf.
Should Americans eliminate any foods from their diet to avoid dioxins?
No. Avoiding or eliminating a particular food or food group is not recommended and could lead to significant health problems because each food group provides important nutrients needed for health. As an example, public health authorities recognize that many Americans, particularly females, are not meeting daily requirements for calcium. Therefore, eliminating dairy products could put this population at risk for increased incidence of osteoporosis.
Diet and health experts such as the U.S. Surgeon General, the Department of Health and Human Services, the Department of Agriculture, the American Medical Association and the American Dietetic Association continue to advise Americans to eat a balanced diet with a variety of nutrient-packed foods every day. This advice is consistent with the 2005 Dietary Guidelines for Americans (http://www.healthierus.gov/dietaryguidelines) and MyPyramid food guidance system (http://www.mypyramid.gov) recommendations.
Because dioxins can be found in human breast milk, is it safe to nurse my infant?
Yes, it is safe to nurse your infant. While dioxins are known to pass from the mother's body to the infant during lactation, numerous health experts recognize that breastfeeding provides important nutritional, immunological and other benefits to the infant in the first months of life. In addition, many studies have shown that breastfed infants are healthier than formula fed infants. The bottom line is, the benefits of breastfeeding far outweigh any risk from minimal exposure to dioxin.
What can I do to minimize my dietary exposure to dioxins?
For most people, following the recommendations of the 2005 Dietary Guidelines for Americans (http://www.healthierus.gov/dietaryguidelines) and MyPyramid food guidance system (http://www.mypyramid.gov) will result in multiple health benefits, including reduced dioxin exposure. Consistent with the Dietary Guidelines and MyPyramid, a balanced diet that is low in saturated fats and total fats also helps consumers minimize any potential exposure to dioxin from food. Dioxins are found mostly in animal fats due to the fat soluble properties of the dioxin compound. While studies show there is no cause for alarm from potential health issues concerning dioxins in the diet, choosing leaner cuts of beef, pork and poultry; trimming the fat and removing skin from chicken before cooking; and eating non- and low-fat dairy products can help maintain optimal health, as well as limit exposure to dioxins. In addition, washing fruits and vegetables can help remove airborne dioxins that have settled on produce in fields.
Following the Dietary Guidelines recommendations will help individuals lower their exposure to dioxins. These guidelines include the recommendations to go lean with protein, including advice to choose lean meats and poultry; to choose non-fat or low-fat milk and milk products; and to increase consumption of fruits, vegetables and grain products. Lean meat includes meats that are naturally lower in fat and meat where visible fat has been trimmed. These strategies help lower the intake of saturated fats as well as reduce the risk of exposure to dioxins.
Final Note:
Humans will always be exposed to some low level of dioxins because there are natural sources of these compounds. To date, there have been no established health effects in humans from this low level exposure. Americans should continue to enjoy foods from all food groups, including lean meats, poultry and fish, as well as low-fat and non-fat milk and dairy products as outlined in the 2005 Dietary Guidelines for Americans.
It is important to remember that as Americans, we enjoy one of the safest food supplies in the world. The federal government, regulators, educators and physicians can all agree that a well balanced diet, rich in a variety of fruits, vegetables and grains, is key to a healthful lifestyle.
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