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Dioxin Levels in Food – Where's the Beef?

Last year the USEPA completed and published the non-cancer portion of its health assessment for dioxin, one of the most toxic substances ever tested.This event passed without much fan-fare and little coverage by the media. With exception to CHEJ, even the environmental and health advocacy community paid it little attention. This is remarkable because the EPA’s health assessment on dioxin adds an important piece of new information that answers the question about the levels of dioxin in the American food supply. Until publishing this report, EPA had sidestepped the question of setting a reference dose for dioxin because they knew if they did this, they could no longer deny the obvious – the average daily intake of dioxin in food exceeds our best measure of what’s safe, EPA’s reference dose.



A reference dose is generally defined as “a level below which exposures are generally considered to be safe.” EPA’s Reference Dose for dioxin is 0.7 picograms TEQ per kilogram per day (pg/kg/d). According to EPA data, the adult daily intake of dioxin is 66 pg/day. Dividing this value by the average weight of an adult (70 kilograms), you get an average daily intake of dioxin of 0.94 TEQ pg/kg/d, 34% higher than the safe level. For children the numbers are even higher because of their smaller body size.

For example, a 2003 study by the National Academy of Sciences Committee on Dioxin in Food found that children ages 1 to 5 were exposed to 1.09 pg TEQ/kg/day and children ages 6-11 years old were exposed to 0.69 pg TEQ/kg/day. According to this analysis, dioxin exposure in children 1 to 5 years old exceeds EPA’s reference dose and that children 6 to 11 years old have dioxin exposure that is virtually identical to the reference dose. A recent research paper found that the average daily intake of dioxin in 207 pre-school aged children was 1.01 pg TEQ/kg/day, well above the EPA reference dose of 0.7 pg /kg day.

EPA has argued for some time that dioxin exposures are going down and in 2009 EPA published a paper that estimated the daily average intake of dioxin to be only 0.54 pg TEQ/kg/day. This estimate was based on an EPA estimate of dioxin levels in food. Unfortunately, there is no consensus of how much dioxin exists in the food we eat. We know that over 95% of our daily exposure results from ingestion of animal fat, primarily meat and dairy and that people who live near specific dioxin sources are exposed to even higher concentrations.

It is clear however that large numbers of the U.S. population, especially children, are being exposed to dioxin in food at levels that exceed EPA’s reference dose. We need to stop pretending that dioxin levels in food are not a problem and take this issue on. We need better data on dioxin levels in food and how it gets there, and for EPA, FDA, and USDA to engage in this issue. This is not likely however, until the public begins to demand it.


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Backyard Talk

New Dioxin Report: What it means


Several weeks ago EPA released the non-cancer portion of the EPA’s health assessment for the chemical known as dioxin. The event passed without industry collapsing, without the public going into panic as was anticipated by the food industry, and basically without the world coming to an end. The myriad forecasts of doom that industry and its apologists predicted did not come to pass. In fact, the media barely took notice. Why? – Because the reassessment did not set any new standards or introduce any new regulations.  It simply provided the scientific basis for determining the risks that dioxin poses, though in this case, just the non-cancer risks (EPA is still working on the cancer report).

The non-cancer effects of dioxin as described in the report are quite serious. In a recent review paper, Dr. Linda Birnbaum, Director of the NIEHS, summarized the adverse health effects of dioxin exposure in humans as including “cardiovascular disease, diabetes, cancer, porphyria, endometriosis, early menopause, reduced testosterone and thyroid hormones, altered immune responses, skin, tooth, and nail abnormalities, altered growth factor signaling, and altered metabolism.”

Most notably, the non-cancer assessment included for the first time a value called the reference dose.  This is a number used to evaluate non-cancer risks and is generally defined as “a level below which exposures are generally considered to be safe.” The EPA’s Reference Dose for dioxin is 0.7 picograms TEQ per kilogram per day (pg/kg/d) which was derived by evaluating developmental and reproductive effects in a community in Italy (Seveso) exposed to dioxin caused by an accident at a pesticide manufacturing plant.

What’s remarkable about the EPA reference dose is when you compare this number to the average daily exposure of the American public to dioxin (defined as the daily intake from all sources, 90% of which comes from food).  Using the most recent data from EPA (see Lorber et al. 2009) the average daily exposure is 0.54 pg TEQ/kg/d compared to EPA’s reference dose of 0.7 pg TEQ/kg/d.  So the average person gets a daily dose of dioxin that’s 77% of EPA’s new reference dose. That’s the good news; the bad news is that the average is so very close to the EPA reference dose and that some groups, especially children, are exposed to higher levels that exceed the new EPA reference dose. This is because children have different eating habits than adults. They tend to eat more diary products that are high in dioxin. Dioxin is prevalent in foods that are high in saturated fat, primarily meat and dairy.

A 2003 study conducted by a National Academy of Sciences Committee on Dioxin in Food bears this out. The committee found that children ages 1 to 5 were exposed to 1.09 pg TEQ/kg/day and children ages 6-11 years old were exposed to 0.69 pg TEQ/kg/day. This analysis shows that dioxin exposure in children 1 to 5 years old exceeds EPA’s reference or safe dose and that children 6 to 11 years old have dioxin exposure that is virtually identical to the EPA reference dose.

As a practical matter, this means that the best risk estimate we have on dioxin shows that the public, especially children are being exposed to unacceptable levels of dioxin that may be causing subtle adverse effects. These subtle effects likely include developmental effects that Dr. Birnbaum described in her review paper as posing the greatest concern “in part because the effects occur at the high end of the background range for the general population.”  These exposures may exceed the EPA’s reference does and even approach the levels observed in the study of Seveso, Italy.    The developmental effects may include altered thyroid and immune status, altered neurobehavior at the level of hearing, psychomotor function, and gender-related behaviors, altered cognition, dentition, and development of reproductive organs, and delays in breast development, in addition to altered sex ratios among exposed offspring.

While no exposure to dioxin is the ideal, we are not there yet.  In the meantime, exposure to dioxin in food, especially for children remains too high and needs to be addressed by EPA, FDA, and USDA. CHEJ strongly urges the EPA to finish and release their review on dioxin and cancer, and to develop a comprehensive action plan to further reduce dioxin emissions and exposures.

For a copy of EPA’s new dioxin health report, visit http://www.epa.gov/dioxin

To see CHEJ’s press release about this report, visit http://bit.ly/dioxinvictory

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Backyard Talk

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