(Beyond Pesticides, February 8, 2012) The U.S. Environmental Protection Agency missed a deadline to release federal guidelines on the dangers of excess dioxin chemicals in the food supply and environment, giving ammunition to critics who are urging the agency to change course. EPA was scheduled to release standards in January 2012 that would for the first time set a maximum human-exposure level for dioxins. The delay comes amid criticism and pressure by food and chemical industries that argue the guidelines are too strict.
The January 31, 2012 cut-off was part of a reassessment process that has stretched out for 20 years, but the agency has promised to finalize its guidelines “as expeditiously as possible,” although it gave no new deadline. In August 2011, EPA announced a plan for moving forward to complete the dioxin Reanalysis, Volume 1, which is to contain an evaluation of all the scientific literature on dioxin dose-response, including information published since the release of a previous draft Reassessment, and post it by the end of January 2012. EPA was then to post Volume 2 of the Reanalysis soon thereafter. These efforts have been met with resistance from the American Chemistry Council, the International Dairy Foods Association, the American Farm Bureau Federation, and others. These groups have argued that EPA is using flawed science and will scare Americans about the food they eat.
Dioxins, also known as polychlorinated dibenzo dioxins (PCDDs), include about 75 chemicals that can disrupt hormonal pathways, cause reproductive and developmental problems and lead to cancers, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), found in the infamous Agent Orange herbicide deployed during the Vietnam War. War veterans exposed to Agent Orange have developed chronic lymphocytic leukemia, Hodgkin’s disease, and non-Hodgkins lymphoma and diabetes. Many children of exposed veterans have been affected by their parents’ exposure to the chemical and show a wide range of symptoms. Most dioxin exposure in the U.S. is attributable to emissions from waste incinerators, copper smelters, and makers of paper pulp, but dioxins are still manufactured and released as contaminants of pentachlorophenol and phenoxy herbicides like 2,4-D. Regulations have curtailed dioxin emissions by 90% since the 1980s, but the pollutants persist in the environment, so they continue to contaminate livestock forage and meat and dairy products. The structure of dioxins closely resembles that of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo furans (PCDFs), which also have similar toxicological and environmental effects.
EPA published its first assessment of dioxins as a guideline for U.S. consumers and policy-makers in 1985. In 1991, the agency launched a reassessment to resolve outstanding issues and incorporate new data. However, the agency’s Scientific Advisory Board warned that a 1994 draft report had a “tendency to overstate the possibility of danger” and did not adequately spell out scientific uncertainties. Soon afterwards industry sued to block the reassessment, arguing the assessment was not based on sound science.
EPA published a draft of its reassessment called, “”Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments”(Reanalysis)” in 2010, recommending that people consume less than 0.7 picograms (less than one trillionth of a gram) of dioxins per kilogram of body weight per day. This is lower than the World Health Organization’s daily limit of roughly 2.3 picograms per kilogram; in the U.S., people currently consume an average of less than 0.5—3 picograms per kilogram per day. The EPA’s strict recommendation has been lauded by cancer-awareness groups and environmentalists, but chemical and agricultural industries protested, arguing that although it is not legally binding, the lower limit could alarm consumers unnecessarily.
A 2003 report from a joint panel of the Institute of Medicine of the National Academies and the Food and Nutrition Board recommended the formation of a federal interagency group to develop and implement a public health strategy to reduce human exposure to dioxin. The report cites, as a high-priority risk management intervention, exposure reduction to dioxins and dioxin-like compounds in girls and young women before they become pregnant. Dioxins and dioxin-like compounds are often transmitted from mother to child through breastfeeding. The report states, “[P]readolescent and teenage girls and young women were of concern ”¦ because body burdens of dioxin-like compounds can, when they enter their child-bearing years, become a potential source of exposure for developing infants in utero and while breastfeeding.” Infants exposed to high levels of dioxins and dioxin-like compounds in utero suffer poor psychomotor skills, altered thyroid hormone levels, and reduced neurological optimality. A recent study investigating the long-term immune effects of dioxin found that exposure to dioxin during development or while nursing diminishes the young’s capacity to fight infection later in life. Another found that exposure to dioxin in the womb can affect female reproduction for generations, reducing fertility and increasing the chance for premature delivery.
Dioxin has been found in milk, cheese, beef, pork, fish, chicken, and other animals, as well as soil and sewage sludge. High levels of dioxin still exist in the Tittabawassee and Saginaw rivers and floodplains in Michigan, after being dumped there decades ago by Dow Chemical Co. Clean-up and restoration for these systems are still being debated. Even though dioxin levels in the environment have dropped considerably in recent years from their peak in the late 1970’s, it is important to be vigilant in the foods consumed in order to avoid an exposure hazard, since dioxins are persistent and bioaccumulative. A diet rich in organic foods can help minimize the risk of dioxin exposure.
See the Toxicological Profile for Chlorinated Dibenzo-p-dioxins (CDDs) by Agency for Toxic Substances and Disease Registry (ATSDR) for more detailed information on dioxin, its health and environmental effects, and exposure.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.