Friday, February 17, 2012

EPA Releases Final Reassessment Of Dioxin Toxicity

Feb 17: U.S. EPA announced that it had finalized its non-cancer science assessment for dioxins, which was last reviewed in the 1980s. Dioxins are toxic chemicals that naturally exist in the environment and can be released into the environment through forest fires, backyard burning of trash, certain industrial activities, and residue from past commercial burning of waste. EPA said its "findings show that generally, over a person's lifetime, current exposure to dioxins does not pose a significant health risk."

    Over the past two decades EPA has worked to reduce emissions from all of the major industrial sources of dioxins. As a result of efforts by EPA, state governments and industry, known and measurable air emissions of dioxins in the United States have been reduced by 90 percent from 1987 levels. The largest remaining source of dioxin emissions is backyard burning of household trash. EPA indicated that most Americans have low-level exposure to dioxins. Non-cancer effects of exposure to large amounts of dioxin include chloracne, developmental and reproductive effects, damage to the immune system, interference with hormones, skin rashes, skin discoloration, excessive body hair, and possibly mild liver damage.

    EPA said it has identified many known sources of dioxins. Working with other Federal partners, such as the U.S. Department of Health and Human Services and the U.S. Department of Agriculture, EPA has taken steps to address dioxin. This includes supporting research on dioxin exposure and effects; assessing dioxin human health risks; measuring dioxin levels in the environment, our diet and in our bodies; and reducing exposure to dioxin.

    The non-cancer health assessment for dioxin released today could be considered in a range of agency activities, from establishing cleanup levels at Superfund sites, to reviewing the dioxin drinking water standard as part of EPA's regularly scheduled review process, to evaluating whether additional Clean Air Act limits on dioxin emissions are warranted. EPA findings are contained in the
Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments, Volume 1. The document provides hazard identification and dose-response information on 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) and the most up-to-date analysis of non-cancer health effects from TCDD exposure. The report also include an oral reference dose (RfD) and a detailed and transparent description of the underlying data and analyses.
    According to the abstract of the Volume 1 report, "This document comprises the first of two EPA reports (U.S. EPA's Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments Volumes 1 and 2 [Reanalysis Volumes 1 and 2])  that, together, will respond to the recommendations and comments on 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) dose-response assessment included in the 2006 NAS report, Health Risks from Dioxin and Related Compounds: Evaluation of the EPA Reassessment. This document, Reanalysis Volume 1, includes (1) a systematic evaluation of the peer-reviewed epidemiologic studies and rodent bioassays relevant to TCDD dose-response analysis; (2) dose-response analyses using a TCDD physiologically based pharmacokinetic model that simulates TCDD blood concentrations following oral intake; and (3) an oral reference dose (RfD) for TCDD. An RfD of 7x10-minus10 mg/kg-day is derived based on two epidemiologic studies: (a) a study that associated TCDD exposures with decreased sperm concentration and sperm motility in men who were exposed during childhood and (b) a study that associated increased thyroid-stimulating hormone levels in newborn infants born to mothers who were exposed to TCDD. A qualitative discussion of uncertainties in the RfD and a focused quantitative uncertainty analysis of the choices made in the development of points of departure for RfD derivation are also provided."
    The Environmental Working Group (EWG) said the release of the safety standard for dioxin toxicity for risks other than cancer, was "a crucial advance in protecting Americans from exposure to this ubiquitous industrial pollutant." Olga Naidenko, PhD, senior scientist with EWG said, "Our bodies, our children's bodies and our food supply have all been contaminated with dioxin for decades as a result of unregulated industrial emissions. Today's decision will serve as the cornerstone of the agency's initiatives to protect public health from chemical contaminants and provide the necessary guidance to states and public health agencies to minimize dioxin exposure." The U.S. government labeled 2,3,7,8-Tetrachlorodibenzo-p-dioxin, or TCDD, a known human carcinogen in 2001. Other serious health hazards of dioxin exposure, particularly during early life, are changes in the neurological and immune systems as well as reproductive and hormonal disorders such as decreased sperm count and motility in men exposed to TCDD as boys.
    Environmental Health News reported that, "The EPA broke the risk assessment into two parts; today's release includes only the non-cancer effects of dioxins. The EPA left a key number the same as when a draft was unveiled in 2010. The daily level of exposure considered acceptable has been set at 0.7 picograms of dioxins per kilogram of body weight. Back in 2010, industry groups criticized the EPA for setting this so-called "reference dose" too low, saying it would alarm consumers and drive costly regulations. The level set by the World Health Organization/United Nations in 2001 is about three times higher. The assessment does not have enforceable standards. But it is critical to guiding many actions, such as cleanup of Superfund and other hazardous waste sites, industrial emission controls, drinking water standards and dietary guidelines for fish."
    Lois Gibbs, Executive Director of the Center for Health, Environment & Justice (CHEJ) said in a release, "We applaud EPA Administrator Lisa Jackson and the Obama Administration for finalizing this important health report on dioxin, one of the most toxic chemicals on the planet. After twenty seven years of delays, I quite honestly never thought this report would ever see the light of day. Today the American people won a major victory against the chemical industry, who has been working behind closed doors for decades to hide and distort the truth about the dangers of dioxin. The science is clear: dioxin is toxic to our children's health and development. We strongly urge the EPA to now finish the job by finishing their review on dioxin and cancer, and to develop a comprehensive action plan to further reduce dioxin emissions and exposures. To start, the EPA should finalize the EPA's proposed cleanup standards for dioxin at toxic sites, which have been languishing at the White House OMB since 2010.  We call on the Obama Administration to dust off the prestigious National Academy of Sciences report on dioxin in food to explore innovative policies to reduce the levels of dioxin in the food supply."
    Representative Edward Markey (D-MA), Ranking Member on the Natural Resources Committee and senior member of the Energy and Commerce Committee, praised EPA's announcement that the non-cancer health assessment of dioxin has been finalized after two decades of delays. Rep. Markey said, "Today, the Environmental Protection Agency has taken a major step toward protecting the public from dioxin by shining light on some of the health impacts this dangerous chemical has on the public. By releasing this important part of the scientific assessment, we can begin to develop a cohesive plan to safeguard American families from dioxin exposure. It is also time for industry groups and chemical companies to stop their efforts to block completion of this important public health document. I urge EPA to continue this progress forward by moving quickly to finalize the cancer portion of the dioxin assessment as well as its cleanup goals for soil at waste sites containing dioxin."
    Access a release from EPA (click here). Access complete information from EPA and link to the complete report (click here). Access the Environmental Health News article (click here). Access a release from CHEJ (click here). Access a release from Rep. Markey with links to related information (click here). [#Toxics]
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