The preponderance of scientific evidence shows that even very low doses of radiation pose a risk of cancer or other health problems and there is no threshold below which exposure can be viewed as harmless, a panel of prominent scientists concluded Wednesday.

The finding by the National Academy of Sciences panel is viewed as critical because it is likely to significantly influence what radiation levels government agencies will allow at abandoned nuclear power plants, nuclear weapons production facilities and elsewhere.

The nuclear industry,, as well as some independent scientists, have argued that there is a threshold of very low level radiation where exposure is not harmful, or possibly even beneficial. They said current risk modeling may exaggerate the health impact.

The panel, after five years of study, rejected that claim.

"The scientific research base shows that there is no threshold of exposure below which low levels of ionized radiation can be demonstrated to be harmless or beneficial," said Richard R. Monson, the panel chairman and a professor of epidemiology at Harvard's School of Public Health.

The committee gave support to the so-called "linear, no threshold" model that is currently the generally acceptable approach to radiation risk assessment. This approach assumes that the health risks from radiation exposure declines as the dose levels decline, but that each unit of radiation — no matter how small — still is assumed to cause cancer.

Some of the observations from the article:

• “A foodborne attack is much more preventable than an airborne or mailborne attack, due to the restricted number of release locations. Requiring all tanks, trucks, and silos to be locked when not being drained or filled would be an obvious step forward, as would security checks for personnel who have access to prebottled milk (farm laborers, truck drivers, receiving labor at the processing facility, and plant engineers) and requiring one person from each stage of the supply chain to be present while milk is transferred from one stage to the next (15). Although these and other measures are included in proposed Food and Drug Administration guidelines (16), they are currently voluntary.”


• “Although enforcement options range from voluntary guidelines to new laws, the most promising approach may be to develop International Organization for Standardization (ISO) security standards that are analogous to the ISO 9000 standards for quality management and the ISO 14000 standards for environmental management (www.iso.ch_iso_en_iso9000—14000_index.html, accessed on November 12, 2004).”


• Current botulinum testing protocols may not permit rapid detection of a widespread outbreak. “Our study highlights the value of rapid in-process testing for detecting an attack, and because stockpiling sufficient ventilators and antitoxin in the event of a large-scale attack would be exorbitantly expensive, it seems wise to aggressively invest in rapid, sensitive, and specific in-process testing.”


• The potential for secondary cases from cross-contamination of otherwise uncontaminated milk also raises concerns. “Two locations in the supply chain, trucks that are cleaned daily but that make two trips daily and processing lines that are cleaned daily, offer the opportunity for uncontaminated milk to become tainted by uncleaned residue from the primary release. The secondary effect from a release in a truck has an ~50% chance of causing damage equivalent to a release that is 8 h later and ~0.5% as large as the primary release…. 640,000 gallons per day of freshly produced milk would need to be discarded until the attack is effectively investigated, the supply chain is turned back on, and consumer confidence returns. This delay could be hastened by effective product tracing, decontamination, and risk communication.”

An accompanying editorial discusses the controversy over the suppression of the article and the rationale for its publication.

More information:

• Scott Shane, “Paper Describes Potential Poisoning of Milk,” N.Y. Times, June 28, 2005
• Bruce Alberts, Editorial, “Modeling Attacks on the Food Supply,” 102 Procs. Of Nat’l Acad. of Sci. 9737 (2005)
• Lawrence M. Wein & Yifan Liu, “Analyzing a Bioterror Attack on the Food Supply: The Case of Botulinum Toxin in Milk,” 102 Procs. Of Nat’l Acad. of Sci. 9984 (2005)

Although the Agriculture Department confirmed on Friday that a cow that died last year was infected with mad cow disease, a test the agency conducted seven months ago indicated that the animal had the disease. The result was never publicly disclosed.

The delay in confirming the United States' second case of mad cow disease seems to underscore what critics of the agency have said for a long time: that there are serious and systemic problems in the way the Agriculture Department tests animals for mad cow.

Indeed, the lengthy delay occurred despite the intense national interest in the disease and the fact that many countries have banned shipments of beef from the United States because of what they consider to be lax testing policies.

This isn't the first time.

• Federal investigators have been probing allegations from a former USDA veterinarian that the USDA was covering up concnerns about mad cow from the very beginning of USDA's mad cow surveillance program in 1990.
  
• Moreover, Canadian news uncovered recently that the USDA may have mishandled two 1997 tests of suspected mad cow. In one, an independent university lab concluded that the cow "had a rare brain disorder never reported in that breed of cattle either before or since — not the dreaded bovine spongiform encephalopathy." CBC discovered, however, that "key areas of the brain where signs of BSE would be most noticeable were never tested. The most important samples somehow went missing."

The field of epigenetics studies how we can have intergenerational consequences for public health hazards without the genes themselves being mutated. Researchers look at, for example, how molecules can attach themselves to the DNA molecule without changing the genetic sequences themselves, but then ride along from generation to generation.

The latest issue of Rachel's Environment & Health News reports on the latest epigenetic discovery:

The latest information appears in a new study by Michael Skinner and colleagues at Washington State University, published in the June 3 issue of Science magazine. Skinner found that mother rats exposed to hormone-mimicking chemicals during pregnancy gave birth to four successive generations of male offspring with significantly reduced fertility. Only the first generation of mothers was exposed to a toxin, yet four generations later the toxic effect could still be detected.

Prior to this study, scientists had only been able to document epigenetic effects on the first generation of offspring. These new findings suggest that harm from toxins in the environment can be much longer lasting and pervasive than previously known because they can impact several generations.

And therefore a precautionary approach to toxics is even more important that previously believed.

• one showing that the pathogen is remarkably dangerous even after being starved and assaulted by food safety measures: according to the study, "starved and injured cells, after more than six months of languishing, still had enough strength to kill 60 percent of their target cell population within six hours, then 90 percent of the target after eight hours"; and
• another, revealing just how Listeria actually gets into our cells and destroys them from the inside.

More information and background:

• Executive summary and full report by the scholars of the Center for Progressive Reform on our flimsy firewalls against mad cow
• Mad about mad cow (6/20/05)
• GAO Finds Weaknesses in Mad Cow Regulation Oversight (3/16/05)
• New Cases of Mad Cow Disease Highlight Need to Close Loopholes in Protection (11/19/04)
• Mad Cow Disease Regulation Fails to Protect U.S. Food Supply (7/26/04)
• Lawmakers Accuse USDA of Misleading Public on Mad Cow (2/23/04)

The loophole has not yet been closed. "Once the cameras were turned off and the media coverage dissipated, then it's been business as usual, no real reform, just keep feeding slaughterhouse waste," said John Stauber, an activist and co-author of Mad Cow USA: Could the Nightmare Happen Here?, to the Associated Press. Stauber adds, "The entire U.S. policy is designed to protect the livestock industry's access to slaughterhouse waste as cheap feed."

Given that we may have a second case of mad cow in the U.S., the issue deserves more than what Rep. Rosa DeLauro describes as "a lot of talk, a lot of press releases, and no action."

Government inaction on mad cow may well stretch back to the early to mid 1990s. Federal investigators have been probing allegations from a former USDA veterinarian that the USDA was covering up concnerns about mad cow from the very beginning of USDA's mad cow surveillance program in 1990. Moreover, Canadian news uncovered recently that the USDA may have mishandled two 1997 tests of suspected mad cow. In one, an independent university lab concluded that the cow "had a rare brain disorder never reported in that breed of cattle either before or since – not the dreaded bovine spongiform encephalopathy." CBC discovered, however, that "key areas of the brain where signs of BSE would be most noticeable were never tested. The most important samples somehow went missing."

Posted by Robert Shull, 01:15:47 PM

Tuesday, June 07, 2005