Web Note: Organic farms are prohibited from spreading municipal sewage
sludge on their fields as fertilizer, whereas this is standard practice on
America's non-organic farms.
LONDON: A new study by researchers at the University of Wisconsin in Madison, US, have shown that that infectious prions - thought to be the causative agents in mad cow disease and human vCJD - can survive wastewater decontamination and wind up in fertiliser, potentially contaminating fruit and vegetables.
Microbiologist Joel Pedersen, of the University of Wisconsin in Madison, US, who led the study, said that the prions would be present in such low quantities that they are unlikely to pose a health threat, but as a precaution, 'we should prevent the entry of prions into wastewater treatment plants.'
He said that prions could end up in wastewater treatment plants through slaughterhouse drains, hunted game cleaned in a sink, or humans with vCJD shedding prions in their urine or faeces.
Prior studies have suggested that prions can survive heat treatment and caustic chemicals.
However, to see how prions fare during sewage treatment, Pedersen's research team spiked sludge from a local treatment plant with infectious prions, and then subjected the toxic brew to a typical wastewater treatment regimen.
This typically involves three weeks of filtration, separation and incubation with microbes that break down contaminants in the sludge, resulting in clean water and 'biosolids' free of most human pathogens, which can be used as a fertiliser.
When Pedersen's team tested the sewage soup at various stages, they found the water was clean, but the biosolids were contaminated with prions.
"The sludge digestion seems to have no effect on the prion protein," New Scientist quoted him, as saying.
Jul 7 2008, 01:51 PM
There is <a href="http://www.sailhome.org/Concerns/BodyBurden/Sources3/CornSyrup/Hexane.html#BSE">evidence</a> that prions are the *result* of toxic burden, not the cause of it.
Jul 7 2008, 01:56 PM
Sorry, didn't realize html doesn't work in this forum. Here it is more clearly:
There is evidence that prions are the *result* of toxic burden, not the cause of it (and subsequent diseases like BSE).http://www.sailhome.org/Concerns/BodyBurde...Hexane.html#BSE
Today, 01:52 PM
Hexane is no doubt a potent toxin capable of causing many ills, but numerous studies have shown prions to be the infectious agent in spongiform encephalopathies. Read "Brain Trust, and Dying for a Hamburger" among other publications.
The title of this article is disingenuous. To imply that Non-Organic consumers are at greater risk of contracting vCJD because prions can survive sewage treatment, is to ignore the fact that prions also easily survive composting. In fact, prions are nearly indestructible--surviving sterilizatiion by autoclaving (heat),irradiation, ethanol, formaldehyde and other solvents. And prions can remain in the soil for years. Researchers in the UK have found infectious prions not only in the nervous tissue (brain/spinal cord) of infected animals, but also the flesh, blood, bone, milk, urine and feces.
Unfortunately using slaughterhouse by-products, such as bonemeal, bloodmeal, and tankage (euphemism for everything left over) along with manure is virtually universal with Organic Gardening (and home gardening). This creates a signifcant public health risk for not only spongiform encephalopathies, but also contamination of produce by E.coli, salmonella, campylobacter, listeria, etc.--not to mention the residues of hormones, antibiotics, pesticides and heavy metals found in manures.
And yes, vegetarians are at risk too, because Organic Farmers are wedded to this cheap source of fertilizer. Frankly, we're rather pissed about it. It's time to start growing food without animal inputs! There is a great demand out there, and research in the UK has shown that it is not only possible on a large scale, but also more sustainable (read "Growing Green" by Hall and Tolhurst).
Grow it and they will come!