Annie Prange
Member
I realize this refers to pet food... and I was wondering if there are any known risks to humans with this process? Especially since some work environments regularly xray employee belongings (lunchbags, purses with medicine, gum and so on) as part of security. Would there be long effects if a food/medicine item was passed through multiple times?
Cheers,
Annie
IRRADIATED CAT FOOD TOXICITY - AUSTRALIA
****************************************
A ProMED-mail post <http://www.promedmail.org>
ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>
[1]
Date: Sat 30 May 2009
Source: The Sydney Morning Herald [edited] <http://www.smh.com.au/national/catfood-irradiation-banned-as-pet-theory-proved-20090529-bq8h.html>
Cat-food irradiation banned as pet theory proved
------------------------------------------------
A series of mysterious cat deaths was caused by the government-mandated practice of irradiating imported pet food.
The Agriculture Minister, Tony Burke, has ordered the controversial sterilization process, which has been in place for more than a decade, to cease immediately, following compelling overseas evidence that some cats can suffer fatal neurological damage after eating irradiated dry food. Dogs do not appear to be affected by similarly treated food.
About 90 cats fell ill last year [2008] and 30 died before a Sydney vet, Georgina Child, made the link in November between the mystery illness and a brand of Canadian gourmet pet food called Orijen.
The manufacturer, Champion Petfoods, blamed the contaminated food on Australian quarantine regulations, which demand that pet food not cooked over a specified temperature undergo irradiation of 50 kiloGrays upon arrival in the country. Of the 60 countries Champion Petfoods exports to, only Australia makes irradiation compulsory.
The Australian Quarantine and Inspection Service and the company that carries out the process, Steritech, insisted at the time the irradiation process was harmless. A limited range of imported human foods, including dried herbs and some tropical fruits, are also irradiated before landing on store shelves, but at much lower levels than that mandated for pet food.
Mr Burke said the inspection service decided to act in response to international reports his department received only late last week [week of 18 May 2009]. Work was being done in state and federal governments to see how safety standards for pet food could be improved. "People expect that any treatments conducted on imported pet food will result in food that is still safe for pets," he said.
Dr Child said the move was welcome but did not go far enough. The irradiation ban is not being extended to imported dog food, leaving cats with access to such food still at risk. "We still don't know why this problem is unique to cats, and we're still not certain why some brands of pet food are affected by irradiation and not others," she said. "What this does show is that all food that has been irradiated needs to be labelled, which isn't the case at the moment."
[A Dundas woman] who lost 2 cats after they were fed the Orijen pet food, said the ban was great news. Champion Petfoods has set up a fund to disperse compensation for veterinary bills for all affected Australian cat owners.
[Byline: Kelly Burke]
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Communicated by:
ProMED-mail Rapporteur Kunihiko Iizuka
******
[2]
Date: Mon 8 Jun 2009
Source: The VIN (Veterinary Information Network) News Service [edited] <http://news.vin.com/VINNews.aspx?articleId=13088>
An outbreak in Australia of neurological disorders in cats fed irradiated diets is a first among pets but not unprecedented.
At least 3 instances of irradiated food causing severe nervous system disease have occurred around the world since 1998. The cases happened in Ireland and the United States in laboratory cats and in Australia among pet cats.
The Australian government in late May [2009] ordered an immediate stop to sterilizing cat food via irradiation after reviewing scientific studies pointing to food irradiation as the culprit behind illnesses characterized by ataxia or paralysis of the limbs, especially the hind limbs. How irradiation may be causing food to become toxic to cats is unknown. The problem affected 90 cats in Australia, of which 30 died, mostly by euthanasia after they became paraplegic or tetraplegic, according to Dr Georgina Child, a neurologist at the Small Animal Specialist Hospital and University of Sydney Teaching Hospital.
Child told The VIN News Service by e-mail that all the cats had eaten an imported dry diet, sold under the brand name Orijen and made in Canada by Champion Petfoods. The food was subject to gamma irradiation upon entry to Australia at levels greater than or equal to 50 kilo-Grays (kGy).
The US Food and Drug Administration (FDA) also allows animal feed, including pet food and treats, to be irradiated up to 50 kGy. By comparison, most human foods in the United States allowed to be irradiated are limited to levels of 30 kGys and below. Packaged meats for astronauts are an exception; those may be treated up to 44 kGy.
The FDA requires all irradiated foods to be labeled as such; Australia does not require labels on irradiated pet food.
Signs in the Australian cats first appeared 3 to 6 months after they were exposed to the dry food, Child said. Some had eaten the food for as few as 3 weeks; others for more than 6 months. Most of the cats were fed other foods, as well. The affected cats ranged in age from less than one year to 15 years. Early signs of illness included a wobbly gait, unwillingness to jump onto sofas or beds, and loss of balance exhibited, for example, by falling off tables, according to a Q&A for consumers prepared by Champion Petfoods.
Child said about half of the affected cats remain paraparetic or tetraparetic; some remain paraplegic or tetraplegic. "Many cats have been at their worst for 2 or more months before showing any improvement," she said, noting that fewer than one-fifth have recovered fully. Child said histopathology showed "diffuse, symmetric, severe white matter degeneration of predominantly the spinal cord but also (the) brain stem and cerebrum, with demyelination the predominant feature."
"No specific treatment has resulted in an improvement in the outcome of affected cats," she said. "A change in diet, nursing care, physiotherapy, and time seem to be the only factors common in recovered cats."
But even patients who are paralyzed and lose vision as a result of eating irradiated food can fully recover, given sufficient time, nursing care, and food that hasn't been irradiated, said Dr. Ian Duncan, professor of neurology at the University of Wisconsin-Madison School of Veterinary Medicine. That's what Duncan saw with cats housed in a private laboratory in Wisconsin that were fed irradiated diets. The irradiation was meant to help keep the cats -- known as "specific pathogen-free" or SPF cats -- from unwittingly acquiring infections. In that episode, which was reported this spring [2009] in the Proceedings of the National Academy of Sciences [Duncan ID et al:
Extensive remyelination of the CNS leads to functional recovery. PNAS April 21, 2009 106(16): 6832-6) abstract available at <http://www.pnas.org/content/106/16/6832.abstract>], the food was irradiated at levels of 25 to 50 kGy.
The signs took about 4 months to appear, and they abated after another 2 to 4 months once the cats were given a non-irradiated diet.
Altogether, about 30 cats were affected, and most made impressive recoveries, Duncan said.
Oddly, only cats that became pregnant while on the irradiated diet developed neurological symptoms, he noted. Male cats and offspring exposed to the same diet did not become ill. Male cats have been affected elsewhere, however.
In the Irish case, 190 domestic short-hair cats housed together developed hind limb ataxia and proprioceptive defects during a period of 4 years, from 1998 to 2001 [JP Cassidy et al:
Leukoencephalomyelopathy in Specific Pathogen-free Cats. Vet Pathol 2007; 44: 912-6; available at <http://www.vetpathology.org/cgi/content/full/44/6/912>]. As with the Wisconsin colony, those animals were SPF cats.
Serendipitously, researchers had a control group in the form of kittens that had been transferred from the SPF colony to a conventional disease status colony on the same site. Both groups of cats were fed on the same commercial formula ration, except that the food bound for SFP cats was irradiated to levels between 36.3 and
47.3 kGy.
The transferred cats did not develop any neurological abnormalities.
More than one-third of the cats fed irradiated food did. "Following supplementation of the irradiated diet with pasteurized proprietary tinned cat food in the winter of 2001, and ultimately, the replacement of the irradiated diet with an equivalent pasteurized diet, no further cases occurred, "the researchers reported. Child said the same researchers since have induced neurological problems in cats at radiation levels as low as 26 kGy. A study with those results is due to be published shortly, she said.
Exactly how irradiation renders food toxic to cats is unclear. It was initially thought to be a vitamin A deficiency; the researchers in Ireland, analyzing the nutritional content of cat food subject to irradiation levels ranging from 28.9 kGy to 48.7 kGy, found that vitamin A content diminished to levels below that recommended for growth and reproduction.
By comparison, pasteurization reduced the vitamin A content in the cat food, as well, but not below recommended levels. Curiously, the researchers found that irradiation did not alter vitamin A in dog food. However, radiation treatment did increase peroxide content in dog food, cat food, and rodent food, up to 25-fold at the highest dose.
"Gamma irradiation can have profound, selective effects on the vitamin A and peroxide contents of dry diets, and caution is advised when feeding such diets long-term and exclusively to SPF animals, particularly cats," the researchers concluded [Caulfield CD et al:
Effects of Gamma Irradiation and Pasteurization on the Nutritive Composition of Commercially Available Animal Diets. J Am Assoc Lab Anim Sci. 2008 Nov; 47(6): 61-6, available at <http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2687132>].
But subsequent studies found that affected animals were not deficient in vitamin A after all, Child said. "Possible causes still include a micronutrient deficiency -- although this seems less likely -- or toxicity induced by irradiation-induced changes in the dry food (more likely),"she said.
Champion Petfoods, maker of the Orijen brand, noted in a Q&A dated November 2008 that its own testing of irradiated cat food found the treatment depleted vitamin A and formed free radicals in the food.
Their statement reads in part: "Irradiation does not affect all foods equally. Orijen is a nutritionally dense food with much higher levels of long-chain fatty acids (DHA, EPA) than conventional pet foods.
These fatty acids are susceptible to oxidation following irradiation.
Byproducts from fatty acid oxidation, mainly free radicals, are released into the body with the potential to cause tissue damage.
"Combined with the loss of antioxidant vitamins [such as vitamin A], free radicals are thought to be a major contributing factor."
Although the irradiation ban applies only to cat food, Champion Petfoods has pulled its dog food from the Australian market as well, Sales and Marketing Manager Peter Muhlenfeld told the VIN News Service. "Cats frequently eat from dog dishes and vice versa," he said in an e-mail. "We do not believe the market to be safe unless both cat and dog foods are allowed entry without irradiation."
According to the company Q&A:
- Only Australia requires irradiation of Orijen cat foods, out of 50 countries in which the food is sold.
- Orijen was sold in Australia only for a 9-month period -- February through October 2008.
- In that period, only 6 pallets of Orijen cat food actually entered retail distribution, enough to feed 200 cats each day during the 9 months.
- During the same period, shipments of Orijen cat food were made to
49 other countries, enough to feed 85 000 cats. In no other country has neurological illness been reported.
Why Australia requires irradiation of imported pet foods is unclear.
Officials at the Australian Quarantine and Inspection Service (AQIS) did not respond to an e-mailed request for information.
Patty Lovera, assistant director of Food and Water Watch, a non-profit consumer organization based in Washington, DC [USA], that monitors food irradiation around the world, said Australia's high vigilance on biosecurity may stem from its being an island nation.
"My impression is that they're very tuned to things coming in that might be some kind of threat to their agriculture," Lovera said.
A notice to industry posted by the AQIS before the government banned cat-food irradiation suggests that is the case. It states: "Heat or irradiation treatments are necessary to address animal quarantine pest and disease risks that may be associated with imported pet foods." A separate notice states that, as an alternative to radiation, importers may subject pet food to a moist heat treatment
-- through which the product must achieve a certain core temperature for a certain duration.
According to the Champion Petfoods Q&A, "The overwhelming majority of cat foods in Australia do not require irradiation." Orijen was required to undergo irradiation because the food includes fresh meats that were cooked at low temperatures. The company takes pride in the distinctions between its products and those of conventional pet-food makers. Its gourmet foods are marketed as "biologically appropriate,"
and made with "fresh, regional ingredients."
"We're different. We sell only what we make ourselves, "it says on its website in an allusion to the use of co-packing facilities by some of its competitors. Co-packers are contracted to produce pet foods for a variety of companies sold under a variety of brand names.
The widespread use of co-packing contributed in 2007 to the largest recall of pet food in North American history, due to contamination by the industrial chemical melamine, which affected 180 brands of pet food. Muhlenfeld said Champion Petfoods has a program to offset medical bills of owners of affected pets up to [AUD] 1000 [USD 796.5]. It also donated [AUD] 10 000 [USD 7965] to organizations in Sydney that work with cat diseases.
The Australian ban on irradiation marks the 1st time in the world that authorities rescinded an approved use of irradiation because it is suspected to cause illness.
George Pauli, a retired chemist who worked for 29 years in the US FDA's Center for Food Safety and Applied Nutrition, said the FDA in one instance reversed an approval on irradiation, but not because anyone became ill. In that case from the 1960s, the US Department of Defense asked to sterilize bacon through irradiation to create a shelf-stable product that didn't need to be refrigerated. "The FDA, when they reviewed it, thought everything looked good, but later on ... they concluded that the data were not nearly as solid and convincing as first thought," Pauli said.
The Defense Department never came back with more data and a request to reconsider, Pauli said. He speculated that the cat cases in Australia are an example of species sensitivity. "More testing has been done on rodents and dogs," he said. "Normally, testing (for human safety) is not done on cats that much."
[Byline: Edie Lau]
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Communicated by:
ProMED-mail Rapporteur Kunihiko Iizuka
[In response to these articles and some international legal maneuvering between regulations and companies, ProMED-mail sought clarification from Australian animal health authorities. Dr Mike Nunn, Principal Scientist (Animal Biosecurity) with Biosecurity Australia provided the following information:
Under Australia's "Quarantine Act 1908", the Australian Quarantine and Inspection Service (AQIS) has responsibility to prevent the introduction, establishment, or spread of pests and diseases. The "Quarantine Proclamation 1998" refers to the level of quarantine risk and the imposition of appropriate conditions that the Director of Quarantine must consider before granting an import permit. A pet food ingredient (or the final product) is considered acceptable if it is heat-treated sufficiently to address Australia's quarantine concerns.
For example, ingredients of mammalian and avian origin generally require heat treatment to achieve a core temperature of at least 100 deg C [212 deg F] for a minimum of 30 minutes. For products that do not meet heat treatment requirements or where a manufacturer is unable to provide AQIS with sufficient information to complete the assessment, importers may be given the option to irradiate the pet food on arrival to address outstanding quarantine concerns.
Gamma-irradiation is a valid and very effective treatment -- in accordance with the scope of the "Quarantine Act 1908" and the "Quarantine Proclamation 1998" -- to address the risk of introducing, establishing or spreading disease within Australia. However, there is now a body of evidence that gamma-irradiation of imported pet food may actually be a causative factor for the disease chronic leukoencephalomyelopathy in cats. As such, and unless future research confirms otherwise, Biosecurity Australia no longer supports gamma-irradiation of pet food for cats as a valid quarantine treatment. However, Biosecurity Australia continues to support gamma-irradiation as a valid and effective quarantine treatment option for other products.
The background is that there have been a number of media reports (and statements by a veterinary clinician and neurologist in Sydney, Dr Georgina Child) that suggested some cats fed a particular brand of imported pet food manufactured by Champion Pet Foods, Canada) had developed a chronic and sometimes fatal neurological syndrome. The particular product concerned was a semi-moist, fish and poultry based product with no cereal ingredient. It was released onto the Australian market in April/May 2008 and the 1st cases of disease in cats were seen in September 2008 and cases continued until February 2009. It is estimated that approximately 1300 kg [approx. 2900 lb] of irradiated product was imported, and a large proportion of this was removed from sale after the manufacturer announced on 20 Nov 2008 a voluntary recall of the product in Australia.
Representatives of AQIS, Biosecurity Australia, Food Standards Australia New Zealand (FSANZ), and the Australian Veterinary Association (AVA) met with Dr Child) who provided a detailed report of her findings. Dr Child reported that the syndrome had affected at least 87 cats in Australia with 27 deaths (23 that were euthanised due to severe neurological signs; 4 died naturally, including 2 that developed seizures). Affected cats developed ataxia, paraparesis and, in the worst-affected cases, paraplegia and tetraplegia. Fewer than 20 percent fully recovered and about 50 percent improved but remain paraplegic or tetraplegic. Many cats have been at their worst for 2 or more months before showing any improvement. Affected cats have ranged in age from less than one year to 15 years. Signs were typically seen 3 to 6 months after 1st exposure to the dry food and the period the food was fed varied considerably (from about 3 weeks to more than 6 months). Post mortem examination of 8 cats has shown lesions very similar to those of cats fed irradiated pet food in Ireland (Cassidy et al, 2007; Caulfield et al. in press) and in the United States (Duncan et al, 2009) Dr Child's findings have since been submitted for publication in the Australian Veterinary Journal.
A range of different breeds and, in some cases, several cats in the same household were affected. The majority of affected cats had eaten other products as well as the particular brand of imported cat food and there was anecdotal evidence that in a perhaps 3 cases affected cats ate dog food (and apparently not cat food) manufactured by the same company and irradiated on import [in Australia]. Based on reports from veterinary clinics selling the product, about 40 percent of cats fed the particular brand of imported cat food 'developed clinical signs of disease.' A detailed toxicological screening of the pet food performed by the National Measurement Institute was unable to identify a causative agent.
Dr Child also advised of an unconfirmed report of possible leukoencephalomyelopathy in a few cats in Queensland in 2007 with a possible link to another irradiated cat food product that was subsequently removed from the market in late 2007. Biosecurity Australia reviewed this information and the results of recent publications related to cats and irradiated cat food. In particular, a report by Cassidy et al (2007) of cats exhibiting hind-limb ataxia associated with leukoencephalomyelopathy from an SPF (specific pathogen free) colony fed long term exclusively on gamma-irradiated food provided evidence of a possible link to the particular gamma-irradiated diet used. Both SPF and conventional status cats were fed to appetite on the same commercial formula ration (Gilbertson and Page Ltd., Welwyn Garden City, UK), except that the ration fed to SPF cats had been gamma-irradiated at between 36.3 kGy and 47.3 kGy. No further cases occurred following the replacement of the irradiated diet with an equivalent pasteurised diet.
An experimental study (Caulfield et al, in press) by the same group into the effect of long-term feeding of irradiated dry cat food was able to reproduce similar neurological lesions. Following feeding of a diet irradiated at either 25.7-38.1 kGy or 38.1-53.6 kGy, increasing numbers of cats presented with progressively severe ataxia from day 140. Analysis of the diet revealed a reduction in vitamin A levels of 43-48 percent, although the reduced level was still within the maintenance levels for adult cats recommended by the Association of American Feed Control officials and the United States National Academy of Sciences' National Research Council. Levels of fat were unchanged, although peroxide levels were substantially elevated -- leading the authors to conclude that free radical formation (due to the irradiation) might play an important role in the pathogenesis of the disease. This study provides some further evidence that some gamma-irradiated diets might cause a neurological syndrome in cats.
In addition, researchers investigating multiple sclerosis (Duncan et al, 2009) recently reported that cats fed an irradiated diet during gestation developed a severe neurological disease, resulting in severe myelin degeneration. Cats returned to a normal diet recovered slowly within 3 to 4 months. Biochemical analysis of the food and tissues from affected cats showed no dietary deficiencies or toxic accumulations.
Biosecurity Australia also reviewed further detailed information provided by Dr Child (such as, copies of the pathology reports on 8 affected cats and a draft short communication submitted to the Australian Veterinary Journal). Biosecurity Australia has also received an unconfirmed report that about 15 years ago, cats fed irradiated dry product in an SPF breeding colony in the United States developed a similar neurological condition on 3 separate occasions (and was advised that the 2 pet food companies involved apparently decided not to report the event in the literature).
Biosecurity Australia advised AQIS that consumption of some irradiated pet food has recently been associated with severe, chronic leukoencephalomyelopathy in cats in Australia and in specific pathogen free (SPF) cat colonies and cat research feeding trials overseas; that the association with consumption of irradiated pet food appears to be restricted to cats; that the causative agent or induced nutritional deficiency associated with the pet food is unknown and unlikely to be determined (but does seem to be linked to the irradiation of either the pet food or its packaging); that there is a reasonable body of evidence that irradiation as a quarantine treatment of pet food was recently associated with the disease syndrome in cats in Australia; and that thus the continued use of gamma-irradiation for pet food for cats can no longer be supported as a quarantine treatment (although Biosecurity Australia continues to support gamma-irradiation as a valid and effective quarantine treatment option for other products).
As a result of this advice, AQIS will no longer offer gamma-irradiation as a quarantine treatment option for imports of dried/semi-moist cat food. Details of associated actions are provided in advice posted on the AQIS website on Wed 3 May 2009 (<http://www.daff.gov.au/aqis/import/general-info/ian/09/33-2009>).
References
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1. Cassidy JP, Caulfield, Jones BR, Worrall S, Conlon L, Palmer AC, Kelly J. (2007): Leukoencephalomyelopathy in specific pathogen-free cats. Veterinary Pathology; 44: 912-6 [available at <http://www.vetpathology.org/cgi/content/full/44/6/912>].
2. Caulfield CD, Cassidy JP, Kelly JP. (2008): Effects of Gamma Irradiation and Pasteurization on the Nutritive Composition of Commercially Available Animal Diets. J Am Assoc Lab Anim Sci. 2008 Nov; 47(6): 61-6 [available at <http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2687132>].
3. Caulfield CD, Kelly JP, Jones BR, Worrall SL, Conlon L, Palmer AC (in press): The experimental induction of leukoencephalomyelopathy in cats. Veterinary Pathology, accepted for publication April 2009.
4. Duncan ID, Brower A, Kondo Y, Curlee JF, Schultz RD (2009):
Extensive remyelination of the CNS leads to functional recovery. PNAS April 21, 2009 106(16): 6832-6 [abstract available at <http://www.pnas.org/content/106/16/6832.abstract>].
End of the agency report.
The ProMED-mail moderator has resumed comments. It is extremely important to note that Champion did a voluntary recall of all of the food.
However, regarding a scientific argument, in some cases the pet foods have been known to contain starch products, such as potato. When heated to high temperatures, such as when French frying potatoes, a product call acrylamide, may be produced. Acrylamide may be toxic to some species or sensitive individuals. The acrylamide issue was raised regarding fast foods and French fries several years ago. The recommendation from most food safety agencies was to eat such foods in moderation.
The irradiated or heat treated pet foods are known to contain starchy products that may well be producing acrylamide under either of import regiments. However acrylamide production by starchy foods has not been investigated when considering irradiation. Cats may be a particularly sensitive species to extremely low levels of some product such as acrylamide.
Acrylamide caused cancer in animals in studies where animals were exposed to acrylamide at very high doses. Acrylamide causes nerve damage in people exposed to very high levels at work. Most regulatory agencies are still assessing the impact of low level ingestion of acrylamide. However, it is unlikely their assessments will be concerned with cats. But indeed, if the cat is ultra sensitive, perhaps they should examine the consequences in this sensitive species.
In humans that have ingested large doses of acrylamide there are reports of numbness, paresthesia, and weakened legs and hands. This may be consistent with clinical signs displayed in cats. - Mod.TG]
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ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material.
Cheers,
Annie
IRRADIATED CAT FOOD TOXICITY - AUSTRALIA
****************************************
A ProMED-mail post <http://www.promedmail.org>
ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>
[1]
Date: Sat 30 May 2009
Source: The Sydney Morning Herald [edited] <http://www.smh.com.au/national/catfood-irradiation-banned-as-pet-theory-proved-20090529-bq8h.html>
Cat-food irradiation banned as pet theory proved
------------------------------------------------
A series of mysterious cat deaths was caused by the government-mandated practice of irradiating imported pet food.
The Agriculture Minister, Tony Burke, has ordered the controversial sterilization process, which has been in place for more than a decade, to cease immediately, following compelling overseas evidence that some cats can suffer fatal neurological damage after eating irradiated dry food. Dogs do not appear to be affected by similarly treated food.
About 90 cats fell ill last year [2008] and 30 died before a Sydney vet, Georgina Child, made the link in November between the mystery illness and a brand of Canadian gourmet pet food called Orijen.
The manufacturer, Champion Petfoods, blamed the contaminated food on Australian quarantine regulations, which demand that pet food not cooked over a specified temperature undergo irradiation of 50 kiloGrays upon arrival in the country. Of the 60 countries Champion Petfoods exports to, only Australia makes irradiation compulsory.
The Australian Quarantine and Inspection Service and the company that carries out the process, Steritech, insisted at the time the irradiation process was harmless. A limited range of imported human foods, including dried herbs and some tropical fruits, are also irradiated before landing on store shelves, but at much lower levels than that mandated for pet food.
Mr Burke said the inspection service decided to act in response to international reports his department received only late last week [week of 18 May 2009]. Work was being done in state and federal governments to see how safety standards for pet food could be improved. "People expect that any treatments conducted on imported pet food will result in food that is still safe for pets," he said.
Dr Child said the move was welcome but did not go far enough. The irradiation ban is not being extended to imported dog food, leaving cats with access to such food still at risk. "We still don't know why this problem is unique to cats, and we're still not certain why some brands of pet food are affected by irradiation and not others," she said. "What this does show is that all food that has been irradiated needs to be labelled, which isn't the case at the moment."
[A Dundas woman] who lost 2 cats after they were fed the Orijen pet food, said the ban was great news. Champion Petfoods has set up a fund to disperse compensation for veterinary bills for all affected Australian cat owners.
[Byline: Kelly Burke]
--
Communicated by:
ProMED-mail Rapporteur Kunihiko Iizuka
******
[2]
Date: Mon 8 Jun 2009
Source: The VIN (Veterinary Information Network) News Service [edited] <http://news.vin.com/VINNews.aspx?articleId=13088>
An outbreak in Australia of neurological disorders in cats fed irradiated diets is a first among pets but not unprecedented.
At least 3 instances of irradiated food causing severe nervous system disease have occurred around the world since 1998. The cases happened in Ireland and the United States in laboratory cats and in Australia among pet cats.
The Australian government in late May [2009] ordered an immediate stop to sterilizing cat food via irradiation after reviewing scientific studies pointing to food irradiation as the culprit behind illnesses characterized by ataxia or paralysis of the limbs, especially the hind limbs. How irradiation may be causing food to become toxic to cats is unknown. The problem affected 90 cats in Australia, of which 30 died, mostly by euthanasia after they became paraplegic or tetraplegic, according to Dr Georgina Child, a neurologist at the Small Animal Specialist Hospital and University of Sydney Teaching Hospital.
Child told The VIN News Service by e-mail that all the cats had eaten an imported dry diet, sold under the brand name Orijen and made in Canada by Champion Petfoods. The food was subject to gamma irradiation upon entry to Australia at levels greater than or equal to 50 kilo-Grays (kGy).
The US Food and Drug Administration (FDA) also allows animal feed, including pet food and treats, to be irradiated up to 50 kGy. By comparison, most human foods in the United States allowed to be irradiated are limited to levels of 30 kGys and below. Packaged meats for astronauts are an exception; those may be treated up to 44 kGy.
The FDA requires all irradiated foods to be labeled as such; Australia does not require labels on irradiated pet food.
Signs in the Australian cats first appeared 3 to 6 months after they were exposed to the dry food, Child said. Some had eaten the food for as few as 3 weeks; others for more than 6 months. Most of the cats were fed other foods, as well. The affected cats ranged in age from less than one year to 15 years. Early signs of illness included a wobbly gait, unwillingness to jump onto sofas or beds, and loss of balance exhibited, for example, by falling off tables, according to a Q&A for consumers prepared by Champion Petfoods.
Child said about half of the affected cats remain paraparetic or tetraparetic; some remain paraplegic or tetraplegic. "Many cats have been at their worst for 2 or more months before showing any improvement," she said, noting that fewer than one-fifth have recovered fully. Child said histopathology showed "diffuse, symmetric, severe white matter degeneration of predominantly the spinal cord but also (the) brain stem and cerebrum, with demyelination the predominant feature."
"No specific treatment has resulted in an improvement in the outcome of affected cats," she said. "A change in diet, nursing care, physiotherapy, and time seem to be the only factors common in recovered cats."
But even patients who are paralyzed and lose vision as a result of eating irradiated food can fully recover, given sufficient time, nursing care, and food that hasn't been irradiated, said Dr. Ian Duncan, professor of neurology at the University of Wisconsin-Madison School of Veterinary Medicine. That's what Duncan saw with cats housed in a private laboratory in Wisconsin that were fed irradiated diets. The irradiation was meant to help keep the cats -- known as "specific pathogen-free" or SPF cats -- from unwittingly acquiring infections. In that episode, which was reported this spring [2009] in the Proceedings of the National Academy of Sciences [Duncan ID et al:
Extensive remyelination of the CNS leads to functional recovery. PNAS April 21, 2009 106(16): 6832-6) abstract available at <http://www.pnas.org/content/106/16/6832.abstract>], the food was irradiated at levels of 25 to 50 kGy.
The signs took about 4 months to appear, and they abated after another 2 to 4 months once the cats were given a non-irradiated diet.
Altogether, about 30 cats were affected, and most made impressive recoveries, Duncan said.
Oddly, only cats that became pregnant while on the irradiated diet developed neurological symptoms, he noted. Male cats and offspring exposed to the same diet did not become ill. Male cats have been affected elsewhere, however.
In the Irish case, 190 domestic short-hair cats housed together developed hind limb ataxia and proprioceptive defects during a period of 4 years, from 1998 to 2001 [JP Cassidy et al:
Leukoencephalomyelopathy in Specific Pathogen-free Cats. Vet Pathol 2007; 44: 912-6; available at <http://www.vetpathology.org/cgi/content/full/44/6/912>]. As with the Wisconsin colony, those animals were SPF cats.
Serendipitously, researchers had a control group in the form of kittens that had been transferred from the SPF colony to a conventional disease status colony on the same site. Both groups of cats were fed on the same commercial formula ration, except that the food bound for SFP cats was irradiated to levels between 36.3 and
47.3 kGy.
The transferred cats did not develop any neurological abnormalities.
More than one-third of the cats fed irradiated food did. "Following supplementation of the irradiated diet with pasteurized proprietary tinned cat food in the winter of 2001, and ultimately, the replacement of the irradiated diet with an equivalent pasteurized diet, no further cases occurred, "the researchers reported. Child said the same researchers since have induced neurological problems in cats at radiation levels as low as 26 kGy. A study with those results is due to be published shortly, she said.
Exactly how irradiation renders food toxic to cats is unclear. It was initially thought to be a vitamin A deficiency; the researchers in Ireland, analyzing the nutritional content of cat food subject to irradiation levels ranging from 28.9 kGy to 48.7 kGy, found that vitamin A content diminished to levels below that recommended for growth and reproduction.
By comparison, pasteurization reduced the vitamin A content in the cat food, as well, but not below recommended levels. Curiously, the researchers found that irradiation did not alter vitamin A in dog food. However, radiation treatment did increase peroxide content in dog food, cat food, and rodent food, up to 25-fold at the highest dose.
"Gamma irradiation can have profound, selective effects on the vitamin A and peroxide contents of dry diets, and caution is advised when feeding such diets long-term and exclusively to SPF animals, particularly cats," the researchers concluded [Caulfield CD et al:
Effects of Gamma Irradiation and Pasteurization on the Nutritive Composition of Commercially Available Animal Diets. J Am Assoc Lab Anim Sci. 2008 Nov; 47(6): 61-6, available at <http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2687132>].
But subsequent studies found that affected animals were not deficient in vitamin A after all, Child said. "Possible causes still include a micronutrient deficiency -- although this seems less likely -- or toxicity induced by irradiation-induced changes in the dry food (more likely),"she said.
Champion Petfoods, maker of the Orijen brand, noted in a Q&A dated November 2008 that its own testing of irradiated cat food found the treatment depleted vitamin A and formed free radicals in the food.
Their statement reads in part: "Irradiation does not affect all foods equally. Orijen is a nutritionally dense food with much higher levels of long-chain fatty acids (DHA, EPA) than conventional pet foods.
These fatty acids are susceptible to oxidation following irradiation.
Byproducts from fatty acid oxidation, mainly free radicals, are released into the body with the potential to cause tissue damage.
"Combined with the loss of antioxidant vitamins [such as vitamin A], free radicals are thought to be a major contributing factor."
Although the irradiation ban applies only to cat food, Champion Petfoods has pulled its dog food from the Australian market as well, Sales and Marketing Manager Peter Muhlenfeld told the VIN News Service. "Cats frequently eat from dog dishes and vice versa," he said in an e-mail. "We do not believe the market to be safe unless both cat and dog foods are allowed entry without irradiation."
According to the company Q&A:
- Only Australia requires irradiation of Orijen cat foods, out of 50 countries in which the food is sold.
- Orijen was sold in Australia only for a 9-month period -- February through October 2008.
- In that period, only 6 pallets of Orijen cat food actually entered retail distribution, enough to feed 200 cats each day during the 9 months.
- During the same period, shipments of Orijen cat food were made to
49 other countries, enough to feed 85 000 cats. In no other country has neurological illness been reported.
Why Australia requires irradiation of imported pet foods is unclear.
Officials at the Australian Quarantine and Inspection Service (AQIS) did not respond to an e-mailed request for information.
Patty Lovera, assistant director of Food and Water Watch, a non-profit consumer organization based in Washington, DC [USA], that monitors food irradiation around the world, said Australia's high vigilance on biosecurity may stem from its being an island nation.
"My impression is that they're very tuned to things coming in that might be some kind of threat to their agriculture," Lovera said.
A notice to industry posted by the AQIS before the government banned cat-food irradiation suggests that is the case. It states: "Heat or irradiation treatments are necessary to address animal quarantine pest and disease risks that may be associated with imported pet foods." A separate notice states that, as an alternative to radiation, importers may subject pet food to a moist heat treatment
-- through which the product must achieve a certain core temperature for a certain duration.
According to the Champion Petfoods Q&A, "The overwhelming majority of cat foods in Australia do not require irradiation." Orijen was required to undergo irradiation because the food includes fresh meats that were cooked at low temperatures. The company takes pride in the distinctions between its products and those of conventional pet-food makers. Its gourmet foods are marketed as "biologically appropriate,"
and made with "fresh, regional ingredients."
"We're different. We sell only what we make ourselves, "it says on its website in an allusion to the use of co-packing facilities by some of its competitors. Co-packers are contracted to produce pet foods for a variety of companies sold under a variety of brand names.
The widespread use of co-packing contributed in 2007 to the largest recall of pet food in North American history, due to contamination by the industrial chemical melamine, which affected 180 brands of pet food. Muhlenfeld said Champion Petfoods has a program to offset medical bills of owners of affected pets up to [AUD] 1000 [USD 796.5]. It also donated [AUD] 10 000 [USD 7965] to organizations in Sydney that work with cat diseases.
The Australian ban on irradiation marks the 1st time in the world that authorities rescinded an approved use of irradiation because it is suspected to cause illness.
George Pauli, a retired chemist who worked for 29 years in the US FDA's Center for Food Safety and Applied Nutrition, said the FDA in one instance reversed an approval on irradiation, but not because anyone became ill. In that case from the 1960s, the US Department of Defense asked to sterilize bacon through irradiation to create a shelf-stable product that didn't need to be refrigerated. "The FDA, when they reviewed it, thought everything looked good, but later on ... they concluded that the data were not nearly as solid and convincing as first thought," Pauli said.
The Defense Department never came back with more data and a request to reconsider, Pauli said. He speculated that the cat cases in Australia are an example of species sensitivity. "More testing has been done on rodents and dogs," he said. "Normally, testing (for human safety) is not done on cats that much."
[Byline: Edie Lau]
--
Communicated by:
ProMED-mail Rapporteur Kunihiko Iizuka
[In response to these articles and some international legal maneuvering between regulations and companies, ProMED-mail sought clarification from Australian animal health authorities. Dr Mike Nunn, Principal Scientist (Animal Biosecurity) with Biosecurity Australia provided the following information:
Under Australia's "Quarantine Act 1908", the Australian Quarantine and Inspection Service (AQIS) has responsibility to prevent the introduction, establishment, or spread of pests and diseases. The "Quarantine Proclamation 1998" refers to the level of quarantine risk and the imposition of appropriate conditions that the Director of Quarantine must consider before granting an import permit. A pet food ingredient (or the final product) is considered acceptable if it is heat-treated sufficiently to address Australia's quarantine concerns.
For example, ingredients of mammalian and avian origin generally require heat treatment to achieve a core temperature of at least 100 deg C [212 deg F] for a minimum of 30 minutes. For products that do not meet heat treatment requirements or where a manufacturer is unable to provide AQIS with sufficient information to complete the assessment, importers may be given the option to irradiate the pet food on arrival to address outstanding quarantine concerns.
Gamma-irradiation is a valid and very effective treatment -- in accordance with the scope of the "Quarantine Act 1908" and the "Quarantine Proclamation 1998" -- to address the risk of introducing, establishing or spreading disease within Australia. However, there is now a body of evidence that gamma-irradiation of imported pet food may actually be a causative factor for the disease chronic leukoencephalomyelopathy in cats. As such, and unless future research confirms otherwise, Biosecurity Australia no longer supports gamma-irradiation of pet food for cats as a valid quarantine treatment. However, Biosecurity Australia continues to support gamma-irradiation as a valid and effective quarantine treatment option for other products.
The background is that there have been a number of media reports (and statements by a veterinary clinician and neurologist in Sydney, Dr Georgina Child) that suggested some cats fed a particular brand of imported pet food manufactured by Champion Pet Foods, Canada) had developed a chronic and sometimes fatal neurological syndrome. The particular product concerned was a semi-moist, fish and poultry based product with no cereal ingredient. It was released onto the Australian market in April/May 2008 and the 1st cases of disease in cats were seen in September 2008 and cases continued until February 2009. It is estimated that approximately 1300 kg [approx. 2900 lb] of irradiated product was imported, and a large proportion of this was removed from sale after the manufacturer announced on 20 Nov 2008 a voluntary recall of the product in Australia.
Representatives of AQIS, Biosecurity Australia, Food Standards Australia New Zealand (FSANZ), and the Australian Veterinary Association (AVA) met with Dr Child) who provided a detailed report of her findings. Dr Child reported that the syndrome had affected at least 87 cats in Australia with 27 deaths (23 that were euthanised due to severe neurological signs; 4 died naturally, including 2 that developed seizures). Affected cats developed ataxia, paraparesis and, in the worst-affected cases, paraplegia and tetraplegia. Fewer than 20 percent fully recovered and about 50 percent improved but remain paraplegic or tetraplegic. Many cats have been at their worst for 2 or more months before showing any improvement. Affected cats have ranged in age from less than one year to 15 years. Signs were typically seen 3 to 6 months after 1st exposure to the dry food and the period the food was fed varied considerably (from about 3 weeks to more than 6 months). Post mortem examination of 8 cats has shown lesions very similar to those of cats fed irradiated pet food in Ireland (Cassidy et al, 2007; Caulfield et al. in press) and in the United States (Duncan et al, 2009) Dr Child's findings have since been submitted for publication in the Australian Veterinary Journal.
A range of different breeds and, in some cases, several cats in the same household were affected. The majority of affected cats had eaten other products as well as the particular brand of imported cat food and there was anecdotal evidence that in a perhaps 3 cases affected cats ate dog food (and apparently not cat food) manufactured by the same company and irradiated on import [in Australia]. Based on reports from veterinary clinics selling the product, about 40 percent of cats fed the particular brand of imported cat food 'developed clinical signs of disease.' A detailed toxicological screening of the pet food performed by the National Measurement Institute was unable to identify a causative agent.
Dr Child also advised of an unconfirmed report of possible leukoencephalomyelopathy in a few cats in Queensland in 2007 with a possible link to another irradiated cat food product that was subsequently removed from the market in late 2007. Biosecurity Australia reviewed this information and the results of recent publications related to cats and irradiated cat food. In particular, a report by Cassidy et al (2007) of cats exhibiting hind-limb ataxia associated with leukoencephalomyelopathy from an SPF (specific pathogen free) colony fed long term exclusively on gamma-irradiated food provided evidence of a possible link to the particular gamma-irradiated diet used. Both SPF and conventional status cats were fed to appetite on the same commercial formula ration (Gilbertson and Page Ltd., Welwyn Garden City, UK), except that the ration fed to SPF cats had been gamma-irradiated at between 36.3 kGy and 47.3 kGy. No further cases occurred following the replacement of the irradiated diet with an equivalent pasteurised diet.
An experimental study (Caulfield et al, in press) by the same group into the effect of long-term feeding of irradiated dry cat food was able to reproduce similar neurological lesions. Following feeding of a diet irradiated at either 25.7-38.1 kGy or 38.1-53.6 kGy, increasing numbers of cats presented with progressively severe ataxia from day 140. Analysis of the diet revealed a reduction in vitamin A levels of 43-48 percent, although the reduced level was still within the maintenance levels for adult cats recommended by the Association of American Feed Control officials and the United States National Academy of Sciences' National Research Council. Levels of fat were unchanged, although peroxide levels were substantially elevated -- leading the authors to conclude that free radical formation (due to the irradiation) might play an important role in the pathogenesis of the disease. This study provides some further evidence that some gamma-irradiated diets might cause a neurological syndrome in cats.
In addition, researchers investigating multiple sclerosis (Duncan et al, 2009) recently reported that cats fed an irradiated diet during gestation developed a severe neurological disease, resulting in severe myelin degeneration. Cats returned to a normal diet recovered slowly within 3 to 4 months. Biochemical analysis of the food and tissues from affected cats showed no dietary deficiencies or toxic accumulations.
Biosecurity Australia also reviewed further detailed information provided by Dr Child (such as, copies of the pathology reports on 8 affected cats and a draft short communication submitted to the Australian Veterinary Journal). Biosecurity Australia has also received an unconfirmed report that about 15 years ago, cats fed irradiated dry product in an SPF breeding colony in the United States developed a similar neurological condition on 3 separate occasions (and was advised that the 2 pet food companies involved apparently decided not to report the event in the literature).
Biosecurity Australia advised AQIS that consumption of some irradiated pet food has recently been associated with severe, chronic leukoencephalomyelopathy in cats in Australia and in specific pathogen free (SPF) cat colonies and cat research feeding trials overseas; that the association with consumption of irradiated pet food appears to be restricted to cats; that the causative agent or induced nutritional deficiency associated with the pet food is unknown and unlikely to be determined (but does seem to be linked to the irradiation of either the pet food or its packaging); that there is a reasonable body of evidence that irradiation as a quarantine treatment of pet food was recently associated with the disease syndrome in cats in Australia; and that thus the continued use of gamma-irradiation for pet food for cats can no longer be supported as a quarantine treatment (although Biosecurity Australia continues to support gamma-irradiation as a valid and effective quarantine treatment option for other products).
As a result of this advice, AQIS will no longer offer gamma-irradiation as a quarantine treatment option for imports of dried/semi-moist cat food. Details of associated actions are provided in advice posted on the AQIS website on Wed 3 May 2009 (<http://www.daff.gov.au/aqis/import/general-info/ian/09/33-2009>).
References
----------
1. Cassidy JP, Caulfield, Jones BR, Worrall S, Conlon L, Palmer AC, Kelly J. (2007): Leukoencephalomyelopathy in specific pathogen-free cats. Veterinary Pathology; 44: 912-6 [available at <http://www.vetpathology.org/cgi/content/full/44/6/912>].
2. Caulfield CD, Cassidy JP, Kelly JP. (2008): Effects of Gamma Irradiation and Pasteurization on the Nutritive Composition of Commercially Available Animal Diets. J Am Assoc Lab Anim Sci. 2008 Nov; 47(6): 61-6 [available at <http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2687132>].
3. Caulfield CD, Kelly JP, Jones BR, Worrall SL, Conlon L, Palmer AC (in press): The experimental induction of leukoencephalomyelopathy in cats. Veterinary Pathology, accepted for publication April 2009.
4. Duncan ID, Brower A, Kondo Y, Curlee JF, Schultz RD (2009):
Extensive remyelination of the CNS leads to functional recovery. PNAS April 21, 2009 106(16): 6832-6 [abstract available at <http://www.pnas.org/content/106/16/6832.abstract>].
End of the agency report.
The ProMED-mail moderator has resumed comments. It is extremely important to note that Champion did a voluntary recall of all of the food.
However, regarding a scientific argument, in some cases the pet foods have been known to contain starch products, such as potato. When heated to high temperatures, such as when French frying potatoes, a product call acrylamide, may be produced. Acrylamide may be toxic to some species or sensitive individuals. The acrylamide issue was raised regarding fast foods and French fries several years ago. The recommendation from most food safety agencies was to eat such foods in moderation.
The irradiated or heat treated pet foods are known to contain starchy products that may well be producing acrylamide under either of import regiments. However acrylamide production by starchy foods has not been investigated when considering irradiation. Cats may be a particularly sensitive species to extremely low levels of some product such as acrylamide.
Acrylamide caused cancer in animals in studies where animals were exposed to acrylamide at very high doses. Acrylamide causes nerve damage in people exposed to very high levels at work. Most regulatory agencies are still assessing the impact of low level ingestion of acrylamide. However, it is unlikely their assessments will be concerned with cats. But indeed, if the cat is ultra sensitive, perhaps they should examine the consequences in this sensitive species.
In humans that have ingested large doses of acrylamide there are reports of numbness, paresthesia, and weakened legs and hands. This may be consistent with clinical signs displayed in cats. - Mod.TG]
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