UNITED STATES DEPARTMENT OF HEALTH AND HUMAN SERVICES
Petition to Declare Poultry Litter) as a Food Additive and to) Ban Its Use as Cattle Feed)
Table of Contents
B. In 1958 Congress enacted legislation that bars the use of an ingredient in
human or animal food unless the FDA has either issued a regulation
governing its safe use or declared that it is generally recognized as safe.
C. In 1967 FDA banned the use of poultry litter as animal feed because of its
concerns about the effects of such use on human health.
D. In 1977 the FDA asked for public comment on its 1967 policy which could p.
help it determine whether poultry litter was either a food additive or generally recognized as safe.
E. In 1980 the FDA, while reaffirming its concerns about the public health risks p.
of using poultry litter as animal feed, revoked its 1967 policy statement and gave jurisdiction for the regulation of such use to the state Departments of Agriculture.
F. In 2008 the FDA, while acknowledging that the use of poultry litter as cattle p.
feed may contribute to Variant Creutzfeldt-Jakob Disease (“vCJD”) in people, refused to ban such use.
G. The states are not adequately regulating the use of poultry litter as animal feed. p.
H. Numerous countries have banned the use of poultry litter as ruminant feed.
3. The impact of soil particles on prion infectivity
4. Potential risk associated with new BSE strains
B. Pathogenic organisms and inadequate litter processing
C. Drugs, residues and antibiotic resistant bacteria
A. The FDA has the legal authority to regulate poultry litter used as cattle feed p.
even if some of the poultry litter is not sold.
B. There is no convincing evidence that poultry litter used as cattle feed is is
“Generally Recognized As Safe” by scientists, and so it is a food additive within
the meaning of section 201(s) of the Federal Food, Drug, and Cosmetic Act.
C. The FDA can legally ban the use of poultry litter as cattle feed because such p.
Department of Health and Human Services Room 1061 5630 Fishers Lane Rockville, MD 20852
I. Preliminary Statement
For more than 40 years the U.S. Food and Drug Administration (“FDA”) has
acknowledged the public health risks of using poultry manure and other poultry litter as feed for cattle. Yet in 1980 the FDA abdicated its responsibility to protect the public health by giving to the states the sole responsibility of regulating such use. The states, however, are either unwilling or unable to perform this task. II. Action Requested
Pursuant to section 4(e) of the Administrative Procedure Act, 5 U.S.C. 553(e), and 21
C.F.R. 10.25 and 10.30, Food Animal Concerns Trust (“FACT”)i requests that the FDA declare poultry litter to be a food additive and to ban its use as feed for cattle. More specifically, a new section should be added at the end of 21 C.F.R. Subpart B: “section 589._____. Poultry litter (a) Definitions. (1) Poultry litter is a heterogeneous mixture consisting of raw manure, feathers, spilled feed and bedding material that accumulate on the floors of the buildings that house broiler chickens, laying hens and turkeys. (2) The terms renderer, blender, feed manufacturer, distributor, and establishment and/or individual that is responsible for feeding ruminant animals have the same meaning as in section 589.2000(a).
(b) Food additive status. The Food and Drug Administration has determined that chicken litter for use in ruminant feed is a food additive subject to section 409 of the Federal Food, Drug, and Cosmetic Act (the act). The use or intended use in ruminant feed of any material derived from chicken litter causes the feed to be adulterated and in violation of the act, unless it is the subject of an effective notice of claimed investigational exemption for a food additive under section
Founded in 1982, FACT is a Chicago-based non-profit organization that promotes better methods of raising
livestock and poultry by improving the welfare of food animals, broadening opportunities for humane farmers, and addressing public health problems that come from the production of meat, milk and eggs.
570.17 of this chapter. (c) Requirements for renderers, blenders, feed manufacturers, distributors, and establishments and individuals that are responsible for feeding ruminant animals. Renderers, blenders, feed manufacturers, distributors, and establishments and individuals that are responsible for feeding ruminant animals shall comply with sections 589.2000(c)(i) and (ii), 589.2000(f), and 589.2000(h). (d) Adulteration and misbranding. (1) Animal protein products, and feeds containing such products, that are not in compliance with paragraphs (b) and (c) of this section, excluding labeling requirements, will be deemed adulterated under section 402(a)((2)(C) or 402(a)(4) of the act. (2) Animal protein products, and feeds containing such products, that are not in compliance with the labeling requirements of paragraphs (b) and (c) of this section will be deemed misbranded under section 403(a)(1) or 403(f) of the act.” III. Factual Background A. Poultry manure and other litter
Poultry litter consists primarily of manure, feathers, spilled feed and bedding material
that accumulate on the floors of the buildings in which birds are raised. It can contain disease-causing bacteria, antibiotics, heavy metals, feed ingredients normally prohibited for cattle such as meat and bone meal from dead cattle, and even foreign objects such as dead rodents, rocks, nails and glass. This material is collected and processed using techniques such as composting or deep-stacking. It is then added to cattle feed because of its high protein and mineral content, and due to costs associated with other manure disposal options.
B. In 1958 Congress enacted legislation that bars the use of an ingredient in human or animal food unless the FDA has either issued a regulation governing its safe use or declared that it is generally recognized as safe.
In 1958 Congress passed the Food Additives Amendment of 1958, which
amended the Federal Food, Drug, and Cosmetic Act (“FFDCA”) to provide a new regulatory scheme for ensuring the safety of ingredients in human food or animal food. As discussed below in more detail in section V, the law divides food ingredients into those that are “food additives” and those that are not because they are “generally recognized as safe” (“GRAS”). This distinction is important because the former may be legally used only if the FDA has issued a regulation prescribing the conditions under which it may be safely used.
The FDA has classified more than 200 ingredients as GRAS for animal food, has issued
regulations governing the safe use of three food ingredients for animal food, and has banned three food additives for animal food. 21 C.F.R. parts 582, 584, and 589.
However, as discussed below, the FDA has never issued a regulation governing the safe
use of poultry litter even though on several occasions it has stated that it could not consider poultry litter to be GRAS.
C. In 1967 FDA banned the use of poultry litter as animal feed because of its concerns about the effects of such use on human health.
In 1967 FDA issued a policy statement that it did not sanction the use of poultry litter as
animal feed because “poultry litter can be expected to contain drugs and antibiotic drugs or their metabolites. It is not practical to determine, or feasible to estimate, the nature and levels of the drugs and their metabolites in litter. Therefore, it is not possible to conclude that poultry litter is safe as a feed or as a component of feed for animals…” 21 C.F.R. 500.40. However, rather than declaring poultry litter to be a food additive, the FDA merely stated that poultry litter shipped via interstate commerce for use as animal feed “may” be considered as adulterated within the meaning of section 402(a)(1) of the FFDCA. (Section 301(a) of the FFDCA prohibits the sale of any adulterated food.)
D. In 1977 the FDA asked for public comment on its 1967 policy which could help it determine whether poultry litter was either a food additive or generally recognized as safe.
In 1977 the FDA sought public comment on its 1967 policy. It explained that its 1967
policy required proving adulteration on a case-by-case basis and “to minimize the difficulties of proving adulteration in each case, FDA could propose to declare recycled animal waste to be a food additive. Alternatively, the agency could propose to affirm the substance as GRAS (generally recognized as safe).” 42 Fed. Reg. 64662 (December 27, 1977) at 64670. (The FDA also stated that it had jurisdiction over recycled animal waste even if relatively little of it is in interstate commerce. Id.).
In 1977 the FDA also reaffirmed the public health risks of poultry litter as animal feed,
stating that such “animal waste could contain disease-producing organisms and parasites, residues of drugs and drug metabolites, and toxic elements and other contaminants of natural and industrial origin” and so “the feeding of animal waste could present hazards to animal and human health.” 42 Fed. Reg. 61662.
E. In 1980 the FDA, while reaffirming its concerns about the public health risks of using poultry litter as animal feed, revoked its 1967 policy statement and gave jurisdiction for the regulation of such use to the state Departments of Agriculture.
In 1980 the FDA stated “the data available to FDA as a result of extensive literature
review and provided in response to the 1977 notice do not resolve all the questions of safety that are raised by the possible occurrence of residues of drugs and drug metabolites in recycled waste.” 45 Fed. Reg. 86272 (December 30, 1980) at 86272. However, the FDA decided to revoke its 1967 policy and to leave regulation to the states “because of the local character of animal waste use.” Id. at 86273.
F.In 2008 the FDA, while acknowledging that the use of poultry litter as cattle feed may contribute to variant Creutzfeldt-Jakob Disease (“vCJD”) in people, refused to ban such use.
While acknowledging that certain ingredients in cattle feed can cause Bovine Spongiform
Encephalopathy (“BSE”) in cattle and thereby lead to variant Creutzfeldt-Jakob Disease (“vCJD”) in people who eat beef from the infected cattle, in 2008 the FDA refused to ban the use of poultry litter in cattle feed because “FDA believes that the risk of cattle exposure to an infectious dose of BSE through poultry litter is low.” 73 Fed. Reg. 22720 (April 25, 2008)(Final Rule on Substances Prohibited from Use in Animal Food or Feed) at 22725.
G. The states are not adequately regulating the use of poultry litter as animal feed.
A survey conducted in 2007 by FACT found that 21 of 32 responding state agencies
reported that they did not monitor or maintain any data on the amount of poultry litter used as cattle feed. Representatives from nine of the remaining states replied that they were not aware of this practice occurring within their state but admitted that this assertion was based on anecdotal evidence or personal experience. As one respondent said, “We do not have any information of the amount used. We only know that it is done.” Two states supplied estimates of the amount used based on limited survey data. ii
H. Numerous countries have banned the use of poultry litter as ruminant feed.
Citing food safety and other health concerns, many countries have already prohibited the
practice of using poultry litter as feed for ruminant animals as part of broader regulations addressing animal feed. These countries include Australia, Canada, European Commission Member States, and New Zealand.
IV.There Is Substantial Scientific Evidence that the Use of Poultry Litter as Animal Feed Adversely Affects Public Health.
The known dangers associated with this agricultural practice create an unacceptable risk
to human health. Documented risks include the spread of neurological diseases, the transmission of pathogens leading to foodborne disease, unsafe levels of drug and heavy metal residues in food, and the development of antibiotic resistant bacteria.
Bovine Spongiform Encephalopathy (BSE), known commonly as Mad Cow Disease, is
the most serious of the many serious health risks associated with feeding poultry litter to cattle. BSE is an important neurological disease in cattle and is also the cause of variant Creutzfeldt-
ii Staff at Food Animal Concerns Trust (FACT) contacted Association of American Feed Control Officials (AAFCO) representatives from each of the 50 states in June and July 2007 to request data or estimates on the quantity of poultry litter used annually in feed for cattle, or recommendations where such data can be found. FACT received feedback via email, phone and letter from 32 states.
Jakob disease (vCJD), a fatal human neurological disease. Because BSE is spread through the recycling of ruminant protein as ruminant feed, steps to control BSE focus on limiting cattle exposure to feed containing rendered ruminant proteins. The feeding of ruminant meat and bone meal (MBM) to poultry is permitted by the FDA as research has not shown poultry to be susceptible to BSE infection. The poultry industry utilizes ruminant meat and bone meal as a feed ingredient. This feeding practice results in poultry litter that often contains ruminant protein either as spilled feed or as undigested proteins that pass through the avian gut. In 1997, when FDA first implemented a ruminant feed ban to address BSE, the FDA did not include a litter ban arguing that (1) BSE was not present in U.S. cattle; (2) there were no studies showing infectivity in feces based on one study of scrapie; and (3) lack of epidemiological evidence from countries with BSE. Since that time BSE has been detected in the U.S. and Canada. Studies have shown infectivity of prions in feces. The FDA’s epidemiological argument is spurious because feeding of litter was prohibited in European countries where epidemiological evidence could have potentially been found.1
In the 2008 Final Rule on Substances Prohibited from Use in Animal Food or Feed, the
FDA determined that the risk of the transmission of BSE to cattle through poultry litter was low based on calculations provided by the North American Rendering Industry (NARI). However, certain highly questionable assumptions were made that likely lead to an underestimation of risk. Given the magnitude of these errors and the continuing uncertainty about BSE and other transmissible spongiform encephalopathies (TSEs), the changes in the 2008 feed rule that will be implemented in 2009 are not adequate to address the risk related to feeding litter. The following factors were not adequately addressed in the FDA’s finding that feeding poultry litter presents an acceptable risk related to the spread of BSE: 1. Prion characteristics
a. The ability of prions to resist degradation by both the avian digestive tract and chemical
processing methods. NARI assumed that the only source of ruminant protein in litter was from spilled
b. The potential for infectious prions to occur in discrete packets in feed instead of being
uniformly distributed. NARI assumed that feed is perfectly mixed down to the microgram level at which
c. The possibility that soil particles could enhance transmission of BSE via mixing with
litter. NARI did not consider the impact of soil on TSE transmissibility.
2. The potential for other strains of BSE or TSEs to be spread, amplified, and/or modified by
Information on other BSE strains was unknown at the time of the NARI calculation.
Because these factors are not included in the NARI risk assessment, the results most
likely underestimate the threat to human health posed by litter feeding.
1. Prion resistance to degradation
The NARI calculation accepted by the FDA considered spilled feed as the only source of
potential infectivity in litter ignoring the much greater risk from protein passing through the avian gut. There is no reason to expect that TSE infectivity would be inactivated by passage through the avian digestive tract. Thus poultry feces in cattle feed is are another potential route of BSE transmission to cattle. No specific studies considering BSE infectivity have been carried out on this possible route of transmission. However, evidence of this route of transmission comes from rodent experiments where infectivity was demonstrated in the feces after oral inoculation. Laboratory experiments show that mice orally challenged with scrapie have detectable infectivity that passes through the gut. Safar and colleagues orally infected Syrian hamsters with scrapie and found infectivity titers of 10 6.6 ID50/g and corresponding levels of PrPSc in feces during the first 7 days post inoculation.2 Hamsters that were not inoculated with scrapie but who cohabitated with or exposed to the bedding of the infected hamsters developed scrapie.
In addition, prions are known to resist inactivation by processes such as ultraviolet
irradiation, metal ion chelators, acidification, boiling, dry heat and chemicals such as formalin, alcohols, and beta-Propiolactone.3 Because of their resistance to degradation, prions should not be expected to lose infectivity under the physical conditions of the avian digestive tract.
In an investigation of the potential for scavenger birds to transmit TSEs, the Scientific
Steering Committee for the European Commission's Health and Consumer Protection Directorate-General expressed doubt that bird digestion could eliminate prion infectivity. The Committee concluded that avian feces pose a risk for TSE transmission.4
Per the WHO/FAO/OIE Technical Consultation on BSE, “…it is noted that in
experimental oral challenges in cattle conducted in the UK, feces must be treated as medical waste for one month following the challenge. It is concluded that digestive contents and fecal material from livestock or poultry currently being fed with MBM potentially contaminated with BSE should not be used as a feed ingredient for animal feed.”5
A more recent study found that the bovine digestive tract did not eliminate prion
infectivity even when it degraded the proteins to the point that they were undetectable using standard immunochemical methods.6
Even if the resistance of prion proteins to degradation is not considered, only 75 to 80
percent of the crude protein in ruminant MBM is normally digested in the avian gut. The remainder of the protein is excreted by the bird, without being digested.7 Clearly the FDA’s assumption that the only potential source of infectivity is from spilled feed is wrong. The NARI assumption accepted by FDA in determining a low risk was that litter contained only 1% of the protein in feed and consequently only 1% of potential infectivity. This assumption is clearly false given that 20% of ruminant protein in feed is indigestible and that infective prions are highly resistant to degradation. It is likely that at least 20% of infectivity would survive in litter
and be transferred to the cattle consuming the litter.
Even if the targeted 90% reduction of infectivity in feed anticipated under the new feed
rules is achieved, the NARI calculation will still significantly overestimate the quantity of feed needed to be consumed for infection. It fails to consider that at least twenty times as much protein and associated infectivity passes through the avian gut compared to that spilled from feeders. This raises serious doubt about the determination that abnormally large quantities of litter would need to be eaten by a cow to receive an infective dose.
2. Distribution of infectivity in feed
Complicating our understanding of BSE are issues regarding the quantity of an infectious
agent needed to cause the disease and its distribution in feed. If the infectious agent in feed tends to occur in discrete clumps or “packets,” more of it could be ingested at one time, thus increasing the likelihood that an amount sufficient to cause disease would be consumed. On the other hand, if the infectious agent is distributed evenly throughout the feed, it is likely that a smaller amount would be consumed at any one point in time by any single animal. NARI’s calculation assumes perfect mixing and dilution of any infectivity in the animal proteins both during rendering and within the poultry house during cleanout. In its own calculations described in the Federal Register notice of the proposed rule, the FDA corrects for incomplete mixing during poultry house cleanout, but accepts NARI’s assertion that perfect mixing occurs during rendering.
However, there is evidence that infectious material is not mixed perfectly during the
rendering of feed as observed by the pattern of infection found in cattle herds. Typically, a low incidence of BSE occurs within a herd, meaning single animals rather than entire herds become infected with the disease. Perfect mixing does not seem to explain the observed pattern of disease transmission. If prion infectivity were evenly distributed in feed, entire herds would become sick rather than individual animals.
The BSE Inquiry conducted in the United Kingdom considered the “packet” theory of
MBM distribution as an explanation for this pattern.8 When the report was completed in 2000, the committee was unable to reach a conclusion on the packet theory for two reasons. First, the necessary packet size needed for infection seemed to be too large given the particle size of rendered product. Second, scientists incorrectly assumed that the infectious dose for BSE was fairly large. Since then, oral infectivity has been shown at the 1 milligram level for brain tissue, 9 one thousand times smaller than the one gram level accepted in 2000.10 This new knowledge about prions strongly supports the packet theory of MBM distribution.
In conclusion, the FDA’s determination that massive quantities of poultry litter would
need to be eaten for BSE infection to occur is likely inaccurate. It not only fails to account for the passage of infectivity through the avian gut but also assumes that infectivity is evenly distributed in batches of MBM rendered for feed. It is much more likely that the infectious material is unequally distributed, an alarming phenomenon given the small dose needed to transmit BSE to cattle.
3. The impact of soil particles on prion infectivity
Recent research implicates soil particles as a possible reservoir of TSE infectivity. These
findings raise additional concerns about how inorganic matter in feed – resulting from contact with the soil during storage and processing, or from feed additives – may impact infectivity. For example, Johnson et al. examine the disease penetrance and infectivity of prion isolates in four environments. They conclude that oral transmissibility may be to 680 times higher in prions bound to inorganic microparticles from soil than in unbound prions.11 Because litter is typically processed and stored outdoors or in outbuildings, contact with soil particles is to be expected. Given its relative popularity as a drought or winter ration, long-term stockpiling may be expected as well. Moreover, inorganic additives in feed, such as anti-caking agents used in poultry feed production, may also impact transmissibility. In 2002, 42,000 tons of bentonite clay were used in the production of animal feeds in the U.S.12
As previously described, prions are well known for their high thermal resistance.
Therefore, as long as poultry are fed ruminant MBM, prions may be present in litter via spilled feed or poultry manure.13 At the point when prions come into contact with soil particles, and subsequently increase their transmissibility, no litter processing method in contemporary use can be expected to attain the temperatures required to eliminate them or even reduce their numbers.
4. Potential risk associated with new BSE strains
Recent research has shown that there are different strains of BSE. The various strains can
either be classical and atypical. Both cases of BSE found in the United States have been the H type of atypical BSE. In addition to the 14 cases of classical BSE found in Canada, one case of H type has been confirmed and one case of L type atypical BSE has been found. There is evidence that one of the H type atypical strains identified in an infected U.S. cow may be an inheritable strain.14 The rate at which this inheritable BSE may occur in the U.S. cattle population is currently unknown. It may have been the origin of the worldwide BSE outbreak. Other research has shown that L type atypical BSE may have properties rendering it more likely to infect humans than classical BSE.15 The existence of different strains of BSE creates uncertainty in evaluating the risks related to livestock feeding. First, the presence of inheritable strains that occur independently of feeding practices creates the potential for a continual reintroduction of BSE into the U.S. feed chain as infected cattle are slaughtered. Second, certain new strains could be more infectious to humans or more transmissible between cattle, causing increased risk of human and cattle illness. Because poultry litter usually contains ruminant MBM, the practice of feeding it to cattle has the potential to select for and amplify strains of BSE. The potential health implications of new BSE strains should be accounted for in risk assessments and policy decisions. The existence of new strains of BSE creates great uncertainties in determining risks related to litter feeding as it is possible that strains will be identified that are both more infectious to humans and more transmissible between cattle. Litter feeding could amplify these strains. This scenario would pose a much greater threat to public health than risks assessments previously have calculated. If FDA cannot adequately evaluate the risk presented by this feeding practice – due to the uncertainty surrounding prion diseases – the Agency should reinstate a ban of feeding poultry litter to cattle immediately.
In addition to the NARI assessment described above, the risk of feeding poultry litter was
also assessed by the Harvard Center for Risk Analysis along with the Tuskegee University Center for Computational Epidemiology. They used mathematical modeling to assess the risk of BSE found in the United States.16 The assessment was updated in 2005, and again in 2006, to include poultry litter feeding in response to public comments.17 The base case scenario examining litter use assumes that only 1% of poultry litter is fed back to cattle. The 1% figure was chosen based on a U.S. Poultry & Egg Association’s 2002 survey of poultry producers.18 The 1% figure includes only the amount of litter fed by poultry producers directly to their own cattle and does not include the bulk of litter (51%) that is sold or traded. Because of this, the base case scenario more accurately represents the best possible outcome as it is the actual amount that producers stated that they themselves used. If any of the litter traded or sold is eventually fed to cattle, this figure would be an underestimate. Even given this presumably low-risk scenario, the assessment found that feeding poultry litter to cattle increased human exposure to infectivity by 73%, an unacceptable risk attributable to this practice. iii
Sensitivity analysis carried out using an assumption that 5% of poultry litter was fed to
cattle resulted in a more than doubling (200 to 420) of the number of new cases of cattle infected with BSE. The assessors did not provide results for amounts of litter fed above 5%. As there are no reliable data on the extent of the practice, it is possible that much more than 5% of litter is fed to cattle. In fact, under current law, all litter legally could be fed to cattle.
When the FDA determined the economic costs of a ban on feeding poultry litter as part
of its 2005 proposed rule for Substances Prohibited From Use in Animal Food or Feed, the Agency assumed that between 1.1 and 2 million tons of litter would be fed to between 1.3 and 3.2 million cows. The proposed rule does not state what percentage of the litter produced this would represent. However, if reports that 5.6 million tons of litter are produced annually are accurate,23 this would mean that the cost estimates calculated by the FDA assumed that between 20% and 36% of litter is fed to cattle. This is much higher than the levels of feeding assessed by the Harvard Risk Assessment group.
The Harvard model also fails to take into account infectivity at low dosages and does
not consider the potential for infectivity to be clumped in packets in feed or how different BSE strains may have different risk profiles. In light of these additional factors, the risks associated with feeding litter to cattle are likely greater than the Harvard model has predicted.
B. Pathogenic organisms and inadequate litter processing
Since the 1960s, the scientific community has recognized that litter feeding has the ability
to transmit pathogenic organisms. In 1968, Alexander identified numerous potentially pathogenic bacteria in litter intended for animal feed including Clostridium spp., Salmonella enterica, Corynebacterium spp., Staphylococcus spp., Streptococcus spp. and Mycobacterium
iii Human exposure was increased from 3800 infective doses to 6600 infective doses.
spp.19 Considering the composition of poultry litter, it is not surprising that it may contain disease-causing microorganisms. Subsequent research has consistently found poultry litter to contain a complex bacterial mix with many potential pathogens in addition to those identified by Alexander. These bacteria include Listeria monocytogenes, Pasteurella multocida,20Actinobacillus spp., Bacillus spp,21Pseudomonas spp., Campylobacter spp., Yersinia spp., Aeromonas hydrophilia, Escherichia coli,22Facklamia spp.,Bordetella spp.and Enterococcus spp.23 In addition to containing bacteria, litter could act a source for the transfer of viruses24,25 and pathogenic fungi.26 While no studies have directly linked the feeding of poultry litter to disease in humans, contaminated feed in general has been implicated in outbreaks of human foodborne disease.27,28 Litter feeding has been directly linked to serious illness in cattle from botulism29,30,31 as well as an outbreak of the potential zoonosis Salmonella.32
Processing methods such as deepstacking, composting and ensiling are generally used to
reduce the prevalence of pathogens in litter. Studies have shown that composting and storage can reduce the level of detectable bacteria in treated litter. Alexander demonstrated that storage of poultry litter for one to two months reduced Salmonella to undetectable levels. Many subsequent studies have shown that storage and processing of litter can reduce levels of pathogenic bacteria in litter.25,33,34
However, the degree to which processing effectively kills pathogens is confounded by the
accuracy of sampling methods used to measure pathogen levels and by the limited number of pathogens examined . Studies that sampled stored litter intended for cattle feed have often failed to detect cultured pathogens,22, 35 but it is unclear if this is because pathogens were not present or because of the sensitivity of methods used for detection.
Laboratory techniques may produce inaccurate results in pathogen-elimination trials. A
recent report by Buhr et al. suggests that the sensitivity of the swab test method typically employed in these studies is limited. Newer and experimental techniques detect significantly higher rates of true positive Salmonella cultures.36 The methods and materials used for isolating bacteria can cause significant variation in outcome, as has beendemonstrated in experimental assays for Enterococcus faecalis37 and for different species of Salmonella.38,39 Moreover, the reliance on bacterial culture assays by most pathogen-elimination trials may have produced misleading results. This is due to the use of cultural methods with limited sensitivity40,41 instead of more sensitive polymerase chain reaction (PCR) testing.42
Additionally, using culture methods can be inaccurate because many of the bacteria most
frequently implicated in fooborne human illness – including Campylobacter spp.,43 Salmonella spp.,44 Listeria,45and some enterococci46 – are known to persist in a viable, non-culturable (VBNC) state when subject to stress. This behavior may be linked to greater virulence and infectivity of the pathogen. Among the factors understood to induce the VBNC state are temperature extremes, lack of water, and acidity. Acetic acid, a common component of chemical poultry litter treatments, has been shown to induce the VBNC state in bacteria associated with pathogenic as well as commensal food bacteria.47
Most of this research has focused on Salmonella, and so it does not provide any
information on the many other potential pathogens in food. While many studies reported a reduction in Salmonella, other studies found a variety of bacteria in samples of poultry litter intended for feed including Escherichia coli. 33,40,22 Martin and Jeffrey did not find Escherichia coli O157:H7 in litter after processing.35 This is not surprising as this strain of pathogenic E. coli is rarely found in poultry. These studies did not sample for other strains of pathogenic E. coli which have been found in poultry and are considered potential zoonoses.48,49 Martin et al. did identify Staphlococcus xylosus in poultry litter intended as cattle feed, but failed to recognize it as a potential pathogen.50 Staphylococcus xylosus is a cause of mastitis in cattle51 and is also a cause of infections in humans.52 Such findings clearly indicate that pathogens may persist in poultry litter despite efforts to eliminate them through processing.
Moreover, the guidelines on processing that are available to producers are confusing,
unmethodical, and frequently contradictory. In the absence of a standardized regulatory structure, a disparate body of guidelines and factsheets published by industry groups, universities, and cooperative extension services has served as the source of best management practices for the use of litter as feed. A considerable number of these documents were developed in the mid-1990s (prior to the emergence of prion diseases in the United States). As such, they do not reflect recent research into litter microbiology nor the recent trends in poultry feeding and litter management (i.e. ammonia reduction treatments).53,54,55 Most guidelines state explicitly that litter should be processed before feeding, but vary widely in their subsequent recommendations for processing methods.
Generally speaking, the available guidelines fail to communicate that poultry litter is a
heterogeneous product whose quality and composition vary according to bedding material, feed, and flock management practices. At least two factsheets advise their readers to select only “quality litter,” but offer no criteria for measuring quality.54,55 Private litter processors seeking this information are unlikely to find help in published research studies, many of which employ expensive technologies such as mechanical aeration. In at least one study of deepstacking efficacy, the method by which the litter sample had been decontaminated was proprietary information and thus not disclosed.56
Without stringent guidelines and vigilant monitoring, there is no assurance of the quality
or microbiological safety of the litter product that is being fed to cattle in the United States today. In fact, there is a report of an outbreak of Salmonella in cattle associated with improper composting.32 When the FDA assessed the costs of a ban on litter as part of controls for BSE, the Agency assumed that there would be additional costs associated with litter storage. However, the Agency ignored the fact that, due to microbiological contamination, all litter must be consistently and effectively processed to reduce potential pathogens.
C. Drugs, residues and the development of antibiotic resistant bacteria
The presence of veterinary drugs and their residues in meat and poultry presents human
health risks. These substances may induce allergic or acute toxic reactions. They may also may disrupt gastrointestinal flora as well as contribute to chronic low-level toxicity. Residues of veterinary ionophores may interact adversely with animal57 and human medications.58
Among the drugs routinely administered via feed to broiler chickens in the United States
are the antibiotics bacitracin, tylosin, bambermycin, lincomycin, virginiamycin, and ionophores narasin and salinomycin.59 In addition to these commonly used antibiotics there are many other veterinary drugs that are used in poultry production either for approved indications or extralabel purposes. There is no publicly available information on the quantity of drugs used in poultry production so it is impossible to accurately characterize the risks this use creates when litter is fed to cattle. It is estimated that, due to their water-soluble nature, 30-90% of veterinary antibiotics are poorly absorbed and excreted whole.60 Modified antibiotic metabolites, also frequently excreted, are often bioactive and can be transformed into the parent compound after excretion.61,62 The FDA regularly maintains maximum residue levels (MRLs) for certain cattle drugs in beef tissue, but the risks associated with accumulated poultry drugs in beef tissue have not been assessed. Title 21 of the Code of Federal Regulations, in which animal drug MRLs are codified, maintains no MRLs for lincomycin, narasin, and salinomycin in cattle tissue.63,64,65
Independent of whether or not a drug is approved for use in cattle, the presence of
antibiotics or antibiotic residues in poultry litter used as feed creates a health risk for cattle. Unexpected drug interactions can cause animal health problems. For example, certain kinds of ionophores can be toxic to cattle. If those ionophores are present in litter fed to cattle, they could combine with the ionophores administered to cattle and create an adverse reaction.66 Ionophore toxicity in poultry litter used as feed has lead to illness and death in cattle.67,68
The last peer-reviewed and published experimental analysis that specifically focused on
veterinary drug residues found in the tissues of beef cattle fed broiler litter was published by Webb and Fontenot in 1975. The study found that litter contained 4 of 5 antibiotics administered to chickens at levels comparable to those found in medicated feeds. It measured tissue concentrations of only one antibiotic, chlortetracycline.69 The use of antimicrobials in poultry has changed since the mid-1970s when this study was completed. It did not look at the antimicrobials commonly used today such as bambermycin, lincomycin, virginiamycin, or ionophores.
In addition to antibiotics and coccidiostats, poultry are often fed the arsenicals arsanilic
acid and roxarsone. Arsenicals are fed to chickens for reasons similar to those associated with non-therapeutic antibiotic use: to grow bigger birds more quickly using less feed. Some arsenicals are also approved for “improved pigmentation” and disease prevention. Currently, three arsenic-containing compounds are approved for use as feed additives in broiler chickens, the most common being roxarsone.70
Arsenic is classified by the U.S. Environmental Protection Agency (EPA) as a Class A
known human carcinogen. It has been linked to elevated risk of liver, bladder, kidney, and lung cancers when ingested. Arsenic ingestion is also associated with mucous membrane damage, eye irritation, darkening and lesions of the skin, liver inflammation and damage, abnormal heart function, hearing loss, peripheral nervous system degeneration, and disruption of the immune system.71
Although an association between human exposure to poultry products and arsenic
toxicity has been acknowledged for some time, the role of poultry litter in toxicity was first shown in 2007. It has been found that Clostridium spp. bacteria in poultry manure are responsible for the conversion of roxarsone into inorganic arsenic, which is toxic. Roxarsone is 3-nitro-4-Hydroxybenzene Arsonic Acid, an additive fed to 70 percent of the nine billion broiler chickens produced annually in the United States.72 This dangerous conversion can begin within 10 days of excretion, but continues throughout the post-cleanout life of stored litter. The mechanism for conversion was elaborated recently by Stolz et al., who write:
The organic-rich manure and anaerobic conditions typically associated with composting provide the conditions necessary for the native microbial populations to transform the roxarsone in the litter releasing the more toxic inorganic arsenic.73
Researchers estimate that up to 75 percent of the more than two million pounds of
roxarsone fed to chickens annually will pass unchanged into their waste.70 The consequences for cattle of inorganic arsenic conversion in their feedstuffs are unknown. Because arsenicals are not approved for use in cattle, the USDA does not routinely screen cattle meat for arsenicals and maximum residue levels have not been set for arsenicals in cattle tissue. Bioaccumulation of arsenic in cattle is likely, but the lack of surveillance by the USDA means the extent of the problem is unknown.
Other research has confirmed that broiler litter contains metals and metalloids. In
addition to arsenic, Kpomblekou et al. found wide variations in the concentrations of other trace and nontrace metals in broiler litter from different facilities in Alabama. They attributed the variation to differences in broiler diet and house maintenance and sanitation practices.74 Bolan et al. report potentially biotoxic levels of arsenic, copper, and zinc in poultry litter produced in South Carolina.75 Cattle may be at increased risk from harmful metals and metalloids found in poultry litter used as feed.iv
In addition to concerns about residues, the use of veterinary drugs in livestock can also
lead to the development of reservoirs of antibiotic resistant bacteria on farms. Overuse in human medicine contributes directly to resistant bacterial infections, but antibiotic use on livestock farms leads to increased resistance in bacteria in farm environments, farm animals, and in food.76,77,78 Antibiotic resistance in foodborne pathogens is linked to increased numbers of infections79 and increased severity of illness.80,81,82 In particular, the large quantities of antibiotics that have been used in poultry production have been shown to negatively affect human health. Research on this topic demonstrates that poultry production is a source of antibiotic resistant bacteria.
The use of antibiotics in poultry has been shown to select for antibiotic resistance that can
be transferred to humans.83 The common use of antibiotics on poultry farms at doses lower than therapeutic levels is particularly problematic. This non-therapeutic use of antibiotics results in greater selection for resistance than drugs used at the use of antibiotics at levels needed for disease treatment.84,85,86,87,88 When transferred to humans, these antibiotic resistant bacteria can iv Copper toxicity can cause liver failure in cattle (http://www.thedairysite.com/diseaseinfo/208/copper-poisoning-in-cattle) and zinc toxicity can lead to decreased appetite in steers (http://jas.fass.org/cgi/content/abstract/25/2/419).
cause serious illness. For example, in 2005 the FDA withdrew approval for the use of fluoroquinolones in poultry because this use contributed to resistance in the foodborne pathogen Campylobacter spp.89 Antibiotic use in hatcheries has also been linked to serious resistant Salmonella infections in humans.90 In addition to causing resistant infections through the transmission of Campylobacter and Salmonella, poultry is a potential source for many other serious resistant pathogens including extra-intestinal pathogenic Escherichia coli,91,92,93 methicillin-resistant Staphylococcus aureus (MRSA),94 and Klebsiella.95
Not surprisingly, poultry litter also contains antibiotic resistant bacteria. These bacteria
are resistant to antibiotics that have a long history of use in animal agriculture as well as those more recently added to the drug arsenal for poultry production. Anywhere between 50 and 90% of Enterococcus isolates found in poultry litter are resistant to commonly used drugs.96,97,98,99 Similarly high levels of resistance have been detected in Salmonella100 and Staphylococcus isolates found in poultry litter and associated farms.98 As would be expected, the majority of the bacterial isolates identified in poultry litter are multidrug resistant.101,22 Through the practice of feeding litter to cattle, resistant bacteria may make their way into cattle, farm environments, and to human populations. Antibiotic resistance bacteria cause serious infections in cattle and humans who consume contaminated beef products.
Because poultry are often fed antibiotic drugs and these drugs are largely secreted in their
manure, poultry litter is in effect a medicated feed article. Unlike medicated feed, the quantities of veterinary drugs present are unknown to the user of the feed. To use litter as feed is therefore contrary to guidelines for judicious use of veterinary drugs and inconsistent with laws that control the use of veterinary medicines in feeds. The associated risk of residues and antimicrobial resistance is high. V. The FDA Has Ample Legal Authority to Declare that Poultry Litter Is a Food Additive and to Ban its Use in Cattle Feed.
The FDA’s animal feed regulations provide, at 21 C.F.R. 570.6(c), that ingredients:
“which have been considered in the past by the Food and Drug Administration to be safe under the provisions of section 402(a)(1) [of the Federal Food, Drug, and Cosmetic Act], or to be generally recognized as safe for their intended use, or to have prior sanction or approval, or not to be food additives under the conditions of intended use, must be reexamined in the light of current scientific information and current principles for evaluating the safety of food additives if their use is to be continued.” (emphasis added)
A. The FDA has the legal authority to regulate poultry litter used as cattle feed even if some of the poultry litter is not sold.
Section 8 of Article I of the United States Constitution gives Congress the power “To
regulate Commerce…among the several States.” Section 301 of the Federal Food, Drug, and Cosmetic Act (“FFDCA”) prohibits “the introduction or delivery for introduction into interstate commerce [or]… the receipt in interstate commerce of any food…that is adulterated or misbranded, and the delivery or proffered delivery thereof for pay or otherwise.”
As discussed above (in section IV.A.5), only a small portion of the poultry litter fed to
cattle is fed to cattle on the same farm as where the litter is produced. Some poultry litter crosses state lines.v It is clear that the Commerce Clause gives Congress the power to have the FDA regulate the use of all poultry litter when some of it is sold in interstate commerce. In Wickard v. Filburn, 317 U.S. 111 (1942), the Supreme Court unanimously held that the Commerce Clause gave Congress the power to penalize a farmer who planted more acreage for wheat than the quota assigned to him under the Agricultural Adjustment Act of 1938 even though the farmer fed part of his wheat to his own poultry and dairy cattle.
In sum, the FDA was correct when it said in 1977 (as discussed above in section III.D.),
that it had jurisdiction over recycled animal waste even if relatively little of it is interstate commerce. 42 Fed. Reg. 64662 (December 27, 1977) a 64670.
B. There is no convincing evidence that poultry litter used as cattle feed is “Generally Recognized As Safe” by scientists, and so it is a food additive within the meaning of section 201(s) of the Federal Food, Drug, and Cosmetic Act.
The regulatory scheme established by the FFDCA divides food ingredients into those that
are “food additives” and those that are not because they are “generally recognized as safe” (“GRAS”). This distinction is important because section 409(a)(2) of the FFDCA provides that the former may be legally used only if the FDA has issued a regulation “prescribing the conditions under which such additive may be safely used.”
Section 201(s) of the FFDCA contains a two-part test for defining when an ingredient is a
food additive: “any substance  the intended use of which results or may reasonably be expected to result, directly or indirectly, in its becoming a component or otherwise affecting the characteristics of any food.[and]  if such substance is not generally recognized, among experts qualified by scientific training and experience to evaluate its safety, as having been adequately shown through scientific procedures (or in the case of a substance used in food prior to January 1, 1958, through either scientific procedures or experience based on common use of food) to be safe under the conditions of its intended use.”
Section 201(u) of the FFDCA says “The term ‘safe,’ as used in paragraph (s).has
reference to the health of man or animal.” The FDA’s animal feed regulations, at 21 C.F.R. 570.3(i), define “safe” and “safety” as meaning “that there is a reasonable certainty in the minds of competent scientists that the substance is not harmful under the intended conditions of use.”
Using poultry litter as cattle feed clearly meets the first part of the section 201(s) test for
a food additive, as the poultry litter affects the characteristics of the cattle feed.
v See, for example, website helping to match buyers and sellers of poultry litter in the neighboring states of Arkansas, Kansas, Missouri, and Oklahoma. www.littermart.com (visited April 6, 2009).
The FDA’s animal feed regulations expand on the second part of this statutory definition
by stating, at 21 C.F.R. 570.30(d), that “A food ingredient of natural biological origin that has been widely consumed for its nutrient properties in the United States prior to January 1, 1958, without any known detrimental effects, which is subject only to conventional processing as practiced prior to January 1, 1958, and for which no known safety hazard exists, will ordinarily be regarded as GRAS.”
There is, of course, no evidence that poultry litter was widely consumed as animal feed
prior to January 1, 1958, and so it could not be considered as GRAS under this regulation. Moreover, as discussed in section III above, the FDA has over the last 40 years repeatedly pointed out the public health risks of poultry litter as animal feed and has refused to say that it is GRAS.
The FDA places the burden of proof on those who assert that an animal feed ingredient,
such as poultry litter, is not a food additive. The FDA’s feed additive regulations provide that the Commissioner, after reviewing the evidence, will revoke the GRAS status of an ingredient “if he concludes that there is a lack of convincing evidence that the substance is GRAS or is otherwise exempt from the definition of a food additive in section 201(s) of the Act. “ 21 C.F.R. 570.38(b)(3). Citing United States v. Article of Food and Drug Consisting of Coli-Trol 80, 518 F.2d 743,745 (5th Cir. 1975), the FDA stated in 1997 that the proponent of an exemption from the definition of a food additive has the burden of proving that the use of the substance is generally recognized as safe. 62 Fed. Reg. 18937 (April 17, 1997) at 18939.
In summary, there is a lack of convincing evidence that chicken litter is GRAS when used
as cattle feed, and thus should be considered a food additive.
C. The FDA can legally ban the use of poultry litter as cattle feed because such use is
Section 409(a)(2) of the FFDCA bars the use of a food additive unless “there is in effect,
and it and its use or intended use are in conformity with, a regulation issued under this section prescribing the conditions under which such additive may be safely used.” Section 409(d) of the FFDCA provides that “The Secretary may at any time, upon his own initiative, propose the issuance of a regulation prescribing, with respect to any particular use of a food additive, the conditions under which such additive may be safely used, and the reasons therefor.” Section 201(u) of the FFDCA says “The term ‘safe,’ as used.in sections 409.has reference to the health of man or animal.”
D. Summary of legal argument
These statutory provisions clearly require the FDA to declare that poultry litter is a food
additive when used as cattle feed because, as discussed in sections III and IV, there is an absence of convincing evidence that such use is generally recognized as safe. Indeed, as discussed in section III.G above, in 2008 the FDA actually acknowledged that there is a “low” risk that such use can lead to vCJD in people.
These statutory provisions also give the FDA the legal authority to ban as unsafe the use
of poultry litter as cattle feed because, as discussed in sections III and IV above, such use can lead to vCJD, antibiotic resistant illnesses, or other diseases in people. VI. Conclusion
For the reasons stated above, the FDA should, pursuant to 21 C.F.R. 570.38(b)(1),
immediately “issue a notice in the FEDERAL REGISTER proposing to determine that [poultry litter] . is not GRAS and is a food additive subject to section 409 of the” FFDCA. VII. Environmental Impact
The action requested is subject to a categorical exclusion under 21 C.F.R. 25.30 and
25.32 and therefore does not require the preparation of an environmental assessment. VIII. Economic Impact
No statement of the economic impact of the requested action is presented because none
has been requested by the Commissioner. 21 C.F.R. 10.30(b). IX. Certification
The undersigned certify that, to the best knowledge and belief of the undersigned, this
petition includes all information and views on which the petition relies, and it includes representative data and information known to the petitioner which are unfavorable to the petition. Respectfully submitted, Richard Wood
Endorsing organizations The following organizations have endorsed FACT’s citizen petition to the FDA requesting that the Agency declare poultry litter a food additive and subsequently ban its use as feed for cattle: Center for Food Safety Center for Science in the Public Interest Consumer Federation of America Consumers Union Food & Water Watch Humane Society of the United States Institute for Agriculture and Trade Policy National Catholic Rural Life Conference National Consumers League National Sustainable Agriculture Coalition Safe Tables Our Priority Union of Concerned Scientists
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TRENDS in Cognitive Sciences Vol.5 No.7 July 2001 Graded representations in behavioral dissociations Yuko Munakata Why do people sometimes seem to know things when they are tested in one a weak representation, but fail another task way, while seeming unaware of this information when tested in a different designed to measure the same knowledge because it way? Such task-dependent behavi