[Federal Register: August 22, 2008 (Volume 73, Number 164)]
[Rules and Regulations]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
DEPARTMENT OF HEALTH AND HUMAN SERVICES
Food and Drug Administration
21 CFR Part 179
[Docket No. FDA-1999-F-2405] (formerly 1999F-5522)
Irradiation in the Production, Processing and Handling of Food
AGENCY: Food and Drug Administration, HHS.
ACTION: Final rule.
SUMMARY: The Food and Drug Administration (FDA) is amending the food
additive regulations to provide for the safe use of ionizing radiation
for control of food-borne pathogens, and extension of shelf-life, in
fresh iceberg lettuce and fresh spinach (hereinafter referred to in
this document as ``iceberg lettuce and spinach'') at a dose up to 4.0
kiloGray (kGy). This action is in partial response to a petition filed
by The National Food Processors Association on behalf of The Food
DATES: This rule is effective August 22, 2008. Submit written or
electronic objections and requests for a hearing by September 22, 2008.
See section VI of this document for information on the filing of
ADDRESSES: You may submit written or electronic objections and requests
for a hearing identified by Docket No. FDA-1999-F-2405] (formerly
1999F-5522, by any of the following methods:
Submit electronic objections in the following way:
Federal eRulemaking Portal: http://frwebgate.access.gpo.gov/cgi-bin/leaving.cgi?from=leavingFR.html&log=linklog&to=http://www.regulations.gov.
Follow the instructions for submitting comments.
Submit written objections in the following ways:
Mail/Hand delivery/Courier [For paper, disk, or CD-ROM
submissions]: Division of Dockets Management (HFA-305), Food and Drug
Administration, 5630 Fishers Lane, rm. 1061, Rockville, MD 20852.
To ensure more timely processing of objections, FDA is no longer
accepting objections submitted to the agency by e-mail. FDA encourages
you to continue
to submit electronic objections by using the Federal eRulemaking
Portal, as described in the Electronic Submissions portion of this
Instructions: All submissions received must include the agency name
and docket number for this rulemaking. All objections received will be
posted without change to http://frwebgate.access.gpo.gov/cgi-bin/leaving.cgi?from=leavingFR.html&log=linklog&to=http://www.regulations.gov, including any
personal information provided. For detailed instructions on submitting
objections, see the ``Objections'' heading of the SUPPLEMENTARY
INFORMATION section of this document.
Docket: For access to the docket to read background documents or
objections received, go to http://frwebgate.access.gpo.gov/cgi-bin/leaving.cgi?from=leavingFR.html&log=linklog&to=http://www.regulations.gov and insert the
docket number(s), found in brackets in the heading of this document,
into the ``Search'' box and follow the prompts and/or go to the
Division of Dockets Management, 5630 Fishers Lane, rm. 1061, Rockville,
FOR FURTHER INFORMATION CONTACT: Lane A. Highbarger, Center for Food
Safety and Applied Nutrition (HFS-255), Food and Drug Administration,
5100 Paint Branch Pkwy., College Park, MD 20740, 301-436-1204.
Table of Contents
II. Safety Evaluation
A. Radiation Chemistry
B. Toxicological Considerations
C. Nutritional Considerations
D. Microbiological Considerations
B. List of Foods Covered by the Petition
C. Toxicity Data
D. Hardy Pathogens
E. Effects on Organoleptic (Sensory) Properties
V. Environmental Impact
In a notice published in the Federal Register of January 5, 2000
(65 FR 493), and amended May 10, 2001 (66 FR 23943), FDA announced that
a food additive petition (FAP 9M4697) had been filed by The National
Food Processors Association on behalf of The Food Irradiation
Coalition, 1350 I St. NW., suite 300, Washington, DC 20005. The
petition proposed that the food additive regulations in part 179,
Irradiation in the Production, Processing, and Handling of Food (21 CFR
part 179), be amended to provide for the safe use of ionizing radiation
for control of food-borne pathogens, and extension of shelf-life, in a
variety of human foods up to a maximum irradiation dosage of 4.5 kGy
for non-frozen and non-dry products, and 10.0 kGy for frozen or dry
products, including: (1) Pre-processed meat and poultry; (2) both raw
and pre-processed vegetables, fruits, and other agricultural products
of plant origin; (3) certain multi-ingredient food products containing
cooked or uncooked meat or poultry. Subsequently, in a letter dated
December 4, 2007, the petitioner amended the petition to request a
response to part of the original request while the remainder of the
request would remain under review. Specifically, the petitioner
requested a response regarding amending the food additive regulations
to provide for the safe use of ionizing radiation for control of food-
borne pathogens, and extension of shelf-life, in iceberg lettuce and
spinach up to a maximum dose of 4.0 kGy. This final rule is a partial
response to the petition and addresses only the use of ionizing
radiation on iceberg lettuce and spinach. The use of ionizing radiation
on the remaining foods included in the petition remains under review.
II. Safety Evaluation
Under section 201(s) of the Federal Food, Drug, and Cosmetic Act
(the act) (21 U.S.C. 321(s)), a source of radiation used to treat food
is defined as a food additive. The additive is not added to food
literally, but is rather a source of radiation used to process or treat
food such that, analogous to other food processing technologies, its
use can affect the characteristics of the food. Importantly, the
statute does not prescribe the safety tests to be performed but leaves
that determination to the discretion and scientific expertise of FDA.
Not all food additives require the same amount or type of testing. The
testing and data required to establish the safety of an additive will
vary depending on the particular additive and its intended use.
In evaluating the safety of a source of radiation to treat food
intended for human consumption, the agency must identify the various
effects that may result from irradiating the food and assess whether
any of these effects pose a public health concern. In doing so, the
following three general areas need to be addressed: (1) Potential
toxicity, (2) nutritional adequacy, and (3) effects on the
microbiological profile of the treated food. Each of these areas is
discussed in this document. Because an understanding of radiation
chemistry is fundamental in addressing these three areas, key aspects
of radiation chemistry relevant to the evaluation of the request that
is the subject of this rulemaking are also discussed. FDA has fully
considered the data and studies submitted in the petition as well as
other data and information relevant to safety.
A. Radiation Chemistry
The term ``radiation chemistry'' refers to the chemical reactions
that occur as a result of the absorption of ionizing radiation. In the
context of food irradiation, the reactants are the chemical
constituents of the food and initial radiolysis products that may
undergo further chemical reactions. The chemistry involved in the
irradiation of foods has been the subject of numerous studies over the
years and scientists have compiled a large body of data regarding the
effects of ionizing radiation on different foods under various
conditions of irradiation. The basic principles are well understood
(Refs. 1 to 4) and provide the basis for extrapolation and
generalization from data obtained in specific foods irradiated under
specific conditions to draw conclusions regarding foods of a similar
type irradiated under different, yet related, conditions. The types and
amounts of products generated by radiation-induced chemical reactions
(``radiolysis products'') depend on both the chemical constituents of
the food and on the specific conditions of irradiation. The principles
of radiation chemistry also govern the extent of change, if any, in
both the nutrient levels and the microbial loads of irradiated foods.
In the next section, FDA will discuss important aspects of
radiation chemistry and related topics as they apply specifically to
iceberg lettuce, spinach, and foods of similar composition.
1. Factors Affecting the Radiation Chemistry of Foods
Apart from the chemical composition of the food itself, the
specific conditions of irradiation that are most important in
considering the radiation chemistry of a given food include the
radiation dose, the physical state of the food (e.g., solid or frozen
versus liquid or nonfrozen state, dried versus hydrated state), and the
ambient atmosphere (e.g., air, reduced oxygen, and vacuum).\1\
\1\ The temperature at which irradiation is conducted can also
be a factor, with more radiation-induced changes occuring with
increasing temperature. Temperature is less important, however, than
the physical state of the food.
The amounts of radiolysis products generated in a particular food
are directly proportional to the radiation dose. Therefore, one can
extrapolate from data obtained at high radiation
doses to draw conclusions regarding the effects at lower doses.
The radiation chemistry of food is strongly influenced by the
physical state of the food. If all other conditions, including dose and
ambient atmosphere, are the same, the extent of chemical change that
occurs in a particular food in the frozen state is less than the change
that occurs in the non-frozen state. This is because of the reduced
mobility, in the frozen state, of the initial radiolysis products,
which will tend to recombine rather than diffuse and react with other
food components. Likewise, and for similar reasons, if all other
conditions are the same, the extent of chemical change that occurs in
the dehydrated state is less than the change that occurs in the fully
The formation of radiolysis products in a given food also is
affected by the ambient atmosphere. Irradiation in an atmosphere of
high oxygen content generally produces both a greater variety, and
greater amounts, of radiolysis products in the food than would be
produced in an atmosphere of lower oxygen content. This is because
irradiation initiates certain oxidation reactions that occur with
greater frequency in foods with high fat content (Refs. 1 and 5).
With few exceptions, the radiolysis products generated in a
particular food are the same or very similar to the products formed in
other types of food processing or under common storage conditions.
These radiolysis products are also typically formed in very small
amounts (Ref. 1).
Radiation-induced chemical changes, if sufficiently large, however,
may cause changes in the organoleptic properties of the food. Because
food processors want to avoid undesirable effects on taste, odor,
color, or texture, there is an incentive to minimize the extent of
these chemical changes in food. Thus, the doses used to achieve a given
technical effect (e.g., inhibition of sprouting, reduction in
microorganisms) must be selected carefully to both achieve the intended
effect and minimize undesirable chemical changes. Typically, the dose
or dose range selected will be the lowest dose practical in achieving
the desired effect. Irradiation also is often conducted under reduced
oxygen levels or on food held at low temperature or in the frozen
2. Radiation Chemistry of the Major Components of Iceberg Lettuce and
The major components of iceberg lettuce and spinach, as with most
fruits and vegetables, are water (approximately 91 to 96 percent) and
carbohydrate (up to approximately 4 percent), with protein also present
as a minor component. The lipid content of both iceberg lettuce and
spinach is quite low (less than 0.5 percent) (Ref. 6).
Because of the high water content of iceberg lettuce and spinach,
their radiation chemistry is dominated by the radiation chemistry of
water, in which reactive hydroxyl and hydrogen radicals are the primary
radiolysis products. These radicals are most likely to recombine to
form water, hydrogen gas, or hydrogen peroxide; they may, however, also
react with other components of iceberg lettuce and spinach (e.g.,
carbohydrates). While most of the chemical effects of radiation-
processing on iceberg lettuce and spinach are expected to result from
the reactions induced by hydroxyl and hydrogen radicals, other food
components (e.g., carbohydrates, proteins, and lipids) may also absorb
radiation directly and generate small amounts of other radiolysis
a. Carbohydrates. Carbohydrates are molecules composed of sugar
units, which are grouped and categorized according to their size. The
simplest and smallest are the monosaccharides (simple sugars such as
glucose) and disaccharides (such as sucrose). Larger complex
carbohydrates (pectin, fiber, and starch) consist of chains of
monosaccharide units and are referred to as polysaccharides. The main
effects of ionizing radiation on carbohydrates in foods have been
studied extensively and discussed at length in the scientific
literature (Refs. 7 and 8), as well as in reviews by such bodies as the
World Health Organization (WHO) (Ref. 9). In the presence of water,
carbohydrates react primarily with the hydroxyl radicals generated by
the radiolysis of water. The result is abstraction of hydrogen from the
carbon-hydrogen bonds of the carbohydrate, forming water and a
carbohydrate radical. Direct ionization of carbohydrates to form
carbohydrate radicals also is possible, but occurs to a far lesser
extent (Refs. 10, 11, and 12).
In polysaccharides, the links between constituent monosaccharide
units may be broken, resulting in the shortening of polysaccharide
chains. Starch may be degraded into dextrins, maltose, and glucose.
Sugar acids, ketones, aldehydes, and other sugar monosaccharides may
also be formed as a result of ionizing radiation. Various studies have
reported that radiolysis products formed from starches of different
origin are qualitatively similar. The nature and concentration of the
main radiation-induced products showed no marked differences among the
various starches. In addition, 40 different products have been analyzed
in irradiated starches and have been found to be produced by heat
treatment or natural oxidation of starch during storage, as well as by
irradiation (Refs. 8 and 10).
The overall effects of ionizing radiation on carbohydrates are
basically the same as those caused by cooking and other food processing
treatments (Refs. 1 and 10). Irradiation of carbohydrates at doses up
to 10 kGy has minimal effect on the carbohydrate functionality and the
resulting products are smaller carbohydrates or other compounds also
produced from carbohydrates through oxidation and/or heat treatment.
FDA concludes that no significant change in carbohydrate nutrient value
or functionality is expected to occur in iceberg lettuce and spinach
irradiated at doses up to 4 kGy.
b. Proteins. FDA has previously provided detailed discussions of
the radiation chemistry of proteins in its rulemakings on the use of
ionizing radiation to treat meat and molluscan shellfish (``the meat
rule,'' 62 FR 64107; December 3, 1997, and ``the molluscan shellfish
rule,'' 70 FR 48057; August 16, 2005, respectively). Studies conducted
with high-protein foods (e.g., meat, poultry, and seafood), have
established that most of the radiolysis products derived from food
proteins have the same amino acid composition and are altered only in
their secondary and tertiary structures (i.e., denatured). These
changes are similar to those that occur as a result of heating, but in
the case of irradiation, even at doses up to 50 kGy, such changes are
far less pronounced and the amounts of reaction products generated are
far lower (62 FR 64107; Refs. 10 and 13). FDA concludes that there will
be few reaction products generated from the small amounts of protein in
iceberg lettuce and spinach and that no significant change in the amino
acid composition of these two foods is expected to result from
irradiation at doses up to 4.0 kGy.
c. Lipids. FDA also has previously provided a detailed discussion
of the radiation chemistry of lipids in the meat and molluscan
shellfish rules. In summary, a variety of radiolysis products derived
from lipids have been identified, including fatty acids, esters,
aldehydes, ketones, alkanes, alkenes, and other hydrocarbons (Refs. 1
and 14). Identical or analogous compounds are also found in foods that
have not been irradiated. In particular, heating food produces
generally the same types of compounds, but in amounts far greater
than the trace amounts produced from irradiating food (Refs. 10 and
There is, however, a class of radiolysis products derived from
lipids, 2-alkylcyclobutanones (2-ACBs), that has been reported to form
in small quantities when fats are exposed to ionizing radiation, but
not when they are exposed to heat or other forms of processing. The
specific 2-ACBs formed will depend on the fatty acid composition of the
food. For example, 2-dodecylcyclobutanone (2-DCB) is a radiation by-
product of tryiglycerides with esterified palmitic acid. Researchers
have reported that 2-DCB is formed in small amounts (less than 1
microgram per gram lipid per kGy ([mu]g/g lipid/kGy) from irradiated
chicken (Ref. 16) and in even smaller amounts from ground beef (Ref.
17). Both of these foods are of relatively high total fat and palmitic
\2\ Beef is generally composed of approximately 15 to 25 percent
fat, depending on the cut. Chicken, depending on the cut and whether
skin is included, is approximately 5 to 19 percent fat. The palmitic
acid content of the fat in beef and chicken is in the range of 22 to
25 percent (Ref. 6)
In the molluscan shellfish rule, the agency provided a detailed
discussion of its assessment of the significance of the formation of 2-
DCB to the safety evaluation of irradiated molluscan shellfish, a food
which, like chicken and ground beef, contains significant amounts of
triglycerides with esterified palmitic acid. In that assessment, FDA
considered all of the available data and information, including the
results of genotoxicity studies and previously reviewed studies in
which animals were fed diets containing irradiated meat, poultry, and
fish. All of these foods contain appreciable amounts of lipids that
contain triglycerides with palmitic acid. While 2-DCB and other
alkylcyclobutanones would be expected to be present in these irradiated
foods, FDA found no evidence of toxicity attributable to their
As noted previously in this document, iceberg lettuce and spinach
contain little fat (less than 0.5 percent); neither food contains
appreciable amounts of palmitic acid.\3\ Because of the low lipid
content and the very low palmitic acid content of iceberg lettuce and
spinach, FDA concludes that formation of alkylcyclobutanones generally,
and 2-DCB specifically, from irradiation of these foods would be in
amounts much smaller than those formed from irradiation of foods of
higher fat content and would not pose a toxicological concern.
\3\ Iceberg lettuce contains approximately 0.016 percent
palmitic acid, and spinach contains approximately 0.046 percent
palmitic acid (Ref.6)
Overall, FDA concludes that no significant differences are expected
to occur between the kinds and amounts of lipids and lipid byproducts
in non-irradiated iceberg lettuce and spinach compared to iceberg
lettuce and spinach irradiated at doses of 4.0 kGy.
3. Consideration of Furan as a Radiolysis Product
During the course of reviewing the chemical effects of irradiation
as part of the evaluation of this and other petitions, FDA became aware
of a report that suggested irradiating apple juice may produce furan
(Ref. 18). Because furan has been shown to cause tumors in laboratory
animals, FDA initiated research on whether the report was accurate and
whether furan was a common radiolysis product in food. The petitioner
also conducted testing and the United States Department of Agriculture
(USDA) initiated additional research. FDA has confirmed that certain
foods form furan in low quantities when irradiated. Studies conducted
by FDA scientists and other researchers show that some foods form furan
when heated and still other foods form furan during storage at
refrigeration temperatures (Refs. 19 and 20). Testing of irradiated
lettuce and spinach show that if furan is formed when these foods are
irradiated, it is formed at levels that are below the limit of
detection in the tests, or below the background levels of natural furan
formation during storage (Refs. 19, 21, and 22). Therefore, FDA
concludes that the consumption of irradiated iceberg lettuce and
spinach will not increase the amount of furan in the diet.
B. Toxicological Considerations
The available information from the results of chemical reactions
described in section II.A of this document suggests that there is no
reason to suspect a toxicological hazard due to consumption of an
irradiated food. While chemical analyses have not identified the
presence of radiolysis products in amounts that would raise a
toxicological concern, the agency notes that the large body of data
from studies where irradiated foods were fed to laboratory animals
provides an independent way to assess toxicological safety. These
studies include those relied on by the agency in previous evaluations
of the safety of irradiated foods (see 70 FR 48057, 65 FR 45280, 62 FR
64107, 55 FR 18538, and 51 FR 13376) and additional data and
information in FDA files or other published reports regarding studies
in which animals were fed a wide variety of foods irradiated at
The agency's analysis incorporates the principles that
toxicological data collected from studies on a given food may be
applied to the toxicological evaluation of foods of similar generic
class and that data from foods irradiated at high doses can be applied
to the toxicological evaluation of foods of similar generic class
receiving lower doses (62 FR 64107; Ref. 10). The agency's analysis
also draws upon the integrated toxicological database derived from the
extensive body of work reviewed by the agency (Ref. 23) and by the
WHO\4\ in previous evaluations of the safety of irradiated foods. Thus,
the agency has re-examined the available data from toxicological
studies that are particularly relevant to the safety of irradiated
iceberg lettuce and spinach, specifically fruits and vegetables which,
as a group, are relatively carbohydrate-rich foods of high water
content. The agency's analysis also takes into account the known
effects of other conditions of irradiation to compare the results of
\4\ During the early 1980s, a joint Food and Agriculture
Organization/International Atomic Energy Agency, World Health
Organization (FAO/IAEA/WHO) Expert Committee evaluated the
toxicological and microbiological safety and nutritional adequacy of
irradiated foods. The Expert Committee concluded that irradiation of
any food commodity at an average dose of up to 10 kGy presents no
toxicological hazard (Ref. 24). In the 1990s, at the request of one
of its member states, WHO conducted a new review and analysis of the
safety data on irradiated food. This more recent WHO review included
all the studies in FDA's files that the agency considered as
reasonably complete, as well as those studies that appeared to be
acceptable but had deficiencies interfering with the interpretation
of the data (see 51 FR 13376 at 13378). The WHO review also included
data from USDA and from the Federal Research Centre for Nutrition at
Karlsruhe, Germany. WHO concluded that the integrated toxicological
database is sufficiently sensitive to evaluate safety and that no
adverse toxicological effects due to irradiation were observed in
the dose ranges tested (Ref. 9).
FDA has evaluated a large number of studies in which various
irradiated fruits or vegetables,\5\ alone or in combination with other
irradiated foods, were fed to animals (Refs. 25 and 26). These studies
were conducted in a variety of animal species, with foods irradiated at
doses ranging from 0.15 to 50 kGy. In the vast majority of these
studies, no adverse effects were reported. Three studies reported
observations that merit further discussion. FDA has concluded that the
effects reported in these three studies were either not attributable to
irradiation or were otherwise not of toxicological significance.
\5\ The irradiated fruits and vegetables in these studies
included: Peaches, strawberries, bananas, cherries, prunes,
potatoes, carrots, onions, black beans, corn, green beans, and
In the first study, dogs fed a diet containing 10 percent onions
(dry weight basis, irradiated at 0.25 kGy) for 90 days were reported to
develop anemia, as did control dogs fed nonirradiated onions (Ref. 27).
Other effects such as increased spleen weights, myeloid metaplasia, and
reticuloendothelial hyperplasia were reported but, again, in both
control and treated dogs. FDA has concluded that the effects cannot be
attributed to irradiation because similar effects were reported in both
dogs fed irradiated onions and dogs fed non-irradiated onions (Ref.
The second study was a multi-generation reproduction study in which
rats were fed a diet containing 35 percent oranges (dry weight basis)
(Ref. 28). Animals in the control group were fed non-irradiated
oranges; animals in the treated groups were fed oranges irradiated at
1.40 or 2.79 kGy. The authors reported decreased reproductive
performance in the second breeding, as measured by several
parameters,\6\ for rats fed irradiated oranges as well as those fed the
control diet. Because the effects were observed in both animals fed
irradiated food and animals fed non-irradiated food, FDA has concluded
that they cannot be attributed to irradiation (Refs. 25 and 26). The
authors also reported a small, but statistically significant difference
in one additional parameter of reproductive performance in treated
animals, body weight of pups at weaning. The pups made up for the
weight depression after weaning. FDA has concluded that this reported
effect is not of toxicological significance for the following two
reasons: (1) It was a very small difference in the overall poor
reproductive performance of all animals in the second breeding, and (2)
the pups from the treated groups made up for the slight weight
depression after weaning. In another segment of this study, the authors
reported a small, but statistically significant reduction in body
weight gain for third generation animals in the treated groups (but not
the parent or second generation animals). FDA has concluded that this
effect is not of toxicological significance for the following two
reasons: (1) There was no apparent dose response,\7\ and (2) the
differences in body weights were within the normal range of variation
for feeding studies (Ref. 26).
\6\ Incidence of female sterility (percent), established
fertility of males (percent), incidence of still births per litter,
and pups born alive reaching weaning age (percent).
\7\ The effect was more pronounced in rats fed oranges
irradiated at the lower of the two test doses, the opposite of what
one would expect if the effect were related to irradiation.
In a third study (Ref. 29), weanling rats fed a mixture of cabbage
irradiated at 6 kGy and chicken stew irradiated at 56 kGy for 19 days
were reported to have reduced levels of alkaline phosphatase in
duodenal tissue. In its evaluation of the safety of irradiated meat,
FDA reviewed this study in detail and concluded that the effect
observed was not of toxicological significance (62 FR 64107 at 64113).
In summary, FDA has reviewed a large body of data relevant to the
assessment of potential toxicity of irradiated fruits and vegetables.
While all of the studies are not of equal quality or rigor, the agency
has concluded that the quantity and breadth of testing and the number
and significance of endpoints assessed would have identified any real
or meaningful risk. The overwhelming majority of studies showed no
evidence of toxicity. On those few occasions when adverse effects were
reported, FDA finds that those effects cannot be attributed to
irradiation. Based on the totality of the evidence, FDA concludes that
irradiation of iceberg lettuce and spinach under the conditions
proposed in this petition does not present a toxicological hazard.
C. Nutritional Considerations
It is well known that the nutritive values of the macronutrients in
the diet (protein, fats, and carbohydrates) are not significantly
altered by irradiation at the petitioned doses (Refs. 30, 31, and 32).
Minerals (e.g., calcium and iron) are also unaffected by irradiation.
Levels of certain vitamins, on the other hand, may be reduced as a
result of irradiation. The extent to which this reduction occurs
depends on the specific vitamin, the type of food, and the conditions
of irradiation. Not all vitamin loss is nutritionally significant,
however, and the extent to which a reduction in a specific vitamin
level is significant depends on the relative contribution of the food
in question to the total dietary intake of the vitamin.
Nutrition-related information relevant to fruits and vegetables
submitted in the petition included analyses of consumption data for
these broad categories and of vitamin levels in specific irradiated
foods from these categories. The petitioner's overall analysis focused
on the the following vitamins the petitioner identified as being
present in relatively high levels in fruits and vegetables generally:
Thiamine; folate; and vitamins C, E, and A (the latter as provitamin
carotenoids). Most of the studies with irradiated fruits or vegetables
submitted in the petition focused on the levels of vitamin C or
provitamin A carotenoids (sometimes also referred to as carotenes),
because fruits and vegetables, as a combined category, are good sources
of these micronutrients. Some studies of the effects of irradiation on
the levels of vitamin E and on folate were also submitted.
FDA has carefully reviewed the data and information submitted in
the petition, as well as other data and information in its files, to
determine whether irradiation of iceberg lettuce and spinach would have
an adverse effect on the nutritional quality of the diet. FDA's
evaluation focused on the effects of irradiation on those nutrients for
which at least one of these foods may be identified as an ``excellent
source''\8\ and for which they contribute more than a trivial amount to
the total dietary intake (i.e., greater than 1 to 2 percent)\9\:
Vitamin A (from beta-carotene, a provitamin A carotenoid), vitamin K,
and folate. FDA's evaluation has also considered the relative radiation
sensitivities of these vitamins.
\8\ In accordance with 21 CFR 101.54(b), foods containing
[gteqt] 20 percent of the Reference Daily Intake (RDI) or Daily
Reference Value (DRV) per reference amount customarily consumed
(RACC), the amount of food customarily consumed per eating occasion
such as in one meal or snack) may be labeled as ``excellent source
of'', ``high in'' or ``rich in'' a given nutrient. By this
criterion, spinach is an excellent source of vitamins A, C, K, and
folate. Iceberg lettuce is an excellent source of vitamin K only.
\9\ Although spinach contains relatively high amounts of vitamin
C, its contribution to the total dietary intake of this vitamin is
negligible. The combined group of spinach and ``greens'' (e.g.,
kale, chard, chives) contributes less than 2 percent to the total
dietary intake of vitamin C; the contribution of iceberg lettuce is
essentially zero (Ref. 33).
Many fruits and vegetables are good sources of vitamin A (including
provitamin A carotenoids). Spinach is considered an excellent source of
vitamin A based on its relatively high content of the provitamin A
carotenoid beta-carotene. Nevertheless, it contributes no more than 3.5
percent to the total U.S. dietary intake of vitamin A\10\ (Refs. 33, 34
\10\ The primary food sources of vitamin A (including provitamin
A carotenoids) in the U.S. diet are carrots, organ meats, dairy
products, eggs, and ready-to-eat cereals. Together, these food
sources contribute approximately 60 percent of the total dietary
intake of vitamin A (expressed in retinol equivalents).
Although vitamin A has been identified as one of the most
radiation-sensitive of the fat-soluble vitamins, carotenoids in plant
products demonstrate fairly high resistance to the effects of
irradiation. One study of carrots irradiated at 2 kGy reported that
carotenoids were stable to irradiation
and that total carotenoid content of irradiated carrots did not differ
from controls through 16 days of storage (Ref. 36). In another study,
carotenoid losses in mangoes and papayas irradiated at doses up to 2
kGy were reported to be negligible (0 to 15 percent) while considerable
losses resulted from freezing or canning with various additives (Ref.
37). In other studies, minor carotenoid losses in broccoli irradiated
at doses of 2 and 3 kGy were observed relative to controls on the day
of treatment only, while no marked effects on total carotenoid content
of irradiated samples were observed at days 4, 9, and 14 of storage
(Ref. 38), and irradiation at doses up to 1 kGy did not affect the
total carotenoid content of spinach stored under refrigeration for 15
days (Ref. 39). In several studies, other processing or storage
parameters were reported to affect the proportions of individual
carotenoids more strongly than irradiation treatment (Ref. 31). FDA
concludes that the small losses of vitamin A that might result from the
proposed irradiation of iceberg lettuce or spinach will have little
impact on the total dietary intake of this vitamin.
Spinach and iceberg lettuce contribute approximately 12 percent and
8 percent, respectively, to the dietary intake of vitamin K (Ref. 40).
Vitamin K is widely distributed in other plant and animal foods,
however, and deficiencies of vitamin K in humans are extremely rare\11\
\11\ Other green vegetables such as broccoli, collards, salad
greens, and kale contain substantial amounts of vitamin K. Other
foods that also contribute to vitamin K intake include: Vegetable
oils, grains, liver, cheese, and eggs.
Vitamin K has also been identified as one of the least radiation
sensitive of the fat-soluble vitamins (Ref. 41). In one study, which
examined the effects of irradiation, freezing, and canning on vitamin K
activity in spinach, along with other vegetables, there was no
appreciable radiation-induced loss in Vitamin K activity at doses as
high as 28 or 56 kGy, doses much higher than the maximum dose requested
in this petition (Ref. 42). FDA concludes that irradiation of iceberg
lettuce and spinach up to a maximum dose of 4.0 kGy will have no impact
on the total dietary intake of vitamin K (Ref. 33).
Spinach is an excellent source of folate.\12\ Nevertheless, in the
context of the total diet, spinach contributes only a little more than
2 percent of the total dietary intake of folate (Refs. 33 and 34).\13\
Studies that examined radiation-induced losses of folic acid in
dehydrated asparagus irradiated to 5 kGy or dehydrated spinach
irradiated at 10 kGy found no loss of folate as measured by
compositional analysis or in a bioavailability assay in rats (Ref. 43).
Another recent study that examined the effects of irradiation of fresh
vegetables at 2.5 kGy, reported folate losses of approximately 10
percent in fresh spinach, green cabbage, and Brussels sprouts (Ref.
44). The folate losses observed in this study are comparable to or less
than the folate losses that have been reported for vegetables following
various heat treatments (Refs. 45 and 46). FDA concludes that
radiation-induced loss of folate in iceberg lettuce or spinach will
have no significant impact on the dietary intake.
\12\ One RACC of raw spinach (85 grams (g) can contain 41
percent of the RDA for folate. One RACC of iceberg lettuce, however,
contains only about 6 percent of the RDA for folate; iceberg lettuce
is not considered a good source of this vitamin. (Ref. 6)
\13\ Enriched and fortified foods (e.g., cereal grains and
grain-based products) make the greatest contribution to folate in
In summary, based on the available data and information, FDA
concludes that amending the regulations, as set forth below, to allow
for the use of ionizing radiation to treat iceberg lettuce and spinach
up to a maximum dose of 4 kGy will not have an adverse impact on the
nutritional adequacy of the overall diet.
D. Microbiological Considerations
Leafy green vegetables such as iceberg lettuce or spinach can serve
as an ideal habitat for the growth of various microorganisms. Among the
common, naturally-occurring microflora of vegetables, Pseudomonas,
Enterobacter, and Erwinia species predominate. Various molds and yeasts
may also be found on leafy green vegetables. Pathogens, which may also
be present in the agricultural environment, can contaminate fresh
produce that is grown, harvested, and in some cases undergoes
preliminary processing (e.g., cutting or trimming) in that environment.
Iceberg lettuce and spinach are often consumed raw and after only
minimal preparation (e.g., rinsing) and, therefore, lack the final
microbial elimination step provided for other foods by cooking.
Contamination of fresh produce with several specific pathogens
continues to be a public health problem. Infections from Salmonella
enterica serovars and Escherichia coli O157:H7, for example, have not
decreased since 1996. Most of the recent serious outbreaks of illness
attributed to consuming lettuce or spinach have resulted from
contamination by E. coli O157:H7. Three notable outbreaks involving
this microorganism occurred in 2006; one of these was associated with
bagged fresh spinach, the other two with lettuce used in fast food
restaurants. Contamination of leafy greens with Listeria monocytogenes
or Salmonella serovars also continues to be a public health problem.
Even though other pathogens may be present, the three microorganisms
named here are those that have been most commonly associated with
recent outbreaks from the consumption of raw spinach or lettuce (Ref.
Data and information relevant to microbiological considerations
presented in the petition included published studies of radiation-
induced reductions in levels of different microorganisms in a variety
of fruits and vegetables under different conditions of irradiation.
Some of these studies also investigated the use of irradiation in
combination with other antimicrobial treatments. FDA has evaluated the
information in the petition, along with other data and information in
its files and in the published literature in assessing the
microbiological issues presented by the petitioner.
There is a large body of work regarding the radiation sensitivities
of non-pathogenic food spoilage microorganisms and pathogenic foodborne
microorganisms. Generally, the common spoilage organisms such as
Pseudomonas and the important pathogens in or on leafy greens are quite
sensitive to the effects of ionizing radiation. Information in the
petition and other information in FDA files shows that E. coli O157:H7
is highly sensitive to ionizing radiation, with published
D10 values\14\ ranging from 0.12 to 0.32 kGy, depending on
the specific food matrix, physical state of the food, temperature, and
other factors. Control of contaminating Salmonella serovars or Listeria
spp. generally requires higher doses than for E. coli O157:H7. This is
shown by the higher D10 values which are in the range of
0.16 to 0.65 kGy, again, depending on the specific food, physical
state, temperature, and other factors (Refs. 48 to 51).
\14\ D10 is the absorbed dose of radiation required
to reduce a bacterial population by 90 percent.
Several recent studies have focused on the effects of ionizing
radiation on pathogen levels in lettuce and spinach, specifically. In a
series of studies by one group of researchers, the average
D10 values for E coli O157:H7 and L. monocytogenes were
reported to be 0.1 kGy and 0.2 kGy, respectively and the D10
value for Salmonella reported to be ca. 0.25-0.3, depending on the
type (Refs. 52 and 53). In another study, treatment with ionizing
radiation at a dose of 1.5 kGy produced a 4-log10 reduction
in colony-forming units (CFU) on romaine lettuce and a 3-
log10 reduction in CFU on baby spinach leaves (Ref. 54).
Another recent study examined the effects of irradiation on bagged,
ready-to-eat spinach leaves inoculated with E. coli O157:H7 and found
that, for single leaves, doses as low as 0.9 kGy resulted in a 5- to 6-
log10 reduction in the levels of this pathogen, while a dose
of 1.2 kGy resulted in its reduction below the limits of detection of
the test (Ref. 39). Collectively, these studies, together with earlier
work, establish that levels of E. coli O157:H7, L. monocytogenes, and
Salmonella serovars in or on iceberg lettuce or spinach will be reduced
by irradiation at dose levels of 0.1 to 1.5 kGy, with the largest
reductions occurring at the higher dose levels.
Still other studies have examined the effects of irradiation on
extension of shelf life and sensory attributes of various types of
vegetables, including iceberg lettuce and spinach. In one study, the
authors reported a reduction in total aerobic bacterial counts of over
2-log10 CFU per gram (CFU/g) in fresh-cut lettuce irradiated
at 1.0 kGy and over 3-log10 CFU/g reductions at 1.5 kGy
(Ref. 55). In a separate study, the same researchers found similar
results on total aerobic bacterial counts and significant reductions in
coliform counts on fresh-cut lettuce when irradiated with similar
doses. In this particular study, the authors also followed numbers of
viable bacteria for 9 days storage, noting that for irradiated samples,
relative microbial reductions persisted while total numbers of bacteria
increased by about 2-log10. Over the same storage period,
coliforms remained below the level of detection in irradiated samples
(Ref. 56). Recent studies by other researchers have examined the
effects of irradiation on levels of pathogens and sensory attributes of
fresh-cut iceberg lettuce, including studies in modified atmosphere
packaging. One of these studies demonstrated deterioration in several
sensory attributes (e.g., firmness, color) when iceberg lettuce is
irradiated at levels of 3 or 4 kGy (Ref. 57). Additional related
studies on iceberg lettuce and other vegetables by the same group of
researchers indicate irradiation above 1.5 or 2 kGy (depending on the
specific vegetable) can negatively affect sensory properties (Refs. 58
and 59). Taken together, the studies described above indicate that
irradiation in the expected practical dose range will reduce, but not
entirely eliminate, spoilage microorganisms.
In evaluating the subject petition, FDA has carefully considered
whether irradiation of iceberg lettuce and spinach under the conditions
proposed in the petition could result in significantly altered
microbial growth patterns such that these foods would present a greater
microbiological hazard than comparable food that had not been
irradiated. In considering this question, FDA has focused on whether
the proposed irradiation conditions would increase the probability of
significantly increased growth of, and subsequent toxin production by,
Clostridium botulinum because this organism is relatively resistant to
radiation as compared to non-spore-forming bacteria. FDA has concluded
that the possibility of increased microbiological risk from C.
botulinum is extremely remote because: (1) The conditions of
refrigerated storage necessary to maintain the quality of iceberg
lettuce or spinach are not amenable to the outgrowth and production of
toxin by C. botulinum and, (2) sufficient numbers of spoilage organisms
will survive such that spoilage will occur before outgrowth and toxin
production by C. botulinum (Refs. 48 and 60).
Based on the available data and information, FDA concludes that
irradiation of iceberg lettuce and spinach conducted in accordance with
good manufacturing practices will reduce or eliminate bacterial
populations with no increased microbial risk from pathogens that may
survive the irradiation process.
FDA has received numerous comments, primarily form letters, from
individuals that state their opinions regarding the potential dangers
and unacceptability of irradiating food. FDA has also received several
comments from individuals or organizations that state their opinions
regarding the potential benefits of irradiating food and urging FDA to
approve the petition. None of these letters contain any substantive
information that can be used in a safety evaluation of irradiated
iceberg lettuce and spinach.
Additionally, FDA received several comments from Public Citizen
(PC) and the Center for Food Safety (CFS) requesting the denial of this
and other food irradiation petitions. Overall, the comments were of a
general nature and not necessarily specific to the requests in the
individual petitions. Many of these comments from PC and CFS were also
submitted to the docket for the agency rulemaking on irradiation of
molluscan shellfish (Docket No. 1999F-4372, FAP 9M4682). The topics
raised in these comments included the following: Studies reviewed in
the 1999 FAO/IAEA/WHO report on high-dose irradiation; a review article
that analyzed studies of irradiated foods performed in the 1950's and
1960's; the findings of a 1971 study in which rats were fed irradiated
strawberries; the findings regarding reproductive performance in a 1954
study in which mice were fed a special irradiated diet; issues
regarding mutagenicity studies; certain international opinions; issues
related to ACBs, including purported promotion of colon cancer; the
findings of certain studies conducted by the Indian Institute of
Nutrition in the 1970's; general issues regarding toxicity data; FDA's
purported failure to meet statutory requirements; data from a 2002
study purportedly showing an irradiation-induced increase in trans
fatty acids in ground beef; studies regarding purported elevated
hemoglobin levels and their significance; and an affidavit describing
the opinions of a scientist regarding the dangers of irradiation and
advocating the use of alternative methods for reducing the risk of
foodborne disease. For a detailed discussion of the agency's response
to the above general comments, the reader is referred to the molluscan
shellfish rule (70 FR 48057 at 48062-48071). Because these comments do
not raise issues specific to irradiated iceberg lettuce or spinach and
because the agency has already responded to these comments in detail,
they will not be addressed further here.
FDA also received two letters from PC and CFS that were submitted
only to the docket for this rulemaking (Docket No. FDA-1999-F-2405
(formerly Docket No. 1999F-5522), FAP 9M4697). Many of the issues
raised in these letters were also raised in comments submitted by PC
and CFS to the docket for the agency rulemaking on irradiation of
molluscan shellfish. Other issues raised in these letters were specific
to the request in FAP 9M4697; these particular comments were not
responded to in the molluscan shellfish rule. Below, the agency
responds to the specific comments raised in these two letters from PC
and CFS that were not addressed in the molluscan shellfish rule.
The agency also received an additional letter from Food and Water
Watch (formerly PC) and CFS after the rule for the irradiation of
molluscan shellfish published. The comments in this letter are also
During the evaluation of this petition and several others
requesting various applications of irradiation, the agency received
several comments on issues related to 2-ACBs. The agency has previously
addressed most of these comments in the molluscan shellfish rule (70 FR
48057 at 48062-48071), and that discussion will not be repeated here.
However, after the publication of the molluscan shellfish rule, the
agency received an additional comment on 2-ACBs. This comment included
a report that contained data on 2-ACBs present in irradiated turkey,
hotdogs, and papayas.
As noted in section II. A of this document, 2-ACBs are formed in
small quantities when fats are exposed to ionizing radiation. Of the
three foods examined in the study submitted with the comment, only
papayas are from the same generic class as iceberg lettuce and spinach.
(Turkey and hotdogs are foods high in protein and fat that have little
in common with leafy greens.) The report presents data indicating that
2-ACB concentrations in papaya flesh are indistinguishable from zero.
There is no additional information in the paper other than
concentrations of various alkylcyclobutanones in the three foods
As previously noted in this document and in the molluscan shellfish
rule, FDA has reviewed studies in which animals were fed diets
containing irradiated foods of high fat content (meat, poultry, and
fish). The agency concluded that no adverse effects were associated
with the consumption of these high fat foods. Iceberg lettuce and
spinach contain far less fat than meat, poultry, fish or molluscan
shellfish. As previously noted in section II.B of this document, FDA
has reviewed studies in which animals were fed diets containing
irradiated fruits and vegetables. No adverse effects were associated
with consumption of these food types. The comment provides no
additional information that would alter the agency's conclusion that
the consumption of irradiated iceberg lettuce and spinach does not
present a health hazard.
B. List of Foods Covered by the Petition
One comment stated that ``FDA has no definitive list of foods that
are covered by the petition,'' citing a personal communication of March
19, 2001. The comment goes on to state that ``[a] Federal Register
filing of May 10, 2001, pertaining to the [above-referenced] petition
establishes that the FDA [sic] no understanding as to which specific
foods are covered by the petition.''
FDA disagrees with this comment. The Federal Register document of
May 10, 2001, corrected an inadvertent exclusion of certain foods from
the scope of the original filing notice. FDA also notes that a listing
of each and every food covered by a food additive petition has never
been required and is not necessary. The agency frequently evaluates
food additive petitions intended to cover broad categories of food
types. Further, this partial response authorizing irradiation of
iceberg lettuce and spinach up to a maximum dose of 4.0 kGy addresses
two specific foods, rendering the issue moot.
C. Toxicity Data
One comment states that the petition should be denied because
``[t]he petitioner submitted no toxicology data on any of the products
that are ostensibly covered by the petition.''
FDA acknowledges that the petitioner did not submit new
toxicological data specific to the foods in the petition. The
petitioner made extensive reference to studies considered in earlier
evaluations of the toxicological safety of irradiated foods by FDA,
WHO, and others. As noted earlier, FDA has reviewed a large body of
data relevant to the assessment of the potential toxicity of irradiated
foods, including irradiated fruits and vegetables. There was no reason
to submit additional copies of studies that had previously been
reviewed by the agency.
One comment states that the petition should be denied ``because the
validity of three of the studies referenced by the petitioner was
questioned by the FDA's Irradiated Foods Task Group (IFTG) in 1982.''
The comment lists three studies, one of which ``was labeled `reject' by
the IFTG'' and two of which were ``labeled `accept with reservation' by
FDA does not disagree that the IFTG had questions regarding these
three studies. FDA does not agree, however, that these 1982 findings by
the IFTG provide a basis to deny the petition or the partial request
that is the subject of this rulemaking. FDA has not relied on studies
that were rejected by the IFTG in assessing the safety of irradiated
iceberg lettuce and spinach or any other irradiated food. Some studies
were accepted with reservation by the agency scientists on the IFTG
because they did not meet modern standards in all respects;
specifically, they may have used fewer animals, or examined fewer
tissues than is common today. Nevertheless, these studies still provide
important information that, when evaluated collectively, supports the
conclusion that consumption of iceberg lettuce and spinach irradiated
under the conditions proposed in this petition is safe. As noted
earlier, FDA has reviewed a large body of data relevant to the
assessment of the potential toxicity of irradiated fruits and
vegetables, and to an assessment of the potential toxicity of
irradiated iceberg lettuce and spinach specifically. The comment
provides no basis to challenge FDA's conclusion that iceberg lettuce
and spinach irradiated under the conditions set forth in the
regulations in this document are safe.
Another comment stated that the petitioner claimed that a fourth
study, conducted by Renner et al. (Ref. 61) ``provided [no] evidence of
toxicity induced by irradiation.'' The comment took issue with the
petitioner's characterization of this study, stating ``[t]he study
found, however, `significant' effects on DNA synthesis and `significant
loss of body weight' among rodents that ate irradiated food compared to
that that ate non-irradiated food.''
The Renner et al. study consisted of six in vivo genetic toxicity
tests that were carried out in several different animal species with
irradiated or non-irradiated cooked chicken, dried dates, and cooked
fish. FDA has previously evaluated the results of these tests and does
not agree with comment's characterization of the study findings, which
appear to be presented out of context.
In the Renner et al. study, the authors concluded that ``[n]one of
the tests provided any evidence of genetic toxicity induced by
irradiation.'' Further, the authors did not attribute a ``significant
loss of body weight'' to consumption of irradiated food, but stated,
rather, that ``[t]he nutritional effects of exposing Chinese hamsters
for 7 days to a diet consisting entirely of dried dates were evidenced
by a significant reduction in food intake and, consequently, a
significant loss of body weight.'' The effect was observed in both
animals fed non-irradiated dates and animals fed irradiated dates. The
authors also reported various effects on DNA synthesis resulting from
feeding Chinese hamsters diets consisting entirely of dried dates or
cooked chicken, irradiated or not. Thus, the authors concluded that
these effects were also not attributable to irradiation. Further, the
authors state that ``In only one case in the nine tests described in
this report and in two previous papers* * *was an effect seen that
could be attributed to an irradiated foodstuff. This was with
irradiated fish in the DNA metabolism test.'' The authors concluded
that the specific
effect observed with irradiated fish in the DNA metabolism test was not
an indication of genotoxic activity, but rather, that it ``* *
*provided evidence for absence of genotoxic potential in fish so
processed.'' The comment provides no basis to conclude that the studies
and information reviewed by the agency and discussed previously in this
document are not adequate to assess the safety of irradiated iceberg
lettuce and spinach.
D. Hardy Pathogens
One comment submitted a copy of a newsletter published by the Food
Safety Consortium. The comment stated that ``when irradiation is
applied to meat in commercial plants, the pathogens present have
evolved to survive the irradiation better, thus the irradiation does
not achieve the levels of de-contamination that are predicted, and
advertised, by the meat irradiation industry based on the lab
studies.'' The article in the newsletter states that pathogens in a
food processing plant are generally more resistant to stressful
conditions than laboratory grown bacteria.
The comment provides no data that can be used in a safety
assessment of irradiated food in general or irradiated iceberg lettuce
and spinach, specifically. FDA also believes that the comment
incorrectly characterizes the science behind the article in the
newsletter. Scientists understand that bacteria grown under stressful
conditions (e.g., high acidity, elevated temperatures) can manifest
resistance to treatments that would be lethal to the same type of
bacteria grown under less stressful conditions. Thus, any bacteria
grown in nutrient-rich media under optimal conditions in the laboratory
may be somewhat less resistant to any given treatment, including
irradiation, than the same bacteria grown in nutrient-poor or other
harsh conditions in a non-optimal environment.
FDA also notes that under the regulations set forth in Sec.
179.25, radiation treatment of food must conform to a scheduled
process, which is a written procedure to ensure that the radiation dose
range selected by the food irradiation processor is adequate under
commercial processing conditions (including atmosphere and temperature)
for the radiation to achieve its intended effect on a specific product
and in a specific facility.\15\ The regulations further require that
the scheduled process be established by qualified persons having expert
knowledge in radiation processing requirements of food and specific for
that food and for the facility in which it is to be irradiated.
\15\ Food irradiation processors are also subject to FDA's
regulation requiring Current Good Manufacturing Practice in
Manufacturing, Packing, or Holding Human Food (CGMP) (21 CFR part
110) and other applicable regulations regarding proper food handling
and storage conditions.
E. Effects on Organoleptic (Sensory) Properties
One comment argued that the petition should be denied because of
``organoleptic damage'' that raises ``serious concerns about the
general wholesomeness of irradiated foods.''
The agency acknowledges that organoleptic changes can occur in
irradiated foods. However, this comment provides no information that
would establish a link between organoleptic changes in, and the safety
of, irradiated foods. Consideration of organoleptic changes, in and of
themselves, is beyond the scope of this rulemaking.
Based on the data and studies submitted in the petition and other
information in the agency's files, FDA concludes that the proposed use
of irradiation to treat iceberg lettuce and spinach with absorbed doses
that will not exceed 4.0 kGy is safe, and therefore, the regulations in
Sec. 179.26 should be amended as set forth below in this document. In
accordance with Sec. 171.1(h) (21 CFR 171.1(h)), the petition and the
documents that FDA considered and relied upon in reaching its decision
to approve the use of irradiation on iceberg lettuce and spinach in a
partial response to the petition will be made available for inspection
at the Center for Food Safety and Applied Nutrition by appointment with
the information contact person (see FOR FURTHER INFORMATION CONTACT).
As provided in Sec. 171.1(h), the agency will delete from the
documents any materials that are not available for public disclosure
before making the documents available for inspection.
This final rule contains no collections of information. Therefore,
clearance by the Office of Management and Budget under the Paperwork
Reduction Act of 1995 is not required.
V. Environmental Impact
The agency has carefully considered the potential environmental
effects of this action. The agency has determined under 21 CFR 25.32(j)
that this action is of a type that does not individually or
cumulatively have a significant effect on the human environment.
Therefore, neither an environmental assessment nor an environmental
impact statement is required.
Any person who will be adversely affected by this regulation may
file with the Division of Dockets Management (see ADDRESSES) written or
electronic objections. Each objection shall be separately numbered, and
each numbered objection shall specify with particularity the provisions
of the regulation to which objection is made and the grounds for the
objection. Each numbered objection on which a hearing is requested
shall specifically so state. Failure to request a hearing for any
particular objection shall constitute a waiver of the right to a
hearing on that objection. Each numbered objection for which a hearing
is requested shall include a detailed description and analysis of the
specific factual information intended to be presented in support of the
objection in the event that a hearing is held. Failure to include such
a description and analysis for any particular objection shall
constitute a waiver of the right to a hearing on the objection. Three
copies of all documents are to be submitted and are to be identified
with the docket number found in brackets in the heading of this
document. Any objections received in response to the regulation may be
seen in the Division of Dockets Management between 9 a.m. and 4 p.m.,
Monday through Friday.
The following sources are referred to in this document. References
marked with an asterisk (*) have been placed on display at the Division
of Dockets Management (address above) and may be seen by interested
persons between 9 a.m. and 4 p.m., Monday through Friday. References
without asterisks are not on display; they are available as published
articles and books.
*1. Diehl, J.F., ``Chemical Effects of Ionizing Radiation,'' pp.
43-88, in Safety of Irradiated Foods, 2d Ed., Marcel Dekker, Inc.,
New York, 1995.
2. Elias, P.S. and A.J. Cohen, Recent Advances in Food
Irradiation, Elsevier Biomedical, Amsterdam, 1983.
*3. WHO, ``High-Dose Irradiation: Wholesomeness of Food
Irradiated With Doses Above 10kGy,'' World Health Organization
Technical Report Series, No. 890, Geneva, pp. 9-37, 1999.
4. Josephson, E.S. and M.S. Peterson, eds., Preservation of Food
by Ionizing Radiation, vol. II, CRC Press, Boca Raton, FL, 1982.
5. Diehl, J.F., ``Radiolytic Effects in Foods,'' pp. 279-357, in
Preservation of Foods By Ionizing Radiation, vol. I, E.S. Josephson
and M.S. Peterson, eds., CRC Press, Boca Raton, FL,1982.
6. U.S. Department of Agriculture, Agricultural Research
Service, USDA National Nutrient Database for Standard Reference,
Release 20, Nutrient Data Laboratory Home Page, http://frwebgate.access.gpo.gov/cgi-bin/leaving.cgi?from=leavingFR.html&log=linklog&to=http://www.ars.usda.gov/nutrientdata, 2007.
*7. Adam, S., ``Recent Developments in Radiation Chemistry of
Carbohydrates,'' pp. 149-170, in Recent Advances in Food
Irradiation, P.S. Elias and A.J. Cohen, eds., Elsevier Biomedical,
*8. Raffi, J., J.P. Agnel, C. Thiery, C. Frejaville, L. Saint-
Lebe, ``Study of Gamma Irradiated Starches Derived form Different
Foodstuffs: A Way for Extrapolating Wholesomeness Data,'' Journal of
Agricultural and Food Chemistry, 29:1227-1232, 1981.
9. Safety and Nutritional Adequacy of Irradiated Food, World
Health Organization, Geneva, 1994.
*10. Memorandum for FAP 9M4697 from K. Morehouse, FDA, to L.
Highbarger, FDA, dated August 10, 2001.
*11. Raffi, J. and J.P. Agnel, ``Influence of Physical Structure
of Irradiated Starches on their ESR Spectra Kinetics,'' Journal of
Physical Chemistry, 87:2369-2373, 1983.
*12. Thiery, J.M., J.P. Theiry, P. Angel, P. Vincent, C.
Battesti, J. Raffi, and J.C. Evans, ``Electron Spin Resonance Study
of Spin-Trapped Radicals from Gamma Irradiation of Glucose
Oligomers,'' Magnetic Resonance In Chemistry, 28:594-600, 1990.
*13. Merritt, C. and I.A. Taub, ``Commonality and Predictability
of Radiolytic Products in Irradiated Meats,'' pp. 27-58, in Recent
Advances in Food Irradiation, P.S. Elias and A.J. Cohen, eds.,
Elsevier Biomedical, Amsterdam, 1983.
*14. Nawar, W.W., ``Volatiles from Food Irradiation,'' Food
Reviews International, 2:45-78, 1986.
*15. Nawar, W.W., ``Comparison of Chemical Consequences of Heat
and Irradiation Treatment of Lipids,'' pp. 115-127, in Recent
Advances in Food Irradiation, P. S. Elias and A. J. Cohen, eds.,
Elsevier Biomedical, Amsterdam, 1983.
*16. Crone, A.V.J., J.T.G. Hamilton, and M.H. Stevenson,
``Effect of Storage and Cooking on the Dose Response of 2-
Dodecylcyclobutanone, a Potential Marker for Irradiated Chicken,''
Journal of the Science of Food and Agriculture, 58:249-252, 1992.
*17. Gadgil, P., K.A. Hachmeister, J.S. Smith, and D.H. Kropf,
``2-Alkylcyclobutanones as Irradiation Dose Indicators in Irradiated
Ground Beef Patties,'' Journal of Agriculture and Food Chemistry,
*18. Seibersdorf Project Report, International Programme on
Irradiation of Fruit and Fruit Juices, Chemistry and Isotopes
Department, National Centre for Nuclear Energy, Madrid, Spain,
*19. Memorandum for FAP 9M4697 from K. Morehouse, FDA, to L.
Highbarger, FDA, dated February 20, 2008.
*20. Locas, C., and V.A. Yaylayan, ``Origin and Mechanistic
Pathways of Formation of the Parent Furan-a Toxicant,'' Journal of
Agricultural and Food Chemistry, 52:6830-6836, 2005.
*21. Fan, X., and K.J.B. Sokorai, ``Effect of Ionizing Radiation
on Furan Formation in Fresh-Cut Fruits and Vegetables,'' Journal of
Food Science. 73(2): C79-C83, 2008.
*22. Letter from petitioner for 9M4697 dated 7/23/2007.
*23. Memorandum to the file for FAP 4M4428, from D. Hattan, FDA,
dated November 20, 1997.
24. WHO, ``Wholesomeness of Irradiated Food: Report of a Joint
FAO/IAEA/WHO Expert Committee,'' World Health Organization Technical
Report Series, No. 659, World Health Organization, Geneva, 1981.
*25. Memorandum for 9M4697 from I. Chen, FDA, to L. Highbarger,
FDA, dated December 21, 2001.
*26. Memorandum to the file for 9M4697 from I. Chen, FDA, and P.
Hansen, FDA, dated June 20, 2008.
*27. Gabriel, K.L., and R.S. Edmonds, ``To Study the Effects of
Radurized Onions When Fed to Beagle Dogs,'' Food Irradiation
Information, Food and Agriculture Organization/International Atomic
Energy Agency, 6 (Suppl.)118, 1976.
*28. Phillips, A. W., et al., ``Long-Term Rat Feeding Studies:
Irradiated Oranges,'' Final Contract Report, Army Contract Report
No. DA-49-007-MD-783, 1961.
*29. Phillips, A.W., et al., ``Long-term Rat Feeding Studies:
Irradiated Chicken Stew and Cabbage,'' Final Contract Report, Army
Contract Report No. DA-49-007-MD-783, 1961.
*30. Underdal, B., J. Nordal, G. Lunde, and B. Eggum, ``The
Effect of Ionizing Radiation on the Nutritional Value of Fish (Cod)
Protein,'' Lebensmittel-Wissenschaft Technologie, 6:90-93, 1973.
*31. Diehl, J.F., ``Nutritional Adequacy of Irradiated Foods,''
pp. 241-282, in Safety of Irradiated Foods, Marcel Dekker, New York,
*32. Josephson, E.S. and M. H. Thomas, ``Nutritional Aspects of
Food Irradiation: An Overview,'' Journal of Food Processing and
Preservation, 2:299-313, 1978.
*33. Memorandum for 9M4697 from A. Edwards, FDA, to L.
Highbarger, FDA, dated July 16, 2008.
*34. Cotton, P.A., A.F. Subar, J.E. Friday, and A. Cook,
``Dietary Sources of Nutrients Among US Adults,'' Journal of the
American Dietetic Association, 104: 921-930, 2004.
35. Institute of Medicine; Dietary Reference Intakes for vitamin
A, vitamin K, arsenic, boron, chromium, copper, iodine, iron,
manganese, molybdenum, nickel, silicon, vanadium, and zinc; National
Academies Press, Washington, DC, 2001.
*36. Hajare, S.N., V.S. Dhokane, R. Shashidhar, S. Saroj, A.
Sharma, and J.R. Bandekar, ``Radiation Processing of Minimally
Processed Carrot (Daucus carota) and Cucumber (Cucumis sativus) to
Ensure Safety: Effect on Nutritional and Sensory Quality,'' Journal
of Food Science, 71(3):S198-203, 2006.
*37. Beyers, M., and A.C. Thomas, ``Gamma-Irradiation of
Subtropical Fruits, 4. Changes in Certain Nutrients Present in
Mangoes, Papayas, and Litchis During Canning, Freezing, and Gamma-
Irradiation,'' Journal of Agricultural and Food Chemistry,27(1):48-
38. Gomes, C. D., P. Da Silva, E. Chimbombi, J. Kim, E. Castell-
Perez, and R.G. Moreira, ``Electron-Beam Irradiation of Fresh
Broccoli Heads (Brassica oleracea L. italica),'' Lebensmittel-
Wissenschaft Technologie, in press, 2008.
*39. Gomes, C.D., R.G. Moreira, E. Castell-Perez, J. Kim, P. Da
Silva., and A. Castillo, ``E-Beam Irradiation of Bagged, Ready-To-
Eat Spinach Leaves (Spinacea oleracea): an Engineering Approach,''
Journal of Food Science, 73(2):E95-102, 2008.
*40. Booth, S.L., J.A.T. Pennington, and J.A. Sadowski, ``Food
Sources and Dietary Intakes of Vitamin K-1 (Phylloquinone) in the
American Diet: Data from the FDA Total Diet Study,''Journal of the
American Dietetic Association, 96:149-154, 1996.
*41. Knapp, F.W. and A.L. Tappel, ``Comparison of the
Radiosensitivities of the Fat-Soluble Vitamins by Gamma
Irradiation,'' Journal of Agricultural and Food Chemistry, 9:430-
*42. Richardson, R.L., S. Wilkes, and S.J. Ritchey,
``Comparative Vitamin K Activity of Frozen, Irradiated, and Heat-
Processed Food,'' Journal of Nutrition, 73: 369-373, 1961.
*43. Pfeiffer, C., J.F. Diehl, and W. Schwack, ``Effect of
Irradiation on Folate Levels and of Bioavailability of Folates in
Dehydrated Foodstuffs,'' Acta Alimentaria, 23:105-118, 1994.
*44. Muller H., and J.F. Diehl, ``Effect of Ionizing Radiation
on Folates in Food,'' Lebensmittel-Wissenschaft Technologie, 29(1-
*45. Stea, T.H., M. Johansson, M. J[auml]gerstad, W.
Fr[oslash]lich, ``Retention of Folates in Cooked, Stored and
Reheated Peas, Broccoli and Potatoes for Use in Modern Large-Scale
Service Systems,'' Food Chemistry, 101(3):1095-1107, 2007.
*46. Melse-Boonstra, A., P. Verhoef, E.J.M. Konings, M. Van
Dusseldorp, A. Matser, P.C.H. Hollman, S. Meyboom, F.J. Kok, C.E.
West, ``Influence of Processing on Total, Monoglutamate and
Polyglutamate Folate Contents of Leeks, Cauliflower, and Green
Beans,'' Journal of Agricultural and Food Chemistry, 50:3473-8,
*47. Centers for Disease Control, ``Preliminary FoodNet Data on
the Incidence of Infection with Pathogens Transmitted Commonly
Through Food -- 10 States, 2006,'' Morbidity and Mortality Weekly
Report, 56, 336-339. 2007.
*48. Memorandum for 9M4697 from R. Merker, FDA, to Lane
Highbarger, FDA, dated June 11, 2008
*49. Niemira, B. A. and X. Fan, ``Low-Dose Irradiation of Fresh
and Fresh-Cut Produce: Safety, Sensory, and Shelf Life,'' pp. 169-
184, in Food Irradiation Research and Technology, C.H. Sommers, and
X. Fan, eds., IFT Press, Chicago, 2006.
*50. Prakash, A. and D. Foley, ``Improving Safety and Extending
Shelf Life* * *'' pp. 90-106, in Irradiation of Food and Packaging
-- Recent Developments, American Chemical Society, Washington, DC,
*51. Monk, J.D., L.R. Beuchat, and M.P. Doyle, ``Irradiation
Inactivation of Food-Borne Microorganisms,'' Journal of Food
Protection, 58(2):197-208, 1995.
*52. Niemira, B.A., C.H. Sommers, and X. Fan, ``Suspending
Lettuce Type Influences Recoverability and Radiation Sensitivity of
Escherichia coli O157:H7,'' Journal of Food Protection, 65:1388-
*53. Niemira, B.A., ``Radiation Sensitivity and Recoverability
of Listeria monocytogenes and Salmonella on 4 Lettuce Types,''
Journal of Food Science, 68: 2784-2787, 2003.
*54. Niemira, B.A., ``Relative Efficacy of Sodium Hypochlorite
Wash Versus Irradiation to Inactivate Escherichia coli O157:H7
Internalized in Leaves of Romaine Lettuce and Baby Spinach,''
Journal of Food Protection, 70:2526-2532, 2007.
*55. Zhang, L., Z. Lu, and H. Wang, ``Effect of Gamma
Irradiation on Microbial Growth and Sensory Quality of Fresh-Cut
Lettuce,'' International Journal of Food Microbiology, 106:348-351,
*56. Zhang, L., Z. Lu, F. Lu, and X. Bie, ``Effect of Gamma
Irradiation on Quality Maintaining of Fresh-Cut Lettuce,'' Food
Control, 17:225-228, 2006.
*57. Fan, X. and K.J. Sokorai, ``Sensorial and Chemical Quality
of Gamma-Irradiated Fresh-Cut Iceberg Lettuce in Modified Atmosphere
Packages,'' Journal of Food Protection, 65:1760-1765, 2002.
*58. Fan, X. and K.J. Sokorai, ``Assessment of Radiation
Sensitivity of Fresh-Cut Vegetables Using Electrolyte Leakage
Measurement,'' Postharvest Biology and Technology, 36:191-197, 2005.
*59. Fan, X., B.A. Niemira, and K.J. Sokorai, ``Use of Ionizing
Radiation to Improve Sensory and Microbial Quality of Fresh-cut
Green Onion Leaves,'' Journal of Food Science, 68:1478-1483, 2003.
*60. Petran, R.L., W.H. Sperber, and A.B. Davis, ''Clostridium
botulinum Toxin Formation in Romaine Lettuce and Shredded Cabbage:
Effect of Storage and Packaging Conditions,'' Journal of Food
Protection, 58, 624-627, 1995.
*61. Renner, H. W., U. Graf, F.E. Wurgler, H. Altmann, J.C.
Asquith, and P.S. Elias, ``An Investigation of the Genetic
Toxicology of Irradiated Foodstuffs Using Short-Term Test Systems,
III--in vivo Tests in Small Rodents and in Drosophila melangaster,''
Food Chemistry and Toxicology, 30:867-878, 1982.
List of Subjects in 21 CFR Part 179
Food additives, Food labeling, Food packaging, Radiation
protection, Reporting and record keeping requirements, Signs and
Therefore, under the Federal Food, Drug, and Cosmetic Act and under
authority delegated to the Commissioner of Food and Drugs, 21 CFR part
179 is amended as follows:
PART 179--IRRADIATION IN THE PRODUCTION, PROCESSING AND HANDLING OF
1. The authority citation for 21 CFR part 179 continues to read as
Authority: 21 U.S.C. 321, 342, 343, 348, 373, 374.
2. Section 179.26 is amended in the table in paragraph (b) by adding a
new item ``12.'' under the headings ``Use'' and ``Limitations'' to read
Sec. 179.26 Ionizing radiation for the treatment of food.
* * * * *
(b) * * *
* * * * * * *
12. For control of food-borne Not to exceed 4.0 kGy.
pathogens and extension of shelf-
life in fresh iceberg lettuce and
* * * * *
Dated: August 19, 2008.
Associate Commissioner for Policy and Planning.
[FR Doc. E8-19573 Filed 8-21-08; 8:45 am]
BILLING CODE 4160-01-S