Source: https://www.federalregister.gov/articles/2008/08/22/E8-19573/irradiation-in-the-production-processing-and-handling-of-food
Timestamp: 2015-05-24 15:18:03
Document Index: 92278014

Matched Legal Cases: ['§ 179', '§ 179', '§ 171', '§ 171', '§ 179', 'art 110']

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 objections.
-49603 (11 pages)
Document Number: E8-19573
Shorter URL: https://federalregister.gov/a/E8-19573 Regulations.gov Docket Info
Use of Ionizing Radiation for the Control of Food-Borne Pathogens and Infectious Protozoa, and Extension of Shelf-Life, in a Variety of Human Foods.
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 paragraph.
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).
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.
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 15).
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 (μg/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 acid content.
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 consumption.
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.
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.
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
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 different studies.
FDA has evaluated a large number of studies in which various irradiated fruits or vegetables,
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.
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,
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,
and (2) the differences in body weights were within the normal range of variation for feeding studies (Ref. 26).
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”
and for which they contribute more than a trivial amount to the total dietary intake (i.e., greater than 1 to 2 percent)
: 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.
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
(Refs. 33, 34 and 35).
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
(Ref. 33).
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).
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.
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 D 10 values
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 D 10 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).
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 D 10 values for E coli O157:H7 and L. monocytogenes were reported to be 0.1 kGy and 0.2 kGy, respectively and the D 10 value for Salmonella reported to be ca. 0.25-0.3, depending on the lettuce type (Refs. 52 and 53). In another study, treatment with ionizing radiation at a dose of 1.5 kGy produced a 4-log 10 reduction in colony-forming units (CFU) on romaine lettuce and a 3-log 10 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-log 10 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-log 10 CFU per gram (CFU/g) in fresh-cut lettuce irradiated at 1.0 kGy and over 3-log 10 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-log 10. 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.
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.”
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.
FDA also notes that under the regulations set forth in § 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.
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.
IV. Conclusions Back to Top
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 § 179.26 should be amended as set forth below in this document. In accordance with § 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 § 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.
6. U.S. Department of Agriculture, Agricultural Research Service, USDA National Nutrient Database for Standard Reference, Release 20, Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/nutrientdata, 2007.
*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.
*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.
*14. Nawar, W.W., “Volatiles from Food Irradiation,”Food Reviews International, 2:45-78, 1986.
*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, 50:5746-5750, 2002.
*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.
*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.
*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.
*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.
*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.
*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):48-51, 1979.
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.
*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, 9:430-433, 1961.
*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(1-2):187-190, 1996.
*45. Stea, T.H., M. Johansson, M. Jägerstad, W. Frølich, “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, 2002.
*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.
*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, 65:1388-1393, 2002.
*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, 2006.
*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.
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*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.
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 as follows: § 179.26 Ionizing radiation for the treatment of food.
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.
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)
3. Iceberg lettuce contains approximately 0.016 percent palmitic acid, and spinach contains approximately 0.046 percent palmitic acid (Ref.6)
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).
5. The irradiated fruits and vegetables in these studies included: Peaches, strawberries, bananas, cherries, prunes, potatoes, carrots, onions, black beans, corn, green beans, and cabbage.
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.
8. In accordance with 21 CFR 101.54(b), foods containing ≥ 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).
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).
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.
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 the diet.
14. D 10 is the absorbed dose of radiation required to reduce a bacterial population by 90 percent.
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.