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Reproduction and longevity of rats fed an irradiated potato diet
Toxicology Letters, 3 (1979) 163-168 o Elsevier/North-Holland Biomedical Press
REPRODUCTION POTATO DIET*
163
AND LONGEVITY
OF RATS FED AN IRRADIATED
A.K. PALMER, D.D. COZENS, D.E. PRENTICE, D. H. CHRISTOPHER Huntingdon
Research Centre, Huntingdon,
J.C. RICHARDSON and
Cambridgeshire PE18 6ES (England)
and H.M. GOTTSCHALK and P.S. ELIAS International Project in the Field Food Irradiation, Karlsruhe (F.R.G.) (Received December 19th, 1978) (Accepted December 2&h, 1973)
SUMMARY
In a series of studies the reproduction and longevity of rats fed irradiated potatoes was investigated. Three groups of 30 male and 60 female rats were fed either standard diet or diets containing 35% peeled, cooked potatoes either non-irradiated or irradiated with a dose of 0.12 kGy.** Fertility and general reproductive performance was studied over 6 cycles after which the surviving parent animals were sacrificed at 2 years of age. Chromosomal analysis, dominant lethal assay and teratological examinations were made. No significant effects attributable to treatment were observed on growth, food intake, organ weights, histopathology, fertility and reproduction. No adverse effects on spermatogenesis (dominant lethal test) or on the incidence of germinal chromosomal aberrations were noted.
INTRODUCTION
Much work has been carried out on the use of irradiation to inhibit sprouting in potatoes and to determine the wholesomeness of the irradiated product. In 1969 a Joint FAO/IAEA/WHO Expert Committee [l] recommended temporary acceptance of potatoes irradiated with doses not exceeding 0.15 kGy and specified certain studies later carried out by the International Project in the Field of Food Irradiation (IFIP). On the basis of these further investigations (this paper and ref. 2) and other data [3,4] the 1976 Joint Expert *This investigation was commissioned by the International Project in the Field of Food Irradiation (IFIP), Federal Research Centre for Nutrition, Postfach 3640, 7500 Karlsruhe (FRG). **l rad = 10m2gray (Gy).
164
Committee [ 51 recommended unconditional acceptance of potatoes irradiated with a maximum dose not exceeding 0.15 kGy. The results of a longevity and reproduction study in rats fed an irradiated diet are summarised here. The detailed results are described in the final report [6] submitted to IFIP. MATERIALS
AND METHODS
In preliminary p~atability studies and the main experiment potatoes of the Majestic variety, obtained from the Soil Research Association, Suffolk, England, and the Palogan variety, obtained through the Council for Nuclear Energy, Madrid, were used. They received no chemical treatment of any kind. Due to unexpected early sprouting of the latter variety, locally obtained King Edward potatoes were used for weeks 31-40 of the study. ~rradia~iu~ and diet preparu~~u~ Approximately half the potatoes were exposed to between 0.085 and 0.15 kGy gamma radiation from the Cobalt-60 irradiation facility of Irradiated Products Ltd., Swindon, Wiltshire, England. The irradiated and unirradiated potatoes were peeled, steamed and incorporated at about 35% (dry weight) with supplementary nutrients to form a balanced diet. The dough was dried and the resulting biscuit ground and fed as a coarse powder.
SPF rats (CD strain) obtained from the Charles River Breeding Laboratories, Mass., U.S.A. were used. The rats were maintained in controlled environmental conditions (21”C+l”C; 50+5% relative humidity) and allowed free access to tap water and food throughout. Experimental design Three groups of 70 male and 70 female rats (F. generation) were fed either Spratts Laboratory Diet No. 2, non-irradiated potato diet or irradiated potato diet for 30 days. The rats were then paired (20 days) on a one male to one female basis. After birth, at day 21 post partum, one male pup from each of 30 litters and one female pup from each of 60 litters were selected to form the F, generation experimental colony. Reproductive studies F, animals were housed 4 to a cage and maint~ned on their respective diets for 11 weeks and then mated, 1 male to 2 females, for 10 days. 1 week after weaning of the FZa litters the F1 parents were mated again with different partners. The second and subsequent matings up to a total of 6 were made 7 days after weaning of each successive litter. During mating, females were weighed on alternate days and then on days 0, 7,14 and 20 of gestation and, with the exception of the second mating, on days 0, 7,14 and 21 post par-turn; males were weighed weekly. Pregnant females were housed individually_ After
165
birth, all young were counted, examined for external abnormalities and weighed at 0,4, 12 and 21 days post partum. Pups were sacrificed at day 21 and examined externally and internally for abnormalities. Litter size, litter and mean pup weight, and pup mortality were assessed. Teratology studies Fz,, pups were examined grossly as soon after parturition as possible. Half the offspring in each litter were examined for soft tissue and half for skeletal malformations by hand sectioning or alizarin staining, respectively. In a repeat teratology study three groups of 30 female rats were fed a diet containing either 35% peeled, cooked non-irradiated potato or 35% peeled, cooked potato irradiated with 0.12 kGy or 0.50 kGy. Animals were introduced to the potato diets in increasing increments of 20% from day 2 of pregnancy, and from day 6 to 20 received potato diet exclusively. On day 20 the rats were killed and ovaries and uterine contents examined to determine numbers of corpora lutea, viable young and resorption sites, litter weight, and incidence of foetal abnormalities. Dominant lethal assay and chromosomal morphology 10 males of Fzc litters were fed the test diets and at 15 weeks of age were each mated with different sets of 3 untreated females on 4 consecutive weeks. Approx. 14 days after presumptive mating the females were killed and the number of corpora lutea, implantations, viable embryos, and early and later embryonic deaths were determined. For examination of germinal chromosome morphology, 30 males from each group of F?, animals were killed at day 22 and seminiferous tissue anaphase preparations (30/rat) were examined for chromosomal aberrations. Longevity study On completion of the reproductive studies, F, animals were rehoused 4 to a cage and maintained on their respective diets. Animals were weighed and food consumption recorded weekly. All animals surviving to week 104 were killed and examined macroscopically and organ/body weight ratios were calculated for liver, kidneys and adrenals. Samples of tissues from the adrenals, brain, heart, kidney, liver, lung, ovaries, pituitary, small intestine, spleen, stomach, testes and thyroids were preserved for histopathological examination. RESULTS
AND DISCUSSION
Preliminary studies These demonstrated
that the potato
diets were acceptable
to the rats.
FO generation The parent animals showed no treatment-related adverse effects with regard to food consumption, body weight, pregnancy rate and litter data. The groups fed potato diets showed a higher mean litter size than rats fed basal diet.
166
Reproduction
studies
Consumption of irradiated potato diet did not adversely affect the mating performance of F, males. Over the six matings, the highest pregnancy rates were observed for the group fed irradiated potato diet and the lowest for the basal diet fed group. The pregnancy rate declined generally with the number of matings and this was attributed largely to ageing. The breeding results are summarised in Table I. Litter size, survival to weaning, birth weight, weaning TABLE I REPRODUCTIVE Group
DATA
Number of litters reared to day 21
Grouo mean litter data at:
1 2 3
30 42 53
11.1* 12.8** 12.1
1st mating 6.3 1.8 6.2 1.0 6.1 1.6
1 2 3
25 38 42
12.2 12.2 12.9
2nd mating 6.3 0 6.5 0 6.4 0
1 2 3
20 33 40
11.9 13.2 13.1
3rd mating 6.3 2.2 6.5 0.1 6.4 1.5
10.6 12.5** 12.4
11.2 4.9** 6.3
49.9 49.5 48.0
1 2 3
10 28 37
11.8 12.5 12.8
4th mating 6.3 0 6.1 2.3 6.4 0.6
9.9 12.4 12.1
17.5 10.5 6.1
44.0 41.5 45.8
1 2 3
0
4 10
11.3 11.0
6.8 8.1
9.5 10.5
22.1 12.8
54.5 50.0
1 2 3
1 8 6
10.0 6.8 9.0
6th mating 6.8 0 7.1* 4.6 6.4 6.4
10.0 6.4 8.1
0 8.2 16.1
39.5 59.9 51.2
-
Birth Number of viable young
Day 21
% loss
Mean pup weight -
Number of % Cumulative Mean pup viable loss weight young 10.8* 12.4 12.3
4.0 4.0 4.4
49.3 46.7 47.4
Litters killed at birth for teratology
5th mating 6.8 6.5
1, standard laboratory diet; 2, non-irradiated potato diet; 3, irradiated potato diet. Difference from Group 3 statistically significant at Wilcoxon test *P < 0.05. Difference from Group 1 statistically significant at Wilcoxon test **P < 0.05.
167 TABLE II DOMINANT LETHAL ASSAY DATA Parameter
Group No.
Values resulting from mating F, males with untreated females during wk 1
2
3
4
Pregnancy rate %
1 2 3
77 83 70
87 90 87
70 90 90
90 90 87
Mean total implantations/ pregnancy
1 2 3
11.5 11.9 12.8
11.0 10.7 12.2
12.8 11.1 12.6
11.7 11.2 12.8
Pre-implantation loss %
1 2 3
14.7 14.9 9.0
20.5 19.7 16.3
14.0 17.6 12.7
13.3a 16.9 6.6a
Post-implantation loss %
1 2 3
4.5 4.0 4.2
5.7 3.6 4.3
4.7 8.0 5.7
6.4 8.0 6.6
1, standard laboratory diet; 2, non-irradiated potato diet; 3, irradiated potato diet aAnimals with corpora lutea too small to count, excluded from group mean values.
weight and incidence of abnormalities were comparable within reproduction cycles for rats fed the potato diets. Litter size was generally greater for rats fed potato diets compared to basal diet. Overall, it appears that the feeding of irradiated potatoes to rats has no influence on their reproduction. Teratology
studies
Examination of the FZb litters revealed that the incidences of minor malformations were comparable in all groups. Observations of one pup with vertebral disorders and one with a partially divided sternum from the irradiated potato group were considered unrelated to treatment since similar abnormalities have been observed previously in control animals. In the repeat teratology study the number of pregnant rats for both groups fed irradiated potato was slightly higher than that of the group fed non-irradiated potato. Intergroup differences in corpora lutea count, implantation rate and the numbers of viable and dead young were not statistically significant and no significant differences were observed in the incidence of major or minor skeletal or soft tissue abnormalities. Dominant
lethal assay and chromosomal
morphology
The mating performance of males and subsequent pregnancy rate among untreated females was comparable in all three groups. Two total litter losses occurred, one at each of the first and third pairings, in the group fed irradiated potato diet. This incidence was too low to support conclusively a relationship
168
to the premating treatment of the male. Int~r~oup comparisons [for femdes with viable young) showed no statistically significant differences in implantation rate, pre- or post-implantation losses, and viable litter size. Examination of anaphase configurations from the testes showed that the incidence of abnormalities per animal was essentially similar for all groups, thus providing no evidence of adverse effects on spermatogenesis from feeding of irradiated potatoes to FO, F1 and F, generations. Longevity study Body weight gain of F, animals was comparable for all groups during the rapid growth phase; thereafter the weight gain of both potato-fed groups was lower than the group fed standard diet, although no si~ificant difference between the two potato-fed groups was noted. Food consumption followed a similar pattern. No untoward effect was noted on mortality, in fact cumulative mortality was lowest in the group fed the irradiated potato diet. At termination of the long-term study absolute and relative organ weights of liver, kidney and adrenals showed no significant differences between the groups fed irradiated and non-irradiated potato. The only changes of significance were the lower liver weights of both groups receiving potatoes compared to rats fed basal diet. Macroscopic and microscopic post-mortem examinations revealed no pathological changes specifically related to any particular diet. The tumour profile was comparable for all groups and consistent with the pattern usually found in rats of this strain at this age, the most predominant types of tumour being pituitary adenomas in males and femdles, and mamma fibro-adenomas in femaIes. From the results of this study it can be concluded that the continuous feeding of a diet containing 35% peeled, cooked irradiated potatoes elicited no adverse effects on the fertility and general reproductive performance and longevity of rats. REFERENCES 1 Joint FAO/IAEA/WHO Expert Committee on the Wholesomeness of Irradiated Food with Special Reference to Wheat, Potatoes and Onions. Wld Hlth Org. Techn. Rep. Ser. No. 451(1970). 2 B. Coquet, D. Guyot, L. Galland, X. Fouillet and J.L. Rouaud, Etude chez la souris concernant les effets des pommes de terre irradies sur les functions riproductrices et la canc&og&&se, International Project in the Field of Food Irradiation, Final Technical Report IFIP-R18 (1974). 3 H.V. Levinsky and M.A. Wilson, Mutagenic evaluation of an alcoholic extract from r-irradiated potatoes, Food Cosmet. Toxicol., 13 (1975) 243-246. 4 A.N. Zajcev, J.I. Shillinger, Z.M. Kamaldinova and I.N. Osipova, Toxicologic and hygienic investigations of potatoes irradiated with a beam of fast electrons and r-rays to control sprouting, Toxicology, 4 (1975) 267-274. 5 Joint FAO/IAEA/WHO Expert Committee on the Wholesomeness of Irradiated Food, Wld Hlth Org. Techn. Rep. Ser. No. 604 (1977). 6 A.K. Palmer, D.D. Cozens, D.W. Prentice, J.C. Richardson and D.H. Christopher, Reproduction and longevity of rats fed an irradiated potato diet, International Project in the Field of Food Irradiation, Final Technical Report, IFIP-RX5 (1975).
REPRODUCTION POTATO DIET*
163
AND LONGEVITY
OF RATS FED AN IRRADIATED
A.K. PALMER, D.D. COZENS, D.E. PRENTICE, D. H. CHRISTOPHER Huntingdon
Research Centre, Huntingdon,
J.C. RICHARDSON and
Cambridgeshire PE18 6ES (England)
and H.M. GOTTSCHALK and P.S. ELIAS International Project in the Field Food Irradiation, Karlsruhe (F.R.G.) (Received December 19th, 1978) (Accepted December 2&h, 1973)
SUMMARY
In a series of studies the reproduction and longevity of rats fed irradiated potatoes was investigated. Three groups of 30 male and 60 female rats were fed either standard diet or diets containing 35% peeled, cooked potatoes either non-irradiated or irradiated with a dose of 0.12 kGy.** Fertility and general reproductive performance was studied over 6 cycles after which the surviving parent animals were sacrificed at 2 years of age. Chromosomal analysis, dominant lethal assay and teratological examinations were made. No significant effects attributable to treatment were observed on growth, food intake, organ weights, histopathology, fertility and reproduction. No adverse effects on spermatogenesis (dominant lethal test) or on the incidence of germinal chromosomal aberrations were noted.
INTRODUCTION
Much work has been carried out on the use of irradiation to inhibit sprouting in potatoes and to determine the wholesomeness of the irradiated product. In 1969 a Joint FAO/IAEA/WHO Expert Committee [l] recommended temporary acceptance of potatoes irradiated with doses not exceeding 0.15 kGy and specified certain studies later carried out by the International Project in the Field of Food Irradiation (IFIP). On the basis of these further investigations (this paper and ref. 2) and other data [3,4] the 1976 Joint Expert *This investigation was commissioned by the International Project in the Field of Food Irradiation (IFIP), Federal Research Centre for Nutrition, Postfach 3640, 7500 Karlsruhe (FRG). **l rad = 10m2gray (Gy).
164
Committee [ 51 recommended unconditional acceptance of potatoes irradiated with a maximum dose not exceeding 0.15 kGy. The results of a longevity and reproduction study in rats fed an irradiated diet are summarised here. The detailed results are described in the final report [6] submitted to IFIP. MATERIALS
AND METHODS
In preliminary p~atability studies and the main experiment potatoes of the Majestic variety, obtained from the Soil Research Association, Suffolk, England, and the Palogan variety, obtained through the Council for Nuclear Energy, Madrid, were used. They received no chemical treatment of any kind. Due to unexpected early sprouting of the latter variety, locally obtained King Edward potatoes were used for weeks 31-40 of the study. ~rradia~iu~ and diet preparu~~u~ Approximately half the potatoes were exposed to between 0.085 and 0.15 kGy gamma radiation from the Cobalt-60 irradiation facility of Irradiated Products Ltd., Swindon, Wiltshire, England. The irradiated and unirradiated potatoes were peeled, steamed and incorporated at about 35% (dry weight) with supplementary nutrients to form a balanced diet. The dough was dried and the resulting biscuit ground and fed as a coarse powder.
SPF rats (CD strain) obtained from the Charles River Breeding Laboratories, Mass., U.S.A. were used. The rats were maintained in controlled environmental conditions (21”C+l”C; 50+5% relative humidity) and allowed free access to tap water and food throughout. Experimental design Three groups of 70 male and 70 female rats (F. generation) were fed either Spratts Laboratory Diet No. 2, non-irradiated potato diet or irradiated potato diet for 30 days. The rats were then paired (20 days) on a one male to one female basis. After birth, at day 21 post partum, one male pup from each of 30 litters and one female pup from each of 60 litters were selected to form the F, generation experimental colony. Reproductive studies F, animals were housed 4 to a cage and maint~ned on their respective diets for 11 weeks and then mated, 1 male to 2 females, for 10 days. 1 week after weaning of the FZa litters the F1 parents were mated again with different partners. The second and subsequent matings up to a total of 6 were made 7 days after weaning of each successive litter. During mating, females were weighed on alternate days and then on days 0, 7,14 and 20 of gestation and, with the exception of the second mating, on days 0, 7,14 and 21 post par-turn; males were weighed weekly. Pregnant females were housed individually_ After
165
birth, all young were counted, examined for external abnormalities and weighed at 0,4, 12 and 21 days post partum. Pups were sacrificed at day 21 and examined externally and internally for abnormalities. Litter size, litter and mean pup weight, and pup mortality were assessed. Teratology studies Fz,, pups were examined grossly as soon after parturition as possible. Half the offspring in each litter were examined for soft tissue and half for skeletal malformations by hand sectioning or alizarin staining, respectively. In a repeat teratology study three groups of 30 female rats were fed a diet containing either 35% peeled, cooked non-irradiated potato or 35% peeled, cooked potato irradiated with 0.12 kGy or 0.50 kGy. Animals were introduced to the potato diets in increasing increments of 20% from day 2 of pregnancy, and from day 6 to 20 received potato diet exclusively. On day 20 the rats were killed and ovaries and uterine contents examined to determine numbers of corpora lutea, viable young and resorption sites, litter weight, and incidence of foetal abnormalities. Dominant lethal assay and chromosomal morphology 10 males of Fzc litters were fed the test diets and at 15 weeks of age were each mated with different sets of 3 untreated females on 4 consecutive weeks. Approx. 14 days after presumptive mating the females were killed and the number of corpora lutea, implantations, viable embryos, and early and later embryonic deaths were determined. For examination of germinal chromosome morphology, 30 males from each group of F?, animals were killed at day 22 and seminiferous tissue anaphase preparations (30/rat) were examined for chromosomal aberrations. Longevity study On completion of the reproductive studies, F, animals were rehoused 4 to a cage and maintained on their respective diets. Animals were weighed and food consumption recorded weekly. All animals surviving to week 104 were killed and examined macroscopically and organ/body weight ratios were calculated for liver, kidneys and adrenals. Samples of tissues from the adrenals, brain, heart, kidney, liver, lung, ovaries, pituitary, small intestine, spleen, stomach, testes and thyroids were preserved for histopathological examination. RESULTS
AND DISCUSSION
Preliminary studies These demonstrated
that the potato
diets were acceptable
to the rats.
FO generation The parent animals showed no treatment-related adverse effects with regard to food consumption, body weight, pregnancy rate and litter data. The groups fed potato diets showed a higher mean litter size than rats fed basal diet.
166
Reproduction
studies
Consumption of irradiated potato diet did not adversely affect the mating performance of F, males. Over the six matings, the highest pregnancy rates were observed for the group fed irradiated potato diet and the lowest for the basal diet fed group. The pregnancy rate declined generally with the number of matings and this was attributed largely to ageing. The breeding results are summarised in Table I. Litter size, survival to weaning, birth weight, weaning TABLE I REPRODUCTIVE Group
DATA
Number of litters reared to day 21
Grouo mean litter data at:
1 2 3
30 42 53
11.1* 12.8** 12.1
1st mating 6.3 1.8 6.2 1.0 6.1 1.6
1 2 3
25 38 42
12.2 12.2 12.9
2nd mating 6.3 0 6.5 0 6.4 0
1 2 3
20 33 40
11.9 13.2 13.1
3rd mating 6.3 2.2 6.5 0.1 6.4 1.5
10.6 12.5** 12.4
11.2 4.9** 6.3
49.9 49.5 48.0
1 2 3
10 28 37
11.8 12.5 12.8
4th mating 6.3 0 6.1 2.3 6.4 0.6
9.9 12.4 12.1
17.5 10.5 6.1
44.0 41.5 45.8
1 2 3
0
4 10
11.3 11.0
6.8 8.1
9.5 10.5
22.1 12.8
54.5 50.0
1 2 3
1 8 6
10.0 6.8 9.0
6th mating 6.8 0 7.1* 4.6 6.4 6.4
10.0 6.4 8.1
0 8.2 16.1
39.5 59.9 51.2
-
Birth Number of viable young
Day 21
% loss
Mean pup weight -
Number of % Cumulative Mean pup viable loss weight young 10.8* 12.4 12.3
4.0 4.0 4.4
49.3 46.7 47.4
Litters killed at birth for teratology
5th mating 6.8 6.5
1, standard laboratory diet; 2, non-irradiated potato diet; 3, irradiated potato diet. Difference from Group 3 statistically significant at Wilcoxon test *P < 0.05. Difference from Group 1 statistically significant at Wilcoxon test **P < 0.05.
167 TABLE II DOMINANT LETHAL ASSAY DATA Parameter
Group No.
Values resulting from mating F, males with untreated females during wk 1
2
3
4
Pregnancy rate %
1 2 3
77 83 70
87 90 87
70 90 90
90 90 87
Mean total implantations/ pregnancy
1 2 3
11.5 11.9 12.8
11.0 10.7 12.2
12.8 11.1 12.6
11.7 11.2 12.8
Pre-implantation loss %
1 2 3
14.7 14.9 9.0
20.5 19.7 16.3
14.0 17.6 12.7
13.3a 16.9 6.6a
Post-implantation loss %
1 2 3
4.5 4.0 4.2
5.7 3.6 4.3
4.7 8.0 5.7
6.4 8.0 6.6
1, standard laboratory diet; 2, non-irradiated potato diet; 3, irradiated potato diet aAnimals with corpora lutea too small to count, excluded from group mean values.
weight and incidence of abnormalities were comparable within reproduction cycles for rats fed the potato diets. Litter size was generally greater for rats fed potato diets compared to basal diet. Overall, it appears that the feeding of irradiated potatoes to rats has no influence on their reproduction. Teratology
studies
Examination of the FZb litters revealed that the incidences of minor malformations were comparable in all groups. Observations of one pup with vertebral disorders and one with a partially divided sternum from the irradiated potato group were considered unrelated to treatment since similar abnormalities have been observed previously in control animals. In the repeat teratology study the number of pregnant rats for both groups fed irradiated potato was slightly higher than that of the group fed non-irradiated potato. Intergroup differences in corpora lutea count, implantation rate and the numbers of viable and dead young were not statistically significant and no significant differences were observed in the incidence of major or minor skeletal or soft tissue abnormalities. Dominant
lethal assay and chromosomal
morphology
The mating performance of males and subsequent pregnancy rate among untreated females was comparable in all three groups. Two total litter losses occurred, one at each of the first and third pairings, in the group fed irradiated potato diet. This incidence was too low to support conclusively a relationship
168
to the premating treatment of the male. Int~r~oup comparisons [for femdes with viable young) showed no statistically significant differences in implantation rate, pre- or post-implantation losses, and viable litter size. Examination of anaphase configurations from the testes showed that the incidence of abnormalities per animal was essentially similar for all groups, thus providing no evidence of adverse effects on spermatogenesis from feeding of irradiated potatoes to FO, F1 and F, generations. Longevity study Body weight gain of F, animals was comparable for all groups during the rapid growth phase; thereafter the weight gain of both potato-fed groups was lower than the group fed standard diet, although no si~ificant difference between the two potato-fed groups was noted. Food consumption followed a similar pattern. No untoward effect was noted on mortality, in fact cumulative mortality was lowest in the group fed the irradiated potato diet. At termination of the long-term study absolute and relative organ weights of liver, kidney and adrenals showed no significant differences between the groups fed irradiated and non-irradiated potato. The only changes of significance were the lower liver weights of both groups receiving potatoes compared to rats fed basal diet. Macroscopic and microscopic post-mortem examinations revealed no pathological changes specifically related to any particular diet. The tumour profile was comparable for all groups and consistent with the pattern usually found in rats of this strain at this age, the most predominant types of tumour being pituitary adenomas in males and femdles, and mamma fibro-adenomas in femaIes. From the results of this study it can be concluded that the continuous feeding of a diet containing 35% peeled, cooked irradiated potatoes elicited no adverse effects on the fertility and general reproductive performance and longevity of rats. REFERENCES 1 Joint FAO/IAEA/WHO Expert Committee on the Wholesomeness of Irradiated Food with Special Reference to Wheat, Potatoes and Onions. Wld Hlth Org. Techn. Rep. Ser. No. 451(1970). 2 B. Coquet, D. Guyot, L. Galland, X. Fouillet and J.L. Rouaud, Etude chez la souris concernant les effets des pommes de terre irradies sur les functions riproductrices et la canc&og&&se, International Project in the Field of Food Irradiation, Final Technical Report IFIP-R18 (1974). 3 H.V. Levinsky and M.A. Wilson, Mutagenic evaluation of an alcoholic extract from r-irradiated potatoes, Food Cosmet. Toxicol., 13 (1975) 243-246. 4 A.N. Zajcev, J.I. Shillinger, Z.M. Kamaldinova and I.N. Osipova, Toxicologic and hygienic investigations of potatoes irradiated with a beam of fast electrons and r-rays to control sprouting, Toxicology, 4 (1975) 267-274. 5 Joint FAO/IAEA/WHO Expert Committee on the Wholesomeness of Irradiated Food, Wld Hlth Org. Techn. Rep. Ser. No. 604 (1977). 6 A.K. Palmer, D.D. Cozens, D.W. Prentice, J.C. Richardson and D.H. Christopher, Reproduction and longevity of rats fed an irradiated potato diet, International Project in the Field of Food Irradiation, Final Technical Report, IFIP-RX5 (1975).