The wholesomeness of irradiated shrimps

Fd Cosmet. ToxicoL Vol. 10, pp. 781-788. Pergamon Press 1972. Printed in Great Britain

The Wholesomeness of Irradiated Shrimps M. J. VAN LOGTEN, ENGELINA M. DEN TONKELAAR and G. J. VAN ESCH Laboratory of Toxicology,

and R. KRO~

Laboratory of Pathology, National Institute of Public Health, Bilthoven, The Netherlands (Received 21 February 1972) Abstract--Seven groups each of ten male and ten female rats received for 90 days either a standard diet or diets containing non-irradiated, 150-krad y-irradiated or 300-krad y-irradiated shrimps at a level of 2-8 or 28 ~ on a dry weight basis. No effects on growth, food intake, composition of blood, serum glutamic-pyruvic transaminase, organ weights or histopathology were attributable to the irradiation, but administration of a diet containing 28 ~ shrimps, either irradiated or non-irradiated, affected the relative weights of the liver, kidneys and ovaries. In the liver, fatty vacuolation occurred to an extent which increased with the dietary level of shrimps, but again the effect was no more marked with the irradiated than with the non-irradiated diets.

INTRODUCTION Irradiation can be used to prolong the shelf life of several foodstuffs. Since cooked shrimps are perishable, the influence of irradiation on their bacteriological condition was studied. That the keeping qualities could be improved by this method was shown by Awad, Sinnhuber & Anderson (1965), Liuzzo, Novak & Ortego (1965) and Scholz, Sinnhuber, East & Anderson (1962), but only limited data were available on the wholesomeness of irradiated shrimps for human consumption. Since these limited data (Brin, Ostashever & Kalinsky, 1961; Hickman, 1969) related to American not Dutch shrimps and since different dosages of radiation were used, a 90-day feeding test in rats was carried out in the Netherlands. In this study, two levels of 7-irradiation (150 and 300 krad) and two dietary levels of irradiated shrimps (2.8 and 28 ~ dry weight) were studied in comparison with non-irradiated shrimps. EXPERIMENTAL h'radiation o f shrimps. The irradiation was carried out by the Institute for Atomic Sciences in Agriculture (ITAL), Wageningen. The shrimps (Crangon vulgaris) were obtained from the Institute for Fishery Products TNO, at IJmuiden. The latter Institute also determined the concentrations of salt and benzoic acid and the total amount of volatile basic nitrogen (TVB) in each batch of shrimps. The TVB is taken as a measure of the protein quality. The 781

782

M . J . VAN LOGTEN, ENGELINA M. DEN TONKELAAR, G. J. VAN ESCH

and

R. KROES

shrimps were cooked on board the ships, cooled with sea-water, peeled, packed in plastics bags and sent to Wageningen for irradiation. Each batch was kept in a deep-freeze for about 1 month. Before irradiation the shrimps were defrosted for 24 hr and 7-irradiation was carried out at about 0°C by means of a cobalt-60 source at dose levels of 150 and 300 krad. After irradiation the shrimps were transported in ice. Seven different batches were used for this experiment. The bacteriological condition (aerobic plate count) was also studied in each batch. Preparation of diets. The shrimps were mixed with a semi-synthetic diet, Muracon-SSPTox (Trouw and Co., Putten, The Netherlands), consisting of casein, soya protein, maize starch, glucose, cellulose, soya oil, lard, minerals and vitamins. Shrimps contain approximately 80 7o water, 18 7o protein and 2 7o fat, so for the 28 7o dietary level (calculated on dry weight) it was necessary to use a diet from which the casein (normally 207O) and soya protein (5 7o) had been omitted. From 2609 g shrimps mixed with 1342 g Muracon-SSP-Tox without protein was produced a diet containing ±25 70 protein, equivalent to 28 7O dry shrimps. For the diet containing 2.8 7o shrimps (dry weight), 391 g shrimps were mixed with 2021 g Muracon-SSP-Tox without protein, supplemented with 481 g casein and 120 g soya protein. Thus a similar diet with approximately 257o total protein was obtained. The shrimps were ground in a mincer before being mixed into the diet. Animals. Weanling male and female SPF Wistar rats were obtained from the Central Institute for the Breeding of Laboratory Animals TNO, Zeist, and were housed in wire cages, two animals to a cage. Food and drinking water were provided ad lib.

Experimental design and conduct Littermates were divided randomly among the following seven groups of ten male and ten female animals: group I (control) fed standard Muracon-SSP-Tox diet; group 2 fed 2.8 7o non-irradiated shrimps; group 3, 2.8 7O 150-krad irradiated shrimps; group 4, 2.8 300-krad irradiated shrimps; group 5, 28 ~o non-irradiated shrimps; group 6, 28 7o 150-krad irradiated shrimps; group 7, 28 7o 300-krad irradiated shrimps. The animals were weighed weekly and the food intake was determined in wk, 1, 2, 5 and 13. The haemoglobin content, haematocrit, total number of erythrocytes and total and differential leucocyte counts were determined on blood samples taken at the end of the experiment. The mean cell volume, mean haemoglobin content per cell and the mean corpuscular haemoglobin concentration were calculated. The activity of glutamic-pyruvic transaminase was measured in the serum of five males and five females in each group. After 13 wk, all animals were killed and examined macroscopically. Liver, kidneys, heart, spleen, thymus, adrenals, thyroid, pituitary gland, lungs, brain, uterus, ovaries, testes and prostate were weighed. These organs, as well as the gastro-intestinal tract, salivary glands, cervical and mesenteric lymph nodes, urinary bladder, quadriceps muscle, skin, eyes, mammary gland and aorta, were studied histopathologically in the control group and in the groups receiving non-irradiated or 300-krad irradiated shrimps. In the groups receiving 150-krad irradiated shrimps, only those organs that showed abnormalities in the other groups were studied. Statistical methods Statistical analyses were carried out for all parameters according to the Student's t test. To study the effect of the irradiation of shrimps, the results for the groups receiving 2-87O irradiated shrimps were compared with those for the group receiving 2-87o non-

WHOLESOMENESS OF IRRADIATED SHRIMPS

783

i r r a d i a t e d shrimps. The results for the g r o u p s receiving 2 8 % i r r a d i a t e d s h r i m p s were similarly c o m p a r e d with those for the g r o u p receiving 28 % n o n - i r r a d i a t e d shrimps. T o d e t e r m i n e w h e t h e r these relatively high dose levels o f s h r i m p s h a d any effects, statistical c a l c u l a t i o n s were also carried out c o m p a r i n g the g r o u p s receiving n o n - i r r a d i a t e d s h r i m p s with the c o n t r o l a n i m a l s receiving the s t a n d a r d diet. RESULTS Shrimp analyses The results o f the d e t e r m i n a t i o n s o f salt, benzoic acid and T V B showed little difference between the seven batches o f shrimps. The m e a n salt c o n c e n t r a t i o n was 0.74~o a n d the m e a n T V B 12.3 rag/100 g. This indicates a n o r m a l , fresh prodfict. Benzoic acid was n o t detectable. The a e r o b i c plate c o u n t o f the s h r i m p s decreased with increasing r a d i a t i o n dose. Food intake and growth T h e m e a n f o o d i n t a k e / a n i m a l / d a y for wk 1, 2, 5 a n d 13 is given in T a b l e 1 a n d b o d y - w e i g h t increases are given in T a b l e 2. The f o o d i n t a k e is a v e r a g e d for the two a n i m a l s in each cage. "Fable 1. Food intake of rats fed diets containing irradiated or non-irradiated shrimps for 90 days Food intake (g/rat/day) at wk Diet

2

5

13

6.6

11.2

20-2

16"5

7.6 8-2 8.4

15'5"* 25-6* 21"1"* 16-5 24.9 20-1 18.11-1- 31.1"j't 22.1

17"3"* 17"9 17"7

24-7** 24.9 25"0

32"0** 32"0 32"0

35'3** 37'4138'8I"I"

Females 6-0

10'3

15-7

11'4

8.1"* 9.0 8.3

14.2' 13.8 13.8

19'0 19.9 28"11[

14.9" 16-7 17'3

17.3** 16.7 17.7

24"3* 24.4 23.5

30.5** 30"6 31-7

30"9** 30"9 33.2

1 Males

Standard (control) 2'8 % shrimps, non-irradiated 150-krad irradiated 300-krad irradiated 28 % shrimps, non-irradiated 150-krad irradiated 300-krad irradiated

Standard (control) 2'8 % shrimps, non-irradiated 150-krad irradiated 300-krad irradiated 28 ~o shrimps, non-irradiated 150-krad irradiated 300-krad irradiated

Values are means for groups of ten rats and those marked with asterisks differ significantly (Student's t test) from those of the controls: *P < 0.05; **P < 0.01. Those marked with daggers differ significantlyfrom the values for the group given non-irradiated shrimps at the same dietary level: t P < O'05;ttP < 0.01.

784

M.J. VAN LOGTEN, ENGELINA M. DEN TONKELAAR, G. J. VAN ESCH a n d R. KROES

T a b l e 1 clearly shows t h a t the weight o f f o o d c o n s u m e d increased as the d i e t a r y level o f s h r i m p s increased. This can be e x p l a i n e d p a r t l y by the fact t h a t the w a t e r c o n t e n t o f the diet was m u c h higher when fresh shrimps, with a w a t e r c o n t e n t o f 80 ~ , were i n c o r p o r a t e d . H o w e v e r , the f o o d i n t a k e o f the males a n d females receiving 28 ~o s h r i m p s in the diet was s o m e 2 - 3 times higher t h a n t h a t o f the c o n t r o l g r o u p . A direct c o m p a r i s o n o f the f o o d i n t a k e s was impossible, as e v a p o r a t i o n o f water from the diets was n o t estimated. In s o m e cases, the f o o d i n t a k e o f the a n i m a l s ingesting 300-krad i r r a d i a t e d s h r i m p s was higher t h a n t h a t o f the a n i m a l s ingesting n o n - i r r a d i a t e d shrimps. The g r o w t h o f the a n i m a l s (Table 2) was also g r e a t e r when s h r i m p s were i n c o r p o r a t e d in the diet except in the case o f the males o f the g r o u p receiving 28 ~ n o n - i r r a d i a t e d shrimps. Haematological and biochemical studies T h e significant differences in h a e m a t o l o g i c a l p a r a m e t e r s (Table 3) were few a n d scattered t h r o u g h o u t the test groups. T h e y were clearly not related to the a d m i n i s t r a t i o n o f n o n i r r a d i a t e d o r i r r a d i a t e d shrimps. T h e d e t e r m i n a t i o n o f the activity o f serum g l u t a m i c - p y r u v i c t r a n s a m i n a s e (Table 3) did not reveal a n y significant differences between the groups. Table 2. Weight gain in rats fed diets containing irradiated or non-irradiated shrimps for 90 days

Diet

Standard (control) 2'8 ~ shrimps, non-irradiated 150-krad irradiated 300-krad irradiated 28 ~ shrimps, non-irradiated 150-krad irradiated 300-krad irradiated

Initial body weight (g)

Weight gain (g) at wk 5

12

154

242

39** 38 41

169 179 167

290** 276 299

41 42 40

151 165t 173it

228 252t 257tt

Males 44

Females

Standard (control) 2-8 ~ shrimps, non-irradiated 150-krad irradiated 300-krad irradiated 28 ~ shrimps, non-irradiated 150-krad irradiated 300-krad irradiated

38

98

134

40 38 37

118'* 123 111

162"* 172 163

39 38 38

115"* 120 120

152" 162 166

Values are means for groups often rats and those marked with asterisks differ significantly (Student's t test) from those of controls: *P < 0"05; **P < 0'01. Those marked with daggers differ significantly from the values for the group given non-irradiated shrimps at the same dietary level: t P < 0'05; t t P < 0"01. The latter ( t t ) values are also significant in respect of the control group.

WHOLESOMENESS OF IRRADIATED SHRIMPS

785

Table 3. Terminal haematological data and serum-enzyme determinations for rats fed diets

conta#ling irradiated or non-irradiated shrimps for 90 days Data for rats fed diets containing shrimps at a level of 2-8 70, irradiated with

28 70, irradiated with

0% Parameter

(control)

0 krad

150 krad

300 krad

0 krad

150 krad

300 krad

Males

Haemoglobin, mg/ml Haematocrit, % Erythrocytes, 106/ram 3 Leucocytes Total, 103/mm 3 Differential (%), B E N L M A MCV, fl MCH, pg MCHC, ~o SGPT§

144 45.0 6"8

145 44-5 7-1

139"1" 42-6tt,~ 6.8

143 43-7 6.8

147 45-7 7-1

151 46-4 7.2

147 45.7 6"8

10.5 0"4 1-6 14.1 82.3 1"6 0"6 66.1 21.2 32.0 17±3

9'6 0'1 2"0 10.7 85.0 2.2 0'3 63"3 20"6 32-5 18i2

9"4 0.1 1"3 8-6 87-4 2'6 0'5 62.3 20.3 32.6 16±2

10'4 0"1 0'8tt,~ 7.9 88"4 2"8 0"9 63"8 20-9 32-8 16±4

9'6 0.1 1-6 7.2** 89"3 1"8 0"7 65.0 21-0 32-2 15±3

9"9 0'1 1"8 7-6 88"2 2"3 0"2 64.7 21.0 32-5 17±3

9"1 0"2 2"0 9-0 86-6 2"2 0"7 67"2 21-7 32'2 15±4

147 45.7 6-9

144 44.1 6.8

141 43"5 6-7

142 43.7 6"6

148 45"7 6"8

146 44-7 6-9

142 43-8 6"6

8'6 0'3 1"8 7'9 87.8 2"2 0"6 66.5 21-4 32.2 16±2

9'1 0"3 1.2 7.8 89.0 1.7 0.4 65.2 21"4 32'8 16±2

8"9 0.1 1.7 12.0 83"2 3-01",~. 0"9 65'0 21'I 32'5 14±2

8'6 0-2 1-4 9"8 85"9 2"7 0"5 66.2 21-6 32.6 14 4-3

8-1 0"3 1 '4 8"5 88"0 1 '8 0"5 67-8 21"9 32-3 15 4 - 2

7'3 0"5 1"9 7.1 88"4 2.1 0-7 65"2 21"3 32"8 1413

7"7 0"3 2.2 11"4 83"2 2-9 0-5 66"2 21"5 32'5 13 4-3

Females

Haemoglobin, mg/ml Haematocrit, % Erythrocytes, 106/mm 3 Leucocytes Total, 103/mm 3 Differential (%), B E N L M A MCV, fl MCH, pg MCHC, ~ SGPT§ B A -

Basophils E = Eosinophils N = Neutrophils L = Lymphocytes M = Monocytes Atypical cells MCV = Mean cell volume M C H = Mean haemoglobin content/cell MCHC = Mean corpuscular haemoglobin concentration

§Values are means for five animals in each group. Values are means for groups of ten rats, except where otherwise stated, and that marked with asterisks differs significantly (Student's t test) from the control value: **P < 0'01. Those marked with daggers differ'significantly from the values for the group given non-irradiated shrimps at the same dietary level: t P < 0.05; t t P < 0.01, with those also marked ++differing significantly in respect of the control group as well.

Organ weights T h e d a t a in T a b l e 4 s h o w t h a t t h e a d d i t i o n o f 28 % s h r i m p s t o t h e d i e t c a u s e d a n i n c r e a s e in t h e w e i g h t s o f t h e liver, k i d n e y s a n d o v a r i e s e x p r e s s e d as a p e r c e n t a g e o f b o d y w e i g h t . T h e t h y m u s w e i g h t w a s i n c r e a s e d in m a l e s b u t d e c r e a s e d in f e m a l e s . I n t h e m a l e s a d e c r e a s e in t h e h e a r t w e i g h t w a s f o u n d . T h e a d d i t i o n o f 28 % 3 0 0 - k r a d i r r a d i a t e d s h r i m p s t o t h e d i e t

786

M. J. VAN LOGTEN, ENGELINA M. DEN TONKELAAR, G. J. VAN ESCH and R. KROES Table 4. Relative organ weights of rats fed diets containing irradiated or non-irradiated shrimps for 90 days Relative organ weight (%~oof body weight) in rats fed diets containing shrimps at levels of 2.8 %, irradiated with

28 %, irradiated with

0% Organ

(control)

0 krad

150 krad

Liver Kidneys Heart Spleen Thymus Adrenals Thyroid Pituitary Testes Prostate Lungs Brain

4"36 0.818 0.337 0.179 0'107 0"013 0'007 0-003 0-972 0.097 0"395 0'638

4.26 0.782 0.287** 0.146"* 0.120 0.012 0.006* 0.003 0-918 0.123 0.365 0.562**

Males 4.36 0.816 0.306 0"154 0-127 0-013 0-007I 0-003 0'928 0'117 0'383 0.577

Liver Kidneys Heart Spleen Thymus Adrenals Thyroid Pituitary Uterus Ovaries Lungs Brain

3-71 0.804 0-376 0-181 0-152 0.025 0.008 0.007 0.262 0-027 0-456 0-950

3.69 0.800 0'356 0.168 0.138 0.024 0.008 0.006 0.224 0.029 0.438 0.826**

3.76 0-883t,++ 0'360 0.181 0.142 0'023 0-008 0.007 0-194 0.032 0.445 0.811

300 krad

0 krad

150 krad

300 krad

4-41 0"831 0-317tt 0.154 0.118 0.020 0.006 0.004 0'913 0"122 0-364 0.537

4.72 0-889** 0-297** 0.171 0.142" 0.014 0-008 0'004 0.956 0.090 0.361 0.622

4.82 0.916 0-313 0.158 0.125 0.014 0.007 0'003I" 0'942 0.103 0.306 0.597

4.69 0.955t,.+ 0.309 0-1461I",$ 0"123I 0'014 0"0061-t,.+ 0"003 0-8871" 0.113[ 0.341 0"552t I,$

3"62 0.839 0.340 0.168 0'130 0-023 0'008 0.007 0-217 0"030 0"453 0-816

4.23* 1.065" 0-360 0.187 0'125" 0.028 0'008 0'007 0.203 0.034* 0.446 0.860*

4.01 1.035 0"336 0'173 0"134 0'023t 0.007 0"007 0.227 0.031 0-427 0.849

4.16 1.009 0"346 0'158II,++ 0'138 0.027 0"008 0-007 0.255 0.035 0.457 0.853

Females

Values are means for groups of ten rats and those marked with asterisks differ significantly (Student's t test) from control values: *P < 0-05; **P < 0.01. Those marked with daggers differ significantly from the values for the group given non-irradiated shrimps at the same dietary level: t P < 0'05; I"~P < 0.01, with those also marked $ differing significantly in respect of the control group as well.

decreased the relative spleen weight in males and females, but spleen weight was also decreased in the a n im a ls receiving 2.8 % n o n - i r r a d i a t e d shrimps. In a d d i t i o n the weight o f the testes was decreased in animals fed 28 ~o 300-krad irradiated shrimps. T h e effect on the relative weight o f the brain was p r o b a b l y a reflection o f the increase in b o d y weight, since brain weight is relatively stable while the b o d y weight changes. T h e o t h e r significant differences were m o s t p r o b a b l y unrelated to the a d m i n i s t r a t i o n o f irradiated shrimps.

Histopathology T h e results o f the h i s t o p a t h o l o g i c a l studies o f the different organs did not show any c h an g es that c o u l d be ascribed to the a d m i n i s t r a t i o n o f n o n - i r r a d i a t e d or irradiated shrimps, except in the liver. T h e principle finding in the o t h e r o r g a n s was p e r i v a s c u l a r cuffing in the lungs, but the incidence o f this, as o f the less c o m m o n p a t h o l o g i c a l changes, was no higher

FIG. I. Liver of rat on control diet, showing a normal histological picture with no infiltration of fat. Frozen section, Oil Red O -80.

FIG. 2. Liver of rat fed 28 ~o non-irradiated shrimps in the diet for 13 wk, showing fat-containing vacuoles localized at the periphery of the Iobule. Frozen section, Oil Red O :-:.80.

787

WHOLESOMENESS OF IRRADIATED SHRIMPS

Table 5. Incidence of vacuolation at the periphery of liver lobules in rats fed diets

contahlhzg irradiated or non-irradiated shrimps for 90 days

No. of rats affected after ingestion of shrimps at dietary levels of 2.8 %, irradiated with 0% (control) Degree of No. of rats vacuolation studied...

In 25 % of lobule, In 33 % of Iobule, In 50% of Iobule,

low moderate high moderate high moderate high

9M

9F

I 1

0 krad

150 krad

300 krad

0 krad

150 krad

300 krad

10MIOF

10M9F

10M 9F

9M 9F

9M 10F

9M 10F

2 4 2 2 I

28 %, irradiated with

3

3 3

1

1 1

I

4 3 I

2 3 1

1 2

1

3 2 1 1 2

3 1 1 2 1 1

1 3

2

1 1 2

3 1 2 1

2 3 1 2 1 1

in the test groups than in the controls. In the liver, however, vacuolation was observed at the periphery of the liver lobules in animals receiving 28 % non-irradiated or 300-krad irradiated shrimps (Figs 1 & 2). Frozen sections of all livers were therefore prepared and stained with Oil Red O for demonstration of fat. The results of the evaluation of the extent and intensity of this vacuolation are given in Table 5. Consideration of this table shows that fatty vacuolation was present at the periphery of the liver lobules, particularly when the diet contained 28 % shrimps on a dry weight basis. The degree of vacuolation was independent of the irradiation. At the lower dietary level of shrimps, the vacuolation was greater in the males than in the females.

DISCUSSION For the present, conclusions about the wholesomeness of irradiated foodstuffs must depend on the carrying out of 90-day or chronic toxicity tests in which a high percentage of the food to be studied is incorporated in the diet. To get a safety factor by this procedure, it is necessary to use unrealistically high dose levels of foodstuffs, as was done for instance in an ea~-lier experiment with irradiated mushrooms (van Logten, den Tonkelaar, van Esch, van Steenis & Kroes, 1971). In the present study, changes were produced in the groups receiving the diets with a high percentage of shrimps, whether or not they were irradiated. These changes occurred in food intake, body weight, the weight of certain organs and the histopathology of the liver. The food intake of the animals receiving shrimps in the diet was much higher than that of the controls, a difference which could partly be explained by the higher water content of the diet. In nearly all cases, a higher growth rate was observed after incorporation of shrimps in the diet, although the males receiving 28 % non-irradiated shrimps did not show this increase in growth. A possible explanation for this could be the fact that the bacterial contamination at this high dietary level of shrimps was rather heavy. After irradiation, the aerobic plate count was much lower, and the growth of the animals fed irradiated shrimps was better. Administration of 28 % shrimps also influenced the relative weights of the liver, kidneys and ovaries. Histopathological studies of all organs revealed differences only in the

788

M.J. VAN LOGTEN, ENGELINA M. DEN TONKELAAR, G. J. VAN ESCH a n d R. KROES

liver. Here, fatty v a c u o l a t i o n was f o u n d in the periphery o f the liver lobule, increasing in extent a n d intensity with the increase in the dietary level o f shrimps. This v a c u o l a t i o n was a c c o m p a n i e d by liver enlargement, b u t was n o t associated with differences in the activity o f serum g l u t a m i c - p y r u v i c t r a n s a m i n a s e , indicating that no serious d a m a g e was present. This fatty m e t a m o r p h o s i s may result from some u n k n o w n n u t r i t i o n a l i m b a l a n c e . Since shrimps are m a r i n e organisms, the possibility also exists that u n k n o w n toxic substances f r o m the sea may a c c u m u l a t e in the shrimps. Such substances could include c o n t a m i n a n t s , such as pesticides, p o l y c h l o r i n a t e d biphenyls a n d heavy metals, a n d n a t u r a l toxic substances. The changes f o u n d in this study were no m o r e serious or extensive in irradiated t h a n in n o n - i r r a d i a t e d shrimps even when the shrimps were fed at a dietary level of 28 ~ o n a dry weight basis. There were no indications that the wholesomeness o f shrimps was decreased by irradiation. Acknowledgements--We are grateful to Dr. M. van Schothorst for the bacteriological studies, to Dr. P. W. Helleman for the haematological studies, to Dr. H. Houwing (I FP, TNO, IJmuiden) for providing the shrimps, to Ir. J. G. van Kooy (ITAL, Wageningen) for the irradiation of the shrimps and to Dr. P. Elias for his help with editing.

REFERENCES Awad, A. A., Sinnhuber, R. O. & Anderson, A. W. (1965). Radiation pasteurization of raw and chlortetracycline-treated shrimps. Fd Technol., Champaign 19 (5), 182. Brin, M., Ostashever, A. S. & Kalinsky, H. (1961). The effects of feeding irradiated pork, bread, green beans, and shrimp to rats on growth and on five enzymes in blood. Toxic. appl. Pharmac. 3, 606. Hickman, J. R. (1969). A summary of toxicological data on irradiated foods other than potatoes, onions and wheat. Joint FAO/IAEA/WHO Expert Committee on Irradiated Food. FAD/IF/69.6. Liuzzo, J. A., Novak, A. F. & Ortego, P. (1965). Physiological changes induced by gamma irradiation of bacteria from shrimp. J. Fd Sci. 30, 710. Scholz, D. J., Sinnhuber, R. O., East, D. M. & Anderson, A. W. (1962). Radiation pasteurized shrimp and ¢rabmeat. Fd Technok, Champaign 16 (7), 118. van Logten, M. J., den Tonkelaar, Engelina M., van Esch, G. J., van Steenis, G. & Kroes, R. (1971). The wholesomeness of irradiated mushrooms. Fd Cosmet. Toxicol. 9, 379.

Salubrit6 des crevettes irradi6es R~sum6---Sept groupes de rats, de dix m~.leset dix femelles chacun, ont re~:u pendant 90 jours soit un r6gime alimentaire standard, soit des r6gimes comportant 2,8 ou 28 ~ en poids sec de crevettes, non irradi6es ou irradi6es aux rayons gamma ~ 150 ou h 300 krad. Aucun effet sur la croissance, la consommation alimentaire, la composition du sang, la transaminase glutamiquepyruvique s6rique, le poids des organes ou l'histopathologie n'a pu ~tre imput6 ~ I'irradiation, mais les r6gimes ~. 28 ~o de crevettes, irradi6es ou non, a influ6 sur les poids relatifs du foie, des reins et des ovaires. Une vacuolation adipeuse du foie s'est manifest~e dans des proportions qui augmentaient avec le taux de crevettes du r6gime, mais de m6me cet effet n'6tait pas plus marqu6 selon que les crevettes ~taient irradi6es ou non.

Die BekOmmlichkeit bestrahlter Krabben Zusammenfassung--Sieben Gruppen aus je zehn m~nnlichen und zehn weiblichen Ratten erhielten 90 Tage lang entweder normales Futter oder Futter, das 2,8 oder 28~o, auf das Trockengewicht bezogen, unbestrahlte, mit 150 krd y-bestrahlte oder mit 300 krd "r-bestrahlte Krabben enthielt. Keine Einfliisse auf das Wachstum, den Futterverbrauch, die Blutzusammensetzung, die Serumglutaminsfi.urepyruvattransaminase, die Organgewichte oder die Histopathologie waren der Bestrahlung zuzuschreiben, abet die Verabreichung eines Futters, das 28 Yoentweder bestrahlte oder unbestrahlte Krabben enthielt, beeinflusste das relative Gewicht yon Leber, Nieren und Ovarien. In der Leber trat Fettvakuolisierung in einem Ausmass ein, das sich mit dem Gehalt des Futters an Krabben erh6hte, abet wiederum war dieser Effekt bei den nichtbestrahlten Krabben nicht gr6sser als bei den bestrahlten.