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Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/lesb20
Bioavailability to rats and toxicity in mice of carbofurah residues bound to faba beans a
b
I.Y. Mostafa , S.M.A.D. Zayed , M. b
Farghaly & F. Mahdy
b
a
Middle Eastern Regional Radioisotope Centre for the Arab Countries , Dokki, Cairo, Egypt b
National Research Centre , Dokki, Cairo, Egypt Published online: 13 Nov 2008.
To cite this article: I.Y. Mostafa , S.M.A.D. Zayed , M. Farghaly & F. Mahdy (1992) Bioavailability to rats and toxicity in mice of carbofurah residues bound to faba beans, Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes, 27:4, 399-405 To link to this article: http://dx.doi.org/10.1080/03601239209372790
PLEASE SCROLL DOWN FOR ARTICLE
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Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/ terms-and-conditions
J. ENVIRON. SCI. HEALTH, B27(4), 399-405 (1992)
Downloaded by [Arizona State University] at 09:54 26 November 2014
BIOAVAILABILITY TO RATS AND TOXICITY IN MICE OF CARBOFURAH RESIDUES BOUND TO FABA BEANS Key words: Faba beans, 14 C-carbofuran, Bound residues, B i o a v a i l a b i l i t y , Toxicity I.Y. Mostafa, S.M.A.D. Zayed*, M. Farghaly*, and F. Mahdy* Middle Eastern Regional Radioisotope Centre for the Arab Countries, Dokki, Cairo, Egypt *National Research Centre Dokki, Cairo, Egypt
ABSTRACT 14
C-carbofuran penetrated readily into seeds of Vicia faba and the r a t e of penetration was found t o be dose dependent. The percentage of bound residues was generally low and did not exceed 3% of the applied dose. When the bound residues were fed t o r a t s 46% of the r a d i o a c t i v i t y was eliminated via CO2 and u r i n e , while t i s s u e s contained 25%. Carbofuran phenol and 3-hydroxy carbofuran represented the main metabolites i n the urine. These data indicate that bean-bound carbofuran residues are highly bioavailable to r a t s . Feeding mice with bound carbofuran residues for 90 days led t o inhibition of erythrocyte cholinesterase a c t i v i t y a f t e r 30 days (35-40%) while the plasma enzyme remained unaffected. Serum transaminases and blood urea nitrogen were s i g n i f i c a n t l y elevated, indicating injury to hepatic and renal s t r u c t u r e s . The r e s u l t s strongly suggest that the bound residues can induce adverse biological e f f e c t s in mice. INTRODUCTION By v i r t u e of t h e i r broad spectrum of a c t i v i t y , high effectiveness and generally low mammalian t o x i c i t y carbamates are finding increasing use as
399 Copyright© 1992 by Maicel Dckker, Inc.
400
MOSTAFA ET AL.
commercial p e s t i c i d e s .
Carbofuran,
2,3-dihydro-2,2-dimethyl-7-benzo-furanyl
N-methyl carbamate, i s an a n t i c h o l i n e s t e r a s e agent which i s e f f e c t i v e a s a systemic and contact i n s e c t i c i d e (Kinoshita and Fukuta, 1980; Gilman and Vardanis, 1974; Kuhr and Dorough, 1976).
I t s metabolism has been extensively
investigated i n mammals, i n s e c t s and p l a n t s .
I t i s usually used for
c o n t r o l l i n g several crop pests and i s under consideration as a p r o t e c t a n t for stored g r a i n s i n Egypt and other c o u n t r i e s . The extensive use of carbofuran
Downloaded by [Arizona State University] at 09:54 26 November 2014
on crop p l a n t s prompted i n v e s t i g a t i o n s on i t s degradation in grain during storage. The aim of the present study i s to examine the p e n e t r a t i o n of carbofuran into faba beans and the b l o a v a i l a b i l i t y and t o x i c i t y of i t s bound residues i n experimental animals. MATERIALS AND METHODS The Chemical The i n s e c t i c i d e carbofuran,
14
C-labelled a t ring-3-carbon atom, was
purchased from I z i n t a Isotope Trading E n t e r p r i s e of the I n s t i t u t e of I s o t o p e s , Budapest, Hungary.
I t had a s p e c i f i c a c t i v i t y of 18.58 mCi/mmole with a
radiometric p u r i t y of 98.0%.
Pure nonlabelled carbofuran was synthesized
according to a published procedure (Metcalf e t a l . , 1968). Treatment of Seeds Sound whole seeds of Vicia faba (var. Giza 1) were used in t h i s experiment.
The moisture
content was determined by oven drying a t 130 C
for 18 hours and was found to be 11-12%. The seeds were stored a t r e l a t i v e humidity of 65-70% and a temperature of 25-30°C, simulating conditions p r e v a i l i n g in farm s t o r a g e . The seeds were t r e a t e d with the r a d i o a c t i v e i n s e c t i c i d e a s previously described (Zayed and Farghaly, 1985).
Three dose
l e v e l s (13, 41 and 62 ppm) were used and samples were taken for a n a l y s i s a f t e r 48 weeks of s t o r a g e . Bound 14 C-Carbofuran Residues Treated beans were washed with water:acetone (3:1) for q u a n t i t a t i v e removal of residues on the seed coat ( s u r f a c e e x t r a c t ) .
The washed seeds were
CARBOFURAN RESIDUES BOUND TO FABA BEANS
401
Downloaded by [Arizona State University] at 09:54 26 November 2014
ground and soxhlet extracted with 95% aqueous methanol for 24 h (methanolic extract). The radioactivity in these extracts was directly measured by liquid scintillation counting (LSC). For the determination of the bound residue, a definite weight of the extracted dry seeds was combusted i n a Harvey Biological Oxidizer (Model OX 600) followed by radioactivity measurement. For quench correction, an internal standard technique was used. Bioavailabilitv of
C-Bound Residues to Rats
Three male albino rats weighing 180-210 g were individually housed in glass metabolism units. The animals were kept without feed for one day and then fed the extracted bean diet. To make the feed palatable, the extracted beans were mixed thoroughly with an equal amount of white cheese and the paste was l e f t to dry. The expired carbon dioxide was trapped in ethanolamine. Urine and feces were collected daily. After 48 h, each rat was lightly anaesthetized with ether and blood removed from the pumping heart. The animal was then killed with an overdose of ether, and samples from liver, kidney and fat were collected for analysis of radiocarbon. The chloroform soluble metabolites extracted from urine were analyzed by thin layer chromatography ( t i c ) on silica gel G plates and identified using appropriate standards in benzene:ether (3:1), v/v; system A) and in hexane:ethylacetate (1:1, v/v) saturated with water (system B). To test for conjugated metabolites, the aqueous fraction was acidified with HC1 followed by extraction with chloroform. Spots were made visible by spraying with vanillin-sulphuric acid reagent (80 ml of ethanolic solution of vanillin (2.5%) added to ice cold 400 ml of cone, sulphuric acid). Carbofuran and i t s metabolites gave pink-purple spots upon heating the sprayed plates for 5 minutes a t 110 C. Toxicitv Studies A group of forty, 4 weeks old healthy female Swiss mice were fed a standard diet mixed with non-labelled carbofuran bound residues to ensure a daily dose of 1.5 ppm insecticide equivalent. The experiment was designed to run for 90 days during which the mice were examined at intervals for changes in body weight gain, water and feed intake, cholinesterase (Michel, 1940) and blood biochemistry. The latter included determination of serum transaminases and blood urea nitrogen. Another group of 20 mice were used as controls and were fed the same diet mixed with non-treated, extracted crushed faba beans.
402
MOSTAFA ET AL. Table 1: l^C-Carbofuran residues in faba beans stored for 48 weeks.
Downloaded by [Arizona State University] at 09:54 26 November 2014
Initial Dose
Surface Extract Residue
Bound Residues
Methanolic Extract Residue
ppm
ppm
%
ppm
%
ppm
13 41 62
4.55 6.97 8.06
35 17 13
4.55 20.50 40.92
35 60 66
0.25 1.11 1.43
Recovery 7.
%
1.9 2.7 2.3
71.9 79.7 81.3
Data are means of three replicates.
Table 2. Elimination and distribution of bean-bound residues fed to rats for 48 hours. Sample
Insecticide* equivalent (ug)
14
C-carbofuran
Percentage of* administered dose
Carbon dioxide Urine Feces Liver Kidney Fat Blood
3.0 9.0 4.0 1.9 0.4 1.2 3.0
11.5 34.6 15.4 7.3 1.5 4.6 11.5
Total Recovery
22.5
86.4
Data are means of three replicates. * Administered dose = 100% (26 ug equivalent per r a t ) .
RESULTS AND DISCUSSIONS Seed Bound Residues Table 1 shows the residues of carbofuran i n treated beans stored for 48 weeks. The percentage of penetration of the toxicant was dose dependent and the binding of 14C-carbofuran i n the seeds was low (< 3%), a behaviour similar t o organochlorine compounds such as lindane (Zayed and Farghaly, 1987). The insecticide was previously shown t o bind t o other substrates such as s o i l (Hussain e t a l . , 1986), sweet potatoes (Hostafa e t a l . , 1986) and other plant species (Dec et a l . , 1986). The incomplete recovery of applied r a d i o a c t i v i t y may be a t t r i b u t e d , a t l e a s t p a r t i a l l y , t o v o l a t i l i t y of the parent substance (Perkow, 1983).
403
CARBOFURAN RESIDUES BOUND TO FABA BEANS
Table 3. Effect of feeding mice with bound carbofuran residues on cholinesterase, transaminases and urea nitrogen.
Downloaded by [Arizona State University] at 09:54 26 November 2014
Days on treatment
Cholinesterase (% remaining activity) lasma
0
100
30
90
0
erythrocyte
Serum glutamic- Serum glutamicoxaloacetic pyruvic transaminase transaminase (u/10
100
198.0+4.3
65+1.0**
330.6±10.5**
100
100
60
100
0 90
(U/L)
Blood urea nitrogen (mg/dL)
41.0+2.1
46.7+3.2
128.0+6.4**
102.8+6.1**
251.9+3.5
50.0+2.3
48.1±4.1
60±2.0**
308.5+9.0**
55.5+3.0*
102.8±3.0**
100
100
249.0+6.0
46.0±5.2
47.5+1.5
100
95
309.5+6.5**
98.5+9.1**
91.3+5.5**
Data means of 3 animals + S.D. Animals fed a diet containing 1.5 ppm bound residues for 90 days. * P < 0.05. ** p
Bioavailabilitv Elimination and distribution of bound C-residues, in rats are shown in Table 2. After 2 days, about 35% of the administered radioactivity was found in urine. Working with ring-labelled carbofuran, Dorough, 1968, reported that 90% of the radioactivity was eliminated in the urine of rats after oral administration. The recovered C-activity amounted t o about 86% of the administered dose; 15% in the feces. The 14 C-residues were detected in blood, liver and fat in appreciable amounts (Table 2). The analysis of urine showed the presence of two main metabolites identified as carbofuran phenol, RF:0.77, 0.83 and 3-hydroxy carbofuran, RF:0.39, 0.42 in systems A and B respectively. The l a t t e r compound represented the major component. Additional amounts of 3-hydroxy carbofuran and carbofuran phenol were obtained after acid hydrolysis. This indicates that both metabolites were present in free and conjugated forms in the urine. 3-hydroxy carbofuran was reported as
404
MOSTAFA ET AL.
a dominant product i n the metabolism of carbofuran in the r a t (Khan e t a l . , 1987).
Downloaded by [Arizona State University] at 09:54 26 November 2014
Biological Activity Toxicity studies did not show any significant effects on body weight gain during the experimentation period. However, erythrocyte cholinesterase a c t i v i t y showed a significant reduction a f t e r 30-60 days while the plasma enzyme a c t i v i t y remained unchanged (Table 3 ) . Also, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT) and blood urea nitrogen (BUN) showed substantial increases i n the treated r a t s suggesting injury t o the l i v e r and kidney (Table 3 ) . No effect could be observed on the a c t i v i t y of serum alkaline phosphatase. These data a r e generally i n agreement with previous reports on the effect of carbamates on r a t l i v e r and kidney enzymes (Ravi e t a l . , 1988). In conclusion, bean-bound carbofuran residues can possess a toxicological potential , as manifested by i n i h i b i t i o n of erythrocyte cholinesterase a c t i v i t y and by inducing injury to hepatic and glomerular t i s s u e s .
REFERENCES Dec, J., Czaplicki, E., Giebel, J., Panel Proceeding Series, STI/PUB/724, IAEA, Vienna, 83-92 (1986). Dorough, H.W., J . Agric. Food Chem., 16, 319-325 (1968). Gilman, A.P., Vardanis, A., J. Agric. Food. Chem., 22, 625-628 (1974). Hussain, A., Azam, F., Malik, K.A., Panel Proceeding Series, STI/PUB/724, IAEA, Vienna, 23-29 (1986). Khan, S.U., Kacew, S., Dupont, S., Stratton, G.D., Wheeler, W.B., J. Agric. Food Chem., 35, 89-93 (1987). Kinoshita, Y., Fukuto, T.R., J . Agric. Food Chem., 28, 1325-1327 (1980). Kuhr, R.J., Dorough, H.W. Carbamate Insecticides; Chemistry, Biochemistry and Toxicology, CRC Press Incorporation, Cleveland, Ohio, 103-106 (1976). Metcalf, R.L., Fukuto, T.R., Collins, C., Borck, K., Abd El-Aziz, S., Munoz, R., Cassil, C.C., J. Agric. Food Chem., 16, 300-311 (1968). Michel, H.O., J. Lab. Clin. Med., 34, 1564-1568 (1949). Mostafa, I.Y., Zayed, S.M.A.D..Farghaly, M.,Panel Proceeding Series, STI/PUB/724, IAEA, Vienna, 95-102 (1986). Perkow, W. Wirksubstanzen der Pflanzenschutz- und Schädlingsbekämp fungsm i t t e l . 2. Auflage, Verlag Paul Parey, Berlin (1983).
CARBOFURAN RESIDUES BOUND TO FABA BEANS
Ravi, K., Mini, B., and Bansal, R.C., P e s t i c i d e s , 22, 8-10 (1988). Zayed, S.M.A.D., Farghaly, M., J . Stored Prod. Res., 21, 199-205 (1985).
Downloaded by [Arizona State University] at 09:54 26 November 2014
Zayed, S.M.A.D., Farghaly, M., J. P e s t i c i d e S c i . , 12, 101-103 (1987) .
405
Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/lesb20
Bioavailability to rats and toxicity in mice of carbofurah residues bound to faba beans a
b
I.Y. Mostafa , S.M.A.D. Zayed , M. b
Farghaly & F. Mahdy
b
a
Middle Eastern Regional Radioisotope Centre for the Arab Countries , Dokki, Cairo, Egypt b
National Research Centre , Dokki, Cairo, Egypt Published online: 13 Nov 2008.
To cite this article: I.Y. Mostafa , S.M.A.D. Zayed , M. Farghaly & F. Mahdy (1992) Bioavailability to rats and toxicity in mice of carbofurah residues bound to faba beans, Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes, 27:4, 399-405 To link to this article: http://dx.doi.org/10.1080/03601239209372790
PLEASE SCROLL DOWN FOR ARTICLE
Downloaded by [Arizona State University] at 09:54 26 November 2014
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/ terms-and-conditions
J. ENVIRON. SCI. HEALTH, B27(4), 399-405 (1992)
Downloaded by [Arizona State University] at 09:54 26 November 2014
BIOAVAILABILITY TO RATS AND TOXICITY IN MICE OF CARBOFURAH RESIDUES BOUND TO FABA BEANS Key words: Faba beans, 14 C-carbofuran, Bound residues, B i o a v a i l a b i l i t y , Toxicity I.Y. Mostafa, S.M.A.D. Zayed*, M. Farghaly*, and F. Mahdy* Middle Eastern Regional Radioisotope Centre for the Arab Countries, Dokki, Cairo, Egypt *National Research Centre Dokki, Cairo, Egypt
ABSTRACT 14
C-carbofuran penetrated readily into seeds of Vicia faba and the r a t e of penetration was found t o be dose dependent. The percentage of bound residues was generally low and did not exceed 3% of the applied dose. When the bound residues were fed t o r a t s 46% of the r a d i o a c t i v i t y was eliminated via CO2 and u r i n e , while t i s s u e s contained 25%. Carbofuran phenol and 3-hydroxy carbofuran represented the main metabolites i n the urine. These data indicate that bean-bound carbofuran residues are highly bioavailable to r a t s . Feeding mice with bound carbofuran residues for 90 days led t o inhibition of erythrocyte cholinesterase a c t i v i t y a f t e r 30 days (35-40%) while the plasma enzyme remained unaffected. Serum transaminases and blood urea nitrogen were s i g n i f i c a n t l y elevated, indicating injury to hepatic and renal s t r u c t u r e s . The r e s u l t s strongly suggest that the bound residues can induce adverse biological e f f e c t s in mice. INTRODUCTION By v i r t u e of t h e i r broad spectrum of a c t i v i t y , high effectiveness and generally low mammalian t o x i c i t y carbamates are finding increasing use as
399 Copyright© 1992 by Maicel Dckker, Inc.
400
MOSTAFA ET AL.
commercial p e s t i c i d e s .
Carbofuran,
2,3-dihydro-2,2-dimethyl-7-benzo-furanyl
N-methyl carbamate, i s an a n t i c h o l i n e s t e r a s e agent which i s e f f e c t i v e a s a systemic and contact i n s e c t i c i d e (Kinoshita and Fukuta, 1980; Gilman and Vardanis, 1974; Kuhr and Dorough, 1976).
I t s metabolism has been extensively
investigated i n mammals, i n s e c t s and p l a n t s .
I t i s usually used for
c o n t r o l l i n g several crop pests and i s under consideration as a p r o t e c t a n t for stored g r a i n s i n Egypt and other c o u n t r i e s . The extensive use of carbofuran
Downloaded by [Arizona State University] at 09:54 26 November 2014
on crop p l a n t s prompted i n v e s t i g a t i o n s on i t s degradation in grain during storage. The aim of the present study i s to examine the p e n e t r a t i o n of carbofuran into faba beans and the b l o a v a i l a b i l i t y and t o x i c i t y of i t s bound residues i n experimental animals. MATERIALS AND METHODS The Chemical The i n s e c t i c i d e carbofuran,
14
C-labelled a t ring-3-carbon atom, was
purchased from I z i n t a Isotope Trading E n t e r p r i s e of the I n s t i t u t e of I s o t o p e s , Budapest, Hungary.
I t had a s p e c i f i c a c t i v i t y of 18.58 mCi/mmole with a
radiometric p u r i t y of 98.0%.
Pure nonlabelled carbofuran was synthesized
according to a published procedure (Metcalf e t a l . , 1968). Treatment of Seeds Sound whole seeds of Vicia faba (var. Giza 1) were used in t h i s experiment.
The moisture
content was determined by oven drying a t 130 C
for 18 hours and was found to be 11-12%. The seeds were stored a t r e l a t i v e humidity of 65-70% and a temperature of 25-30°C, simulating conditions p r e v a i l i n g in farm s t o r a g e . The seeds were t r e a t e d with the r a d i o a c t i v e i n s e c t i c i d e a s previously described (Zayed and Farghaly, 1985).
Three dose
l e v e l s (13, 41 and 62 ppm) were used and samples were taken for a n a l y s i s a f t e r 48 weeks of s t o r a g e . Bound 14 C-Carbofuran Residues Treated beans were washed with water:acetone (3:1) for q u a n t i t a t i v e removal of residues on the seed coat ( s u r f a c e e x t r a c t ) .
The washed seeds were
CARBOFURAN RESIDUES BOUND TO FABA BEANS
401
Downloaded by [Arizona State University] at 09:54 26 November 2014
ground and soxhlet extracted with 95% aqueous methanol for 24 h (methanolic extract). The radioactivity in these extracts was directly measured by liquid scintillation counting (LSC). For the determination of the bound residue, a definite weight of the extracted dry seeds was combusted i n a Harvey Biological Oxidizer (Model OX 600) followed by radioactivity measurement. For quench correction, an internal standard technique was used. Bioavailabilitv of
C-Bound Residues to Rats
Three male albino rats weighing 180-210 g were individually housed in glass metabolism units. The animals were kept without feed for one day and then fed the extracted bean diet. To make the feed palatable, the extracted beans were mixed thoroughly with an equal amount of white cheese and the paste was l e f t to dry. The expired carbon dioxide was trapped in ethanolamine. Urine and feces were collected daily. After 48 h, each rat was lightly anaesthetized with ether and blood removed from the pumping heart. The animal was then killed with an overdose of ether, and samples from liver, kidney and fat were collected for analysis of radiocarbon. The chloroform soluble metabolites extracted from urine were analyzed by thin layer chromatography ( t i c ) on silica gel G plates and identified using appropriate standards in benzene:ether (3:1), v/v; system A) and in hexane:ethylacetate (1:1, v/v) saturated with water (system B). To test for conjugated metabolites, the aqueous fraction was acidified with HC1 followed by extraction with chloroform. Spots were made visible by spraying with vanillin-sulphuric acid reagent (80 ml of ethanolic solution of vanillin (2.5%) added to ice cold 400 ml of cone, sulphuric acid). Carbofuran and i t s metabolites gave pink-purple spots upon heating the sprayed plates for 5 minutes a t 110 C. Toxicitv Studies A group of forty, 4 weeks old healthy female Swiss mice were fed a standard diet mixed with non-labelled carbofuran bound residues to ensure a daily dose of 1.5 ppm insecticide equivalent. The experiment was designed to run for 90 days during which the mice were examined at intervals for changes in body weight gain, water and feed intake, cholinesterase (Michel, 1940) and blood biochemistry. The latter included determination of serum transaminases and blood urea nitrogen. Another group of 20 mice were used as controls and were fed the same diet mixed with non-treated, extracted crushed faba beans.
402
MOSTAFA ET AL. Table 1: l^C-Carbofuran residues in faba beans stored for 48 weeks.
Downloaded by [Arizona State University] at 09:54 26 November 2014
Initial Dose
Surface Extract Residue
Bound Residues
Methanolic Extract Residue
ppm
ppm
%
ppm
%
ppm
13 41 62
4.55 6.97 8.06
35 17 13
4.55 20.50 40.92
35 60 66
0.25 1.11 1.43
Recovery 7.
%
1.9 2.7 2.3
71.9 79.7 81.3
Data are means of three replicates.
Table 2. Elimination and distribution of bean-bound residues fed to rats for 48 hours. Sample
Insecticide* equivalent (ug)
14
C-carbofuran
Percentage of* administered dose
Carbon dioxide Urine Feces Liver Kidney Fat Blood
3.0 9.0 4.0 1.9 0.4 1.2 3.0
11.5 34.6 15.4 7.3 1.5 4.6 11.5
Total Recovery
22.5
86.4
Data are means of three replicates. * Administered dose = 100% (26 ug equivalent per r a t ) .
RESULTS AND DISCUSSIONS Seed Bound Residues Table 1 shows the residues of carbofuran i n treated beans stored for 48 weeks. The percentage of penetration of the toxicant was dose dependent and the binding of 14C-carbofuran i n the seeds was low (< 3%), a behaviour similar t o organochlorine compounds such as lindane (Zayed and Farghaly, 1987). The insecticide was previously shown t o bind t o other substrates such as s o i l (Hussain e t a l . , 1986), sweet potatoes (Hostafa e t a l . , 1986) and other plant species (Dec et a l . , 1986). The incomplete recovery of applied r a d i o a c t i v i t y may be a t t r i b u t e d , a t l e a s t p a r t i a l l y , t o v o l a t i l i t y of the parent substance (Perkow, 1983).
403
CARBOFURAN RESIDUES BOUND TO FABA BEANS
Table 3. Effect of feeding mice with bound carbofuran residues on cholinesterase, transaminases and urea nitrogen.
Downloaded by [Arizona State University] at 09:54 26 November 2014
Days on treatment
Cholinesterase (% remaining activity) lasma
0
100
30
90
0
erythrocyte
Serum glutamic- Serum glutamicoxaloacetic pyruvic transaminase transaminase (u/10
100
198.0+4.3
65+1.0**
330.6±10.5**
100
100
60
100
0 90
(U/L)
Blood urea nitrogen (mg/dL)
41.0+2.1
46.7+3.2
128.0+6.4**
102.8+6.1**
251.9+3.5
50.0+2.3
48.1±4.1
60±2.0**
308.5+9.0**
55.5+3.0*
102.8±3.0**
100
100
249.0+6.0
46.0±5.2
47.5+1.5
100
95
309.5+6.5**
98.5+9.1**
91.3+5.5**
Data means of 3 animals + S.D. Animals fed a diet containing 1.5 ppm bound residues for 90 days. * P < 0.05. ** p
Bioavailabilitv Elimination and distribution of bound C-residues, in rats are shown in Table 2. After 2 days, about 35% of the administered radioactivity was found in urine. Working with ring-labelled carbofuran, Dorough, 1968, reported that 90% of the radioactivity was eliminated in the urine of rats after oral administration. The recovered C-activity amounted t o about 86% of the administered dose; 15% in the feces. The 14 C-residues were detected in blood, liver and fat in appreciable amounts (Table 2). The analysis of urine showed the presence of two main metabolites identified as carbofuran phenol, RF:0.77, 0.83 and 3-hydroxy carbofuran, RF:0.39, 0.42 in systems A and B respectively. The l a t t e r compound represented the major component. Additional amounts of 3-hydroxy carbofuran and carbofuran phenol were obtained after acid hydrolysis. This indicates that both metabolites were present in free and conjugated forms in the urine. 3-hydroxy carbofuran was reported as
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a dominant product i n the metabolism of carbofuran in the r a t (Khan e t a l . , 1987).
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Biological Activity Toxicity studies did not show any significant effects on body weight gain during the experimentation period. However, erythrocyte cholinesterase a c t i v i t y showed a significant reduction a f t e r 30-60 days while the plasma enzyme a c t i v i t y remained unchanged (Table 3 ) . Also, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT) and blood urea nitrogen (BUN) showed substantial increases i n the treated r a t s suggesting injury t o the l i v e r and kidney (Table 3 ) . No effect could be observed on the a c t i v i t y of serum alkaline phosphatase. These data a r e generally i n agreement with previous reports on the effect of carbamates on r a t l i v e r and kidney enzymes (Ravi e t a l . , 1988). In conclusion, bean-bound carbofuran residues can possess a toxicological potential , as manifested by i n i h i b i t i o n of erythrocyte cholinesterase a c t i v i t y and by inducing injury to hepatic and glomerular t i s s u e s .
REFERENCES Dec, J., Czaplicki, E., Giebel, J., Panel Proceeding Series, STI/PUB/724, IAEA, Vienna, 83-92 (1986). Dorough, H.W., J . Agric. Food Chem., 16, 319-325 (1968). Gilman, A.P., Vardanis, A., J. Agric. Food. Chem., 22, 625-628 (1974). Hussain, A., Azam, F., Malik, K.A., Panel Proceeding Series, STI/PUB/724, IAEA, Vienna, 23-29 (1986). Khan, S.U., Kacew, S., Dupont, S., Stratton, G.D., Wheeler, W.B., J. Agric. Food Chem., 35, 89-93 (1987). Kinoshita, Y., Fukuto, T.R., J . Agric. Food Chem., 28, 1325-1327 (1980). Kuhr, R.J., Dorough, H.W. Carbamate Insecticides; Chemistry, Biochemistry and Toxicology, CRC Press Incorporation, Cleveland, Ohio, 103-106 (1976). Metcalf, R.L., Fukuto, T.R., Collins, C., Borck, K., Abd El-Aziz, S., Munoz, R., Cassil, C.C., J. Agric. Food Chem., 16, 300-311 (1968). Michel, H.O., J. Lab. Clin. Med., 34, 1564-1568 (1949). Mostafa, I.Y., Zayed, S.M.A.D..Farghaly, M.,Panel Proceeding Series, STI/PUB/724, IAEA, Vienna, 95-102 (1986). Perkow, W. Wirksubstanzen der Pflanzenschutz- und Schädlingsbekämp fungsm i t t e l . 2. Auflage, Verlag Paul Parey, Berlin (1983).
CARBOFURAN RESIDUES BOUND TO FABA BEANS
Ravi, K., Mini, B., and Bansal, R.C., P e s t i c i d e s , 22, 8-10 (1988). Zayed, S.M.A.D., Farghaly, M., J . Stored Prod. Res., 21, 199-205 (1985).
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Zayed, S.M.A.D., Farghaly, M., J. P e s t i c i d e S c i . , 12, 101-103 (1987) .
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