This article was downloaded by: [Monash University Library] On: 04 May 2015, At: 12:30 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
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 toxicological potential in mice of bound residues of malathion in beans a
a
S.M.A.D. Zayed , M. Farghaly & I.Y. Mostafa
a
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: S.M.A.D. Zayed , M. Farghaly & I.Y. Mostafa (1992) Bioavailability to rats and toxicological potential in mice of bound residues of malathion in beans, Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes, 27:4, 341-346 To link to this article: http://dx.doi.org/10.1080/03601239209372784
PLEASE SCROLL DOWN FOR ARTICLE
Downloaded by [Monash University Library] at 12:30 04 May 2015
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), 341-346 (1992)
BIOAVAILABILITY TO RATS AND TOXICOLOGICAL POTENTIAL IN MICE OF BOUND RESIDUES OF MALATHION IN BEANS
Downloaded by [Monash University Library] at 12:30 04 May 2015
Key words:
Beans,
14
C-malathion, Bound residues, B i o a v a i l a b i l i t y , Toxiclty
S.M.A.D. Zayed, M. Farghaly,* I.Y. Mostafa Middle Eastern Regional Radioisotope Centre for the Arab Countries, *National Research Centre Dokki, Cairo, Egypt
ABSTRACT Under conditions of local p r a c t i c e , the application of 2,3-succinate14
C-malathion on beans led t o the formation of 17-18% of bound 14Cresidues a f t e r 30 weeks. When fed t o r a t s , 75% of these residues became bioavailable a f t e r 2 days with the major p a r t , excreted via expired a i r (8%) and urine (60%). The main radioactive metabolites detected i n urine were malathion monocarboxylic acid and malathion dicarboxylic acid. Feeding of bound residues to mice (1.8 ppm in feed) for 90 days resulted in a reduction in body weight gain a f t e r 60 days and i n h i b i t i o n of erythrocyte cholinesterase a c t i v i t y a f t e r 90 days. Increased levels of serum glutamic oxaloacetic transaminase and alkaline phosphatase were also observed. The r e s u l t s strongly suggest that bean-bound malathion residues can cause adverse biological e f f e c t s in mice. INTRODUCTION Malathion [S-l,2-di(ethoxycarbonyl) ethyl 0,0-dimethyl phosphorodithioate] i s one of the most important s e l e c t i v e organophosphorus i n s e c t i c i d e s used f o r the control of various pests on vegetables, f i e l d crops, f r u i t s , stored grains and domestic animals. Because of i t s low mammalian t o x i c i t y , the i n s e c t i c i d e
341 Copyright © 1992 by Marcel Dekker, Inc.
342
ZAYED, FARGHALY, AND MOSTAFA
can be mixed d i r e c t l y with g r a i n s , where i t c o n t r o l s p e s t s by both contact and vapour a c t i v i t y . of
C-malathion
32 weeks.
I n a previous work (Zayed e t a l . , 1990), the maximum binding t o faba beans was shown t o be 12% of the applied dose a f t e r
I n the p r e s e n t work, t h e b l o a v a i l a b i l i t y and t o x i c o l o g i c a l
p o t e n t i a l of bound malathion r e s i d u e s i n faba beans were i n v e s t i g a t e d .
Downloaded by [Monash University Library] at 12:30 04 May 2015
MATERIALS AND METHODS The Chemical 14 The i n s e c t i c i d e , ( s u c c i n a t e - 2,3- C) malathion ( I ) was purchased from Amersham I n t e r n a t i o n a l Corporation, United Kingdom. I t had a s p e c i f i c a c t i v i t y of 37mCi/mmole and a r a d i o m e t r i c p u r i t y of 98.0%.
For feeding
s t u d i e s , pure n o n - l a b e l l e d malathion was s y n t h e s i z e d by condensing 0,0-dimethyl phosphorodithioic a c i d and d i e t h y l rnaleate (Schrader, 1963).
H3CO
S \ P
- S - *CH - C00C2H5
/
I
H3CO
*CH2 - C0OC2Hs
(I)
Treatment of seeds V i c i a faba beans ( v a r . Giza 1 ) , w i t h m o i s t u r e content of 11-12% and s t o r e d a t a r e l a t i v e humidity of 60-70%, were t r e a t e d with
C-malathion a t
c o n c e n t r a t i o n s of 14.5 and 26 ppm according t o a p r e v i o u s l y r e p o r t e d procedure (Zayed and Farghaly, 1985). recommended i n p r a c t i c e .
The lower dose approximates t h a t u s u a l l y
Seeds were s t o r e d f o r 30 weeks a t 25-30°C.
Bound 14 C-malathion r e s i d u e s i n beans Samples of t r e a t e d seeds were washed extract).
w i t h water s e v e r a l times ( s u r f a c e
Washed beans were then crushed i n a mortar and e x t r a c t e d f o r 24 h
BOUND RESIDUES OF MALATHION IN BEANS Table 1. Residues of
Actual dose
C-malathion in faba beans stored for 30 weeks.
Methanol Extract
Honexcractable
Recovery*
ppm
%
ppm
7.
ppm
%
%
14.5
4.20
29
5.08
35
2.61
18
82
26.0
8.32
32
10.92
42
4.42
17
91
ppm
Downloaded by [Monash University Library] at 12:30 04 May 2015
Surface Extract
343
*Applied Dose = 100%. Data are mean of 3 replicates.
with 95% aqueous methanol in a Soxhlet apparatus (methanol extract). The radioactivity in these extracts was directly determined by liquid s c i n t i l l a t i o n counting (LSC). The non-extracted 14 C-residues were determined by combustion of a definite weight of extracted beans in a Packard TriCarb sample oxidizer (Model 306), followed by liquid s c i n t i l l a t i o n counting (Table 1). Bioavailabilitv to the rat Male albino rats weighing 200-230 g were individually housed in metabolism cages. The exctracted beans were mixed thoroughly with an appropriate amount of cheese to make the feed palatable and were fed to rats (25 ug malathion equivalent per animal). Urine and faeces were collected for 48 hours and the expired CO, was trapped in 10% NaOH solution. After two days, rats were sacrificed and samples from liver, f a t , brain and blood were analyzed for total radiocarbon by combustion followed by LSC. The metabolites in urine were analyzed by thin layer chromatography ( t i c ) using the following systems for development: A- Acetonitrile : water : ammonia (85:14:1; v/v/v) B- Isopropanol : ammonia : water (75:24:1; v/v/v).
344
ZAYED, FARGHALY, AND
MOSTAFA
Authentic samples were run alongside as references and spots were made visible by spraying the plates with freshly prepared Hanes-Isherwood reagent (Hanes and Isherwood, 1949).
Downloaded by [Monash University Library] at 12:30 04 May 2015
Toxlcltv studies in mice Bound residues prepared from a parallel experiment with non-labelled malathion were used for a feeding study. A group of 40 healthy 4 weeks old male Swiss mice was fed for 90 days on standard diet mixed with the extracted crushed beans ensuring a daily dose of 1.8 ppm insecticide equivalent. Another group of 20 male mice were used as controls and were fed with the same diet mixed with extracted crushed pesticide-free beans. Animals were weighed and examined, for body weight gain, feed intake and behaviour. Plasma and erythrocyte cholinesterase activity was also determined (Michel, 1949). Some haematological parameters and blood biochemistry were also investigated. RESULTS AND DISCUSSION Bioavailabilitv When male r a t s were fed bean-bound 14 C-malathion residues, a considerable amount of residues was eliminated from the animals within 48 hours (Table 2). The total recovery of 14 C-activity amounted to 75% of the administered dose. The main excretion route was the urine (60%) while small amounts (8%, 3% and 4%) could be found in the expired a i r , feces and organs respectively. Comparable percentages of radioactivity were reported to be eliminated in urine and feces after oral administration of malathion to rats (Bourke et a l . , 1968). Chromatographic analysis of urine revealed the presence of malathion monocarboxylic acid (R, 0.35 and 0.36 in systems A and B, respectively) and malathion dicarboxylic acid (Rf 0.14 and 0.50 in systems A and B, respectively) as the main metabolites. This i s in agreement with previous findings following oral administration of malathion to r a t s (Abd-El-Raof et a l . , 1981; Bradway and Shafik, 1977). The recovery of 68% of the applied radioactivity in expired CO, and urine clearly indicates that bean-bound malathion residues are highly available to r a t s . Toxicitv studies Feeding mice with bound malathion residues a t a level of 1.8 ppm for 90 days caused a reduction in body weight gain (20-30%) after 60 days. The
345
BOUND RESIDUES OF MALATHION IN BEANS
Table 2. Elimination and distribution of bound malathion residues fed to rats for 48 hours.
Insecticide equivalent*
Downloaded by [Monash University Library] at 12:30 04 May 2015
Sample
Percentage of administered dose*
Carbon dioxide Urine Feces Liver Kidney Fat Blood
2.00 15.00 0.80 0.50 0.03 0.34 0.05
8.0 60.0 3.3 2.0 0.1 1.4 0.2
Total Recovery
18.72
75.0
•Administered dose = 100% (25 ug equivalent per r a t ) . Data are means of three replicates.
Table 3. Effect of bean-bound malathion residues on some enzyme activities in male mice.
Treatment period (days)
0 30 0 60 0 90
Serum glutamic oxaloacetic transaminase (U/M
Alkaline phosphatase (U/L)
151+7.3
15±1.4
482+9.4**
66+3.0**
119+3.6
13+2.0
310+8.4**
39+3.0**
112±3.4
24+4.1
418±8.1**
68+4.0**
Data means of three animals + S.D. * Control values = 100 ** Significance P < 0.01.
% remaining cholinesterase activity* plasma
ervthrocvte
100
100
89
100
100
100
91
98
100
100
> 100
75
346
ZAYED, FARGHALY, AND MOSTAFA
Downloaded by [Monash University Library] at 12:30 04 May 2015
erythrocyte cholinesterase a c t i v i t y was inhibited by about 25% a f t e r 90 days (Table 3). An increased a c t i v i t y of serum glutamic oxaloacetic transaminase (SGOT) and alkaline phosphatase was observed over the experimental period (Table 3), suggesting injury t o hepatic t i s s u e s . The r e s u l t s generally suggest that the bound residues can cause some adverse e f f e c t s i n mice. Due to a low concentration of residues i n the feed (1.8 ppm), the e f f e c t s were not p a r t i c u l a r l y profound and further work should be conducted a t higher l e v e l s . REFERENCES Abd-El-Raof, T.K., Dauterman, W.C., Mailman, R.B., Toxicol. Appl. Pharmacol., 59, 324-330 (1981). Bourke, J.B., Broderick, E.J., Hackler, L.R., Lippold, P.C., J. Agric. Food Chem., 16, 585-589 (1968). Bradway, D.E., Shafik, T.M., J. Agric. Food Chem., 25, 1342-1344 (1977). Hanes, C.S., Isherwood, F.A., Nature (London) 164, 1107-1112 (1949) . Michel, H.O., J. Lab. Clin. Med., 34, 1564-1568 (1949) . Schrader, G. Die Entwicklung neuer Insektizider Phosphorsäure, Ester, Verlag Chemie GmbH, 138 (1963) . Zayed, S.M.A.D., Farghaly, M., J. Stored Prod. Res., 21, 199-205 (1985). Zayed, S.M.A.D., Farghaly, M., Hegazi, B., IAEA Panel Proceeding Series, STI/PUB/822, Vienna, 35-43 (1990).
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 toxicological potential in mice of bound residues of malathion in beans a
a
S.M.A.D. Zayed , M. Farghaly & I.Y. Mostafa
a
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: S.M.A.D. Zayed , M. Farghaly & I.Y. Mostafa (1992) Bioavailability to rats and toxicological potential in mice of bound residues of malathion in beans, Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes, 27:4, 341-346 To link to this article: http://dx.doi.org/10.1080/03601239209372784
PLEASE SCROLL DOWN FOR ARTICLE
Downloaded by [Monash University Library] at 12:30 04 May 2015
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), 341-346 (1992)
BIOAVAILABILITY TO RATS AND TOXICOLOGICAL POTENTIAL IN MICE OF BOUND RESIDUES OF MALATHION IN BEANS
Downloaded by [Monash University Library] at 12:30 04 May 2015
Key words:
Beans,
14
C-malathion, Bound residues, B i o a v a i l a b i l i t y , Toxiclty
S.M.A.D. Zayed, M. Farghaly,* I.Y. Mostafa Middle Eastern Regional Radioisotope Centre for the Arab Countries, *National Research Centre Dokki, Cairo, Egypt
ABSTRACT Under conditions of local p r a c t i c e , the application of 2,3-succinate14
C-malathion on beans led t o the formation of 17-18% of bound 14Cresidues a f t e r 30 weeks. When fed t o r a t s , 75% of these residues became bioavailable a f t e r 2 days with the major p a r t , excreted via expired a i r (8%) and urine (60%). The main radioactive metabolites detected i n urine were malathion monocarboxylic acid and malathion dicarboxylic acid. Feeding of bound residues to mice (1.8 ppm in feed) for 90 days resulted in a reduction in body weight gain a f t e r 60 days and i n h i b i t i o n of erythrocyte cholinesterase a c t i v i t y a f t e r 90 days. Increased levels of serum glutamic oxaloacetic transaminase and alkaline phosphatase were also observed. The r e s u l t s strongly suggest that bean-bound malathion residues can cause adverse biological e f f e c t s in mice. INTRODUCTION Malathion [S-l,2-di(ethoxycarbonyl) ethyl 0,0-dimethyl phosphorodithioate] i s one of the most important s e l e c t i v e organophosphorus i n s e c t i c i d e s used f o r the control of various pests on vegetables, f i e l d crops, f r u i t s , stored grains and domestic animals. Because of i t s low mammalian t o x i c i t y , the i n s e c t i c i d e
341 Copyright © 1992 by Marcel Dekker, Inc.
342
ZAYED, FARGHALY, AND MOSTAFA
can be mixed d i r e c t l y with g r a i n s , where i t c o n t r o l s p e s t s by both contact and vapour a c t i v i t y . of
C-malathion
32 weeks.
I n a previous work (Zayed e t a l . , 1990), the maximum binding t o faba beans was shown t o be 12% of the applied dose a f t e r
I n the p r e s e n t work, t h e b l o a v a i l a b i l i t y and t o x i c o l o g i c a l
p o t e n t i a l of bound malathion r e s i d u e s i n faba beans were i n v e s t i g a t e d .
Downloaded by [Monash University Library] at 12:30 04 May 2015
MATERIALS AND METHODS The Chemical 14 The i n s e c t i c i d e , ( s u c c i n a t e - 2,3- C) malathion ( I ) was purchased from Amersham I n t e r n a t i o n a l Corporation, United Kingdom. I t had a s p e c i f i c a c t i v i t y of 37mCi/mmole and a r a d i o m e t r i c p u r i t y of 98.0%.
For feeding
s t u d i e s , pure n o n - l a b e l l e d malathion was s y n t h e s i z e d by condensing 0,0-dimethyl phosphorodithioic a c i d and d i e t h y l rnaleate (Schrader, 1963).
H3CO
S \ P
- S - *CH - C00C2H5
/
I
H3CO
*CH2 - C0OC2Hs
(I)
Treatment of seeds V i c i a faba beans ( v a r . Giza 1 ) , w i t h m o i s t u r e content of 11-12% and s t o r e d a t a r e l a t i v e humidity of 60-70%, were t r e a t e d with
C-malathion a t
c o n c e n t r a t i o n s of 14.5 and 26 ppm according t o a p r e v i o u s l y r e p o r t e d procedure (Zayed and Farghaly, 1985). recommended i n p r a c t i c e .
The lower dose approximates t h a t u s u a l l y
Seeds were s t o r e d f o r 30 weeks a t 25-30°C.
Bound 14 C-malathion r e s i d u e s i n beans Samples of t r e a t e d seeds were washed extract).
w i t h water s e v e r a l times ( s u r f a c e
Washed beans were then crushed i n a mortar and e x t r a c t e d f o r 24 h
BOUND RESIDUES OF MALATHION IN BEANS Table 1. Residues of
Actual dose
C-malathion in faba beans stored for 30 weeks.
Methanol Extract
Honexcractable
Recovery*
ppm
%
ppm
7.
ppm
%
%
14.5
4.20
29
5.08
35
2.61
18
82
26.0
8.32
32
10.92
42
4.42
17
91
ppm
Downloaded by [Monash University Library] at 12:30 04 May 2015
Surface Extract
343
*Applied Dose = 100%. Data are mean of 3 replicates.
with 95% aqueous methanol in a Soxhlet apparatus (methanol extract). The radioactivity in these extracts was directly determined by liquid s c i n t i l l a t i o n counting (LSC). The non-extracted 14 C-residues were determined by combustion of a definite weight of extracted beans in a Packard TriCarb sample oxidizer (Model 306), followed by liquid s c i n t i l l a t i o n counting (Table 1). Bioavailabilitv to the rat Male albino rats weighing 200-230 g were individually housed in metabolism cages. The exctracted beans were mixed thoroughly with an appropriate amount of cheese to make the feed palatable and were fed to rats (25 ug malathion equivalent per animal). Urine and faeces were collected for 48 hours and the expired CO, was trapped in 10% NaOH solution. After two days, rats were sacrificed and samples from liver, f a t , brain and blood were analyzed for total radiocarbon by combustion followed by LSC. The metabolites in urine were analyzed by thin layer chromatography ( t i c ) using the following systems for development: A- Acetonitrile : water : ammonia (85:14:1; v/v/v) B- Isopropanol : ammonia : water (75:24:1; v/v/v).
344
ZAYED, FARGHALY, AND
MOSTAFA
Authentic samples were run alongside as references and spots were made visible by spraying the plates with freshly prepared Hanes-Isherwood reagent (Hanes and Isherwood, 1949).
Downloaded by [Monash University Library] at 12:30 04 May 2015
Toxlcltv studies in mice Bound residues prepared from a parallel experiment with non-labelled malathion were used for a feeding study. A group of 40 healthy 4 weeks old male Swiss mice was fed for 90 days on standard diet mixed with the extracted crushed beans ensuring a daily dose of 1.8 ppm insecticide equivalent. Another group of 20 male mice were used as controls and were fed with the same diet mixed with extracted crushed pesticide-free beans. Animals were weighed and examined, for body weight gain, feed intake and behaviour. Plasma and erythrocyte cholinesterase activity was also determined (Michel, 1949). Some haematological parameters and blood biochemistry were also investigated. RESULTS AND DISCUSSION Bioavailabilitv When male r a t s were fed bean-bound 14 C-malathion residues, a considerable amount of residues was eliminated from the animals within 48 hours (Table 2). The total recovery of 14 C-activity amounted to 75% of the administered dose. The main excretion route was the urine (60%) while small amounts (8%, 3% and 4%) could be found in the expired a i r , feces and organs respectively. Comparable percentages of radioactivity were reported to be eliminated in urine and feces after oral administration of malathion to rats (Bourke et a l . , 1968). Chromatographic analysis of urine revealed the presence of malathion monocarboxylic acid (R, 0.35 and 0.36 in systems A and B, respectively) and malathion dicarboxylic acid (Rf 0.14 and 0.50 in systems A and B, respectively) as the main metabolites. This i s in agreement with previous findings following oral administration of malathion to r a t s (Abd-El-Raof et a l . , 1981; Bradway and Shafik, 1977). The recovery of 68% of the applied radioactivity in expired CO, and urine clearly indicates that bean-bound malathion residues are highly available to r a t s . Toxicitv studies Feeding mice with bound malathion residues a t a level of 1.8 ppm for 90 days caused a reduction in body weight gain (20-30%) after 60 days. The
345
BOUND RESIDUES OF MALATHION IN BEANS
Table 2. Elimination and distribution of bound malathion residues fed to rats for 48 hours.
Insecticide equivalent*
Downloaded by [Monash University Library] at 12:30 04 May 2015
Sample
Percentage of administered dose*
Carbon dioxide Urine Feces Liver Kidney Fat Blood
2.00 15.00 0.80 0.50 0.03 0.34 0.05
8.0 60.0 3.3 2.0 0.1 1.4 0.2
Total Recovery
18.72
75.0
•Administered dose = 100% (25 ug equivalent per r a t ) . Data are means of three replicates.
Table 3. Effect of bean-bound malathion residues on some enzyme activities in male mice.
Treatment period (days)
0 30 0 60 0 90
Serum glutamic oxaloacetic transaminase (U/M
Alkaline phosphatase (U/L)
151+7.3
15±1.4
482+9.4**
66+3.0**
119+3.6
13+2.0
310+8.4**
39+3.0**
112±3.4
24+4.1
418±8.1**
68+4.0**
Data means of three animals + S.D. * Control values = 100 ** Significance P < 0.01.
% remaining cholinesterase activity* plasma
ervthrocvte
100
100
89
100
100
100
91
98
100
100
> 100
75
346
ZAYED, FARGHALY, AND MOSTAFA
Downloaded by [Monash University Library] at 12:30 04 May 2015
erythrocyte cholinesterase a c t i v i t y was inhibited by about 25% a f t e r 90 days (Table 3). An increased a c t i v i t y of serum glutamic oxaloacetic transaminase (SGOT) and alkaline phosphatase was observed over the experimental period (Table 3), suggesting injury t o hepatic t i s s u e s . The r e s u l t s generally suggest that the bound residues can cause some adverse e f f e c t s i n mice. Due to a low concentration of residues i n the feed (1.8 ppm), the e f f e c t s were not p a r t i c u l a r l y profound and further work should be conducted a t higher l e v e l s . REFERENCES Abd-El-Raof, T.K., Dauterman, W.C., Mailman, R.B., Toxicol. Appl. Pharmacol., 59, 324-330 (1981). Bourke, J.B., Broderick, E.J., Hackler, L.R., Lippold, P.C., J. Agric. Food Chem., 16, 585-589 (1968). Bradway, D.E., Shafik, T.M., J. Agric. Food Chem., 25, 1342-1344 (1977). Hanes, C.S., Isherwood, F.A., Nature (London) 164, 1107-1112 (1949) . Michel, H.O., J. Lab. Clin. Med., 34, 1564-1568 (1949) . Schrader, G. Die Entwicklung neuer Insektizider Phosphorsäure, Ester, Verlag Chemie GmbH, 138 (1963) . Zayed, S.M.A.D., Farghaly, M., J. Stored Prod. Res., 21, 199-205 (1985). Zayed, S.M.A.D., Farghaly, M., Hegazi, B., IAEA Panel Proceeding Series, STI/PUB/822, Vienna, 35-43 (1990).
