The Science of the Total Environment, 78 (1989) 173-178 173 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Nether lands

CONTAMINATION OF STORED FOOD A N D F E E D COMMODITIES FROM INDOOR USE OF HCH A N D DDT IN MALARIA CONTROL P R O G R A M M E S

RAMINDERJIT SINGH BATTU, PARM PAL SINGH, BALBIR SINGH JOIA and RAJINDER LAL KALRA

Department of Entomology, Punjab Agricultural University, Ludhiana 141 004 (India)

(Received April 12th, 1988; accepted June 17th, 1988)

ABSTRACT

Samples of wheat grain, straw, flour and green fodder taken from houses sprayed with either HCH or DDT for mosquito control showed the presence of HCH residues at concentrat ions of up to 91.2, 208.8, 33.1 and 459.0mgkg 1 and DDT residues up to 11.3, 86.1, 2.2 and 5 .4mgkg 1, respectively. The mean level of HCH residues in samples of wheat grain collected from randomly selected houses in areas sprayed with HCH for the control of malaria was ~ 8 times higher than tha t for corresponding samples from DDT sprayed areas. In contrast , DDT residues in wheat grain samples from the DDT sprayed area were 3 times higher than the samples from the HCH sprayed area. The results suggest tha t significant amounts of residues of HCH and DDT become transferred to commodities stored in houses sprayed with these insecticides for mosquito control.

INTRODUCTION

The vector-borne diseases prevalent in tropical and sub-tropical areas of the world are considered to threaten more than one-third of the human population (Bfichel, 1983). Consequently, insecticides have been used intensively in public heal th programmes all over the world to control disease-transmitting organisms. Persistent compounds, such as HCH and DDT, are still being applied in substantial amounts to control disease vectors in many developing countries, chiefly because of their low cost. In this context, it has been maintained that the spraying of DDT within domestic dwellings, in rout ine anti-malaria operations, does not cause any significant contaminat ion problems (WHO, 1971; Fontaine, 1978; Spindler, 1983). However, only limited information is available on the impact on the human environment of using persistent organochlor ine compounds in public heal th programmes, and the need to evaluate vector control programmes with respect to their residue implications has been stressed (Farvar, 1979; Kalra and Chawla, 1985).

In India, the present consumption of HCH and DDT is ~ 45 and 19 million kilogrammes per year, respectively (ICS, 1986), of which ~ 50% HCH and 80% DDT is used for indoor spraying of domestic houses and catt le sheds in rural areas for mosquito control under the National Malaria Eradicat ion

0048-9697/89/$03.50 ~" 1989 Elsevier Science Publishers B.V.

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Programme. For this purpose, aqueous suspensions prepared from 50% water dispersible powder formulations of either HCH at the rate of 3 g m- 2 or DDT at the rate of 2 g m 2 are sprayed in rural premises. Several surveys conducted in India have shown widespread occurrence of residues of HCH and DDT in certain food items, even though there are no recommendations for use of these insecticides during growth and storage of such commodities. The residue levels of these insecticides in several situations have been found to be quite high and could not be expected to have arisen from general regional levels of contamina- tion (Kalra and Chawla, 1981, 1985).

The present studies were carried out to assess the extent of contaminat ion of wheat grain, straw, flour and green fodder as a result of anti-malaria insec- ticide applications when these commodities are stored in the t reated premises. Wheat grain and straw are generally kept in rural dwellings from the time of harvest in April until the next harvest for use as human food and cattle feed. Stored wheat grain is ground from time to time to obtain flour which is kept packaged in cloth bags or in metal bins. Green fodder is obtained regularly from fields and may be stored in houses for a short period before being fed to the cattle.

MATERIALS AND METHODS

Sampling

Two adjoining districts in Punjab State, India, viz. Sangrur, where HCH is applied for mosquito control, and Ludhiana, where DDT is used for this purpose, were selected for this study. From four rural dwellings in each district, samples of wheat grain, straw, flour and green fodder were collected at six intervals before and after insecticide applications for mosquito control (Tables 1 and 2). For the experimental period, mean air temperatures for July October ranged from 23.8 to 30.8°C and for December from 13.4 to 14.5°C.

In addition, 20 samples of wheat grain from the crop harvested in April, 1983, and stored for home consumption were also collected in January, 1984, from randomly selected houses in each of the two districts. Enquiries showed that the dwellings covered in the study had been treated with insecticides for malaria control in varying manners. While there had been complete coverage of some houses, others were only partially treated with the insecticides during the period of storage of the wheat grain; some had not been treated at all. The method of storage of wheat grain also varied ranging from stocking in metal bins to storage in gunny bags; in some cases it was even left uncovered in heaps.

Analytical method

The samples of wheat grain, straw and flour were extracted with acetoni- t r i le:water (2:1, v/v), part i t ioned into n-hexane and cleaned-up by t reatment with concentrated sulphuric acid (Singh and Chawla, 1982). Green fodder

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samples were processed in a s imilar manner , except t ha t the ex t r ac t ion was performed wi th undi lu ted ace toni t r i le . The residues were es t imated on a P a c k a r d Becker GLC model 417 fitted wi th a t r i t ium source e lec t ron cap ture de tec to r and a glass co lumn (1 m × 2 mm i.d.) packed wi th 1.5% OV-17 + 1.95% OV-210 on Gas Chrom Q. The ident i t ies of res idues were confirmed by micro- a lkal i de r iva t iza t ion (EPA, 1980). The recovery va lues de te rmined by spiking samples with compounds of in te res t were > 80%. The residue va lues repor ted have not been cor rec ted for recovery .

RESULTS AND DISCUSSION

All 192 samples of the var ious commodi t ies col lected at d i f ferent in te rva l s over a per iod of about 6 months from houses sprayed wi th HCH or DDT con ta ined residues of these insect ic ides (Tables 1 and 2). HCH residues consis ted main ly of a lpha and gamma isomers, while DDT residues consis ted chiefly of p ,p ' -DDT and o,p'-DDT.

In samples ob ta ined at the first sampling, average HCH residues levels of 0.5, 1.3, 0.5 and 0.2 mg kg 1 were found in whea t grain, straw, flour and green fodder col lec ted from ru ra l houses in an a rea where HCH was being used for mosqui to cont ro l (Table 1). These res idue concen t r a t i ons could be due to the ubiqui tous na t u r e of pers i s ten t o rganoch lo r ine compounds as well as con t amina t ion resu l t ing from previous appl ica t ions of insect ic ides in the region. After t r e a t m e n t of the dwell ings for mala r i a control , HCH residues of up to 91.2, 208.8, 33.1 and 459 .0mgkg -1 were observed in whea t grain, straw, f lour and green fodder, respect ively . The con t amina t i on of these commodi t ies could have occur red as a resu l t of d i rec t fall-out of r iCH dur ing appl ica t ion or con tac t with

TABLE 1

Increase in residue levels of HCH (mean and range, mgkg ~) in samples of various commodities collected from four rural houses sprayed with HCH for mosquito control

Date of Wheat grain Wheat straw Wheat flour Green fodder sampling (1983)

23 July 0.47 1.29 0.45 0.17 (0.23 0.70) (0.81 1.92) (0.10-1.06) (0.054).40)

27 July ~ 8.97 7.70 4.09 116.64 (3.49-13.86) (40,00-208.75) (1.77-8.00) (1.00459.00)

26 August 2.96 23.14 3,28 0.33 (0.73~5.60) (8.67~5.4) (1.21-8.70) (0.07-0.73)

14 September a 8.34 95.00 10.46 0.82 (4.56-13.14) (41.50-177.0) (2.20-33.10) (0.78-1.20)

12 October 23.95 22.22 4.76 0.96 (2.80-91.20) ( 8 . 5 8 ~ 5 6 . 7 0 ) (0.40-14.20) (0.07-3.18)

19 December 2.29 4.96 3.49 0.41 (Q.30-9.91) (2.50-8.65) (0.42-11.84) (0.31-0.54)

aSamples collected one day after HCH application.

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TABLE 2

Increase in residue levels of DDT (mean and range, mgkg 2) in samples of various commodities collected from four rural houses sprayed with DDT for mosquito control

Date of Wheat grain Wheat straw Wheat flour Green fodder sampling (1983)

2 July 0.11 0.23 0.05 0.02 (0.09-0.14) (0.07-0.66) (0.05~.06) (0.01-0.02)

7 July a 1.14 21.06 0.17 0.68 (0.32 3.10) (4.05 59.70) (0.08~).29) (0.12 1.45)

19 August 1.79 0.64 0.29 0.99 (0.20-5.60) (0.20-1.31) (0.084).62) (0.01-0.19)

7 September" 0.47 28.26 1.10 2.38 (0.30-0.71) (2 .00-86 .06) (0.28--2.21) (0.09-5.35)

6 October 3.96 10.41 0.39 0.27 (0.81 11.32) (5.33 24.34) (0.16-0.77) (0.04-0.58)

7 December 0.53 0.38 0.46 0.04 (0.30-0.78) (0.30-0.45) (0.194).95) (0.02-0.05)

aSamples collected one day after DDT application.

insect ic ide- t reated walls and other surfaces of the premises dur ing storage. The vola t i l iza t ion of residues from a con tamina ted surface and their subsequent adsorp t ion by the s tored commodit ies could be ano the r factor con t r ibu t ing towards the presence of insect icide residues in the samples. In a s tudy being conducted on the level of residues in the air of rooms t rea ted with insecticides at the dosages applied for mosqui to control , HCH and DDT concen t ra t ions r ang ing from 155.4 to 2000.1pgm ~ and from 1.8 to 14.6pgm 3, respectively, have been observed dur ing the month fol lowing appl icat ion (unpublished data). High levels of residues in whea t s t raw and green fodder could arise because of the re la t ively large surface area avai lable for exposure to insec- ticide residues.

Similarly, for var ious commodit ies collected from rura l houses t rea ted with DDT for malar ia control , re la t ively h igher DDT residue levels were observed after insect icide applicat ions. Compared with pre- t rea tment maximum DDT residues of 0.2, 0.7, 0.06 and 0.02 mg kg 1 in whea t grain, straw, flour and green fodder, respectively, levels of up to 11.3, 86.1, 2.2 and 5.4 were found to occur in these mater ia ls after DDT appl ica t ion (Table 2).

All 40 samples of whea t gra in collected randomly from rura l houses in distr icts sprayed with both HCH and DDT conta ined residues of both insec- ticides (Table 3). The whea t grain from HCH sprayed areas had ~ 8 times h igher HCH residues (mean value 0.9 mg kg 1) than samples from DDT sprayed areas (mean value 0 . 1 m g k g 1). In contras t , DDT residues in wheat grain samples from DDT sprayed areas were 3 times h igher than those in samples from HCH sprayed areas. Singh et al. (1988) have also observed a re la t ionship between the use of HCH and DDT within domestic dwellings for malar ia control and con tamina t ion of wheat gra in s tored in the t rea ted houses.

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TABLE 3

Mean and range of HCH and DDT residues in wheat grain samples collected at random from rural houses in areas treated with these insecticides for mosquito control

Pattern of insecticide u s e

Residue level (mg kg- 1 )

HCH DDT

HCH-sprayed villages 0.89 0.03 (0.07 2.81) (Traceq).08)

DDT-sprayed villages 0.11 0.09 (0.02 2.08) (0.01q).41)

Trace: < 0.01mgkg 1.

T h i s s t u d y shows t h a t w h e n r u r a l d w e l l i n g s a re t r e a t e d w i t h H C H or D D T for m o s q u i t o c o n t r o l , s i g n i f i c a n t a m o u n t s of r e s i d u e s of t hese i n s e c t i c i d e s a re t r a n s f e r r e d to c o m m o d i t i e s s t o r ed in these p remises . D ue to t he p r e s e n c e of h i g h leve ls of H C H a n d DDT r e s i d u e s in w h e a t g r a i n a n d flour, t h e r e is a p o s s i b i l i t y of s u b s t a n t i a l h u m a n d i e t a r y i n t a k e of t hese c o m p o u n d s . As w h e a t s t r a w a n d g r e e n fodder a re u sed as feed for m i l c h a n i m a l s , i n s e c t i c i d e r e s i d u e s i n these c o m m o d i t i e s a re l i ke ly to b e c o m e b i o c o n c e n t r a t e d a n d t h u s m i g h t be c o n t r i b u t i n g t o w a r d s t he h i g h leve ls of H C H a n d D D T r e s i d u e s f o u n d in c e r t a i n m i l k a n d m i l k p r o d u c t s ( K a l r a e t al., 1983). E s t i m a t e d d i e t a r y i n t a k e of H C H a n d DDT r e s i d u e s for m a n f o l l o w i n g the c o n s u m p t i o n of c o n t a m i n a t e d w h e a t f lour a re g i v e n in T a b l e 4.

T h e r e is a n u r g e n t n e e d to assess the c o n t r i b u t i o n of i n s e c t i c i d e s u sed in p u b l i c h e a l t h p r o g r a m m e s to t he s e r i o u s p o l l u t i o n of t he e n v i r o n m e n t r e p o r t e d in s eve ra l m a l a r i a - i n f e s t e d d e v e l o p i n g c o u n t r i e s , a n d to s t u d y in de t a i l t he m e c h a n i s m of c o n t a m i n a t i o n of food a n d feed kep t i n p r e m i s e s t r e a t e d w i t h i n s e c t i c i d e s for m o s q u i t o con t ro l .

TABLE 4

Estimated dietary intake of HCH and DDT residues (#g person- 1 day 1) for an adult man following the consumption of wheat flour contaminated as a result of anti-malaria insecticide applications. Intake of wheat flour = 536 g day- 1 (assuming that 80% of cereals recommended by Gopalan and Rao (1980) is constituted by wheat flour)

Insecticide Intake level (ttg)

Minimum Maximum

Acceptable daily intake for a 60 kg person (Pg)

HCH 3.28 × 536 10.46 x 536 a - 1758.1 = 5606.6

DDT 0.17 x 536 1.10 × 536 300 = 91.1 589.6

~ADI value not available.

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ACKNOWLEDGEMENTS

T h i s s t u d y w a s f i n a n c e d i n p a r t b y t h e I n d i a n C o u n c i l o f M e d i c a l R e s e a r c h ,

N e w D e l h i , u n d e r t h e p r o j e c t " T h e c o n t r i b u t i o n o f D D T a n d H C H u s e d i n

p u b l i c h e a l t h p r o g r a m m e s t o w a r d s t h e c o n t a m i n a t i o n o f e n v i r o n m e n t " .

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