Organochlorine pesticide residues in paddy fish in Malaysia and the associated health risk to farmers*

Bulletin ofthe World Health Organization, 62 (2): 251-253 (1984) (3 World Health Organization 1984 Organochlorine pesticide residues in paddy fish in Malaysia and the associated health risk to farmers* DONALD F. CHEN, PETER G. MEIER, & MORTON S. HILBERT Paddy fish (Trichogaster pectoralis Regan) were collected from five sampling lo- cations in a major paddy-growing area of Malaysia and analysed for organochlorine residues. During the same period, ten farmingfamilies, chosen at randomfrom each of the five sampling sites, were interviewed. Information was obtained about the quantity of paddyfish consumed, the amount and type ofpesticide used on thepaddy-field, and thefre- quency of application. The pesticide residues found in the fish samples were aldrin/dieldrin, chlordane, HCH, and DDT. Only the projected maximum intake levelfor aldrin/dieldrin approached the acceptable daily intake as recommended by FAO/WHO; other residue levels were rela- tively low. However, this study considered only fish; the total daily intake of pesticide residues by the Malaysian paddyfarmer may be considerably increased by consumption of other contaminatedfood. The dual cultivation of rice and fish in paddy-fields is a common practice among paddy-farmers in Malay- sia. As a result of the application of persistent and toxic insecticides to the rice, the fish cultured in these fields may be contaminated by a variety of pesticide residues. The farming families, who are the main con- sumers of the paddy fish, may thus be exposed to potential health risks. MATERIALS AND METHODS A total of 332 paddy fish (Trichogaster pectoralis Regan) was collected from five sites in the District of Krian, State of Perak, Malaysia. The sampling locations were Tanjong Piandang (paddy-field), Sun- gei Kota (paddy-field), Jalan Bhara (sump pond), Parit Tanjong Piandang (irrigation/drainage canal), and Sungei Burong (irrigation/drainage canal). The fish catch from each site was divided into between 6 and 16 samples, each weighing approximately 500 g. The fish in each sample were filleted and homogen- ized and 10-g (wet weight) subsamples were removed and analysed for organochlorine residues, using gas chromatography. Several methods were employed for the analysis of the data (1-3). During the same period, a survey was conducted among 50 paddy-farming families who lived close to the fish-sampling areas. Because the villages were very small, it was possible to interview only 10 * From the Department of Environmental and Industrial Health, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA. Requests for reprints should be addressed to Dr Meier. families in the vicinity of each collection site. Those interviewed represented approximately 20-301o of the population. Farms were visited at random until the sample set was completed. The information gathered from the questionnaire survey included the amount of paddy fish harvested and consumed by an individual farmer. Additional information concern- ing the type and amount of insecticides used by the farmers and the frequency of application was also obtained in the interview. The average intake of pesticide was determined by multiplying the mean pesticide residue level in fish (ng/g) by the average daily consumption of fish (g/day) per kg of body weight (bw) of the individual. RESULTS AND DISCUSSION The common paddy fish, Trichogaster pectoralis Regan, is a major source of protein for many Malaysian farmers. Daily fish consumption varied between 54 g and 205 g, and was a function of avail- ability of fish (4). For example, fish are harvested once per season at Tanjong Piandang and the daily es- timated fish intake at that site is only 54 g. At Sungei Burong and Parit Tanjong Piandang, however, fish are caught twice weekly, and the daily fish consump- tion is 173 g and 205 g, respectively. Farmers from the remaining two sites, Sungei Kota and Jalan Bharu, indicated that fish were collected once every 1-4 weeks and hence fish consumption there is inter- mediate. 4398 -251 252 D. F. CHEN ET AL. Table 1. Amount of fish consumed and the respective pesticide residue concentrations at sampling sites in Malaysia Average Concentration of pesticide residues in fish (ng/g)aquantity Sampling of fish No. of site consumed samples Aldrin/ Chlordane HCH DDT b (g/day) dieldrin xx $y Tanjong Piandang 54 6 24.9 ± 7.9 15.0 ± 6.7 12.7 ± 5.2 8.2 6.5 3.5 ± 2.0 14.3 ± 6.8 Sungei Kota 97 16 16.7±7.7 13.3±12.8 6.7±8.5 4.0±2.4 1.4±0.7 1.3±2.9 Jalan Bharu 119 12 21.4±14.0 17.1 ± 11.8 10.7±11.2 3.9±1.9 1.8 ± 2.1 6.8±3.5 Sungei Burong 173 8 15.4±5.9 5.6±4.3 5.4±2.5 3.3 ± 0.8 2.9±1.7 3.9±1.5 Parit Tanjong Piandang 205 8 6.9±4.4 2.8 ± 2.7 2.2 ± 2.2 4.6 ±4.2 1.7 ± 1.0 6.4± 3.6 a Mean ± standard deviation. b Includes DDT, DDE and DDD. Several common pesticides were found in the fish obtained from different sites at varying concen- trations. The highest average pesticide residues were observed in fish from Tanjong Piandang and these concentrations were attributed to the long exposure period (Table 1). At this collection site, the dieldrin level in fish varied from 18.8 to 40.3 ng/g. At Jalan Bharu, the range for this compound was even greater (8.0-63.8 ng/g). Numerous factors contribute to this variability, but spot application of pesticide may be the most important. It is therefore important to examine many subsamples from each site in environ- mental surveys. The average daily intake of pesticide residues was calculated from these data, assuming an average body weight of 60 kg for the consumer. The highest ob- served daily intakes were: aldrin/dieldrin, 44.4 ng/kg of body weight; chlordane, 55.0 ng/kg of body weight; HCH, ,B-isomer, 15.6 ng/kg of body weight and -y-isomer, 8.4 ng/kg of body weight; and DDT, 21.8 ng/kg of body weight. These findings were com- pared with the acceptable daily intake (ADI) values recommended for these compounds by FAO/WHO (Fig. 1). This showed that all the observed daily in- takes of pesticide residues were below the FAO/ WHO ADIs. In fact the aldrin/dieldrin level ap- proaches the ADI (0.1 sg/kg of body weight) only if the highest observed concentration in fish (24.9 ng/g) is multiplied by the highest consumption rate of 205 g/day. These results imply that the Malaysian farmer is not exposed to a considerable health risk. However, it should be noted that this comparison was made only with fish. Rice also makes up a large portion of the diet. Although the pesticide levels in rice were not determined, published values for DDT in rice show a mean of 200 ng/g (5). Besides the rice, the farmer 100.0 m r UT: ST POAICTED WTAKE NIMBT 0""RWE0 DALY NTAG _ FAOIWNSO AINs w w 0.- L 0.01 ml~~~ro*'I ALNINDDALSU ONLOSDANE M' O ST Fig. 1. Comparison of daily intake of pesticide residues in fish by Malaysian paddy-farmers and WHO/FAO- recommended maximum acceptable daily intakes (ADI). may also ingest residues in vegetables, poultry, and pork. Exposure to the pesticides during application could also add to his body burden. Hence, the sum of all these separate components could exceed the FAO/ WHO ADI for some compounds. It is thus not sur- prising that the mean residue level of organochlorine insecticides in the sera of paddy-farmers (185 ng/g) was nearly twice that found in the general Malaysian population.a ' HOR, Y. H. Pesticide pollution - a case study of the organo- chlorine insecticide residues in the sera of the selected groups of the localpopulation. Project report, submitted to the Faculty of Science and Environment Studies, University of Agriculture, Serdang, Selangor, Malaysia. PESTICIDE RESIDUES IN PADDY FISH 253 CONCLUSIONS The residue levels of pesticides found in paddy fish were moderately high considering the short exposure period. These levels should not cause toxic effects in the fish. However, the residues can accumulate to alarming levels in human subjects, particularly when contaminated fish are consumed frequently and in great quantities, as found in this study. On the basis of these findings, it is recommended that existing pro- grammes aimed at educating the Malaysian paddy- farmers on the potential health risk associated with rice-fish culture and the hazards of persistent and toxic insecticides should be improved. Also, add- itional fish sampling and pesticide analysis should be performed in other districts to determine if this study, although small in scope, provided representative data. All possible routes of exposure (i.e., in food, water, and direct) should be considered when assess- ing the potential health risk to the Malaysian paddy- farmers. ACKNOWLEDGEMENTS This work was made possible through the cooperation of the Agricultural Officer at Kuala Kurau and the various paddy farmers. The use of instruments at the University of Michigan Great Lakes Research Division is greatly appreciated. RESUME RESIDUS DE PESTICIDES ORGANOCHLORES DANS LES POISSONS DE RIZIERE EN MALAISIE ET DANGERS QUI EN RESULTENT POUR LA SANTE DES PAYSANS Trois cent trente-deux poissons de riziere de l'espece Tri- chogasterpectoralis Regan ont et preleves en cinq points de sondage dans une vaste zone de riziculture de Malaisie et analyses pour deceler la presence eventuelle de residus organochlores. Dans le meme temps, dix familles de paysans choisies au hasard en chacun des cinq points ont e inter- rogees. On leur a demande des renseignements sur la quantite de poisson consommee, le volume et la nature des pesticides utilises dans la riziere et leur frequence d'appli- cation. Les plus fortes concentrations moyennes de residus de pesticides dans les poissons etaient les suivantes: aldrine/ dieldrine, 24,9 ng/g; chlordane, 27,8 ng/g; HCH, isomere beta, 8,2 ng/g et isomere gamma, 3,5 ng/g; DDT, 14,3 ng/g. Si l'on suppose que chaque personne pese en moyenne 60 kg, on a constate la consommation journaliere la plus elevee suivante: aldrine/dieldrine, 44,4 ng/kg de poids; chlordane, 55 ng/kg de poids; HCH, beta-isomere, 15,6 ng/kg de poids et gamma-isomere, 8,4 ng/kg de poids; DDT, 21,8 ng/kg de poids. Seule la dose maximale projet&e d'aldrine/dieldrine etait voisine de la dose journaliere ad- missible recommandee par la FAO et l'OMS; pour les autres residus, le niveau etait assez faible. Toutefois, 1'etude ne portait que sur le poisson; or la dose journali&e totale de residus de pesticides absorbee par le riziculteur malaisien peut etre augment6e considerablement par la consommation d'autres aliments contamines. REFERENCES 1. SNYDER, D. & REINERT, R. Rapid separation of poly- chlorinated biphenyls from DDT and its analogues on silica gel. Bulletin ofenvironmental contamination and toxicology, 6: 385-390 (1971). 2. Manual of analytical methodsfor the analysis ofpesti- cides in humans and environmental samples. Washing- ton, DC, US Environmental Protection Agency, 1980. 3. HAMMARSTRAND, K. Gas chromatographic analysis of pesticides. California, Varian Associates, 1976. 4. CHEN, D. F. K. Analysis of organochlorine pesticide residues in Malaysian fish and the health risk to human consumption. Ann Arbor, University of Michigan, 1982 (doctoral thesis). 5. CAREY, A. E. ET AL. Pesticide residue levels in soils and crops, 1971. National soils monitoring programme (III). Pesticides monitoringjournal, 12: 117-136 (1978).