Chemical contaminants in selected fish, fisheries products and important foodstuffs of Bangladesh

Abstract

Chemical contamination and adulteration in foodstuffs are quite alarming at present in Bangladesh. This PhD thesis investigates the chemical contaminants in 8 groups of fish, fisheries products and important foodstuffs of Bangladesh (total sample 1215) during April, 2008 to May, 2016. This study also investigates the migration of pesticides from soil and water to paddy in the experimental paddy fields. Samples were supplied to Pesticide Analytical Laboratory, Entomology Division, BARI, Gazipur for identification of residues level of harmful chemicals. BCSIR Laboratory was used for formalin test and proximate analysis of meat, fish, milk, mangoes. Institute of Marine Sciences and Fisheries Laboratory, University of Chittagong and Department of Fisheries Lab, University of Dhaka, were used for proximate analysis of cereal, meat and fish. Proximate analysis was carried on accordingly to the method of AOAC. Chemical residues identification was carried out by BARI laboratory manual 2009. For chemicals test, elute was injected in either run by GC with ECD/FTD/FID and GCMS-EI or GCMS-NCI modes depending on the nature of contaminants. Overall, 31.77% samples of different categories were contaminated with chemicals (e.g., pesticides or formalin). The highest pesticide residues was detected in fruits (in 66.67% sample) followed by fish and fisheries products (60.19%); meat, fat and liver (36.36%); water (26.67%); vegetables (20.98%) and cereals (6.45%). On the other hand, no chemical was detected in milk or eggs. This study also found no migration of pesticides from soil and water to paddy. The pesticide contaminations in fish and fisheries products samples varied geographically: DDT, Heptachlor, Diazinon, Chlorpyriphos, Acephate, Qunalphos, Carbaryl, etc. were abundant in Dhaka, Chittagong and Rajshahi divisions; in contrast, they were not detected in Khulna division. In fish and fisheries products the highest level of DDT was detected in Penaeus monodon (0.127±0.006 ppm) while the lowest level was detected in Pumpus chinensis (0.046 ppm). In the samples, Heptachlor ranged from 0 to 0.210±0.008 ppm and the chemical was only detected in Penaeus monodon from Chittagong among four divisions. Diazinon was found in Labeo rohita, Macrobrachium rosenbergii, Corica soborna, Herpodon nehereus, M. brevicornis, Pumpus chinensis, Pampus argenteus, Trichurus haumela, M. rosenbergii, and P. indicus fish species from different divisions. The highest level of Diazinon was detected in Labeo rohita (1.273±0.097 ppm) from Dhaka division, while the lowest level was detected in M. brevicornis (0.063±0.030 ppm) from Chittagong division. Chlorpyriphos was detected in P. indicus sampled from Chittagong division that was not detected in other divisions. The highest level of Acephate was detected in Labeo rohita (0.917±0.012 ppm) from Rajshahi division, while the lowest level was found in Tenualosa ilisha (0.086 ppm) from Chittagong division. Both Qunalphos and Carbaryl were only detected in fish and fisheries samples from Dhaka division. In most of the fish and fisheries products samples the contamination level exceeded the Acceptable Daily Intake (ADI) and Maximum Residue Limit (MRL) level of FAO and WHO. This study further found that 30.97% fish and shrimp were contaminated by formalin. However, Formalin concentrations varied amongst species and locality: 57.14% Kaski (Corica soborna), 54.29% Lotia (Herpodon nehereus), 54.29% Hilsa (Tenualosa ilisha), 51.43% Kakila (Xenentodon cancila), 48.57% Rupchanda (Pumpus chinensis), 48.57% Catla (Catla catla), 45.71% Mola (Amblypharyngodon mola) 42.86% Pabda (Ompok pabda), 42.86% Rui (Labeo rohita), 40% Chela (Chela cachius), 37.14% Tangra (Mystus vittatus), 37.14% Chapila (Gudusia chapra), 31.43% Prawn (Macrobrachium rosenbergii), 28.57% Shrimp (M. monoceros), 28.57% Vadha (Nandus nandus), 25.71% Sharputi (Puntius sarana), 20% Bowal (Wallago attu) samples from different markets of Chittagong and Dhaka City were contaminated. No formalin was detected in Shrimp (P. indicus), Tilapia (Oreochromis niloticus), Ayer (Mystus aor), Khalisha (Colisa faciatus) and Silver Carp (Hypopthalmichthys molitrix). In beef samples only Diazinon (0.387±0.0E-7 ppm), Quinalphos (0.371±0.021 ppm) and Acephate were detected. In parble (Trichosanthes dioica) only Diazinon (0.047 ppm) and Malathion (0.350 ppm) were detected. These concentrations of pesticides in both beef and parble were beyond the ADI and MRL level. Malathion was also detected as 0.253±0.077, 0.222±0.057, 0.265±0.044, 0.376, 0.293±0.002, 0.250, 0.175, in Solanum melongena, Abelmoschus esculentus, Vigna unguiculata, Momordica charantia and Solanum melongena, respectively. Canal waters were more pesticide contaminated than river water. In drinking water and other supply water the TDS was less than 50 ppm and pH ranged from less than 6.5 to 7.5. The highest level of TDS (332 ppm) was found in both WASA supply water and green coconut water, whereas, the lowest level (19 ppm) was found in Taiwan machine pure drinking supply water. Green coconut, rain water, AC release water and WASA supply water had pH less than 6.5 but Mum and Taiwan machine pure drinking supply water had pH 6.5 to 7.5. Water: River water, WASA water, drinking water, canal water are contaminated and adulterated alarming position because the results beyond of ADI and MRL level. AC water, coconut water, rain water and mum water were free from contamination. Air Condition water is newly invented for using in Bangladesh. Namely AC (1.5 tons) releases 2.25/liters H20 per hour. This type of water is pure and suitable for drinking and so it is a glorious invention for supporting us. The protein standard level (g/100g) was 21.8%, 19.1% and 17.1% in Hilsha (Tenualosa ilisha), Shrimp (Penaeus monodon) and Mola (Amblypharyngodon mola) respectively. Formalin and AlPH3 contaminated foodstuffs decreased protein values. This study concludes that a considerable amount of the samples were adulterated or contaminated by the chemicals which are harmful for human and ecosystem as many of them exceeded the ADI and MRL levels. To get rid of this a combined efforts of the government agencies, policymakers, sellers, farmers, scientists and consumers are needed.