Monday, January 13, 2020
Lead Contamination in Agro-Based Products as Current Public Health Threat in Bangladesh
Lead contamination in agro-based products as current public health threat in Bangladesh A. M. M. Maruf Hossain1*, M. Shahidul Islam2, Md. Moklesur Rahman1, Md. Mustafa Mamun1, M. Azizul Islam Kazi2, and Syed Fazle Elahi1 1Department of Soil, Water and Environment, Faculty of Biological Sciences, University of Dhaka; 2Analytical Research Division, BCSIR Laboratories, Dhaka. *Corresponding author Abstract: Agro-based products are primary to all human food sources. Contamination in these is also the easiest way of human health getting affected in large scale. Among the myriad of agro-based products, commercially produced milks and eggs were sampled. Chicken eggs were sampled from Dhaka and its nearby other seven districts covering the central region of Bangladesh. Dhaka, Narsingdi, Kishoreganj, Mymensingh, Tangail, Gazipur, Narayanganj, and Munshigonj were selected for the study. Twelve eggs were randomly sampled from each district’s egg stock market. In Dhaka, Gazipur, and Tangail’s market both brown and white colored eggs were found. Six eggs from each type were sampled from these three districts. In the rest five districts only brown colored eggs could be found. Commercial liquid milks of 13 prominent milk producers have been sampled with replication. Introduction: Poultry plays a vital role in the economy of Bangladesh in recent years. The contribution by livestock is 3% of the total GDP (BBS, 2004) and nearly 10% of the agricultural GDP (Poultry Business Directory, 2007). As food poultry provides meat and egg. An egg is a good source of energy, protein, and fat. A 50 g weighing grade A chicken egg provides estimated values of 297 KJ energy, 6g protein, 5g fat (1. 5g saturated, 2. 0g monounsaturated, and 0. 8g polyunsaturated), and 190mg cholesterol. Chicken eggs are the most commonly eaten eggs, and are highly nutritious (FAO, 2007). They supply a large amount of complete, high-quality proteins (which contains all essential amino acids for humans), and provide significant amounts of several vitamins and minerals, including vitamin A, riboflavin, folic acid, vitamin B6, vitamin B12, choline, iron, calcium, phosphorus and potassium. Again liquid milk is an important source of fat, lactose sugar, and proteins (Casein, Albumin). Egg and milk are essential contexts to our daily diet. Bangladesh has a long historical record of raising poultry under traditional backyard farming. In 1935 improved variety of birds were first introduced in the countries. In the long run it is in the early nineties that a number of private parent stock farms have started their operation to produce commercial Day Old broiler and layer Chicks. Today for commercial egg production layer chicks from these farms are being used. Commercial egg production mostly uses the layer breeds of Hyline Brown, Hyline White, Hisex Brown, Hisex White, ISA Brown, Lohman Brown, Shaver White, and Shaver 579. The prominent milk producers have their own farms in Bangladesh. They produce and market both pasteurized and UTH (ultra high temperature) processed milks. For egg and milk urban people depend completely on commercially produced products while rural people have some practice of backyard farming. As industrial and agricultural practices are not strictly regulated and maintained environment-friendly in Bangladesh, contamination can happen in many ways especially with heavy metals. For this reason a widely distributed egg samples have been collected from Dhaka and its surrounding other seven districts where industrial activities and hence pollution is most prevalent. Similarly a number of liquid milks were sampled with replication to reflect a representative picture. Materials and Methods: Sampling area for egg: The egg sampling area constituted eight districts including capital Dhaka and covered the central region of Bangladesh. Dhaka, Narsingdi, Kishoreganj, Mymensingh, Tangail, Gazipur, Narayanganj, and Munshigonj were selected for the study. Twelve eggs were randomly sampled from each district’s egg stock market. In Dhaka, Gazipur, and Tangail’s market both brown and white colored eggs were found. Six eggs from each type were sampled from these three districts. In the rest five districts only brown colored eggs could be found. The sampling area is shown in gray color in Figure 1. Figure 1: Map of Bangladesh representing the darkened study area Milk sampling: Commercial liquid milks of 13 prominent milk producers have been sampled with three replications in each. These covered liquid white, mango, chocolate, and banana milks. Aarong – white, Aarong – chocolate, Aarong – mango, Milkvita – white, Milkvita – chocolate, RD – white, RD – mango, RD – banana, Amo – white, Amo – chocolate, Amo – mango, Pran – white, and Starship – chocolate liquid milks were selected for the study. Sample pretreatment: ? The egg samples were boiled in deionized water and after complete boiling albumen and yolk were separately oven-dried at 80oC to remove all moisture. The samples were oven-dried unless the difference between two readings of weight was found negligible. Each of oven-died albumen and yolk were treated and analyzed separately. ? A portion of the liquid milk samples were used for density measurement. Milk samples were treated and analyzed as it is. Sample preparation method: The samples were prepared by using HNO3 – HClO4 digestion (Kebbekus & Mitra, 1998). Since the samples were of organic origin with a very high organic content, HNO3 – HClO4 digestion was preferred over the more common HNO3 extraction for the determination of heavy metals. This strongly oxidizing digestion decomposes organics quickly and efficiently. Sample analysis: Analysis of all prepared samples was performed through atomic absorption spectrophotometry (AAS). BDH standard solution was used for preparation of lead (Pb) standard curve. During the sample preparation for arsenic determination, hydrochloric acid (at least 11. 6 ml concentrated HCl for 100 ml total sample) and KI (at least 1 %) were added. For the other heavy metals no special treatments were done. Hydride vapor generation technique was used in the determination of arsenic and mercury. Chromium, cadmium, lead, and arsenic determination were done in air-acetylene flame whereas mercury determination was done in cold vapor. The lead (Pb) contamination in eggs is calculated by using the average parameter values of total 96 eggs sampled, where albumen and yolk have been studied separately in each egg (Table – 1). Table – 1: Average physical parameters for 96 egg samples from 8 districts Average physical parameter |Average |Standard error | |Whole weight of eggs, g |55. 5098 |0. 7590 | |Shell: albumen: yolk ratio |1: 4. 8672: 1. 9775 |NA | |Albumen raw weight, g |34. 4401 |- | |Albumen moisture content, % |84. 0603 |0. 1512 | |Albumen dry weight, g |5. 900 |- | |Yolk raw weight, g |13. 9930 |- | |Yolk moisture content, % |51. 3656 |0. 1616 | |Yolk dry weight, g |6. 8054 |- | The lead (Pd) contamination in comme rcially produced chicken eggs in Bangladesh is presented in Table 2 (average dry weight basis). Revise SPSS with all new â€Å"data†Table – 2: Pb contamination of chicken eggs in Bangladesh Sample classes |Pb in Egg albumen |Pb in total |Pb in Egg yolk |Pb in total |Total Pb in each |Pb in total egg | | | µg/g |Egg albumen | µg/g |Egg yolk |egg (albumen + |(albumen + yolk), | | |(dry weight) | µg |(dry weight) | µg |yolk),  µg | µg/g | | | |(dry weight) | |(dry weight) | | | | |Values for 6 |5. 905 |30. 6918 |18. 3190 |124. 6680 |155. 3599 |12. 6356 | |Brown Egg |samples | | | | | | | |(Dhaka) | | | | | | | | | |St. error |1. 1043 | – |4. 439 | – | – | – | |White Egg (Dhaka) |Values for 6 |11. 1847 |61. 4041 |6. 4769 |44. 0777 |105. 4818 |8. 5790 | | |samples | | | | | | | | |St. error |1. 7396 | – |2. 627 | – | – | – | |Brown Egg (Narsingdi) |Values for 12|10. 4818 |57. 5453 | 15. 0153 |102. 1849 |159. 7302 |12. 9911 | | |samples | | | | | | | | |St. error |2. 3770 | – |3. 458 | – | – | – | |Brown Egg |Values for 12|9. 4945 |52. 1248 |10. 6030 |72. 1574 |124. 2822 |10. 1080 | |(Kishoreganj) |samples | | | | | | | | |St. error |0. 5917 | – |0. 7616 | – | – | – | |Brown Egg Mymensingh)|Values for 12|9. 4769 |52. 0279 |5. 7009 |38. 7969 |90. 8248 |7. 3869 | | |samples | | | | | | | | |St. error |1. 1593 | – |0. 6024 | – | – | – | |Brown Egg (Tangail) |Values for 6 |11. 565 |60. 7000 |5. 4060 |36. 7898 |97. 4898 |7. 9290 | | |samples | | | | | | | | |St. error |4. 4361 | – |1. 8938 | – | – | – | |White Egg (Tangail) |Values for 6 |11. 3587 |62. 594 |0. 7730 |5. 2602 |67. 6197 |5. 4996 | | |samples | | | | | | | | |St. error |2. 4524 | – |0. 4713 | – | – | – | |Br own Egg (Gazipur) |Values for 6 |6. 8734 |37. 7349 |1. 755 |11. 4023 |49. 1372 |3. 9964 | | |samples | | | | | | | | |St. error |2. 0868 | – |0. 6178 | – | – | – | |White Egg (Gazipur) |Values for 6 |5. 9167 |32. 4825 |2. 2874 |15. 666 |48. 0491 |3. 9079 | | |samples | | | | | | | | |St. error |2. 1738 | – |1. 2855 | – | – | – | |Brown Egg |Values for 12|0. 7702 |4. 2285 |5. 4222 |36. 9002 |41. 1288 |3. 451 | |(Narayanganj) |samples | | | | | | | | |St. error |0. 4071 | – |1. 9852 | – | – | – | |Brown Egg (Munshigonj)|Values for 12|11. 3360 |62. 2346 |8. 8177 |60. 0079 |122. 2426 |9. 9421 | | |samples | | | | | | | | |St. rror |2. 3649 | – |2. 7654 | – | – | – | Maximum permissible limit in chicken meat is 0. 1  µg /g and in chicken fat is 0. 1  µg /g(1). The average statistics for all egg samples are presented in Table 3 . Table – 3: Statistics of all egg samples |Total sample number |192 | |Mean |8. 1611 | |Std. Error of Mean |0. 5253 | |Minimum |ND* | |Maximum |34. 5637 | * = Not detected The average lead (Pb) contamination picture in commercially produced liquid milks in Bangladesh is presented in Table 4. Table – 4: Pb contamination picture in liquid milks in Bangladesh |Sample classes |Average density |Volume as packed, mL|Average Pb |Standard error |Average total Pb | | | | |concentration in | |in packet,  µg | | | | |sample,  µg/mL | | | |Aarong – white |1. 0207 |250 |0. 8102 |0. 2451 |202. 500 | |Aarong – chocolate |1. 0511 |200 |1. 5344 |0. 2675 |306. 8800 | |Aarong – mango |1. 0554 |200 |0. 9447 |0. 3961 |188. 9400 | |Milkvita – white |1. 0226 |250 |0. 9739 |0. 3212 |243. 4750 | |Milkvita – chocolate |1. 0548 |200 |1. 2925 |0. 6512 |258. 5000 | |RD – white |1. 193 |230 |1. 9657 |0. 1987 |452. 1110 | |RD – mango |1. 0523 |200 |1. 6984 |0. 4812 |339. 6800 | |RD – banana |1. 0552 |200 |1. 209 |0. 5012 |241. 8000 | |Amo – white |1. 0257 |250 |1. 4943 |0. 1246 |373. 5750 | |Amo – chocolate |1. 0577 |200 |0. 181 |0. 1789 |163. 6200 | |Amo – mango |1. 0619 |200 |0. 8997 |0. 8047 |179. 9400 | |Pran à ¢â‚¬â€œ white |1. 0256 |200 |1. 2886 |1. 0079 |257. 7200 | |Starship – chocolate |1. 0508 |200 |4. 7589 |1. 4347 |951. 7800 | Maximum permissible limit in milks is 0. 02  µg /mL(1). The average statistics for all milk samples are presented in Table 5. Table – 5: Statistics of all milk samples |Total sample number |39 | |Mean |1. 5145 | |Std. Error of Mean |0. 2165 | |Minimum |ND | |Maximum |7. 0713 | Standard for lead (Pb) content of milk and poultry products: Comparing the obtained data from the egg and milk samples with the standards set in â€Å"Codex general standard for contaminants and toxins in foods (CODEX STAN 193-1995, Rev. -2006)†, it is evident that these foods are heavily contaminated with Pb in Bangladesh. In case of both egg and milk, the average Pb levels are about hundred times higher than the maximum permissible limits whereas the maximum respective values are quite large. 1. CODEX STAN 193-1995, Rev. 2-2006. http://www. codexalimentarius. net/web/index_en. jsp 2. Kebbekus, B. B. , and S. Mitra. (1998). Environmental chemical analysis. (Blackie Academic & Professional, London). [pic]
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