RESUMO
OBJECTIVE: In recent years, lead (Pb) has arisen as a foremost contaminant due to overpopulation, rapid industrialization, and expansion that could contaminate the human food chain. However, the correlation between the environmental contamination of Pb and its spatial transfer to the dairy products is still unmapped. In this paper, we intend to evaluate the concentration of environmental Pb and its spatial distribution in dairy feed and products in Narayangonj, a highly polluted district of Bangladesh. MATERIALS AND METHODS: A total of 125 samples of soil, water, forage, and milk were collected from five upazilas (Narayangonj Sadar, Bondor, Rupgonj, Araihazar, and Sonargoan) of Narayangonj. The samples were digested by acid digestion, and Pb was detected by flame atomic absorption spectrophotometer and graphite furnace atomic absorption spectrometer. The bioconcentration factor of the samples was also calculated. RESULTS: In this study, 25% of the soil, 20% of the water, 5% of the forage, and 2% of the milk samples contained Pb at a variable level. Among the environmental samples, the highest concentration (26-39 µg/kg) of Pb was detected in the soil, followed by in the water (0.023-0.059 µg/kg) and forage (0.017-0.035 µg/kg). The contamination (0.041-0.068 µg/kg) in the milk, however, was lower than the soil but higher than the water and forage. The concentration of Pb in all the samples was within a safer limit. None of the forage samples was the potential bioaccumulator. CONCLUSION: Although no linear correlation was established between the environmental samples, forage, and milk, the study identifies the potentials of the spatial distribution of Pb from the environment to the dairy feed and products. Therefore, feasible procedures should be adapted to cease the residue to the human food chain.
RESUMO
OBJECTIVE: To analyze the presence of selective antibiotic residues (oxytetracycline, amoxicillin, and ciprofloxacin) in milk during the antibiotic treatment course, and to evaluate the thermal effect on antibiotics residual status in milk of antibiotic-treated cows. MATERIALS AND METHODS: The raw fresh milk was collected from 18 lactating cows before antibiotics treatment, which were brought to the veterinary hospital and suffered from either mastitis, foot and mouth disease, fever, local wound, or non-specific diarrhea, and so on. Out of the 18 lactating cows, six were treated with oxytetracycline, six were treated with amoxicillin, and six were treated with ciprofloxacin parenterally. Milk samples were also collected at 2nd day during treatment and final collection was done after maintaining the withdrawal period. Since milk is heated before consumption, it was boiled at 100°C for 20 min to evaluate the thermal effect on antibiotics residual status. Thin-layer chromatography was done for screening of antibiotics residue before and after boiling of the milk. RESULTS: At day 0 (before antibiotic treatment), no antibiotics (oxytetracycline, ciprofloxacin and amoxicillin) residue was detected in raw milk of antibiotic treated cows. In contrast, on day 2 (during antibiotic treatment), 100% raw milk samples showed positive for antibiotics residue. After boiling, all milk samples showed positive for such specific antibiotics residue. On the other hand, no antibiotics residues were detected on day 9, which indicates the completion of the withdrawal period of the respective antibiotic. The intensities of bands for antibiotic on thin-layer chromatography plate of antibiotic residues in milk samples (oxytetracycline, amoxicillin, and ciprofloxacin) expressed that the respective antibiotic residual status was higher in the boiled milk compare to the raw milk. CONCLUSION: Proper maintenance of withdrawal period after antibiotic treatment would minimize the risk of antibiotic residues in milk, and boiling does not change these specific antibiotics residual status in milk. Therefore, awareness regarding the proper maintenance of withdrawal period after antibiotic treatment in lactating cows is one of the best strategies that may positively reduce the risk of antimicrobial drugs residue in milk.