Assessment Of Human Health Risk Based On Heavy Metal Distribution Characteristics In Broiler Chicken Tissues: A Case Study In Pearl River Delta

With the economic developed, the pace of life is accelerating, anthropogenic inputs of heavy metals in the environment are increasing, more and more toxic substances are being thrown into the environment, and the animal origin foods are inevitably become “invaded” by heavy metals. Chicken is one of the main food of animal origin in South China and the dominant species of poutry(including chicken, duck, and goose), the poultry production in Guangdong province is ranked secondary in China. Guangdong province is not only a better economic development province but also an agricultural productive province, with the Pearl River Delta as its economic development center. However, previous reports had shown that the environment of this region is polluted by heavy metals significantly. Here comes the question, whether the pollution of heavy metals in the environment will pose a threat to food security and human health? To answer this question, a study of the quality and safety of chicken tissues from this region has been done. The study is conductive to reveal the impact of economic development and the intensive farming on people’s lives from the side. This dissertation is systematically studied on four sections, and the mainly conclusions are as follows.1. Heavy metals(As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, and Zn) pollution presented in chicken tissues, which purchased from livestock markets. Based on the statistic analysis, the distribution of heavy metals in chicken tissues were concluded as follows.(1) Chicken might have the ability to accumulate the nutrition elements(Zn, Cu, Mn, Se) or alternatively excrete the toxic elements(Cd, As, Ni, Pb).(2) As is much easier accumulated in chicken liver then the other chicken tissues, and Cr and Ni are tended to accumulate in chicken kidney.(3) The correlation analysis indicated that migrations of As and Co happened between chicken muscle and chicken liver.2. Estimation of heavy metal exposures to consumers through chicken diet and assessment of human health risk(non carcinogenic risk and carcinogenic risk) of adults(Body Weight=60 kg) and children(Body Weight=30 kg) from heavy metal exposures are studied. Children are the environmental vulnerable popution right after the infants and the people who need special care. At the level of the 97.5th percentile of the heavy metal contamination, the ranges of hazard index(HI) of the non carcinogenic risk from As, Cd, Ni, and Pb for adults and children are 0.12-0.38 and 0.23-0.76, respectively. At the level of the 97.5th percentile of the heavy metal contamination, children in urban households in Guangdong province who consume more slaughtered chicken than otherpopulation is threatened by heavy metals exposure, and the most likely to face the non carcinogenic effects. By inversion calulation, the daily consumpiton thresholds of chicken meat, chicken liver, and chicken stomach are 450 g, 107 g, and 248 g for adults, and 225 g, 53.6 g, and 124 g for children. In order to protect the children from harm, critical measures must be established by the relevant departments and organizations. Basically, the degree of human health risk from heavy metals exposure mainly depends on the food intake and the degree of heavy metals pollution in food, which means to eat less might be the best choice unless the situation is better developed.3. The microwave-assisted extraction method of arsenic species from chicken tissues using Response Surface Methodology(RSM) was optimized. RSM was applied to optimize the parameters for microwave-assisted extraction(MAE) of six major inorganic and organic arsenic species(As(III), As(V), DMA, MMA, p-ASA, and ROX) from chicken tissues. The inorganic and organic arsenic species in the extracts were analyzed by HPLC-ICP-MS at the same time with the same chromatography column and the same elution fluid. Effects of extraction medium, solution p H, liquid-to-solid ratio, and the temperature and time of MAE on the extraction efficiency(EE) of the arsenic species were studied. The optimum MAE conditions were found to be: 100 mg of chicken tissue, extracted by 5 m L of 22% v/v methanol, 90 mmol L-1(NH4)2HPO4, and 0.07% v/v TFA(with p H adjusted to 10.0 by diluted nitric acid and ammonium hydroxide), ramping for 10 min to 71 oC, and holding for 11 min. The optimum MAE method obtained acceptable values of extraction efficiency for the spiked and the nonspiked chicken tissues(104.0±13.8% and 91.6±7.8%, respectively), except for the chicken tissues with low level of As(under the quantitation limits). Limits of quantitation(S/N=10) for As(III), As(V), DMA, MMA, p-ASA, and ROX in chicken tissues(dry mass) using the MAE method and HPLC-ICP-MS detection were 0.012, 0.058, 0.039, 0.061, 0.102, and 0.240 mg kg-1, respectively.4. Heavy metal pollution in sediments of a typical maricul-ture zone in South China was carried out. This study shown that the aquacultural zone was significantly more polluted than the non-aquacultural zone, and that the surface sediment in the aquacultural zone(100 ≤ RIE < 150, moderate risk) posed much higher potential risks than the non-aquacultural zone(RIE < 100, low risk), suggesting the additional sources of heavy metal inputs in the aquacultural zone.