Akele M L, Abebe D Z, Alemu A K, Assefa A G, Madhusudhan A, de Oliveira R R
Department of Chemistry, College of Natural and Computational Sciences, University of Gondar, P.O. Box 196, Gondar, Ethiopia.
Bio-analysis Group, Department of Analytical Chemistry, University of Barcelona, Diagonal 645, 08028, Barcelona, Spain.
Environ Monit Assess. 2017 Sep 11;189(10):499. doi: 10.1007/s10661-017-6203-0.
Concentrations of essential (Cu, Mn, and Zn) and toxic (Cr, Cd, and Pb) trace metals in 30 raw cow's milk samples were quantified using flame atomic absorption spectrometry. The samples were collected from the Nara-Awudarda, Tana-Abo, and Kosoye Amba-Rass sites in North Gondar, Ethiopia, preserved in a deep freezer (-20 °C), and then digested by Kjeldahl apparatus with HNO/HO (5:2; v/v) at 300 °C for 2.5 h. The data were subject to principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA). Overall hazard quotient (HQ) and carcinogenic risk (CR) values were also estimated to assess metal-related health risks. The mean concentrations of Cr, Mn, Cu, Zn, Cd, and Pb in the milk samples ranged 0.468-0.828, 1.614-2.806, 0.840-1.532, 1.208-5.267, ND-0.330, and ND-0.186 mg/kg, respectively. The lowest values were obtained for Kosoye Amba-Rass milk samples, while the highest were found for those collected from Nara-Awudarda milk samples, probably due to high mineral enrichment and metal leaching (especially Cd and Pb) from coal deposits. PCA revealed clustering of samples with respect to their geographic origin. Validation of PLS-DA model showed 100% classification efficiency using external validation samples and detected Cd and Cu as trace metal markers. The HQ and CR values were within the safe level; however, the former is close to the alert threshold level for Nara-Awudarda milk samples. Thus, further studies on common foodstuffs, constituting a higher proportion in the local diet, are required in this area to provide a complete risk assessment.
采用火焰原子吸收光谱法对30份生牛奶样品中的必需微量元素（铜、锰和锌）和有毒微量元素（铬、镉和铅）进行了定量分析。这些样品采集自埃塞俄比亚北贡德尔的纳拉-阿乌达达达、塔纳-阿博和科索耶安巴-拉斯地区，保存在深冻柜（-20℃）中，然后用凯氏定氮仪在300℃下以硝酸/过氧化氢（5:2；v/v）消化2.5小时。对数据进行了主成分分析（PCA）和偏最小二乘判别分析（PLS-DA）。还估计了总体危害商（HQ）和致癌风险（CR）值，以评估与金属相关的健康风险。牛奶样品中铬、锰、铜、锌、镉和铅的平均浓度分别为0.468 - 0.828、1.614 - 2.806、0.840 - 1.532、1.208 - 5.267、未检出 - 0.330和未检出 - 0.186毫克/千克。科索耶安巴-拉斯牛奶样品的含量最低，而纳拉-阿乌达达达牛奶样品的含量最高，这可能是由于煤矿床中矿物质富集和金属浸出（特别是镉和铅）所致。主成分分析揭示了样品按地理来源的聚类情况。偏最小二乘判别分析模型的验证显示，使用外部验证样品时分类效率为100%，并检测出镉和铜为微量元素标志物。危害商和致癌风险值在安全水平内；然而，前者接近纳拉-阿乌达达达牛奶样品的警戒阈值水平。因此，该地区需要对当地饮食中占比更高的常见食品进行进一步研究，以提供完整的风险评估。
