Detection and health risk assessment of toxic heavy metals in chilled and frozen meat collected from Sharkia province in Egypt.

Background: The consumption of meat is a fundamental aspect of global diets, providing essential nutrients and proteins vital for human nutrition. However, ensuring the safety of meat products has become progressively challenging due to potential contamination by toxic heavy metals (HMs) and pathogenic microorganisms. Aim: This study focuses on assessing the prevalence of Lead (Pb), Mercury (Hg), Arsenic (As), and Cadmium (Cd), in chilled and frozen meat in Sharkia Governorate, Egypt. Methods: A total of 30 samples, comprising 15 chilled and 15 frozen beef samples, were collected from various marketing stores in Sharkia. Analysis of toxic metals was conducted via atomic absorption spectrophotometer (AAS) following wet digestion. Results: The average levels (mg/kg) in chilled meat samples were found to be 0.64 ± 0.14 for Pb, undetectable for Hg, 0.02 ± 0.14 for Cd, and 4.66 ± 0.57 for As. In frozen samples, the average concentrations were 0.89 ± 0.21 for Pb, 0.08 ± 0.03 for Hg, 0.02 ± 0.004 Cd, and 5.32 ± 0.59 for As. Generally, the levels of HMs in frozen meat samples were observed to be higher than in chilled samples. Importantly, the levels of Pb were higher than maximum residual concentrations [maximum permissible limit (MPL)] in 53.3% of the chilled and 66.6% of the frozen, Cd levels in chilled and frozen were within the permissible concentrations in all samples, Hg was not identified in all the chilled and in 67% of frozen samples, and As levels were higher than the permissible levels in all samples chilled and frozen. The assessment of human health risk for adults revealed an estimated daily intake (EDI) value of beef meat below the threshold of the oral reference dose (RFD) for all analyzed metals except for As, where 46.7% of chilled samples and 60% of frozen samples exceeded the RFD. Furthermore, both the Hazard Quotient (THQ) for As and Hazard index (HI) for all the analyzed metals were above 1 in 33.3% of chilled samples and 46.7% of frozen samples. Conclusion: This indicates the remarkable adverse effects on human health associated with the consumption of meat with elevated levels of HMs, emphasizing the need for stringent quality control measures within the food industry.

Toxicity assessment using different bioassays and microbial biosensors.

Toxicity assessment of water streams, wastewater, and contaminated sediments, is a very important part of environmental pollution monitoring. Evaluation of biological effects using a rapid, sensitive and cost effective method can indicate specific information on ecotoxicity assessment. Recently, different biological assays for toxicity assessment based on higher and lower organisms such as fish, invertebrates, plants and algal cells, and microbial bioassays have been used. This review focuses on microbial biosensors as an analytical device for environmental, food, and biomedical applications. Different techniques which are commonly used in microbial biosensing include amperometry, potentiometry, conductometry, voltammetry, microbial fuel cells, fluorescence, bioluminescence, and colorimetry. Examples of the use of different microbial biosensors in assessing a variety of environments are summarized.

Intron retention in the 5'UTR of the novel ZIF2 transporter enhances translation to promote zinc tolerance in arabidopsis.

Root vacuolar sequestration is one of the best-conserved plant strategies to cope with heavy metal toxicity. Here we report that zinc (Zn) tolerance in Arabidopsis requires the action of a novel Major Facilitator Superfamily (MFS) transporter. We show that ZIF2 (Zinc-Induced Facilitator 2) localises primarily at the tonoplast of root cortical cells and is a functional transporter able to mediate Zn efflux when heterologously expressed in yeast. By affecting plant tissue partitioning of the metal ion, loss of ZIF2 function exacerbates plant sensitivity to excess Zn, while its overexpression enhances Zn tolerance. The ZIF2 gene is Zn-induced and an intron retention event in its 5'UTR generates two splice variants (ZIF2.1 and ZIF2.2) encoding the same protein. Importantly, high Zn favours production of the longer ZIF2.2 transcript, which compared to ZIF2.1 confers greater Zn tolerance to transgenic plants by promoting higher root Zn immobilization. We show that the retained intron in the ZIF2 5'UTR enhances translation in a Zn-responsive manner, markedly promoting ZIF2 protein expression under excess Zn. Moreover, Zn regulation of translation driven by the ZIF2.2 5'UTR depends largely on a predicted stable stem loop immediately upstream of the start codon that is lost in the ZIF2.1 5'UTR. Collectively, our findings indicate that alternative splicing controls the levels of a Zn-responsive mRNA variant of the ZIF2 transporter to enhance plant tolerance to the metal ion.

Oxytetracycline residues in bovine carcasses slaughtered at Mansoura Abattoir, Egypt.

Oxytetracycline residues were examined in 600 samples (200 each of muscles, livers and kidneys) collected randomly from bovine carcasses slaughtered at Mansoura abattoir in Dakahlia Province, Egypt. A microbial inhibition test using Bacillus subtilis ATCC- 6633 was employed to screen the obtained samples for antibiotic residues in meat. The results showed that 2% of samples were positive. Oxytetracycline residues exceeded the maximum residue limits (MRLs) in 1.33% of the examined samples. Thus, regulatory authorities should insure proper withdrawal period before slaughtering of the animals (28 days for oxytetracycline). Public health importance was discussed.

Heavy metal residues in canned fishes in Egypt.

A total of 75 random canned fish samples, 25 each of canned (canned tuna, sardine and mackerel) during 2009, were collected from Zagazig Markets for determination of lead, cadmium, zinc, copper and tin residues using atomic absorption spectrophotometer. The obtained results revealed that the mean values of the lead residues in the examined canned tuna, sardine and mackerel were 0.127 +/- 0.02, 0.013 +/- 0.004 and 0.023 +/- 0.01 (ppm) respectively. The mean concentrations of cadmium residues were 0.022 +/- 0.001, 0.048 +/- 0.003 and 0.027 +/- 0.003 ppm, respectively. While in case of zinc, the residual levels were 1.97 +/- 0.12, 2.369 +/- 0.32 and 1.126 +/- 0.24 ppm, respectively. Copper residual levels in the examined samples were 0.293 +/- 0.08, 0.221 +/- 0.03 and 0.08 +/- 0.02 ppm, respectively. In case of tin, the residual levels were 1.496 +/- 0.30, 1.209 +/- 0.26 and 0.379 +/- 0.11 ppm respectively.