Heavy Metal Residues Research Articles

Individual and combined hepatocytotoxicity of DDT and cadmium in vitro.

The organochlorine insecticide dichlorodiphenyltrichloroethane (DDT) and heavy metal cadmium (Cd) are widespread environmental pollutants. They are persistent in the environment and can accumulate in organisms. Although the individual toxicity of DDT and Cd has been well documented, their combined toxicity is still not clear. Since liver is their common target, in this study, the individual and combined toxicity of DDT and Cd in human liver carcinoma HepG2 and human normal liver THLE-3 cell lines were investigated. The results showed that DDT and Cd inhibited the viability of HepG2 and THLE-3 cells dose-dependently and altered lysosomal morphology and function. Intracellular reactive oxygen species and lipid peroxidation levels were induced by DDT and Cd treatment. The combined cytotoxicity of DDT and Cd was greater than their individual cytotoxicity, and the interaction between Cd and DDT was additive on the inhibition of cell viability and lysosomal function of HepG2 cells. The interaction was antagonistic on the inhibition of cell viability of THLE-3 cells. These results may facilitate the evaluation of the cumulative risk of pesticides and heavy metal residues in the environment.

Selection of copper and zinc dosages in pig diets based on the mutual benefit of animal growth and environmental protection

Dietary copper and zinc additives facilitate the growth and development of animals, but heavy metal in feces threatens the ecological environment, and balance is the key to solving the problem. In this study, a trial of 2000 pigs (early nursery, 9–15 kg; late nursery, 15–25 kg; grower: 25–60 kg) was conducted to analyze the effects of different diets (gradient dosage of copper and zinc additives) on growth performance, antioxidant performance, immune function, and fecal heavy metal excretion of piglets and growing pigs. Although no significant differences were observed in average daily gain (ADG) and average daily feed intake (ADFI) between treatments during the entire nursery-grower period, the addition of appropriate high doses of copper and zinc to the diet had a beneficial effect on the antioxidant status and immune function of weaned piglets. Especially at early nursery, compared with the low-copper group (5 mg/kg Cu), the high-copper group (120 mg/kg Cu) could significantly increase the peroxidase (POD), glutathione peroxidase (GSH-PX), total antioxidant capacity (T-AOC), catalase (CAT) and copper/zinc superoxide dismutase (Cu/Zn-SOD), cortisol in the serum. Moreover, the addition of zinc and copper in the diet not only increased the concentration of corresponding trace elements in the serum, but also affected the concentration of other trace elements in the serum. The reduction of copper and zinc content in the diet contributed to reducing the copper and zinc content in feces. In conclusion, we have formulated the mutual benefit dosages of copper and zinc (9–15 kg: 5 mg/kg Cu and 50 mg/kg Zn; 15–25 kg: 4 mg/kg Cu and 50 mg/kg Zn; 25–60 kg: 4 mg/kg Cu and 10 mg/kg Zn) for weaning piglets and growing pigs, which would help ensure the healthy growth of animals and reduce environmental heavy metal residues. CapsuleThis study developed a mutually beneficial dose of copper and zinc in pig diets, which promotes animal growth and protects the environment.

The Measurement of Cadmium, Zinc and Silver in Chicken Meat in Isfahan Province, Iran

Background: One of the concerns of consumers of animal protein sources is the residues of heavy metals in meat. The accumulation of these elements in meat and the consumption by humans can cause acute and chronic disorders in the function of vital organs. Methods: For the estimation of cadmium, zinc and silver in the poultry meat products, 100 samples of chicken breasts, thighs, hearts and livers were collected from meat markets in Isfahan Province. The tissues were digested and passed through filter paper, and the cadmium, zinc and silver contents were measured by an atomic absorption spectrophotometer. Results: The mean contents of cadmium in the chicken thigh, breast, liver and heart samples were 0.055±0.021, 0.048±0.023, 0.074±0.031, and 0.012±0.004 mg/kg, respectively. The mean contents of zinc in the chicken thigh, breast, liver and heart samples were 17.19±8.10, 15.70±5.75, 22.10±10.87, and 19.70±10.38 mg/kg, respectively. The concentrations of cadmium and zinc were below the international permissible limits in all samples. The mean concentrations of silver in some chicken thigh, breast, liver and heart samples were 0.0080±0.0044, 0.0048±0.0013, 0.012±0.009 and 0.0036±0.006, respectively. Of note, silver was not detected in most chicken samples. Conclusion: This study did not find cadmium, zinc and silver in the chicken meat samples above the international permissible limits. However, frequent monitoring for heavy metals in poultry meat sold in public markets is warranted to prevent their transmission to the human food chain.

Study of the Some Heavy Metals Residues in the Camel Meat in different regions of Kirkuk governorate during the spring and Summer Seasons

For the purpose of searching for levels of some heavy contamination in muscle, liver and kidney meat for Camel in Kirkuk governorate in spring and summer seasons, samples were collected randomly from males (aged 4-5 years) from three reigns of Kirkuk governorate (Kirkuk center, Shwan and Laylan) During the March and April (spring season) and May and July months of (summer season) in 2020. There was a significant effect (p ≤ 0.05) on the factors (meat type, location and season) in the concentration of lead, Kidney meat in the Kirkuk center in the spring season recorded the highest concentration of lead and significant difference (8.008 ppm) The lowest concentration (2.211 ppm) was found in Liver in Spring. The highest concentration level of cadmium in muscle in summer season from Kirkuk center (4.191 ppm) in muscle, and lowers Concentration of cadmium (2.961 ppm) recorded in kidney from Laylan in summer season. The concentration of zinc in the Liver at the Kirkuk center in the summer season was the highest concentration (138.221 ppm), while the Kidney in the spring season from Kirkuk center recorded the lowest concentration (28.347 ppm). For Copper the liver in the Kirkuk center in the spring season had the highest concentration (26.754 ppm), while the Liver from the Kirkuk center at summer was recorded lowest concentration (4.663 ppm). For Cobalt, in spring season in Kirkuk, the Muscle recorded the highest concentration of cobalt (8.194 ppm) in summer, while the lowest concentration was recorded in Kidney the spring season from Kirkuk center (1.913 ppm). All types of metals recorded levels higher than the internationally accepted limits.

A fuzzy best–worst method (BWM) to assess the potential environmental impacts of the process of ship recycling

ABSTRACT The marine environment has been under threat due to the residues and pollution created during the ship recycling process. Materials contained in ship structure or equipment are the main concern that causes pollution of soil, air, marine, and freshwater resources at the ship recycling process. Accordingly, chemical and biological contaminants that may be released to the environment are the main elements of the ship recycling process. The emphasis of this research is therefore on the assessment of materials found in the ship structure or equipment of hazardous materials. To do so, this paper has applied the best–worth method (BWM) using fuzzy sets. The sets are based on surveys and questionnaires answered by industry experts. The findings of the research show that H4 (heavy metal residues) (H6) (polychlorinated organic compounds (PCBs), tin compound tributyltin (TBT), and asbestos (H3) are the most hazardous materials. Therefore, the study results also have the potential to assist professionals, policymakers, and regulatory authorities in the successful handling of hazardous materials that may release into the environment during the recycling process of ships. Consequently, the research provides a robust analytical model to assess the actual hazardous materials for the prevention and control of environmental pollution.

Effects of Dietary Inclusion Level of Microwave-Dried and Press-Defatted Black Soldier Fly (Hermetia illucens) Larvae Meal on Carcass Traits and Meat Quality in Broilers.

Simple SummaryInsects are a potential source of protein for broiler diets because of the high price and limited supply of soybean. Black soldier fly (Hermetia illucens; HI) larvae are promising candidates as an alternative protein source to soybean meal; a microwave drying method is a convenient approach for producing HI larvae meal (HILM), as it is time- and energy-efficient. However, whether microwave-dried HILM is an appropriate protein source for producing healthy chickens for consumers has not been evaluated. Therefore, we examined the effect of 0, 25, and 50% dietary replacement of soybean meal with HILM on carcass traits, meat quality, and safety. We observed satisfactory results for the meat quality and fatty acid composition without detrimental effects on undesirable heavy metal residues in the meat. However, the carcass weight was reduced in 50% HILM-substituted diets, suggesting that a low level of HILM is beneficial. Microwave-dried HILM is a promising ingredient for broiler diets. However, further research is needed to overcome the lowering of the carcass weight in terms of utilization efficiency by improving the manufacturing process.Limited information is available regarding the use of microwave-dried Hermetia illucens larvae meal (HILM) as a dietary protein source for broiler diets. Therefore, we investigated the effects of microwave-dried HILM on carcass traits, meat quality, fatty acid (FA) profiles of abdominal fat and meat, and heavy metal residues of the meat in broilers. A total of 126 male broilers were randomly assigned to three dietary treatment groups (6 replicates and 7 birds/pen): a control diet and two experimental diets in which soybean meal was replaced with 25 or 50% HILM. The broilers were slaughtered at 35 days; the carcasses were weighed, and breast and leg meats were excised from 12 birds per treatment (2 birds/pen) for meat analysis. The breast meat quality and proximate composition showed satisfactory results. For the higher HILM diet, the content of saturated FA in the abdominal fat was increased and that of polyunsaturated FA was decreased (p < 0.001); the FA profile of leg meat did not significantly differ between groups. The concentrations of undesirable heavy metals in the HILM and leg meat were below permissible levels. However, the carcass weight was decreased (p < 0.001) in the 50% HILM group. Microwave-dried HILM is a potential ingredient for broiler diets, with up to 25% substitution showing no detrimental effects on carcass traits, meat quality, FA profiles, and heavy metal residues in the meat.

Hazard analysis and critical control point of milkfish floss production as indigenous food from Banten province

Milkfish floss is indigenous food from Banten which is produced by Small and Medium Enterprise (SME). Milkfish floss is potential to be developed due to the high demand from outside Banten areas, but it is very easy to get rancidity, spoilage by the microbes, or existing dust and hair. Therefore, milkfish floss production process still needs to improve the processing method according to the standards to produce a safe and good product. Quality assurance is done by compiling hazard analysis and control point (HACCP) documents. The aim of this study was to identify hazards of raw material and production chain, determine CCPs in every chain, and create HACCP document plan. The research method was conducted by interview, observation, laboratory analysis, and literature review. The compiling of the HACCP document is carried out in several steps including creating a HACCP team, identification of consumers and product descriptions, making processing flow diagrams, identifying hazards, determining critical control points (CCPs), determining the critical limit, monitoring, and correcting action. The hazards that may occur in milkfish floss are residues of heavy metals, pathogenic microbes, thorns, dust, and hair. The CCPs of raw material are fish, lemongrass, lime leaves, shallot, and garlic, while the CCPs of the processing are the acceptance of fish, cleaning, steaming, frying, draining, and packaging.

PRESENCE OF HEAVY METALS (LEAD AND CADMIUM) IN MEAT SAMPLED FROM THE TAMALE ABATTOIR AND RISK ASSESSMENT

The study investigated the presence and concentration of possible heavy metals residues in meat processed at Tamale abattoir. A total of twenty-seven (27) animal parts (liver, kidney and muscles) from goats, sheep and cattle were sampled and analysed for heavy metals using the Graphite Furnace Atomic Absorption Spectrophotometer (GFAAS). Means and standard deviations of Pb and Cd concentrations were computed from the data collected to test for the difference in heavy metal concentrations in the various meat samples. Liver samples from all three different animals were found to contain the highest concentration of Pb (3.17±2.39 mg/kg) and Cd (3.47±3.19 mg/kg). The sampled muscles of all animals used had an average Cd concentration above the permissible. Pb concentrations in cattle and sheep were found to be higher than the permissible limits indicated by the World Health Organisation and United States Environmental Protection Agency. The average daily dose (ADD) of Pb exposure to humans via ingestion were 7.64 × 10˗9 ˗ 2.19 × 10˗8 for children and 3.27 ˗ 9.35 × 10˗9 for adults. For Cd, the ADD were 1.96 ˗ 4.57 × 10˗6 for children and 1.13 ˗ 2.63 × 10˗7 for adults. Human health risk assessment proved no eminent risk of carcinogenicity to consumers, but it is estimated that the higher levels of Pb and Cd in the meat samples may pose a potential health risk over a period of continual exposure. Keywords: Heavy Metals, Kidney, Liver, Muscle, Abattoir

Hydrophobic deep eutectic solvent-based ultrasonic-assisted dispersive liquid-liquid microextraction for preconcentration and determination of trace cadmium and arsenic in wine samples

In present study, DL-lactic acid/trioctylmethylammonium chloride-based deep eutectic solvent (DES), which was considered as an environmental friendly extraction solvent to replace traditional organic reagent, was firstly presented for monitoring of trace cadmium (Cd) and arsenic (As) in wine samples by ultrasonic-assisted dispersive liquid-liquid microextraction (UA-DLLME) method. Moreover, different extraction conditions, including the type and volume of DES and dispersive solvent, pH of the solution, salt amount, time of vortex and sonication, were systematically evaluated. At the optimized extraction conditions, good linear relationships (0.50–8.0 μg·L−1 for Cd, 2.0–50 μg·L−1 for As) were obtained and limits of detection of Cd and As were 0.080 and 0.30 μg·L−1, respectively. In addition, the accuracy (as recoveries %), and intra-/inter-day precision (as relative standard deviation %) were in the ranges of 90.6–103.6% and 2.9–4.5%, respectively. Finally, the proposed method was applied to analyze 6 kinds of wine samples, which possessed wide practical application value in monitoring heavy metal residues in wine and even complex food matrices.

Effect of controlled soil drying on the grain yield and nutritional quality of rice

AbstractControlled soil drying can substantially enhance water use efficiency by reducing irrigation water. However, grain quality traits are yet to be studied under such an irrigation regime, particularly on nutritional quality and heavy metal residues. This study investigated these issues by using two varieties Yongyou 2640 (YY‐2) and Nanjing 9108 (NJ‐9). Rice (Oryza sativa L.) was grown in the field under controlled soil drying (SD) and continuous flooding irrigation (FI). The results showed that, compared with FI, SD increased grain yield and nutritional quality simultaneously for both NJ‐9 and YY‐2. When compared with NJ‐9, YY‐2 had greater grain and protein yield, higher concentrations of As and Cd, and higher photosynthetic rate and transpiration rate when plants were rewatered. Although the relative content of protein and essential amino acids decreased in the SD regime, the absolute content (protein yield and amino acid yield) was increased. Besides, SD improved protein components and essential amino acid score (AAS) and decreased residues of As. The results demonstrated that SD improved photosynthetic characteristics and increased grain abscisic acid levels of inferior grains during soil drying. The results suggest that the adoption of SD may exert a synergistic effect on both grain yield and grain quality.

Effects of Long-term Fertilization Systems on Heavy Metals Residues in Sod-podzolic Soil and Oats Yield

Background: The paper presents the results of studies conducted on the basis of the former Smolensk branch of Pryanishnikov Institute of Agrochemistry, in the village of Olsha, Smolensk district, Smolensk region. In a long field experiment, various fertilizer systems were studied, their effect and aftereffect on the qualitative and quantitative crop yield, soil properties.Methods: A stationary field experiment was established in 1978. The aftereffect of fertilization systems on oats has been studied since 2009. The aftereffect was studied in 2015-2016 and 2017. With one dose of organic fertilizer (compost based on cattle manure - cattle), over 30 years of experience, 17.4 tons of organic matter, 435 kg of total nitrogen, 198 kg of phosphorus (P2O5), 621 kg of potassium (K2O) entered the soil. A single calculated dose of nitrogen, phosphorus and potassium corresponded to 25.5 kg of active ingredient per ha-1. Result: With prolonged use of fertilizers, the content of heavy metals in the soil did not exceed the calculated permissible concentration. However, at a fivefold norm (N150P150K150 + 15 t ha-1), the cadmium content was overestimated. An ecologically justified dose of aftereffect in the Smolensk region on sod-podzolic soil should be considered a fourfold dose of mineral components and compost (N120P120K120 + 12 t ha-1).

Analysis and Evaluation of Pollutant Residues in Freshwater Fish at Jiamusi Section of Songhua River

Carp from Jiamusi section of Songhua River were collected to analyze and evaluate the residues of heavy metals, organochlorine pesticides, polycyclic aromatic hydrocarbons and volatile organic compounds in muscle tissue. The results showed that 100% of heavy metals, organochlorine pesticides and polycyclic aromatic hydrocarbons were up to standard, and a small amount of volatile organic compounds were detected. The structure and morphology of fish tissue samples were not abnormal, and the structure of nucleus and cytoplasm was normal. No pathological changes or morphological abnormalities were found. Fish were healthy.

Deep High-moisture Soil pH Test Equipment and Method

Excessive use of chemical fertilizers in the soil will cause excessive residues of heavy metals, soil hardening and high soil alkalinity. A soil pH tester is generally used to test the soil pH scale to ensure the normal growth of crops. However, the tester cannot be used directly in the case of soil hardening and the soil should be moistened before measurement. In addition, existing soil pH testers can only perform single-point tests, and multiple tests are generally required in order to obtain accurate experimental data. Common deep soil pH test devices are difficult to use and have the problem of inaccurate measurement results due to excessive impurities in the soil in the process of use, resulting in errors in soil analysis which require secondary revision to improve the soil environment. To make up for the defects of existing technologies, this study designs a deep high-moisture soil pH tester, which has the advantage of high soil impurity filtering performance and addresses the problem of inaccurate measurement results due to excessive impurities in the soil.

Analysis and Risk Assessment of Heavy Metal Residues in Fish in Songhua River Basin

Thirty samples of crucian carp and carp are collected in upstream pine forest, midstream Dadingzi mountain and downstream Jiamusi section in the main stream of Songhua river. The ICP method is used to test heavy metals content of the fish. The exposure health risks of exposed way of edible fish in the Songhua River is assessed by exposure to the health risk assessment model. The results show that the noncarcinogenic target risk quotient (THQ) of each heavy metals is less than 1. The biggest heavy metal of the noncarcinogenic risk is As. From high to low in the order, the THQ is As>Cu>Mn>Pb>Cd. Composite exposure non carcinogenic hazard index (HIsF) is 0.18∼0.23. As of fish exposed can cause the evident in the risk of cancer, TR is 2.89×10−5∼6.78×10−5.

Investigation on pesticide and heavy metal residues of late vegetable in Zengcheng District of Guangzhou

Investigation on pesticide and heavy metal residues of late vegetable in Zengcheng District of Guangzhou

Assessment of Pb, Cd, As and Hg concentration in edible parts of broiler in major metropolitan cities of Tamil Nadu, India.

The risk of heavy metals contamination in meat and meat products is of great concern for both food safety and from human health point of view. The present study was carried out to assess the heavy metal residues such as Pb, Cd, As and Hg in broiler chicken meat, neck and edible organs (liver and kidney). In the present study, 150 samples were randomly collected from major cities (Chennai, Coimbatore, Madurai, Trichy, and Salem) of Tamil Nadu state, India and analyzed for Pb, Cd, As and Hg residues (mg/kg) using inductively coupled plasma-mass spectrometry (ICP-MS) technique. The results revealed that lead (Pb) concentration was higher in meat and liver samples of all cities and the highest concentration was detected in Chennai followed by Coimbatore, whereas in kidney and neck samples, Chennai metropolitan alone exceeded the MRL value of 0.5 and 0.1 mg/kg respectively. The residues of cadmium and mercury in meat and meat samples were within the permissible limit in all the metropolitans. Arsenic was found exceeding the MRL of 0.1 mg/kg in the breast samples of all the metropolitans (0.2141-2.2285 mg/kg, the highest being in Trichy), except for Madurai, which recorded very low value (0.0239 mg/kg). Arsenic was found in the range of 0.1110-1.0850 mg/kg in liver samples thus exceeding MRL value. Neck and kidney samples did not contain any Arsenic. Thus it can be concluded that the lead concentration in meat and edible organ samples collected from all the metropolitans exceeded the MRL values and is an indication of contamination. Appropriate precautions are warranted to minimize the heavy metal consumption contamination especially of Pb and As.

Determining the Levels of Some Heavy Metals in Springs and Groundwater Wells in the Northeastern Region of Libya

This study was designed to detect heavy metals (Zn, Cd, Pb, and Cu) in several springs and groundwater wells in the northeastern region of Libya. Samples were collected from different regions in both seasons (dry and wet). An atomic absorption spectrophotometry equipped with Slotted Tube Atomic Trap (STAT) was used. The limit of detection (LOD) was in the range of 0.008 to 0.03 μg mL-1, and the limit of quantification (LOQ) was in the range of 0.02 to 0.09 μg mL-1. % RSD (relative standard deviations) ranged between 0.0001 to 0.329%. Results showed the presence of heavy metal residues in the regions in two seasons (dry-wet) during the study in some springs and groundwater wells. The zinc (Zn), cadmium (Cd), and Copper (Cu) values were below permitted limits, according to the World Health Organization (WHO), Libyan National Center for Standardization (LNCSM), and Food and Agriculture Organization (FAO). Lead (Pb) in the dry season was much higher than the wet season in accordance with WHO and LNCSM. The other values were below permissable limits according to WHO, LNCSM, and FAO. This study’s results show the presence of dangerous levels of lead during the dry season in the groundwater wells on SahlAlmarj I, Alabyar III. Overall, the investigation of chemical and agricultural fertilizers is an effective method of monitoring the quality of drinking water. Such investigations are needed to identify possible sources of contamination of storage tanks and pipelines to ensure the delivery of safe drinking water to end-users.

Implementation of food safety management systems that meets ISO 22000:2018 and HACCP: A case study of capsule biotechnology products of chaga mushroom.

In our study, a food safety management system was developed for a chaga mushroom biotechnology product manufacturer, with the purpose of meeting the quality demands of customers and enhancing the manufacturer's reputation. The study focused on identifying the potentially significant hazards present at each stage of the production process for chaga mushroom capsule products, and on ensuring that the biotechnology company in question has fully implemented ISO22000:2018 and the HACCP methodology. The results indicate that, in the 1 year following the implementation of ISO 22000:2018, there was a statistically significant drop (P <0.05) in the coliforms level of the tested biotechnology product samples that started in the ninth month following implementation. The rapid screening of mycotoxin, heavy metal, and pesticide residue levels also increased monitoring intensity and strengthened the periodic rotation plan, enabling control over potential problems relating to raw materials and ensuring product quality. This finding reveals the importance and necessity of rapid screening for small- and medium-sized food industry enterprises. Furthermore, 1 year after the system's implementation, the defect rate for chaga products was also observed to have declined, and the number of process flow anomalies requiring correction was also found to have decreased significantly (P <0.05), indicating that safety and quality levels were improving and stabilizing. If implemented over a longer period of time, the food safety management system's benefits would stand out even more, and significant improvements would be observed for more monitored items. PRACTICAL APPLICATION: Few studies have touched on food safety management systems (FSMSs) developed for capsule health food products. The enterprise examined in this study had actively worked to improve its quality system and meet its customers' needs through the implementation of the FSMSs.

Postharvest Quality and Safety of Potted Greenhouse Tomato Grown on Forest Soil-Biosolids substrate, Blended with NPK Fertilizer

Studies on the effects of biosolids (BS) amended substrate on food quality and safety in tomato production have not been adequately addressed. The objective of this study was to investigate the influence composted BS and NPK fertilizer in forest soil on post-harvest quality and safety of potted greenhouse tomatoes. Potted tomatoes ‘Maxim F1’were grown in a randomized complete block design with four replications. Inorganic fertilizer NPK fertilizer was applied at 0, 100 and 200 kg ha-1; BS was applied at 0%, 10%, 20%, 30%, and 40% v/v, in all possible combinations. Tomato were harvested and analyzed for ascorbic acid, chlorophylls, carotenoids and total phenolic compounds; weight loss, fruit firmness, titratable acidity and total soluble solids, as well as heavy metals and microbial contaminants. Results revealed that tomato fruit at 10% BS in combination with NPK fertilizer at 100 kg ha-1had highest β-carotene (6.1 mg 100 g-1), lycopene (26.1 mg 100 g-1), ascorbic acids (128.0 mg 100 g-1), total phenolic acids (13.2 mg 100 g-1), total soluble solids (17%). However, the same rates produced tomato fruits with lower titratable acidity (2.2%) and had heavy metal residues within the permissible level, according to International EPA standards on biosolids utilization on food crops production. Similarly, no trace of targeted bacteria; Salmonella, Escherichia coli, Staphylococcus was observed on the ready to eat tomato. This study reveals BS 10% with NPK fertilizer at 100 kg ha-1 substrate as a better option of plant nutrient source for quality and safe greenhouse tomato production.

Chemical residues in ready to eat fish products

A total of one hundred random samples of ready to eat (RTE) fish products represented by fried Oreochromis niloticus, grilled Oreochromis niloticus, smoked Herring and salted Sardine (25 of each) were collected from different fish markets and restaurants in Menofia governorate, Egypt. The aim of this study was to estimate the concentration levels of chemical residues such as heavy metals residues (mercury, lead and cadmium) and pesticides residues (aldrin and malathion) through subjection the examined samples to atomic absorption spectrophotometer for detecting the residues of mercury, lead and cadmium and gas chromatography for the residues of aldrin and malathion. The mean values of mercury (mg/Kg) in fried O. niloticus, grilled O. niloticus, smoked herring and salted sardine were 0.43±0.01, 0.59±0.01, 0.70±0.01 and 0.94±0.02, respectively. The mean values of lead (mg/Kg) in fried O. niloticus, grilled O. niloticus, smoked herring and salted sardine were 0.27±0.01, 0.33±0.01, 0.45±0.01 and 0.61±0.01, respectively. The mean values of cadmium (mg/Kg) in fried O. niloticus, grilled O. niloticus, smoked herring and salted sardine were 0.11±0.01, 0.14±0.01, 0.20±0.01 and 0.29±0.01, respectively. The mean values of aldrin (ppb) only detected in fried O. niloticus, grilled O. niloticus and salted sardine were 82.95±4.19, 151.26±7.40 and 193.02±8.81, respectively. The mean values of malathion (ppb) only detected in grilled O. niloticus and salted sardine were 96.57 and 248.19±10.32, respectively. As conclusion, chemical examination of RTE fish products is a sensitive indicator verifying the quality and good hygienic status of RTE fish products. Keywords: Mercury; Lead; Cadmium; Aldrin; Malathion