Avicenna Journal of Environmental Health Engineering
Volume:11 Issue: 2, Sep 2024

Environmental issues arising from industrialization and urbanization have grown in frequency and complexity in recent decades. The textile sector is the largest user and generator of dye-laden wastewater, despite its widespread use in several industries. The study explored the adsorption of crystal violet (CV) dye, which is typically found in textile wastewaters, onto peanut hull powder (PHP). Batch tests were done depending on the initial solution pH (2-10), contact time (10-90 min), temperature (15-40 °C), adsorbent dose (0.5-3 g), and adsorbent particle size (150-1180 µm). Depending on the point of zero charge (pHpzc), the optimum value of pH for the solution was above 4.6. The best parameters for removing CV dye using PHP were pH = 6, temperature of 25 °C, adsorbent dose of 1.5 g, and particle size of 150 µm. The highest removal percentage was 95% at a CV concentration of 20 mg/L. The study found that PHP is a viable and inexpensive adsorbent for adsorptive elimination of CV from colored wastewater.

To use biotechnology for environmental decontamination, the current study attempted to isolate bacterial strains capable of assimilating hydrocarbons. To this end, oil-contaminated soil samples were obtained from a gas station in Mascara (Alegria). Two bacterial strains were identified from the tainted soil. The results demonstrated the capacity of these strains to use hydrocarbon substrates as carbon sources, including diesel, benzene, naphthalene, and toluene. The strains’ capacity to break down diesel oil at 1%, 2%, 3%, and 4% (v/v) concentrations was evaluated. According to the biochemical traits identified, the isolated strains S4 and S11 were associated with the gender of Pseudomonas and Staphylococcus, respectively. Based on these findings, both strains grew best when fed a 2% diesel oil substrate. Using oil diesel, benzene, naphthalene, and toluene as substrates, the isolates’ growth measurement characteristics revealed that strain S4 degraded hydrocarbon substrates more effectively than strain S11. In summary, these bacterial strains can reduce petroleum pollution and aid in the bioremediation process.

Due to the widespread use of play doughs among children and the ability to absorb heavy metals and transfer contaminants through the skin, it is essential to determine the level of chemical and microbial contamination of these products to provide a clear picture of their quality. This descriptive cross-sectional study was conducted in the Reference Laboratory of Food and Drug Administration of the Ministry of Health and Medical Education of Iran. For this purpose, 12 samples of play dough were examined. A flame atomic absorption spectroscopy was used to evaluate the concentrations of heavy metals in different samples of play dough. Bacterial isolates were cultured in nutrient-rich microbial culture media and then used for phenotypic isolation and differential detection of bacteria. Based on the results, arsenic was observed in all samples and its mean concentration was 0.12 ppm. Cadmium and lead were present in all samples with mean concentrations of 0.06 and 0.12 ppm, respectively. According to the results, heavy metal concentrations did not exceed the threshold in any of the samples, and all concentrations were within the safe range. The results demonstrated that no microbial contamination related to Escherichia coli, coliforms, Salmonella, Staphylococcus aureus, molds, and yeasts was observed in the dough samples. Therefore, play dough products can be used as safe children’s toys in Iran. However, due to the possibility of microbial contamination over time and repeated use, hygiene practices should be taught to children regarding the use of play toys such as frequent hand washing before and after use.

The effect of environmental pollution on contamination and the safety of foods for human consumption is a serious global issue, which has been widely addressed. Heavy metals are among the most frequent environmental pollutants that are extremely health-threatening. This cross-sectional study aimed at investigating the heavy metal content in different types of bread used in Zahedan, Southeastern Iran. A total of 36 different bread types, such as Sangak, Lavash, and Taftoon, baked by bakeries in Zahedan, were examined for various heavy metals (cadmium, lead, chromium, arsenic, copper, cobalt, mercury, zinc, and nickel) by inductively coupled plasma-optical emission spectrometry. The hazard quotient (HQ) of Taftoon, Lavash, and Sangak was<1 in males, females, and children. In addition, the total health risk of the nine studied heavy metals had a ranking order of HIchildren>HIfemales>HImales>1, demonstrating an increasing potential. The total carcinogenic risk factor for bread was 9.98×10-5 and 3.26×10-3 in males and females, respectively. Regarding the carcinogenicity of heavy metals in bread samples collected in Zahedan, it is highly recommended that measures, such as implementing a food control system, proper flour storage, and training farmers, should promptly be taken to reduce contamination.

A highly stable and high-density amino group (6.54 µmol/m2 ) was loaded on super-hydrophobic silica aerogel derived from pumice by the ultrasonic method and used to remove arsenate (As). After ultrasonic amine grafting, the specific surface area did not change, as 832 m2 /g of a specific surface, a hole volume of 3.84 cm3 /g, and an average hole diameter of 12.39 nm were observable. The selected parameters were directly dependent on As adsorption (100% As removal at the pH rate of 6.85, reaction time of 120 minutes, and initial solute concentration of 95.21 µg/L based on multiple non-linear regression analyses). The kinetics of As adsorption was best explained by the pseudo-first-order kinetic, which is proof of the chemical adsorption mechanism. The heterogeneous surface with multilayer adsorption sites for As adsorption was obtained from various isotherm models. The maximum uptake capacity of 42.2 mg/g was observed based on the Khan model. The spent adsorbent was successfully regenerated and reused by HCl, but a substantial reduction in adsorption capacity was detected after five regeneration-reuse cycles. Based on the results, the ultrasonic method was found to be more effective, economical, and environmentally friendly compared to conventional sol-gel methods for the surface amine functionalization of silica aerogel to remove As from the aqueous solution.

Our objective was to determine the relationship between short-term and long-term exposure to air pollution and COVID-19 mortality and morbidity through a systematic review and meta-analysis. To do so, Scopus, PubMed, and Web of Science databases were searched for original studies up to February 1, 2023. Observational studies reporting risk estimates for the association between air pollution exposure and COVID-19 outcomes were included. The methodological quality of the selected articles was assessed using the Newcastle-Ottawa scale (NOS). Pooled estimates were calculated using a random effects model. We employed the I² statistic and chi-square test to assess heterogeneity among studies. Egger’s and Begg’s tests were used to evaluate potential publication bias. A total of 2823 articles were identified in the initial database search. After screening, 12 studies met the inclusion criteria and were included in the meta-analysis. The results indicated a significant association between PM10 and O3 exposure and COVID-19 mortality, with relative risks of 1.02 (95% confidence interval: 1.01 to 1.04) and 1.09 (95% confidence interval: 1.04 to 1.14), respectively. Our meta-analysis suggests that exposure to O3 and PM10 is associated with an increased risk of COVID-19 mortality. Additionally, the study found a significant link between exposure to NO2 , PM2.5, and PM10 and increased COVID-19 mortality, with PM2.5 showing the strongest association. These findings underscore the need for effective policies to mitigate the health impacts of air pollution and highlight the importance of integrated strategies to address the broader effects of climate change.

Heavy metals from hazardous waste, such as batteries, electronics, cleaning products, and cosmetics, can be transported to soil through landfill leachates. Due to their persistent structure, toxic metals such as chromium (Cr), cobalt (Co), lead (Pb), and cadmium (Cd) accumulate in the soil and can cause various ecological and health risks. Hence, this study aimed to assess the extent of heavy metal pollution in the soil of landfill sites in Iran. The present study reviewed previous research on the assessment of heavy metal contamination such as Pb, arsenic (As), Cr, Cd, zinc (Zn), Co, and nickel (Ni) in soils of landfill sites. For this purpose, “Magiran”, “SID”, «IranMedex», “Scopus», “PubMed”, “ScienceDirect” and “Web of Science” databases were searched for related articles published until 2024. Persian and English keywords including heavy metals, waste disposal sites, soil, and Iran were used for search. Eventually, out of 206 articles, 21 studies met our inclusion criteria and were included in the study. The concentrations of heavy metals, including Pb, As, Cr, Cd, Zn, Co, and Ni, were found to be higher than national and international standards in some soil samples. Therefore, landfill sites, as an anthropogenic resource, have the potential to transmit pollution to the soil. Contamination levels depend on waste composition, hazardous content, leachate production and migration, landfill age and design, soil characteristics, and operating conditions. Health and ecological risks can be mitigated by reducing hazardous waste, recycling heavy metal-containing wastes, installing anti-seepage systems, and maintaining continuous monitoring.

Microplastics (MPs) are persistent pollutants that pose significant long-term environmental risks, particularly in urban landfill soils, which have received less attention than aquatic environments. This review sought to address this gap by investigating microplastic contamination across various soil layers at landfill sites. The results indicated that factors such as landfill age and waste composition significantly influence the types and concentrations of MPs. Concentrations varied with soil depth, with higher levels observed in older landfills containing substantial quantities of plastic waste. Regions characterized by extensively weathered plastic waste exhibited a greater prevalence of smaller microplastic particles. The extensive production of plastic waste, coupled with its associated health and environmental risks, highlights the urgent need for policies to reduce plastic consumption and enhance recycling efforts. Given the critical role of soil in the food chain and its connections to air and water pollution, ongoing monitoring of soil contamination by MPs is essential. Additionally, identifying sources of microplastic pollution and implementing strategies to mitigate their entry into the environment are crucial to addressing this growing environmental concern.