Iranian Journal of Health and Environment

The investigation of biological degradation of sodium dodecyl sulfate and its associated COD in wastewater using anoxic baffled reactor

Seyed Gholamreza Moussavi

Background and Objective: This study investigated the efficiency of an anoxic baffled reactor (AnBR) system for the biological treatment of synthetic wastewater containing sodium dodecyl sulfate (SDS) as a representative anionic surfactant, with the goal of enabling safe discharge into the environment.
Materials and Methods: The research aimed to examine the effects of SDS concentration as a substrate, hydraulic retention time (HRT), and the type of electron acceptor (nitrate or organic materials) in the AnBR reactor. Daily measurements of influent and effluent wastewater were conducted to assess surfactant, chemical oxygen demand (COD), and nitrate levels.
Results: The average COD removal efficiencies at SDS concentrations of 200, 250, 350, and 500 mg/L were 99.6%, 99.8%, 99.6%, and 99.3%, respectively, under steady-state conditions. The SDS removal efficiency for all concentrations was 99.8 ± 0.2%. As the HRT decreased from 24 to 4 hours, the COD removal efficiency dropped from 99.4% to 90.9%. At an SDS concentration of 250 mg/L and an HRT of 4 hours, the effluent SDS concentration was 11 mg/L, which meets the discharge standards for surface water (1.5 mg/L). The removal of nitrate from the influent indicated a significant decrease in system efficiency, demonstrating that nitrate was consumed as an electron acceptor and SDS was degraded under anoxic conditions. PCR testing revealed that Bacillus species were the dominant bacteria in the AnBR.
Conclusion: Given the high removal efficiencies of SDS and COD, this process can be recommended for the degradation of anionic surfactants in wastewater from industries producing such pollutants.

Assessment of cancer and non-cancer health risks associated with exposure to black carbon particles in the ambient air of Tehran city

Alireza Pardakhti

Background and Objective: Black carbon is a byproduct of the incomplete combustion of fossil and biomass fuels. Long-term exposure to black carbon has been linked to an increased risk of lung cancer and cardiovascular diseases. This study aims to evaluate the carcinogenic and non-carcinogenic risks associated with black carbon exposure in the ambient air of Tehran.
Materials and Methods: Hourly black carbon concentrations were collected from the air quality monitoring stations operated by Tehran's Air Quality Control Company and averaged to calculate annual means for 2021, 2022, and 2023. The risk assessment for black carbon exposure in Tehran was conducted using the US EPA model.
Results: The findings reveal that in Tehran, the carcinogenic risk index (CR) due to black carbon exposure in ambient air is higher for adults than for children. The non-carcinogenic risk quotient (HQ) for both age groups remains below the threshold value of one, indicating a low and negligible non-carcinogenic risk. However, children demonstrate a higher HQ compared to adults. The lifetime cancer risk associated with black carbon exposure is calculated to be 1.4 × 10^-3, while the annual cancer risk is estimated at 0.02 × 10^-3.
Conclusion: The results indicate that the carcinogenic risks associated with black carbon exposure exceed acceptable levels for both adults and children. Adults face a cancer risk six times greater than children, though the non-carcinogenic risk is assessed as low. Reducing black carbon emissions is critical for improving public health in traffic-congested cities, and further research on this topic is strongly recommended.

Measurement of toxic and essential metal in yogurt and kashk and risk assessment by Latin Hypercube method

Sara Sohrabvandi

Background and Obejective: Many elements can naturally or artificially enter human food and pose risks to human health. Some of these elements are toxic, while others are essential for humans. The purpose of this study is to investigate the concentrations of toxic elements (aluminum (Al), arsenic (As), cadmium (Cd), nickel (Ni), and lead (Pb)) and essential elements (cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn), and zinc (Zn)) in yogurt and kashk samples.
Materials and Methods: In this study, the concentration of 10 elements was measured using an ICP-OES device in 48 samples (with two repetitions each) of yogurt and kashk collected from Tehran. The risk associated with human exposure to these metals was then calculated using the Latin Hypercube method.
Results: The results showed that in all samples, the highest and lowest average concentrations of essential elements (in µg/kg) were attributed to iron (567.53) and cobalt (10.58), respectively. Similarly, the highest and lowest average concentrations of toxic elements were attributed to arsenic (28.60) and cadmium (1.08), respectively.
Conclusion: Finally, it can be concluded that the average concentration of all elements—except for Pb, Co, and Cd—was higher in kashk than in yogurt. Additionally, the average concentration of all elements was below the established standards. However, the risk analysis results indicated that children are more exposed to non-carcinogenic risks from yogurt and carcinogenic risks from the consumption of both yogurt and kashk compared to adults.

The microbiological quality assessment of dewatered and stored sludge in one of the wastewater treatment plants in Tehran during the winter season for agricultural use

Shahrokh Nazmara

Background and Objective: Sewage sludge, a byproduct of wastewater treatment plants, is rich in organic matter and nutrients. With appropriate treatment, sludge can be utilized as a fertilizer for agriculture and soil amendment. This study aimed to evaluate the microbial quality of wastewater treatment plants in Tehran.
Materials and Methods: This study was conducted during the winter of 2018. A total of 25 samples were collected from the dewatering tank and sludge storage areas. Fecal coliform counts were determined using EPA Method 1681, while Salmonella and parasite egg counts were assessed using EPA Methods 1682 and 1992, respectively.
Results: In the dewatered sludge, fecal coliform levels ranged from a minimum of 67 MPN/g.TS on the first day to a maximum of 18,518 MPN/g.TS on the third day. Salmonella levels measured on the fifth, eighth, and tenth days were 0.55, 0.32, and 0.66 MPN/4g.TS, respectively. Parasite egg counts recorded on the second, ninth, and tenth days were 4 OVA/4g.TS. In the stored sludge, regardless of depth or geographic location of the disposal land, fecal coliform counts during retention times of 2, 3, 4, 5, 6, 7, 8, and 9 years were 10, 186, 480, 30, 27, 29032, 2, and 11 MPN/g.TS, respectively. Salmonella and parasite eggs were not detected in the stored sludge.
Conclusion: The findings indicate that, in the sludge storage unit compared to the sludge dewatering unit, achieving Class A standards for sludge is feasible through continuous quality monitoring.

Estimation of the amount of electrical and electronic waste (e-waste) generated by households and government offices in Abadeh Tashk city, Fars province, using the consumption and use method

Soheila Rezaei

Background and Objective: The rapid development of technology in recent decades has led to a significant increase in the consumption of electronic products, with global e-waste generation reaching approximately 2.5 million tons per year. However, there is limited local data on the amount of e-waste produced. This study aims to estimate the quantity and composition of valuable and hazardous components in e-waste generated by households and government offices in Abadeh Tashk.
Materials and Methods: A questionnaire was used to determine the number of 27 types of electrical and electronic equipment present in 200 households and 40 government offices in Abadeh Tashk city in 2022. The production of e-waste was then estimated using the consumption-and-use method, based on the average weight and lifespan of the equipment. Valuable components such as iron, copper, aluminum, plastic, silver, gold, tin, and zinc, along with hazardous components including cobalt, barium, arsenic, antimony, chromium, nickel, lead, and mercury, were identified and quantified.
Results: It was estimated that households generated 25 kg/year of e-waste per household, equivalent to 7.9 kg/year per capita. Government offices produced a total of 3.53 tons/year of e-waste. The total weight of valuable components was 574.85 kg for households and 24.41 kg for government offices, while the total weight of hazardous components was estimated at 25.99 kg and 1.07 kg, respectively. Iron and plastic accounted for more than 70% of the valuable components, while arsenic and lead constituted over 60% of the hazardous components in these wastes.
Conclusion: Considering the significant presence of valuable components in the e-waste of Abadeh Tashk city and the potential for their recycling, as well as the environmental and health risks posed by hazardous components, effective planning for e-waste management is essential. Such efforts could mitigate adverse effects on human health and the environment while promoting resource recovery.

Evaluation of environmental health status of Saveh confectionery workshops in the conditions of Corona epidemic

Hossein Azarpira

Background and Objective: Regular assessment of confectionery workshops and comparison of their conditions with health standards can enhance the sanitary quality of products. This study aimed to evaluate the environmental health status of confectionery workshops in Saveh in 2022.
Materials and Methods: In this cross-sectional analytical study, the environmental hygiene status of all confectionery workshops in Saveh was evaluated using a researcher-designed, validated, and reliable checklist comprising 51 questions tailored for COVID-19 conditions, based on Step 2 guidelines for combating the virus. A total of 36 confectionery workshops were assessed, and responses to the questions were recorded as "Yes," "No," or "Not Applicable." Data were analyzed using independent samples t-tests and one-way ANOVA in SPSS software.
Results: The average health compliance in Saveh’s confectionery workshops was 61% for personal hygiene, 68% for food hygiene, 60% for tool and equipment hygiene, 55% for building hygiene, and 74% for hygiene education. Significant relationships were found between areas such as building hygiene, food hygiene, and hygiene education, and workshop characteristics such as building size, sales volume, production scale, and worker age and experience (p < 0.05). However, no significant relationship was observed between the number of refrigerators and the hygiene of tools and equipment (p > 0.05).
Conclusion: The results of this study indicate that the overall health status of confectionery workshops in Saveh was relatively favorable. However, the building hygiene variable (55%) had the lowest level of compliance among the investigated factors, highlighting an area that requires attention.

Study of the litter in urban environment in Behbahan in 2023 based on the clean environment index

Ahmad Badeenezhad

Background and Objective: Littered waste is one of the most common forms of pollution in urban environments, primarily caused by citizens’ behavior in waste disposal. This study aimed to investigate the density and composition of littered waste in Behbahan, Iran, in 2023 and assess the pollution status using a specific environmental index.
Materials and Methods: This descriptive cross-sectional study evaluated the density and composition of littered waste in Behbahan's urban environment using visual surveys. The findings on the density and composition of abandoned waste were interpreted using the Clean Environment Index, an environmental ranking method that assesses the severity of litter pollution.
Results: The study revealed that the density of littered waste in the surveyed areas ranged from 0.011/m² to 0.954/m². The average density of littered waste in commercial, residential, and recreational land uses was 0.809/m², 0.196/m², and 0.011/m², respectively. Cigarette butts were the most common type of litter, constituting 61% of the total waste on average. The Clean Environment Index values for the surveyed locations ranged from 0.39 to 32.56, indicating that 63.6% of the sites were categorized as clean or moderately polluted, while 36.3% were classified as extremely polluted.
Conclusion: Given the significant proportion of cigarette butts in the composition of littered waste in Behbahan and their impact on the pollution index, efficient management strategies for this type of waste are crucial. The finding that over one-third of the surveyed locations fell into the "extremely dirty" category highlights the need to enhance the efficiency of the urban cleaning system.

Assessment of benzoic acid, sorbic acid and ethanol level by high performance liquid chromatography and gas chromatography in industrial kefir products offered in the Iranian retail market

Behrouz Akbari-adergani

Background and Objective: Benzoate and sorbate are utilized to prevent the growth of microorganisms and to extend the shelf life of most food products. However, according to national hygienic regulations, the use of these two preservatives in kefir is not permitted. In this study, the concentration of these preservatives in kefir was determined using high-performance liquid chromatography. Additionally, due to the importance of this issue and compliance with national regulations—which specify a maximum ethanol limit of 0.5% in kefir—the ethanol content of this product was also determined using the gas chromatography method.
Materials and Methods: In this descriptive-cross-sectional study, 88 samples of industrially produced kefir from different brands were randomly collected from various regions of Iran and sent to the laboratory at 4 °C. Statistical analysis of the data was performed using SPSS software, and one-way ANOVA was applied to compare the mean values. In all tests, a significance level of 0.05 was considered.
Results: Sorbate was not detected in any of the samples, while benzoate was observed in only 11 samples, with an average concentration of 0.6763 mg/L. The average concentration of ethanol was 0.2997%, and in 10 samples, the ethanol content exceeded 0.5%, which is in violation of national regulations.
Conclusion: The presence of trace amounts of sorbate in the product may be attributed to the activity of lactic acid bacteria. The increase in alcohol percentage could also be due to insufficient control over the fermentation process during production. To improve nutritional quality and safeguard consumer health, it is recommended that limits be established for preservatives in this product.

Ecotoxicological assessment of mixture exposure to silver and graphene oxide nanoparticles, case study: histopathology effects of gill and intestine tissues of guppy fish (Poecilia reticulata)

Soheil Sobhanardakani

Background and Objective: Growing concerns exist regarding the impact of nanoparticles on organisms and environmental health. This study aimed to investigate the effects of silver and graphene oxide nanoparticles on the gill and intestinal tissues of guppy fish (Poecilia reticulata) during acute toxicity exposure.
Materials and Methods: The acute toxicity (LC50) for both nanoparticles was calculated over a 96-hour period using Probit software. Histopathological examination of the gill and intestinal tissues exposed to the nanoparticles was performed using the hematoxylin-eosin staining method. A semi-quantitative approach was employed to assess the severity of tissue damage.
Results: The LC50 values for silver nanoparticles, graphene oxide nanoparticles, and their combination were determined to be 2.6 mg/L, 65.2 mg/L, and 1.8 mg/L, respectively. Simultaneous exposure to these nanoparticles exhibited a cumulative acute toxicity effect on fish tissues, with the severity increasing progressively from 24 to 96 hours. Notable injuries included hyperplasia, fusion, and adhesion of secondary lamellae in the gill tissue, as well as villi fusion, structural expansion of villi, increased blood cell count, and erosion in the intestinal tissue of the fish.
Conclusion: Simultaneous exposure to silver and graphene oxide nanoparticles significantly increases the acute toxicity in guppy fish. This study highlights the need for further research to fully understand the implications of nanoparticle exposure across the food chain.

Evaluating the environmental impacts of the thermal power plant with the approach of life cycle and carbon footprint (case study: Iranshahr steam power plant)

Narjes Okati

Background and Objective: Assessing the life cycle and evaluating the carbon footprint in thermal power plants is crucial due to their reliance on fossil fuels. This study was conducted to evaluate the environmental impacts and carbon footprint of the Iranshahr steam power plant.
Materials and Methods: Primary data were collected and analyzed using SimaPro software and the ReCiPe 2016 method (Hierarchist perspective). The carbon footprint was assessed through data modeling based on the International Panel on Climate Change (IPCC) method. The functional unit was defined as one kilowatt-hour (kWh) of electricity generated, and the system boundary was set as gate-to-gate.
Results: The study revealed that the most significant environmental impacts of the power plant were related to human carcinogenic toxicity, accounting for 42% at the midpoint level, and damage to human health, contributing 86% at the endpoint level. Sensitivity analysis identified natural gas as the most influential factor affecting the results. According to the IPCC method, fossil fuel consumption contributed 94% to the global warming potential. The highest amount of CO₂ emitted was 0.946 kg per kWh of electricity produced.
Conclusion: The CO₂ emissions per kWh of electricity produced (0.946 kg/kWh) exceeded the average CO₂ emission factor for fossil fuel power plants in Iran (0.64 kg/kWh). Based on these findings, it is recommended to prioritize the use of renewable and clean energy sources, such as wind and solar power, as alternatives for electricity generation in the region.

Statistical analysis and bibliometric study of waste rubber utilization in concrete

Marzie Razavi

Background and Objective: The significant growth in global vehicle usage has introduced various environmental challenges, particularly the management of waste tires. Due to their long decomposition time and the environmental hazards associated with their accumulation, waste tires pose a severe threat to ecosystems. A sustainable approach to mitigating these adverse effects involves the partial replacement of fine and coarse aggregates in concrete with waste tires. However, existing research on the impact of waste tire utilization on the mechanical properties of concrete remains limited, and global trends in this field have not been sufficiently analyzed. This study aims to evaluate the potential of waste tires for improving the mechanical properties of concrete and to analyze global trends in this innovative approach.
Materials and Methods: To assess the effects of crumb and powdered tires on the compressive strength and workability of concrete, the Taguchi experimental design method and analysis of variance (ANOVA) were employed. Additionally, data from the Scopus database were analyzed using VOSviewer software to evaluate research trends and scientific collaborations related to waste tire utilization in concrete.
Results: Using optimal ratios of crumb and powdered tires enables the production of concrete with suitable compressive strength. The coefficients of determination (R²) for the 7-day compressive strength, 28-day compressive strength, and workability were 92.41%, 97.82%, and 80.07%, respectively. Bibliometric analysis revealed that China and India are leading countries in publishing scientific articles in this field, reflecting a strong research focus on the use of waste tires in concrete.
Conclusion: This study demonstrates that incorporating waste tires into concrete can be an effective approach to enhancing its mechanical properties. However, developing innovative technologies to optimize mixtures and improve the long-term durability of concrete remains crucial. Moreover, the bibliometric results highlight the importance of fostering greater international and multidisciplinary research in this area. Such efforts can contribute to advancing sustainable technologies in the construction industry.

The effects of microplastics on human health and the environment (a review study)

Alieh Tabasi

Background and Objective: Microplastics are emerging and persistent environmental pollutants. The most common types include polyethylene, polypropylene, polyvinyl chloride, polyformaldehyde, polystyrene, and polyamide. Due to their chemical and toxic properties, ability to absorb and release persistent organic pollutants, and association with heavy metals, microplastics pose a serious threat to both the environment and human health. Therefore, this study aimed to investigate the effects of microplastics on human health and the environment.
Materials and Methods: This descriptive review was conducted in 2024 to document the process of searching, screening, and reporting based on the PRISMA checklist for systematic reviews. Articles published between 2019 and April 2024 were searched using keywords such as "Microplastics," "Health Risk," "Emerging Contaminants," and their Persian equivalents in electronic databases, including PubMed, ScienceDirect, Scopus, Magiran, and SID.
Results: The effects of microplastics on human health include the absorption of aromatic hydrocarbons, dioxins, and other pollutants, leading to neurological and respiratory disorders such as asthma, pulmonary fibrosis, lung cancer, dizziness, gastrointestinal disorders, and genotoxic and cytotoxic effects. Furthermore, microplastics have detrimental effects on plants, microbial populations, soil structure, and the health of animals and humans.
Conclusion: Microplastics represent a significant environmental challenge, threatening human health and biodiversity. These particles enter the food chain and can cause hormonal imbalances and chronic diseases. Raising public awareness and reforming policies on plastic production and consumption are essential steps to mitigate this pollution.