Iranian Journal of

Background and Objective: Nowadays, the increasing use of antibiotics to control diseases and mismanagement and inappropriate disposal of medicinal wastes cause environmental problems and threatens human health. The present study was conducted to determine removal of antibiotic Metronidazole as one of the most used drugs during the process of composting.
Materials and Methods: In this experimental study, a mixture of livestock manure, fruit, straw and sludge were used for the preparation of compost. Duration of the process was 40 days. Metronidazole was added to the compost reactors at three concentrations of 20, 50 and 100 mg/kg. Totally, 42 Samples were taken weekly. HPLC was used to analyze the samples. The experiment was repeated twice. SPSS22 software was used to analyze the results.
Results: The rate of Metronidazole removal after day 21 and end of the thermophilic phase was 99.9, 96.73 and 93.48 % in the reactors contained 20, 50 and 100 mg/kg, respectively. Increasing concentrations in the reactors caused the removal rate to decrease, while increasing removal time caused to increase the removal rate. At the end of the process, the removal rate for all three reactors was 99.99 %. The physico-chemical properties of the final compost were within the national standard.
Conclusion: The use of an aerobic composting process to degrade antibiotic Metronidazole is an economical, effective and, environmentally friendly method. At the end of the process, 99.99 % of Metronidazole was degraded.
 

Background and Objective: Despite their high nutritional value, fruits and vegetables may pose a risk to public health due to nitrate accumulation. This study aimed to assess the health risks associated with dietary exposure to nitrates present in fruits and vegetables sold in produce markets of Shahre-Rey.
Materials and Methods: In this cross-sectional study, samples of apples, oranges, potatoes, onions, and both greenhouse- and field-grown tomatoes and cucumbers (n = 13, 12, 22, 18, 24, and 32, respectively) were collected during autumn and winter 2023 and spring and summer 2024. Nitrate concentrations were measured using a spectrophotometric method. The non-carcinogenic hazard quotient (HQ) was calculated based on the measured nitrate levels. In addition, using GBD data, the contribution of nitrate to the disease burden of colorectal cancer was estimated through YLL (Years of Life Lost), YLD (Years Lived with Disability), and DALY (Disability-Adjusted Life Years) indices.
Results: The mean nitrate concentration varied significantly across the products, with the highest level found in field cucumbers (294.06 mg/kg) and the lowest in apples (51.99 mg/kg). In some products, nitrate levels exceeded the permissible limits set by the Iranian national standard. The highest non-carcinogenic risk was observed in potatoes, with a mean HQ of 0.231. Potatoes also had the highest incidence rate of colorectal cancer (2.02 per 100,000 population), the greatest DALY (23.15), and the highest nitrate-related mortality. The mean DALY attributed to nitrate exposure was estimated at 107.38 for potatoes, 94.87 for onions, and 12.10 for greenhouse cucumbers.
Conclusion: Certain agricultural products, particularly potatoes and onions, are significant sources of dietary nitrate exposure and may contribute to an increased risk of colorectal cancer. Continuous monitoring and management of nitrate levels in these products are essential.