Assessment of Fungal Aerosols Dispersion from Municipal Solid Waste Disposal Site: A Case Study of Karaj, Iran
Omid Alizad Farzin 1, Hatam Godini 1,2*, Mohammad Noorisepehr 1,2, Elaheh Mahmoudi 3
1 Department of Environmental Health Engineering, School of Health, Alborz University of Medical Sciences, Karaj, Iran.
2 Research Center for Health, Safety, and Environment, Alborz University of Medical Science, Karaj, Iran.
3 Department of Mycology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran.
A R T I C L E I N F O |
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ABSTRACT |
ORIGINAL ARTICLE |
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Introduction: Fungal aerosols from landfill sites can play a fundamental role in environmental pollution and health. The present study aimed to assess the dispersion of fungal aerosols from municipal solid waste disposal site.
Materials and Methods: In this cross-sectional study, the concentration of fungal aerosols was determined in four geographical directions at distances of 250, 500, 750, and 1000 m around landfill site. Relative humidity and temperature were also measured. Moreover the concentration and type of the fungal taxa isolated from landfill site under different environmental and metrological conditions were evaluated.
Results: The results showed that the maximum and minimum concentrations of fungal aerosol in the landfill site were 256.18 ± 59.7 CFU/m3 and 76.56 ± 23.2 CFU/m3, respectively. The most frequent fungi detected from municipal landfill site included Penicillium (43.67%), Cladosporium (33.54%), Yeast (7.60%), Aspergillus (5.91%), Curvularia (3.62%), Chrysosporium (1.57%), Alternaria (1.54%), Scopulariopsis (0.84%), and Ulocladium (0.60%) taxa. The maximum identified fungal aerosol concentration in the area around the solid waste landfill was 350 CFU/m3. Furthermore, the concentration of fungal aerosols in the environment was significantly related to relative humidity, wind direction, and temperature in spring and winter (P < 0.05).
Conclusion: Municipal solid waste disposal site can be a potential source for fungal aerosol dispersion. Moreover, fungal aerosols concentration is correlated with wind direction and speed, relative humidity, and temperature. |
Article History:
Received: 12 May 2023
Accepted: 10 July 2023
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*Corresponding Author:
Hatam Godini
Email:
Godini_h@yahoo.com
Tel:
+98 916 3611395 |
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Keywords:
Fungi,
Aerosols,
Solid Waste,
Wind,
Humidity,
Karaj City. |
Citation: Alizad Farzin O, Godini H, Noorisepehr M, et al. Assessment of Fungal Aerosols Dispersion from Municipal Solid Waste Disposal Site: A Case Study of Karaj, Iran. J Environ Health Sustain Dev. 2023; 8(3): 2039-49.
Introduction
Solid waste and related disposal technologies are considered as one of the air contaminant sources1. Inhibiting environmental contamination in landfill and recycling centers is important for preventing airborne diseases 2. Most studies on the health risks related to solid waste landfills have focused on the effects of hazardous chemicals in landfills, but limited research has highlighted bioaerosols 3. Despite the recognition of the health risks associated with bioaerosol exposure, no specific permissible limit is provided for this group of contaminants in the environment, especially in municipal landfill and recycling centers, and the presented levels are as suggestion 4.
The particulate matters (PMs) emitted from solid waste landfill and recycling centers can contain biological and non-biological materials, which can transfer to the areas far from the production site through airflow 3. The emission of fungal aerosols in the environment plays an important role in causing respiratory symptoms, allergic reactions, and respiratory tract infections 5-7. According to Schlosser et al., landfill environment provides an appropriate condition for transmitting biological agents, especially fungi. They found that fungal Aspergillus species possesses maximum risk for residents around the landfills and threatens human health 3. Aerosol emission in landfill and recycling centers is facilitated with various waste management activities such as discharge, transportation, handling, separation, and compaction, as well as final covering of landfill 8.
The dispersion of fungal aerosols leads to respiratory tract and skin diseases, which threatens the health of employees in landfill and recycling centers 9-11. Due to the importance of bioaerosol dispersion in environmental contamination, extensive studies have been recently conducted on their spread from landfill and recycling centers worldwide 3, 5, 12-16. Considering the quality and conditions of solid waste management, different results have been reported. Given that identifying and analyzing the fungal flora of contaminated air in the solid waste processing centers are important, the fungal contamination level and dominant fungi of the sites were determined, and the role of environmental factors in dispersing fungal aerosols was examined. In this study, after identifying common fungal taxa, allergenicity (as allergens and non-allergens) of fungal taxa was classified based on mycological texts.
Materials and Methods
Sampling site
In this study, sampling was performed in 2017 in the municipal landfill and recycling center of Karaj, located in Halghe Dareh in the southwest of Karaj city, Alborz province, Iran. In this regard, 16 stations were assessed in four main directions, so that monitoring was conducted at a 250 m distance from landfill site in each direction and the stations were distanced 250 m apart. The map and sampling locations are displayed in Figure 1. Then, 192 samples were collected and tested from the 16 stations through using an active sampling technique. Sampling was done for six months in winter and spring, and two samples were taken every month with an interval of 15 days.
Figure 1: The map and sampling locations of solid waste disposal site, Karaj, Iran
(A: map of world, B: map of Iran, C: map of Karaj, D: Map of solid waste disposal site and sampling points)
Sampling method
A Quick Take 30 (SKC, USA) sampling instrument with the flow rate of 28.3 L/min for 2.5 min was utilized based on the standard NIOSH method 17, 18. Before using the instrument, flow rate was calibrated on 28.3 L/min by a rotameter based on the manufacturer's instruction. After sterilizing Biostage with 70% alcohol, a plate with Sabro dextrose agar (SDA) supplemented with chloramphenicol (0.05%) was placed inside Biostage and sampling was performed for 2.5 min at 1.5m height from ground 6, 19, 20. Then, the obtained samples were transferred to laboratory for separation and identification. The sampling frequency was 15 days. Sampling was performed at a height of 1.5 meters and 6 times for each station in each season.
Isolation and identification of fungal aerosols
Three culture media of SDA (Sigma, Germany), Sabro dextrose broth (SDB) (Sigma, Germany), and potato dextrose agar (PDA), (BioMerieux, France) supplemented with chloramphenicol (0.05%) were applied for observing microscopic, macroscopic, and sporulation structure. The sampled culture medium plates were transferred from the instrument to laboratory and incubated at 28˚C. In addition, they were evaluated for fungal growth intermittently and daily until 10 days. The number of colonies formed in the plates was counted and expressed in the unit of CFU/m3 by considering flow rate and sampling time. The obtained colonies were identified based on the morphological characteristics of the colonies. Microscopic identification was performed using the direct KOH test on a wet mount 21, 22.
Molecular identification
The isolated fungal taxa were detected through PCR-sequencing method. The fungal genomic DNA was extracted using Kit (Roche, Switzerland) according to the kit's protocol. The quantity and quality of DNA samples were assessed by NanoDrop 2000c (Boeco, Germany). The PCR amplification of genomic DNA was carried out to amplify the ITS-5.8S rDNA region using the universal primers ITS4 and ITS5 (ITS4:5΄-TCCTCCGCTTATTGATATGC-3΄, ITS5: 5΄-GGAAGTAAAAGTCGTAACAAGG -3΄) 23.
The PCR was performed in final volume of 25 μL including 13 μl of 2X ready to use Master Mix (SinaClon, Iran), 1μl of each 20 pmol forward and reverse primers, 7μl of sterile distilled water, 1μl Taq polymerase, and 2μl extracted DNA template, using a PCR thermal cycler (Peqlab, Belgium). The thermal cycle was performed for 5 min at 94°C of initial denaturation, 35 cycles of a second denaturation at 94°C for 45 sec, annealing at 56°C for 40 sec, and elongation at 72°C for 20 sec. The PCR was completed through a final elongation at 72°C for 10 min. Sequencing of PCR-amplified products was performed using the Applied Biosystems 3730 XL Bioneer (Korea) using ITS4 primer. A search of sequences was carried out using the Blast program
with a database maintained at the NCBI (Library of Medicine, Bethesda, MD, USA; http://www.ncbi.nlm.nih.gov/BLAST/).
Meteorological parameters measurement
The relative humidity and temperature in sampling points were measured using digital TES-1360 (TES Electronic Corp. Taiwan). Temperature and relative humidity measurement ranges of TES-1360 were -20 to +60 oC and 1-95%, respectively. The accuracy of the device for measuring temperature and relative humidity were ±0.8 oC and ±3 %, respectively. This device was calibrated by the licensed company. Meteorological information including wind speed, wind direction, ambient temperature and other meteorological conditions related to the sampled place was obtained from Alborz Meteorological Organization.
Statistical analysis
Two-way ANOVA and Scheffe's post hoc tests were respectively applied for comparing the difference in mean concentration of fungal aerosols in different stations, as well as the difference among stations. The mean concentration of bioaerosols in winter and spring was compared using t-test. In order to assess the relationship between environmental parameters such as temperature, relative humidity, and wind speed in the sampling days with the concentration of fungal aerosols, the normality of the data was first specified through using Kolmogorov-Smirnov test and the required results were obtained by Pearson correlation coefficient test. A univariate linear regression was applied for determining the effect of meteorological parameters on the total number of fungi.
Ethical issue
This study has been approved by the Ethics Committee in Alborz university of medical sciences (IR.Abzums.rec.1396, 27).
Results
All fungi taxa identified by culture method were also determined by molecular test, but the number of fungi taxa identified by culture method was less than molecular method. Therefore, since the molecular method is more accurate, the results were reported based on the molecular method.
Fungal aerosol concentrations
The presence of fungi taxa in all samples (192 samples) collected from Karaj landfill site was confirmed. The mean concentration of all enumerated fungi taxa was 204.34 ± 49.56 CFU/m3 on the municipal solid-waste disposal site of Karaj. In addition, the mean concentrations of fungi taxa in spring and winter were 256 ± 59.7 and 76.56 ± 23.2, respectively. The isolated fungal taxa percentage is presented in Figure 2, which indicates the separated fungi as Penicillium (43.67%), Cladosporium (33.54%), Yeast (7.60%), Aspergillus (5.91%), Curvularia (3.62%), Chrysosporium (1.57%), Alternaria (1.54%), Scopulariopsis (0.84%), and Ulocladium (0.60%) taxa, respectively.
Figure 2: Mean percentage of bioaerosols based on the percentage of isolated species from municipal solid waste disposal site of Halghe Dareh, Alborz province, Karaj, Iran
Fungal aerosol variations with sampling direction
Figure 3 represents the mean concentration of total fungal aerosol at different directions in the seasons under study. The mean concentration of total fungal aerosol in spring was more than winter at all directions. The maximum concentrations of fungal aerosols were observed in the west, north, south, and east directions during spring, as well as north, west, south and east directions in winter, respectively. Furthermore, the maximum and minimum mean concentrations of fungal aerosol were 256.18 ± 59.7 CFU/m3 in spring at west stations and 76.56 ± 23.2 CFU/m3 in winter at east stations, respectively.
Figure 3: Concentrations of fungal aerosol (mean and standard deviation) in each direction during spring and winter in terms of CFU/m3 (north, west, south, and east geographical directions are abbreviated as N, W, S, and E).
The mean concentrations of fungal aerosols at four main directions during spring and winter at different stations are shown in Figure 4. During the sampling period, the highest and lowest amount of colony concentrations was 350 CFU/m3 in S1 station at spring and 37.34 in E4 station at winter (Figure 4), respectively.
Figure 4: Mean concentration of fungal aerosol in each direction in terms of CFU/m3 and different stations during spring and winter (north, west, south, and east geographical directions are abbreviated as N, W, S, and E).
Table 1 summarizes the results of statistical analysis for the concentration of fungal aerosols, and variables related to season and sampling station (P ≤