Environment International 118 (2018) 189–193 Contents lists available at ScienceDirect Environment International journal homepage: www.elsevier.com/locate/envint A review on recent progress in observations, and health effects of bioaerosols T Charmi Humbala, Sneha Gautama, , Ujwalkumar Trivedib ⁎ a b Department of Environmental Science and Engineering, Marwadi University, Rajkot 360003, India Department of Microbiology, Faculty of Science, Marwadi University, Rajkot 360003, India A R T I C LE I N FO A B S T R A C T Keywords: Bioaerosol Health effects Respiratory diseases Cancer Bioaerosol is a particulate mixture of solid and semi-solid matter combined with biotic matter like pollens, microbes and their fragments. The present review stresses on a cumulative understanding of sources, components, quantification and distribution of bioaerosols with respect to size, and its significant impacts on human health. The present review will be instrumental in devising strategies to understand and manage bioaerosols and reducing their human exposure and associated health hazards. The present review aims explore the relationship between particle and associated biological agents responsible for behaviours like dispersal, total potential health hazards and toxicology level during exposure to bioaerosol. 1. Introduction Previous (Mandal and Brandl, 2011; Chen and Hildemann, 2009) indicated generation of bioaerosol due to human activities (i.e., sneezing/coughing, washing floors/toilet cleaning, walking/talking etc.). Dedesko et al. (2015) demonstrated the influence of meteorological parameters (i.e., temperature, and humidity) on formation and dispersion of bioaerosols. Moreover, Srikanth et al. (2008) suggested the relationship between bioaerosols and human diseases such as influenza, lungs diseases, allergies etc. The immunomodulatory or immunostimulatory effects of bioaerosols contribute significantly in the development of adaptive immunity. However, the over exposure can cause hyperactive stimulation of immune system causing allergic responses (Severson et al., 2010). A number of bioaerosol studies assesses the impact of bioaerosols on living organisms, but the exact role and mechanism of pathogenesis remain illusive. Fig. 1 highlights different types of microorganisms associated with bioaerosols and associated diseases. A comprehensive review has been presented through reviewed approximately published article in English language journals only that reported bioaerosols, source and its impact on human health. The findings from computer searches by using of some keywords (i.e., bioaerosols, diseases, exposure, and health problems), will help to readers for better understanding on impact of bioaerosols on human health. Bioaerosols are a particulate mixture of dust, microbes and their fragments. They are transmitted through air with a particle size ranging from 0.001 nm to 100 μm. The pathophysiological effects of these bioaerosol pollutants depend on their size, concentration, physiochemical properties and size distribution (Mandal and Brandl, 2011). Because of the micro to nano scale size, bioaerosol scan easily deposit in various parts of the body via lungs, and circulatory system. Such deposition can cause a number of health complications involving single organ to an entire organ system (Georgakopoulos et al., 2009). These are alarming reasons why awareness of bioaerosols is of great importance and hence it becomes necessary to investigate the source distributions and their impacts on human health. Massive industrial development and population expansion has caused deleterious anthropogenic activities (waste sorting and composting, agricultural, the livestock industry and food processing activities) (Ghosh et al., 2015). Exposure of human to bioaerosols in populated countries like China, India etc. is a primary concern because of associated adverse health impacts (Pearson et al., 2015). Many recent studies revealed that enhancement in the level of bioaerosols has become a serious environmental concern (Ghosh et al., 2015; Lacey and Dutkiewicz, 1994). Not only humans but pet and husbandry animals are also distressed from increasing prevalence of the bioaerosol exposer. In recent decades, bioaerosols are reported to contribute as much as up to 34% indoor air pollution with life threatening consequences (Mandal and Brandl, 2011). ⁎ Corresponding author. E-mail address: sneha.gautam@marwadieducation.edu.in (S. Gautam). https://doi.org/10.1016/j.envint.2018.05.053 Received 17 April 2018; Received in revised form 28 May 2018; Accepted 31 May 2018 0160-4120/ © 2018 Published by Elsevier Ltd. 2. Sampling methods Size and composition of airborne bioaerosol depend on their Environment International 118 (2018) 189–193 C. Humbal et al. Species Diseases Infections Species Diseases Legionella pheumophila Legionnaires Inhalation of aerosol with containing bacteria Mycobacterium tuberculosis Varibrio cholera Cholera Taking contaminated water/air Typhoid Taking contaminated water Bacillus anthracis spore Anthrax Salmonella Typhi Varibrio cholerae Cholera Morbillivirus measles Mumps & Rubella Coughing / sneezing; bodily fluids Bordetella pertussis Whooping Cough Tuberculosis InfecƟons Inhalation of contaminated air Taking contaminated water/air Taking contaminated water/air Inhalation of contaminated air 2 – 3 µm < 1 – 2 µm Size Fig. 1. Microbes in bioaerosols and their related diseases. Hänninen, 2006), and yeast extract glucose chloramphenicol (YGC) (Borrego et al., 2012). Fibrous filter made of a fine fibrous mat, where the particle is captured while passing the filter is also very efficient. Similarly, few filters have a pore-like structure in which particles are deposited (Uhrbrand et al., 2011). However, it can be seen that the efficiency is affected by several factors such as measurement time, relative humidity, temperature, microbial species (Wang et al., 2001). Moreover, glass – impinger method was found to be very suitable method to collect bacteria and fungi from the air streams (Thorne et al., 1992). Li (1999) compared to using impinger to collect bioaerosol and filtration methods. formation and mechanical stress in particular environmental conditions. Therefore, the selection of sampling tool to monitor the concentration level of bioaerosol should be quite different from the general employed procedure for analysis. Very few research articles could be found on new sampling methods to assess the bioaerosol and its microbial analysis. However, previous employed methods such as impingers, cyclones, impactors, filters, spore traps, electrostatic precipitation, thermal precipitators, condensation traps, gravitational samplers, etc. of common particle are being used to collect the bioaerosol with or without modification (Haig et al., 2016). Moreover, many samplers have been reported to separate the particle from the air through gravity (Wang et al., 2001), centrifugal force (Haig et al., 2016) and other methods (i.e., Filtration, Electrostatic Precipitator Thermal Precipitator etc.) (Ghosh et al., 2015). According to particle size, few options are available such as inertial bioaerosol sampler (i.e., sieves, stacked sieves, and impactors), which rely on properties of the particle to deviate from laden gas flow due to inertia (Haig et al., 2016). Moreover, non-inertial bioaerosol samplers (i.e., filtration, electrostatic precipitator, and thermal precipitator) are also available to show nondependency (i.e., less reliant on particle size) upon the selective particle size (Ghosh et al., 2015). Impingers and cyclones method are being used to collect airborne particle in the liquid medium. In case of impinge, it is operated through the gas flow from the inlet to collection chamber containing liquid, where number of factors (i.e., gas flow rate, distance from inlet to outlet, and surface of the liquid) are influenced by the size and diameter of the particle (Han and Mainelis, 2012). On the other hand, centrifugal force worked in cyclone (conventional), where air is forced into the collection chamber by the vortex formed in the system. Macher et al. (1995) reported that new cyclone sampling techniques to collect the sample through standard centrifuge tube from the top of the sampler chamber instead of the peripheral portion of the system. Such an optimization makes procedure very simple (Macher et al., 1995). Moreover, the investigators also reported high efficiency with multiple tubes to identify size fractioned samples (i.e. large, medium and small – sized bioaerosols) in initial (centrifuge) tube, second tube, and filter, respectively. Media plays a vital role in the collection of bioaerosol. The most commonly used is a filter to transfer bioaerosol on a plate or in liquid for further analysis (i.e., microscopic examination or culturing experiments) (Wu et al., 2010). Several studies are reported stating utilization of different forms of cultivation media like maltextractagar (MEA) (Lehtinen et al., 2013), Sabouraud dextrose agar (SDA) (Park et al., 2015), dichloran rose-bengal chloramphenicol (DRBC) (Tolvanen and 3. Components of bioaerosols Bioaerosols pose a substantial health risk globally (Burger, 1990; Kim et al., 2017). Bioaerosols comprise of diverse classes of microorganisms and their products. The major microbial constituents are fungi and bacteria while their products constitute endotoxin, mycotoxins, and allergens (Kim et al., 2017). A recent focus is also stretched upon the presence of Beta-glucans (a common cell-wall component of fungi) in bioaerosol which causes a number of health-related consequences such as cancer, auto-immune diseases and severe respiratory tract dysfunctions. Looking at the severity of bioaerosol in health management, it is, therefore, essential to understand the nature and components of bioaerosols. This section discusses the classification of major microbial (and their products) constituents of bioaerosols. 3.1. Fungi Fungi are ubiquitously present in nature over a wide range of environmental condition (Lee et al., 2006). The kingdom fungi consist of a diverse group of eukaryotic organism ranging from microscopic to macroscopic in size. A recent survey estimates about 2.2 million to 3.8 million species of fungus existing in almost all the terras of the earth (Hawksworth and Lücking, 2017). The pathogenic fungal species like Aspergillus spp., Fusarium spp., Scedosporium spp., and Mucorales spp. are most common components in bioaerosol (Diaz-Guerra et al., 2000; Grigis et al., 2000; Jung et al., 2009). These fungi are known to cause a number of health-related related complications such as acute toxicity, hypersensitivity (majorly asthma), invasive mycoses and respiratory abnormalities (Bush and Portnoy, 2001; Jung et al., 2009; Verhoeff and Burge, 1997). Near all the known species of fungi possess the ability to propagate (in air or water as a particulate) via sporulation. The fungal spores can 190 Environment International 118 (2018) 189–193 C. Humbal et al. 4.1. Respiratory effects survive in a wide range of physio-chemical conditions making them a persistent bioaerosol (Górny et al., 2001). Respiration is of the major gateway of bioaerosol in human lungs. Respiratory exposure of bioaerosol associated to allergens, pollens, and microbes causes a number of respiratory diseases. Maheswaran et al. (2014) reported respiratory exposure on 422 Canadian children's, where 7–10 years and 11–14 years of children affected by non-atopic/ non-atopic asthma (OR = 1.79, 95%, CI: 4941.14–2.81) and bronchial hyper-responsiveness (OR = 4951.74, 95% CI: 1.05–2.89), respectively. Moreover, Ma et al. (2015) suggested positively higher asthma intensity with mold sensitivity. Asthma with mold sensitivity in children's bedrooms (OR = 4.82, 95%, CI: 1.29–18.02) and living rooms (OR = 7.5195%, CI: 1.49–37.8) reported by Karvonen et al. (2015). In other hand, Baldacci et al. (2015) observed that exposure to pollen is responsible for decreased lung function and a significant increase in the pulmonary inflammation. Similarly, 15% asthma epidemic are reported due to presence of grass pollen (Canova et al., 2013). Hoppin et al. (2014) reported that irritating airways and inflammation are caused due to presence of endotoxin and glucans from bacteria and molds. Lung function decreases significantly upon exposure to endotoxins (80 mg and 20 mg for health subject and asthmatics subjects, respectively) (Kharitonov and Sjöbring, 2007). 3.2. Bacteria Bacteria constitute a very large domain of prokaryotic microorganisms which are found to dwell in almost all the terra of the earth including the extreme environment (extremophiles) (Van den Burg, 2003). It is estimated that about 107 to 109 species of bacteria are present on earth of which only 10,000 are known due to their stringent growth requirements (Curtis et al., 2002; Schloss and Handelsman, 2004). Bacteria are very diverse in terms of the metabolism and morphology with the size ranging from 0.3 μm (Mycoplasma) to 0.5 mm (Thiomargarita namibiensis) (Robertson et al., 1975; Schulz and Jorgensen, 2001; Williams, 2011). Air is known to be a salient carrier of a number of airborne pathogenic bacteria like Bordetella pertussis, Bacillus anthracis, Corynebacterium diphtheriae and Neisseria meningitidis which are known to be causative organisms of Pertusis, Anthrax, Diphtheriae and Meningitis, respectively (GBD 2013 Mortality and Causes of Death Collaborators, 2015; Heininger, 2010; Hendricks et al., 2014; Theilen et al., 2008). These organisms can deliver a lethal effect to human upon transmission as bioaerosol. Many Bacillus species transmitted as bioaerosol are known to be potent allergens causing respiratory tract discomfort (Fierer et al., 2008). 4.2. Communicable diseases 3.3. Endotoxins Transmission of pathogenic microbes via bioaerosol carriers are the responsible for the communicable disease via direct contact (i.e., licking, touching, etc.) or indirect contact (i.e., cough and sneeze) (Chretien et al., 2015; Baker and Gray, 2009; Vanrompay et al., 2007). Wu et al. (2015) reported the number of cases of zoonotic infections on farmer or workers which are directly or indirectly associated with veterinary practices, livestock farms and catching animals. These infected subjects work as medium to communicate the diseases from one person to another one through family get-together, society programs and associated animals they pet. Ling et al. (2015) reported the higher distribution of bacteria Chlamydophilapsittaci through birds especially pigeons and psittacine birds. Commandeur et al. (2014) conducted study to identify the high infection of microorganism on worker, those associated with goat farms in Netherland over three years survey. And found a large number of patients (approximately 4000) were visited and reported at MHS (municipal health services) in same time period (Roest et al., 2011). Table 1 shows comprehensive summary of communicable diseases due to higher level of biological agent. The lipopolysaccharide component of Gram-negative bacterial cell wall is known as an endotoxin which further consists of a lipid component –Lipid A that displays the toxic effect to the host (Armstrong et al., 2013; Kim et al., 2017; Tirsoaga et al., 2007). Endotoxins are mainly released upon the cellular and can bind to the dust particles causing its respiratory exposure (Duquenne et al., 2013; MattsbyBaltzer et al., 1991). Routine occupational exposure of endotoxin contaminated bioaerosols are known to cause an array of occupational hazards like hypersensitivity, septic shock, fever, chest congestion, systemic inflammatory response, respiratory system dysfunction and even death (Park et al., 2015; Thilsing et al., 2015). In severe cases, human exposure to such bioaerosols also caused lung cancer (Hayleeyesus et al., 2015; Johnson and Choi, 2012). 3.4. β glucans β glucans are the cell wall component of fungi made up of glucose polymers where glucose moiety can be linked through β(1 → 3), β(1 → 4) and β(1 → 6) glycosidic bonds (Manzi and Pizzoferrato, 2000). Although, β glucans are routinely used to treat diabetes and elevated blood cholesterol, harmful effects of over exposure to β glucans contaminated bioaerosols vary from immunomodulatory responses to allergic reactions (Kim et al., 2017; Manzi and Pizzoferrato, 2000). 4.3. Cancer Several studies suggest a significant correlation between cancer subjects and exposure to bioaerosol (Hayleeyesus et al., 2015; Hoppin et al., 2014; Johnson and Choi, 2012). Review study done by Johnson and Choi (2012) demonstrated the involvement of meat and poultry related industries responsible for lung cancer. They also suggested that contribution of bioaerosol including dander, feather, skin material, and microbes are more prominent than smoking in meat/poultry industry causing 30% excess risk of lung cancer due to bioaerosol. On the other hand, Mclean et al. (2004) reported the significant contribution of higher exposure to bioaerosol including animal urine, virus, faecal matter etc., on workers and associates in meat/poultry area by utilizing the dose–response relationship. Felini et al. (2011) reported the higher exposure to bioaerosol due to industrial (meat/poultry) activities such as gathering of live chickens (OR = 3.6, 95% CI: 1.2–10.9), meat distribution center (OR = 8.9, 95% CI: 2.7–29.3), and other activities (OR = 4.8, 95% CI: 1.5–16.6). Similarly, earlier studies pointed out on pancreatic cancer due to higher exposure (OR = 3.0, 95% CI:1.0–8.2) to bioaerosol in associated worker of pig farm (Johnson and Choi, 2012; Felini et al., 2011). Several researchers identified high risk of lung cancer through the 4. Health exposure to bioaerosols Bioaerosol distribution in the atmosphere adversely affects human health via various mechanisms (Van Leuken et al., 2016; Pearson et al., 2015). The pathophysiology of bioaerosols depends on their physical, biological and chemical properties (Pearson et al., 2015; Yoon et al., 2011). However, the composition of bioaerosols is very complex and assessment of their comprehensive toxicity is difficult (Pearson et al., 2015). Toxicity of an individual component may not be sufficient to understand its overall toxicity (Thorne, 2000, 2001). The toxicity can vary depending on a number of factors such as oxidative potential, and its microbial composition. Therefore, chemical characterization is essential. The characterization is likely to vary with source types, i.e., a particular source type may be associated with a typical chemical signature of the bioaerosol (Thorne, 2001). 191 Environment International 118 (2018) 189–193 C. Humbal et al. Table 1 Comprehensive details of recent results/observations of communicable diseases through biological agent. Study location (s) Biological agent Key observations Authors (year) Netherlands Australia Italy – Animals shed C. burnetii influenza A (H7N7) virus Bacteria USA Bacteria Denmark Bacteria Taking control measures during collection goat/vaccinations, and the culling of pregnant infected animals. Exposed population to become infected (infd50) was 1.5 bacteria (95% confidence interval: 0.75–38.7). Observed in higher concentration in milk, urine, faeces and birth products. High level of exposure identified in poultry farms. Introduced to new area such as potential protective effects of microbial exposures on atopy and atopic diseases, and other potential health effects such as skin and neurological conditions and birth effects. Genetic studies suggested strategies for treatment and vaccine development to minimize the impacts due to biological agents. Observed the significant impact of biological agent during inhalation, where Mycobacterium tuberculosis (Mtb) contaminated air or presence of bacteria enters in deeper part of lungs. To identified high exposure to communicable diseases in teachers, children and health care workers. Dijkstra et al. (2012) Netherlands Culling of pregnant infected animals. Coxiella burnetii Bacteria, virus Brooke et al. (2013) Parker et al. (2006) Puzelli et al. (2014) Douwes et al. (2003) Berrington and Hawn (2013) Pedersen et al. (2016) Rohani and Drake (2011) Acknowledgements relationship between higher exposure and industrial activities (slaughtering/collecting/distribution of chickens) (Felini et al., 2012; McLean et al., 2004). Furthermore, recent study reported by Gandhi et al. (2014) found the comprehensive details about the high risk of brain cancer in 46,819 workers associated with poultry/non-poultry industrial area, where slaughtering (OR = 5.8, 95% CI: 1.2–28.3) and working in of shell–fish farm (OR = 13.0, 95% CI: 1.9–84.2). We are thankful to Marwadi University, Rajkot, Gujarat, India for providing the financial support and manpower to carry out field study and research. We acknowledge valuable suggestions and critical insights provided by the faculties of Department of Environmental Science and Engineering and Department of Microbiology, Marwadi University Rajkot. 5. Future perspectives and conclusions References A number of possible directions and key research challenges on prediction and control of bioaerosol can be identified. These may include: Bioaerosol measurement and monitoring: All applied monitoring methods should be precise and must be according to standard guidelines, to collect accurate data with minimum loss/error. Moreover, methods should contain all possible factors i.e., specific location and climatic condition to assess accurate quantitative and qualitative observations and relevant data, to make specific policies. Biological, microbiological and chemical analysis: The detection of microorganisms, organic and inorganic components in bioaerosol is essential for the identification of toxicological properties of bioaerosol and its possible impact on the human health. Tempo-spatial methods i.e., source distribution and tracer methods of bioaerosol should be optimized to better understand the definite behaviour of bioaerosol distribution. Bioaerosol and its formation: Studies based on the formation of fine particles including of tiny microorganisms could be hardly found. Therefore, few studies need to be carried out on bioaerosol formation and their impact on human health, especially in developing countries. A higher concentration of bioaerosol is responsible for a number of human diseases such as respiratory problems, lung infections and cancer. It is observed that concentration of bioaerosol is very high in most enclosed environments (indoor/outdoor). However, the significant variations in concentration of bioaerosol can be observed between indoor and outdoor environment, where higher concentration is reported in the indoor environment compared the outdoor environment. 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