PAHs & VOCs
Fires, whether wildfires or structural, produce various harmful pollutants, notably polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). These substances pose significant health risks and environmental challenges. The article provides an in-depth understanding of PAHs and VOCs, their formation during fires, their impact on health and the environment, necessary personal protective equipment (PPE), and their persistence in the environment.
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PAHs (Polycyclic Aromatic Hydrocarbons):
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Definition: Organic compounds composed of multiple aromatic rings, formed during the incomplete combustion of organic materials.
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Health Risks: Carcinogenic, causing respiratory problems, skin irritation, immune system suppression, and long-term effects like lung, bladder, and skin cancers.
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VOCs (Volatile Organic Compounds):
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Definition: Organic chemicals that evaporate easily at room temperature, including benzene, formaldehyde, and toluene.
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Health Risks: Immediate symptoms like headaches, dizziness, respiratory irritation, eye, nose, and throat irritation, and long-term effects like liver, kidney, and central nervous system damage.
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Formation During Fires:
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Incomplete Combustion: Produces PAHs and VOCs, common in wildfires and structural fires.
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Material Composition: Different materials release different PAHs and VOCs. For example, wood and vegetation produce PAHs, while building materials and household products release a broader spectrum of VOCs.
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Acidic Soot: Causes building materials to off-gas additional chemicals, increasing hazards.
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Interaction with People and Environment:
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Human Exposure: Through inhalation, dermal contact, and ingestion.
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Environmental Persistence: PAHs bind tightly to soil and sediments, while VOCs can degrade quickly or persist in indoor environments, contributing to secondary pollutants like ozone.
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Personal Protective Equipment (PPE):
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Respiratory Protection: N95 masks, respirators with organic vapor cartridges, and self-contained breathing apparatus (SCBA).
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Skin Protection: Gloves, coveralls, and other protective clothing.
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Eye Protection: Safety goggles or face shields.
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Longevity in the Environment Post-Fire:
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PAHs: Persist in soil and sediments, bioaccumulate in tissues of living organisms, posing risks through the food chain.
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VOCs: Degrade quickly in the atmosphere or persist in indoor environments, influenced by environmental factors.
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Conclusion: PAHs and VOCs from fires pose significant health risks and environmental challenges. Comprehensive protective measures, including PPE and environmental assessments, are essential to safeguard health and the environment post-fire.
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“The bioconversion of VOC pollutants to metabolic end- and intermediate products (VOCs), biomass, or carbon dioxide and water remains the second step. Malhautier et al. (2005) define working biofilters as a complex and structured ecosystem. Considering this, soils are perfect natural biofilters as they provide a multitude of species and microbial consortia (capable of different organic compound-degrading pathways), environmental conditions (from anaerobic to aerobic), and a variety of different VOC adsorbents (water, humic acids, clay minerals).”
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Due to their ubiquitous detectability and their information content, VOCs have been extensively studied aiming at different organisms, functions, and interactions since the last 90 (!) years (e.g., Brown 1922 cited in Linton and Wright 1993). The scope of this review is to summarize the state of the art and latest advances in soil microbial VOC research, in particular since the excellent review by Stotzky and Schenck (1976).
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“Microorganisms in the soil of potted plants are important for removal of volatile organic compounds (VOCs) from indoor air.” The study showed that “The change in bacterial community structure was, however, different between the two experiments indicating that several taxonomic units can degrade gasoline components.
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ASBESTOS
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Asbestos, a naturally occurring mineral, was widely used in building materials for its fire-resistant properties. However, when a house fire occurs, asbestos-containing materials can become damaged and release toxic fibers into the air. These fibers are microscopic and can be inhaled, leading to serious health issues such as asbestosis, lung cancer, and mesothelioma . The aftermath of a fire can leave asbestos fibers lingering in the environment, posing a long-term health risk to residents and workers involved in cleanup efforts.
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Soil testing is crucial in the aftermath of a house fire to determine the extent of asbestos contamination. Testing helps identify the presence of asbestos fibers in the soil, which is essential for developing an appropriate remediation plan . One effective method of managing asbestos-contaminated soil is capping it in place with an organic layer of compost and mulch. This method prevents the release of asbestos fibers into the air, reducing the risk of exposure. In contrast, excavating and removing contaminated soil can disturb the fibers, increasing the risk of airborne asbestos and exposing workers to hazardous conditions .
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Organic matter like compost containing fungi with mycelium networks, can break down harmful substances using their enzymatic processes. Fungi can play a role in detoxifying asbestos through a process called bioremediation. This involves using natural organisms to break down or neutralize harmful substances. Certain fungi, such as Aspergillus niger, have been found to break down chrysotile asbestos into less harmful components like magnesium. This process is often enhanced by the presence of additional organic compounds found in the natural environment.
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“Bioremediation of asbestos by fungi, particularly Fusarium oxysporum and Verticillium leptobactrum , has been tested in controlled laboratory studies. These two species have been repeatedly isolated from naturally occurring serpentinic rocks that contain asbestos particles, suggesting that they adapt easily to this selective mineral substrate (Martino et al., 2004; Daghino et al., 2005).
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“Experiments have shown that the chelating activity of exudates from some fungi and lichen (which has a fungal component) modify the chemical composition of chrysotile fibres in vitro, affecting their chemical reactivity and structure and potentially altering toxicity. These organism-driven weathering processes can reduce chrysotile fibre toxicity (Daghino et al., 2006, 2009), and accordingly increase iron (Fe), magnesium (Mg) and nickel (Ni) concentrations in surrounding substrates (Chardot-Jacques et al., 2013). These dissolved elements could provide plant nutrition but can also be lost though leachate (Chardot-Jacques et al., 2013). In one experimental study, the iron released was not incorporated into the fungal biomass (Daghino et al., 2008), but the fungi’s progressive removal of reactive iron ions, which are responsible for asbestos’s DNA damage, was encouraging (Daghino et al., 2006)
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Bioremediation with fungi is a promising method because it is low-cost, environmentally friendly, and does not produce hazardous by-products. However, it is still in the experimental stages and requires further research to be widely implemented.
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Additionally, “biological treatment is a prospect for in situ land reclamation and under industrial conditions, which can be a viable alternative to landfilling and an environmentally friendly substitute or supplement to thermal, mechanical, and chemical methods, often characterized by high cost intensity. Plant and microbial metabolism products are part of the green chemistry trend, a central strategic pillar of global industrial and environmental development.”
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Transporting asbestos-contaminated soil off-site for disposal can have significant environmental and health impacts. During transit, particulate emissions can occur, releasing asbestos fibers into the air and affecting nearby communities . Off-loading the material at disposal sites can further expose workers to asbestos, increasing their risk of developing asbestos-related diseases . Additionally, the displacement of contaminated soil can lead to the spread of asbestos fibers to new locations, exacerbating the health risks. Capping the material in place with an organic layer is a safer and more sustainable approach, minimizing the potential for airborne asbestos and protecting both workers and the environment
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There has been some fascinating research on using fungi to treat asbestos contamination. Scientists are exploring the potential of fungi as bioremediation agents to detoxify asbestos-contaminated sites. Here are a few key points from recent studies:
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Fungi and Iron Removal: Certain fungi, such as Fusarium oxysporum and Verticillium leptobactrum, have shown the ability to remove iron atoms from asbestos particles, making them less toxic. This process involves the fungi releasing chelators that bind to iron atoms, effectively stripping them from the asbestos fibers.
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Biological Detoxification: Research has highlighted the role of plants, microorganisms, and their metabolites in supporting asbestos detoxification. This approach is seen as a viable alternative to traditional methods, which can be costly and environmentally damaging.
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Fungal Hyphae and Asbestos Fibers: Fungal hyphae can form networks that bind asbestos fibers, reducing their potential to become airborne and cause harm. This physical alteration, combined with the chemical changes induced by fungal chelators, can significantly reduce the carcinogenic potential of asbestos.
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Fusarium oxysporum is a widespread fungus that primarily inhabits soil. It thrives in various environments, including agricultural fields, forests, grasslands, and even extreme conditions like deserts and tundras. This fungus can exist as a saprophyte, breaking down organic matter in the soil, or as a plant endophyte, colonizing plant roots1. While some strains are harmless, others are pathogenic and can cause diseases like wilt in plants.
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Verticillium leptobactrum is a fungus that is primarily found in soil environments. It is known for its role in biological control, as it can combat plant-parasitic nematodes like Meloidogyne javanica and Globodera pallida. This fungus has been studied for its potential in agricultural settings, particularly in managing pests that affect crops such as potatoes
Chelating is a chemical process where a substance, called a chelating agent, binds to metal ions, forming a stable, water-soluble complex. This process is often used to remove heavy metals or toxic metals from systems, such as soil, water, or even the human body.
Chelating agents, like EDTA (ethylenediaminetetraacetic acid), can "grab" onto metal ions through their multiple binding sites, essentially encapsulating the metal and preventing it from reacting with other substances. This is particularly useful in applications like detoxifying contaminated environments, treating heavy metal poisoning in humans, or even improving nutrient absorption in plants.
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SOURCES
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https://link.springer.com/article/10.1007/s00374-010-0442-3?form=MG0AV3#Sec13 Volatile organic compounds (VOCs) in soils | Biology and Fertility of Soils
https://link.springer.com/article/10.1007/s00374-010-0442-3?form=MG0AV3#Sec13 Volatile organic compounds (VOCs) in soils | Biology and Fertility of Soils
https://link.springer.com/article/10.1007/s11356-023-26137-8?form=MG0AV3 Removal of a complex VOC mixture by potted plants—effects on soil microorganisms | Environmental Science and Pollution Research
https://www.osha.gov/asbestos/?form=MG0AV3&form=MG0AV3
https://www.epa.gov/asbestos/protecting-workers-asbestos?form=MG0AV3&form=MG0AV3
https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1001?form=MG0AV3&form=MG0AV3
https://www.harvestogroup.com/post/soil-testing-importance-and-benefits?form=MG0AV3&form=MG0AV3
https://biorestore.org/asbestos-encapsulation-an-alternative-to-removal/?form=MG0AV3&form=MG0AV3
https://halpernlawyer.com/blog/can-plants-detoxify-asbestos/?form=MG0AV3&form=MG0AV3 Can Plants Detoxify Asbestos? – The Halpern Law Firm : Challenging Global Waste Management – Bioremediation to Detoxify Asbestos
https://www.mdpi.com/1996-1944/17/7/1644 Plants, Microorganisms and Their Metabolites in Supporting Asbestos Detoxification—A Biological Perspective in Asbestos Treatment
https://link.springer.com/article/10.1007/s12230-016-9554-0?form=MG0AV3&form=MG0AV3
https://www.mdpi.com/1996-1944/17/7/1644 Plants, Microorganisms and Their Metabolites in Supporting Asbestos Detoxification—A Biological Perspective in Asbestos Treatment
https://www.usbr.gov/lc/phoenix/reports/reach11eis/APPEND3.PDF?form=MG0AV3&form=MG0AV3
https://link.springer.com/article/10.1007/s11356-023-26494-4?form=MG0AV3&form=MG0AV3
https://www.osha.gov/asbestos/?form=MG0AV3&form=MG0AV3
https://www.epa.gov/asbestos/protecting-workers-asbestos?form=MG0AV3&form=MG0AV3
https://biorestore.org/asbestos-encapsulation-an-alternative-to-removal/?form=MG0AV3&form=MG0AV3
https://www.med.upenn.edu/asbestos/project1.html?form=MG0AV3&form=MG0AV3
https://www.cnr.it/en/focus/064-2/fungi-as-potential-agents-of-bioremediation-of-asbestos-contaminated-soil?form=MG0AV3&form=MG0AV3 Fungi as potential agents of bioremediation of asbestos-contaminated soil
https://www.mdpi.com/1996-1944/17/7/1644?form=MG0AV3&form=MG0AV3 Plants, Microorganisms and Their Metabolites in Supporting Asbestos Detoxification—A Biological Perspective in Asbestos Treatment
https://www.cnr.it/en/focus/064-2/fungi-as-potential-agents-of-bioremediation-of-asbestos-contaminated-soil?form=MG0AV3&form=MG0AV3 Fungi as potential agents of bioremediation of asbestos-contaminated soil
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