From Volcanic Popcorn to the Material of the Future: A Critical Review of Expanded Perlite Applications and Environmental Impacts

Abstract

The comprehensive review delves into the diverse applications of expanded perlite, highlighting the need for sustainable solutions in the face of changing market demands. The analysis of the environmental impact of traditional materials reveals critical issues, including increased energy consumption, resource depletion, and increasing waste generation. The search for safe materials with reduced environmental impact and renewable properties is proving critical to supporting a sustainable future. The analysis not only points out the economic benefits and widespread use of materials containing expanded perlite in various industries but also presents current trends in the use of this material, supporting options for environmentally friendly solutions. This study also examines the idea of Life Cycle Assessment (LCA), the application of which for expanded perlite provides valuable insight into the production, transportation, and potential recycling of this material. Furthermore, the paper identifies the most promising solutions and identifies areas where further research is needed, providing insight into the current state of affairs and future challenges associated with the use of this material.

1. Introduction

The article “That Wonderful Volcanic Popcorn” from the December 1954 issue of Popular Mechanics, authored by Charles Ballenger and Richard Dunlop, extols the versatility of perlite [1]. Perlite is presented as a material with the potential to reduce construction costs, lower heating bills, improve fire protection, increase refrigerator capacity, offer economical solutions for food preservation, and meet various industrial needs—including special effects in Hollywood. Globally, there is a shift towards sustainable development, seeking alternatives to conventional materials that have significant environmental impacts, such as high energy consumption, resource depletion, and waste generation. The pursuit of discovering new natural materials aims to address these challenges by ensuring they are renewable, economically viable, and minimize environmental footprints. Population growth drives the demand for infrastructure and housing, making the search for abundant and cost-effective raw materials crucial. Particularly sought after are energy-efficient materials that enhance thermal insulation and contribute to mitigating climate change. The ideal material combines strength, durability, thermal insulation, fire resistance, and acoustic properties. Versatile materials applicable across various industries offer economic benefits and a wide range of applications. Legal regulations increasingly favor sustainable materials, supported by certifications such as LEED (Leadership in Energy and Environmental Design) certification [2], BREEAM (Building Research Establishment Environmental Assessment Method) [3], and the Green Star rating system [4]. These standards promote environmentally friendly practices and inform consumers about the environmental impact of products. Waste management laws encourage recycling and responsible disposal, contributing to a circular economy [5,6]. Carbon taxes incentivize industries to adopt eco-friendly technologies and materials with lower carbon footprints. Ultimately, sustainable building practices—from design to disposal—ensure the efficient use of resources and contribute to a healthier environment for future generations. The quest for innovative raw materials that integrate diverse properties stems from the need for sustainable, efficient, and low-emission solutions. This pursuit aims to meet high performance standards, adapt to evolving market needs, and promote resource efficiency and energy conservation. Implementing materials that fulfill these criteria enhances our ability to create a resilient and environmentally sustainable built environment. The increased interest in perlite, which has contributed to an increase in the production of this raw material, stretches back to the early 1990s, when there has been a steady increase in global perlite production. In 2008, production peaked at almost 3.8 million tons per year. However, the following two years showed a significant decline in global supply, which decreased to about 3.4 million tons. The decline was primarily due to production reductions in Greece, the leading supplier then, which was struggling with the effects of the financial crisis. In addition, the United States has seen a decline in production since 2004. Market conditions gradually improved in 2011, mainly due to a significant increase in production among Asian suppliers, such as Turkey and Iran. As a result, the global supply increased to more than 3.7 million tons in 2012. However, in 2013, supply dropped to 3.6 million tons due to a further decline in production in Greece [7,8,9]. Currently, China (1500 million tons per year) and Turkey (1100 million tons per year) are the main players in the perlite producer market (Figure 1).

In Poland, the expanded perlite is not very common. Due to the lack of native deposits in Poland and the lack of real chances of discovering them, the entire supply of perlite comes from import, mainly from Hungary, Slovakia and Germany. The largest import was in 2016 and amounted to 68,500 tons; currently the import is decreasing—its average value since 2017 is approximately 24,000 tons per year. In the country, raw perlite is subjected to expansion, which is currently carried out in five enterprises, whose total annual production on average over 10 years is 35,000 tons per year [7]. Portugal’s supply of perlite comes from imports, mainly from Spain, Turkey, and Germany. Total imports of this material in 2019 were 1884 tons, including 1609 tons from Spain, 170 tons from Turkey, and 95 tons from Germany [10]. Expanded perlite, discovered by Lee Boyer in 1939 in Arizona, USA [1], is a type of volcanic glass characterized by a structure of fine, porous grains formed through the rapid cooling of lava with high water content. This process leads to the formation of vesicles enclosed within the perlite glass structure [11,12,13,14]. The production process of expanded perlite involves several stages, which are presented in Figure 2.

The production of expanded perlite begins with the crushing and drying of raw perlite ore. The material is first crushed into smaller particles to prepare it for the expansion process, and then it is dried to remove any surface moisture. After drying, the perlite can be expanded using one of two primary methods: the thermal method or the chemical method. In the thermal expansion method, the crushed perlite is heated in a furnace to a temperature of approximately 900 °C. At this high temperature, the trapped water within the perlite rapidly vaporizes, causing the material to expand up to 20 times its original volume. This sudden expansion creates a lightweight and porous structure that characterizes expanded perlite. Alternatively, in the chemical expansion method, the perlite is treated with sodium hydroxide (NaOH), although this approach is less common and is typically used to achieve specific properties in the expanded perlite. Following expansion, the material undergoes a cooling and sorting process. Once cooled, the expanded perlite is sorted by particle size, making it ready for use in various applications. Expanded perlite is valued for its lightweight, insulating, and fire-resistant properties, which make it suitable for uses such as construction materials, insulation, and filtration [15,16,17].

From an environmental perspective, perlite offers several advantages. Its production requires relatively low energy consumption compared to other building materials, resulting in a smaller carbon footprint. As a natural and non-toxic material, perlite does not release harmful substances into the environment during use. Moreover, at the end of its life cycle, it can be recycled or safely disposed of. Perlite’s insulating properties contribute to increased energy efficiency in buildings, reducing the need for heating and cooling and thereby lowering greenhouse gas emissions. Its fire resistance enhances structural safety, and its acoustic properties improve the comfort of occupied spaces. In the context of sustainable development, the use of perlite aligns with goals to reduce negative environmental impacts by promoting the efficient use of natural resources and energy. Its versatility and beneficial properties make it an attractive material for the construction industry and other sectors seeking eco-friendly solutions. The main properties of expanded perlite are summarized in

Table 1. The main properties of expanded perlite.

Properties	Value
pH	from 6.6 to 8 [18]
bulk density (loose)	25–400 kg/m3 [8,19,20]
true (skeletal) density	0.84 g/cm3 to 2.45 g/cm3
thermal conductivity	0.034–0.04 W/m·K [21] for the bulk density of 90 kg/m3 at a room temperature of 24 °C to obtain 0.059 W/m·K [22,23]
specific heat	837 J/kg·°C [24]
fire behavior	non-flammable—Fire class A1
melting point	+1260 °C
chemical composition	the average values of main elements of chemical composition measured on XRF of expanded perlite from China [25], Greece [26], Turkey [27], and US [28]

.

Expanded perlite has several key properties that make it suitable for industrial applications, especially in construction and insulation. Its pH ranges from 6.6 to 8, making it neutral to slightly alkaline and compatible with various materials. With a low bulk density (25–400 kg/m³), it is lightweight and easy to handle, reducing transport costs. The true density (0.84–2.45 g/cm³) provides sufficient structural integrity, while its low thermal conductivity (0.034–0.059 W/m·K) makes it an effective insulator, enhancing energy efficiency. Expanded perlite’s specific heat capacity is 837 J/kg·°C, and it is non-flammable with a Class A1 fire rating, adding to its safety in building applications. Its high melting point (+1260 °C) ensures durability under extreme temperatures. The chemical composition, analyzed across various global sources, shows stability, supporting its versatility in construction, horticulture, filtration, and insulation applications.

Figure 3 provides detailed insights into the microstructure and chemical composition of expanded perlite, highlighting the unique properties that contribute to its effectiveness in various applications. The two microscopic images in Figure 3 at the top illustrate the porous and flaky structure of expanded perlite at different magnifications (200 µm and 20 µm). These microstructures reveal the high porosity and irregular surfaces of expanded perlite, which are essential for its low bulk density and excellent insulation properties. The high porosity also increases the surface area, making perlite suitable for applications such as filtration and soil aeration.

The bar graph below these photos shows the basic chemical composition of expanded perlite. The composition is dominated by oxygen (40.4%), followed by silicon (Si) (19.2%), aluminum (Al) (14%), and ferrous (Fe) (11.7%). Other elements include carbon (C), sodium (Na), calcium (Ca), potassium (K), magnesium (Mg), titanium (Ti), and phosphorus (P).

The atomic structure diagram on the right represents the distribution of elements, such as sodium, potassium, calcium, magnesium, and iron, along with oxygen and silicon atoms. This elemental composition contributes to the high melting point, non-flammability, and chemical resistance of expanded perlite, which are critical for its applications in high-temperature environments and as a fire-resistant building material.

Due to its structure, perlite has many applications in various sectors. It is commonly used in the construction industry as an insulating material in roofs, walls, and floors, as it provides excellent thermal insulation and protects against heat loss [13,29,30,31,32] and acoustic insulation as soundproofing panels [33,34,35,36], particularly ceiling panels, which can comprise up to 75% of the material. It is also used as a lightweight aggregate in plaster and concrete [37,38,39,40]. Perlite can be used as pozzolans in the production of mortars and grouts [41,42]. In the form of microbeads, it is increasingly employed as a binder component in wall cladding panels or roofs [32,33,34,35,36,37]. The demand from the construction industry drives the development of perlite supply, and new applications continue to emerge. This is attributed to perlite’s advantageous properties, such as non-toxicity, neutral pH, resistance to external factors, chemical and biological inertness, complete non-flammability, excellent thermal insulation and acoustic characteristics, durability, affordability, and market availability [8,38,39,40,41,42,43,44,45]. It is also used in horticulture as a substrate ingredient for growing plants, as it can retain water and provide adequate root ventilation. In addition, because of its lightweight properties, perlite is used in the production of lightweight concrete [43,44], refractory materials, and ceramics. It serves as a filter material for water purification [45,46], aids in wine clarification [47], refines sugar [48], oils [49,50,51], and edible fats, acts as a sorbent [52,53] and carrier for fertilizers in horticulture (agroperlite) [54,55], functions as a filler in paints and plastics [56], and is employed in cryogenics to insulate gas tanks stored at low temperatures (Figure 3) [57]. The prospects for perlite consumption are closely linked to its use in horticulture, particularly in hydroponic farming [58], where it optimizes water management, reduces nutrient and fertilizer consumption, and gains popularity in regions facing water scarcity, such as the Netherlands, Spain, and the United States [59]. When incorporated into soil mixtures, perlite significantly enhances soil aeration, optimizes moisture retention, and boosts crop yields.

The objective of this article is to conduct a comprehensive and critical review of the existing literature on the applications of perlite and its impact on the circular economy and on plants and living organisms. The article presents various applications of perlite in a number of fields, with a particular focus on its environmental aspects and impact on living organisms. These include horticulture and agriculture, as well as less conventional areas such as animal bedding and antibiotic carriers. The purpose is to identify the most promising directions for future development and to identify research gaps in the existing literature.

2. Life Cycle Assessment (LCA) of Perlite

One method to assess the environmental impact of materials throughout their entire life cycle is the Life Cycle Assessment (LCA) method, as detailed in ISO 14040:2009 [60] and ISO 14042:2002 [60]. A crucial criterion in this method is the analysis of a material’s environmental impact during all stages of its life cycle. The assessment estimates possibilities for minimizing environmental burdens, such as the consumption of raw materials and energy during production, emissions to air, water, and soil, and waste generation. In the context of expanded perlite, several aspects need to be analyzed from an LCA perspective, as illustrated in Figure 4.

Although perlite is a natural aggregate, the process of mining involves impacts on the landscape, soil erosion, and habitat degradation from mining operations. The production of expanded perlite is also not an environmentally neutral process. During the production process, energy is consumed and greenhouse gas emissions are generated, both during the thermal processing of the raw material and the expansion process. During the production process, there can be emissions of dust and gases, which can have a negative impact on air quality and human health. It should also be noted that the water used in the perlite production process can be recovered and recycled.

Due to the necessity of processing the mined raw material and the wide range of perlite applications, transportation is often required either to bring the raw material to the production plant or to distribute the finished product to various destinations. This results in fuel consumption and greenhouse gas emissions associated with transporting perlite over different distances. Nevertheless, many of these environmental “losses” are offset by the material’s properties and its wide range of applications. One such benefit is the energy savings and reduction in greenhouse gas emissions resulting from perlite’s insulating properties, which contribute to decreased energy consumption in buildings.

Toboso-Chavero et al. [61] highlight a more sustainable management of this raw material, taking into account the social context and benefits of the product. The authors, on the grounds of a comparative LCA analysis of various substrates used in horticulture, conclude that perlite, as a material with much greater applicability considering the environmental cost of its manufacture, should be used in other sectors of the economy. This is also guided by the aspect of the product’s recyclability. The construction industry sector is considered the most favorable from the point of view of LCA analysis. At the same time, the spectrum of applications of perlite in the construction sector is the largest. This is proven by the considerations of Abed et al. [62], who studied the strength properties of using a mixture of perlite and recycled concrete aggregate as an aggregate.

Studies comparing perlite with alternative materials provide valuable insights into modern building material design, which should take many factors into account. This approach aims to create materials that can reversibly change their physical or chemical properties in response to external stimuli, combining many often unobvious properties and characteristics [63,64,65]. Other researchers have also provided perspectives on LCA in the context of perlite. A study by Vinci et al. (2019) [66] compared seven hydroponic substrates, including perlite, and applied LCA and life cycle costing (LCC) methodologies to evaluate their environmental and economic impact. Perlite was found to have a high environmental impact, while sand and bark were identified as more sustainable options. The sand was considered the best substrate in terms of both cost and sustainability. LCAs were conducted on extensive green roofs using different combinations of perlite, coal bottom ash, and fly ash-based aggregates. The study Pushkar (2019) [67] performed Life Cycle Assessments on extensive green roofs using different combinations of perlite, coal bottom ash, and fly ash-based aggregates. This study aimed to identify the most environmentally friendly roofing alternative and applied a two-stage analysis of variance (ANOVA) to analyze the results. The study by Gómez-Cuervo et al. (2017) [68] evaluated organic and inorganic packed biofilters for treating methane emissions, with perlite used as a packing material in the organic biofilter. Environmental indicators and operational conditions were assessed, and this study concluded that both configurations provided a feasible and stable performance. The main environmental hotspots were related to nutrient requirements, infrastructure, waste disposal, and direct emissions. From the perspective of responsible materials management, the use of materials in successive cycles is also important. Kucharczyk and Pichór’s research proves that it is possible to use ground expanded perlite from waste as a sustainable replacement for the precursor ground granulated blast furnace slag (GGBFS) in alkali-activated systems [69]. The topic of using aggregate from recycled perlite blocks as a component of geopolymers [17,70] and supplementary cementitious materials [71] is now one of the new directions being developed by researchers.

In addition to qualitative analyses, various quantitative indicators can illuminate the economic, social, and environmental benefits of perlite. For instance, standard LCA metrics such as Global Warming Potential (GWP) measured in CO₂-equivalents, total primary energy demand, and water footprint may be applied to compare the life-cycle performance of perlite with alternative materials. Likewise, integrating Life Cycle Costing (LCC) and Social Life Cycle Assessment (SLCA) can reveal how perlite-based solutions influence both economic viability (e.g., cost savings from reduced energy needs) and social indicators (such as employment or community well-being). While some studies [61,66,67,68] have partially examined these metrics, further data collection and standardized reporting are necessary to showcase perlite’s full application value across multiple sectors.

Expanded perlite has significant environmental impacts throughout its life cycle, including landscape disruption, soil erosion, and habitat degradation from mining, as well as energy consumption and greenhouse gas emissions during production. While its insulating properties can reduce energy use and emissions in buildings, it is crucial to balance these benefits against environmental costs. Sustainable management suggests using perlite in sectors such as construction, where benefits outweigh impacts, and promoting recycling and reuse of waste perlite to enhance sustainability.

3. Impact of Perlite on Plants

3.1. Perlite in Heavy Metal Remediation

At the forefront of innovative remediation techniques today is the conversion of waste materials and by-products into efficient sorbents [72,73], which helps reduce the negative environmental impact of urbanization. Phytoremediation techniques enable sorption of heavy metals, which is possible through kinetic ion exchange capacity or using macroporous ion exchangers [74].

Heavy metal contamination in soil and water is a significant concern because these metals are not biodegradable and tend to result in bioconcentration, biomagnification, and bioaccumulation in living organisms, causing catastrophic illnesses and disorders [75]. Sorption depends largely on experimental conditions, such as pH, metal concentration, ligand concentration, competing ions, and particle size.

3.2. Perlite as a Growth Medium in Green Roofs and Soilless Cultivation

Beyond heavy metal remediation, perlite has various applications related to plant–soil interactions. One notable use is in green roofs. In a study by Agra et al. (2018) [76], it was tested as a potential substrate for growing plants on green roofs in northern Israel with a Mediterranean climate. This study demonstrated that perlite is an effective growth medium regardless of the type of water used for irrigation (gray water or tap water) and the substrate type (perlite or coal ash). However, the authors emphasized the importance of controlling parameters such as pH, elemental concentrations, electrical conductivity (EC), and chemical oxygen demand (COD) to ensure optimal plant growth.

In Izmir, Turkey, a study analyzed three different substrates—coir, loofah, and perlite—for designing green roofs with succulents [77]. The results indicated that perlite was the most favorable substrate in terms of variables such as EC, pH, drainage, temperature, humidity, plant height, and number of leaves. Nevertheless, the authors recommend combining different substrates to achieve maximum green roof performance, leveraging the advantages of each substrate group [77]. Martini et al. (2023) [78] found that the endemic herb Origanum dictamnus L. shows potential for cultivation on green roofs. Using a soilless substrate containing perlite can reduce structural stress on buildings. They also noted that the cultivation site affects heavy metal accumulation in plants, underscoring the importance of site selection to minimize environmental pollution, especially when the plant is intended for food use.

Perlite has also been tested as a potting substrate for Pennisetum ‘Vertigo^®’ plants [79]. The results showed that perlite is effective and beneficial for this species, and the application of the Goëmar Goteo biostimulant stimulated root elongation in perlite, positively affecting plant growth. Studies combining perlite with cocopeat highlight the attractiveness of this mixture for soilless cultivation [80], as it improves bulk density, porosity, water-holding capacity, and wettability, making it an effective substitute for peat soil in commercial crop production.

Similarly, the effect of perlite on the growth of Melissa officinalis L. was studied. While nanoperlite and MgO/perlite nanocomposites had no significant effect on overall plant growth, nanoperlite at 150 mg/L increased the number of shoots. The maximum content of volatile compounds was obtained at 100 mg/L MgO/perlite nanocomposite, suggesting these materials may act as elicitors for synthesizing valuable secondary metabolites in in vitro cultures [81]. Savvas et al. (2018) [82] concluded that soilless cultivation systems (SCS) as hydroponics using perlite offer independence from natural soil substrates and minimize issues with pathogens and nutrient deficiencies in the greenhouse industry. Automation and environmental monitoring enable efficient nutrient delivery, increasing water use efficiency and reducing environmental impact.

This complements earlier work by Bilderback et al. (2005) [83], which highlighted long-term changes in substrate properties in potted plants. Mixing mineral aggregates such as perlite with organic components can help maintain substrate integrity and reduce physical changes over extended production cycles. Perlite substrates are often compared with peat substrates. One study compared tomato seedlings grown in peat–moss–turface and peat–moss–perlite mixtures, finding that plants in the peat–turface medium were taller and heavier than those in peat–perlite. Differences in nutrient content between substrates influenced plant growth and yield, indicating that proper substrate selection can affect tomato productivity [84]. Herrera et al. (2008) [85] compared five substrate mixtures for tomato cultivation and found that a mixture with perlite addition was most optimal. Plants grown in this mixture had quality indicators similar to those grown in conventional mixtures of old peat and white sphagnum peat, offering a good balance between nutrient supply and adequate porosity and aeration.

This study evaluated the crop yield of Beit Alpha cucumber (Cucumis sativus L. ‘Socrates’) fertilized with aquaculture effluent in pine bark and perlite substrates. Plant density and season were shown to affect yield depending on the type of substrate. Pine bark had a higher yield than perlite, especially when one plant per pot was used, but lowered pH and EC of leachate. Pine bark had a higher yield than perlite by 11% for one plant per pot and can be used as an intermediate substrate to lower pH in aquaculture [86]. In situations of water deficit in semi-arid areas, high pH is a limiting factor for crop production and quality. Appropriate water regimes and the use of perlite for moisture storage can help overcome drought. The experiment was conducted from March to July 2016 in a field in Diyala, Iraq, to determine the effect of tomato (Solanum lycopersicum L.) genotypes ‘Bobcat’, ‘Finenss’, and ‘Hadeer’ on plant growth and development and water management. It was proven that the combination of ‘Bobcat” + 100% irrigation + 5% perlite had the highest water use efficiency. The authors recommend irrigation management in tomato production as a strategy that can save about 50% of irrigation water without reducing yields. Perlite reduces the adverse effects of water deficit and improves growth and production under normal and deficit conditions [87].

3.3. Effects of Perlite on Microorganisms and Environmental Aspects

Optimizing the use of perlite can contribute to efficient and healthy plant growth in the horticultural industry. Another important issue raised by many researchers is the effect of salinity on perlite and its ability to maintain plant growth and yield. The results suggested that perlite could handle different levels of salinity, but salinity affected ion content, metabolites, and yield quality and quantity. A study focusing on the hydroponic culture of spiny chicory, also known as stamnagathi (Cichorium spinosum L.), showed that high salinity (120 mmol/L NaCl) negatively affected plant growth, especially in perlite, pumice, and sand, but did not affect chlorophyll content and leaf fluorescence. The use of perlite as a substrate increased phenolic content and decreased protein content under salinity. However, low salinity concentrations improved some plant quality parameters, suggesting that stamnagathi can tolerate low salinity in hydroponic cultivation [88].

In a greenhouse experiment with melon cv. ‘Tempo F1’ in peat, perlite, and sand mixtures, the effects of proline and potassium nitrate on salinity-stressed plants were studied. Salinity caused decreases in growth, yield, water content, stomatal density, ion uptake, and chlorophyll content. Adding 5 mM KNO₃ or 10 mM proline mitigated salinity’s negative effects by maintaining membrane permeability and increasing Ca²⁺, N, and K⁺ concentrations in leaves [89]. Yelboğa’s (2020) [90] study focused on grafted tomato seedling production, considering the environmental impacts of various resources used in the production process, including peat and perlite. This study identified coal for greenhouse heating and expanded polystyrene (EPS) trays as having higher environmental impacts, suggesting considering rigid plastic alternatives with higher recycling potential. A study on growing melon (Cucumis melo L. cv. Galia) in perlite using salt water for irrigation showed that all vegetative and fruit yield parameters were significantly reduced when salinity started early (14 days after transplanting). However, this inhibitory effect gradually diminished when salinity was applied later. Salinity treatments affected fruit by reducing sugars, acidity, and total soluble solids, indicating that brackish waters can be used to grow melon with minimal yield losses if concentration and exposure time are carefully monitored [91].

The effect of plants on the chemical composition of perlite was demonstrated by the research of Silber et al. (2010) [92], especially by increasing the concentration of water-soluble elements such as phosphorus, calcium, and magnesium. In addition, the kinetics of element release depend on pH and ionic strength, and the release of nutrients such as P, Ca, Mg, and K was higher in the spent perlite than in new perlite. It is worth noting that perlite maintained at a low pH, below 5, can lead to excessive release of aluminum, which can be harmful to plants, so caution is advised in such cases.

These considerations make it possible to formulate another important issue related to attempts to optimize plant growth in perlite. Previous research has focused on using additional ingredients such as potassium nitrate, proline, silicon, etc., to improve plant health and performance during heat stress, salinity, drought, or exposure to heavy metals. Other studies have examined the effects of increasing chromium (VI) concentrations on the structure and ultrastructure of various organs of broad beans grown on perlite. The observed changes varied in different organs and did not always correlate with chromium content. The main effect of toxicity was damage to cell membranes due to chromium (VI)’s ability to oxidize. Chromium can be retained in the vacuoles and cell walls of roots and leaves mainly as chromium (III), while the changes in the upper parts of plants were due to the indirect effect of chromium on mineral content [93].

The effect of a limited concentration of cadmium (5 μg mL⁻¹) on the structure and ultrastructure of leaves, stomatal apparatuses, and plastids of beans grown on perlite was studied by Barceló et al. (1988) [94]. The observed changes were related to the plant area with the highest cadmium concentration, and plastid ultrastructure and chlorophyll synthesis were most disturbed in young trifoliate leaves compared to primary leaves. The effects of cadmium toxicity on these structures have been discussed in the context of the plant’s uptake mechanisms for this element [94]. Plants of the hawkweed (Typha latifolia) were grown in a mixture of sewage sludge compost, commercial compost, and perlite and irrigated with solutions containing different metals. The concentrations of nickel, copper, and zinc in the roots and leaves of these groups were higher than in the water-irrigated control group. While perlite in the mix did not significantly affect metal accumulation, a reduction in chlorophyll concentration in one group suggested a toxic effect of metallic solutions on plants [95].

In addition, there are interesting studies analyzing the effects of microorganisms on crops grown on perlite substrate. One study evaluated Escherichia coli contamination in microgreens of lettuce and radish plants grown in peat moss and perlite irrigated by different methods. The type of irrigation did not affect the bacterial population on the edible parts, but E. coli populations on non-edible parts were higher in perlite than in peat moss. E. coli was detected only in radishes grown in perlite, indicating the need for protective strategies to minimize pathogen contamination [96]. The review presents new findings on the uptake and transport of inorganic and organic nitrogen by arbuscular mycorrhizal fungi. Mycorrhizal fungus Glomus mosseae was shown to transport supplied organic nitrogen to wheat plants within a 48-h labeling period in semi-hydroponics (perlite). However, the amount of nitrogen transported depended on nitrogen availability in the pot culture, and ecotypic differences were observed in fungal isolates [97].

Recent advancements in sustainable construction have focused on incorporating industrial waste as raw materials for building components, transforming recycled materials into valuable resources with specific properties [98]. Dzięcioł and Szlachetka (2024) [99] investigated the application and environmental safety of perlite-based concrete, emphasizing its ability to immobilize potentially toxic elements (PTEs) in soil and plants. Their research demonstrated that incorporating 10% perlite-based concrete (PPC) increased soil zinc content to 96.6 mg/kg, a 304% rise. Similarly, fly ash perlite-based concrete (PBFC) at the same concentration significantly increased soil copper content to 21.7 mg/kg, representing a 112% rise. This study also evaluated the environmental safety of using perlite concrete and activated carbon in infrastructure projects, such as earthworks and road subbases, where these materials interact with soil and water environments [99].

Due to its unique physical and chemical properties, perlite plays a critical role in supporting plant growth and development. It is an efficient substrate in soilless cultivation systems, such as hydroponics and green roofs, providing proper aeration, drainage, and water retention. Mixing perlite with materials such as cocopeat or peat improves soil structure by increasing porosity and water-holding capacity, fostering better root development. Perlite also enhances water use efficiency in plants, which is crucial in regions with limited water resources, and mitigates the adverse effects of abiotic stresses such as drought and salinity. However, high salt concentrations can limit perlite’s ability to support plant growth. While perlite demonstrates sorption capacity for heavy metals such as cadmium and chromium, its exposure to these elements may cause structural and physiological disturbances in plants. Additionally, interactions between plants and perlite can alter its chemical composition, and at low pH levels, this can lead to the release of toxic aluminum. The use of biostimulants or mineral fertilizers in conjunction with perlite can enhance crop performance and reduce the negative effects of stress. Nonetheless, crops grown on perlite substrates are more susceptible to contamination by pathogens such as Escherichia coli, necessitating appropriate preventive measures. Perlite also fosters symbiosis with arbuscular mycorrhizal fungi, which significantly enhance nutrient uptake by plants.

4. Impact of Perlite on Living Organisms

4.1. Toxicological Impact

Toxicological studies suggest that perlite exhibits relatively low toxicity. Limited data on the toxicology of perlite in animal studies indicate that the amount of ingested substance that kills 50% of a test sample—LD₅₀ (oral ingestion)—is more than 10 g/kg, and a chronic inhalation study in guinea pigs and rats [100] shows that the no observed adverse effect level (NOAEL) for the inhalation route is 226 mg/m³. Studies of perlite mine workers have found no adverse effects on respiratory health. However, residents exposed to mine dust, including perlite, may show some increases in the incidence of certain diseases, but these data require further analysis. Perlite is regulated as a “nuisance dust” in most countries [28].

Given the distinctive properties of perlite dust and the absence of compelling evidence associating it with chronic illnesses, Roubik et al. (2022) [101] in 2022 conducted pilot laboratory tests in which perlite was used for simulation and preparation of breathing trials assessing gas exchange under avalanche snow and potentially for testing of new avalanche safety equipment before their validation in real snow. In this study, thirteen male subjects underwent three breathing phases—into snow, wet perlite, and dry perlite. The experiment participants inhaled perlite for no longer than 418 s. This type of research is undoubtedly innovative, but due to the fact that the effects of inhaling perlite dust are currently unknown in simulation studies where perlite is used as a surrogate of high-density snow for studying gas exchange, a given volunteer should participate only once.

4.2. Pro-Ecological and Pest Control Applications

Investigating the microarthropod community in artificial soil containing different amounts of organic matter, a study was conducted in a cypress stand, where mesh boxes were filled with perlite grains mixed with three different amounts of organic matter. The results indicate that the abundance of Collembola, Oribatida, and Prostigmata correlates positively with organic matter content, suggesting that the existing amount of organic matter in the studied forest is sufficient to support the microarthropod population. It was estimated that 1 g of organic matter could potentially support 106 Collembola, 81 Oribatida, and 130 Prostigmata, indicating that perlite has a positive effect on the development of the microarthropod community [102].

Perlite was analyzed in a study as an alternative control tactic for hard ticks (Ixodidae) [103], looking for alternative methods of tick control due to developing resistance to synthetic chemical acaricides. Inert dust, including perlite, has proven effective in immobilizing and killing ticks. Perlite remains effective for longer periods, does not degrade in the environment, and can be used in integrated tick management strategies.

The efficacy of Imergard^TM WP (Imerys, 100 Mansell Court East, Suite 300, Roswell, GA, USA) perlite-based dust compared to CimeXa^TM (Rockwell Labs, 1257 Bedford Ave, North Kansas City, MO, USA), which is a silica gel-based product, was studied by Showler et al. (2023) [104]. Performed laboratory tests on the lone star tick, Amblyomma americanum, when both desiccant dusts proved effective in immobilizing and killing ticks. Imergard WP’s perlite-based dry dust can prophylactically protect cattle and other animals from ixodid pests of medical and agricultural importance. Perlite can potentially be stored indefinitely, can retain its lethal properties if an adequate amount remains on the ground, and may be acceptable for limited use in environmentally sensitive habitats.

The application of desiccant dust with bioactive additives on Rhipicephalus (Boophilus) microplus, known as the southern cattle fever tick, proved highly lethal to tick larvae despite the fact that the dusts, including perlite, were inert substances. Absorbent dusts have many advantages, such as extended residues, flexibility in application, and safety for the environment, animals, and humans [105]. The effects of perlite sand on the skin of the Sprague–Dawley rat were investigated. Contact of perlite sand with the skin induced an inflammatory reaction, which increased with prolonged exposure to the substance. Although perlite sand has an inert chemical compound, prolonged contact with it under production conditions can contribute to the development of skin diseases, so additional protective measures are recommended for workers who come into contact with the substance [106]. This study evaluated the effectiveness of siderophore-producing microorganisms (SPMs), such as Rhizobium bacteria, Pseudomonas bacteria, and the root fungus Piriformospora indica, in improving the condition of alfalfa under cadmium (Cd) stress conditions. SPM-inoculated alfalfa showed higher biomass and nutrient uptake both under normal conditions and under Cd stress. The microorganisms minimized Cd toxicity by increasing the activity of antioxidant enzymes and reducing the concentration of Cd in shoots, which can help plants survive in soil contaminated with this heavy metal, providing an effective and environmentally friendly approach to combat heavy metal toxicity in plants, animals, and humans [94].

A study conducted in 2022 on guppy aquarium fish analyzed the effect of a sorption complex, which included perlite, on reducing toxins under equal conditions. The results suggest that a premix dose of 4% allowed an almost threefold reduction in toxins, in this case, lead, making this sorbent complex a potential preventive measure for lead acetate-induced food toxicosis in aquarium fish. The sorbent premix can be recommended for use in both aquaria and fisheries after industrial testing [107].

4.3. Applications in Animal Husbandry

Perlite is also used in animal husbandry technology. The use of perlite in broiler diets was investigated using the activity of the enzyme lipase in the small intestine as an example [108]. The results showed that the consumption of perlite significantly increased the activity of the lipase enzyme at different weeks and locations in the small intestine of broiler chickens. The addition of 2% perlite showed a significant effect on lipase activity compared to the control group. A 2017 study analyzed the effect of different levels of expanded perlite addition in the diet on egg yield and quality traits in laying hens. The results showed that the addition of perlite had a positive effect on feed conversion ratio and egg weight. No significant differences were observed in final body weight, feed intake, egg yield, and egg weight. Perlite in the diet had no negative effect on shape, yolk, or protein index. Perlite supplementation can be used at rations as low as 1% without changing animal performance [109].

However, it should be remembered that the use of perlite as a feed additive for other animals requires proper research and documentation of safety and efficacy. In addition, perlite has applications not only as a feed additive but also in other areas of agriculture, such as litter in poultry houses, fillers, anti-caking and adsorbent additives in veterinary preparations, pesticides, fertilizers, and other purposes [110].

While perlite shows promise in various applications affecting living organisms, further research is necessary to fully understand its safety and efficacy, especially when used as a feed additive for other animals.

5. Discussion

Life Cycle Assessment (LCA) evaluates the environmental impact of materials across their entire life cycle [60]. In the case of perlite, mining can alter landscapes [61,62], and its expansion process requires substantial energy, emitting greenhouse gases and other pollutants [63,65]. Although water used during production is often recycled, transportation still contributes to emissions. However, perlite’s insulating properties can contribute to a reduction in building energy consumption, thereby partially offsetting its environmental impact [66].

Due to its advantageous properties, including aeration, drainage, and water retention, perlite is extensively utilized in soilless cultivation and hydroponics [77,78,79]. Mixing it with cocopeat enhances soil structure and water-holding capacity [81,86]. Research focuses on optimizing perlite under stress conditions—heat, salinity, drought, and heavy metal exposure [91,92,111]. For instance, adding calcium sulfate has been shown to mitigate salinity’s negative effects on tomato plants grown in perlite [111]. Additionally, siderophore-producing microorganisms, including Rhizobium and Pseudomonas, can improve plant resistance to cadmium in perlite substrates [99,111].

Toxicological studies indicate that perlite is often treated as a “nuisance dust” [100]. Occupational exposure in mine workers has not been linked to significant respiratory issues [99], although prolonged skin contact may cause inflammatory reactions, underlining the need for protective measures [105]. Perlite also shows potential in pest control, effectively targeting hard ticks without degrading in the environment [102,103]. In animal husbandry, it can enhance poultry digestive enzyme activity and feed conversion [107,108], while in aquaculture, a perlite-containing sorbent helps reduce lead toxicity in fish [106]. Innovative remediation efforts utilize perlite’s ion-exchange capacity for heavy-metal adsorption [72,73,74], addressing concerns over non-biodegradable pollutants [75,76]. Finally, perlite incorporation into soil promotes beneficial microarthropods, thereby supporting biodiversity and nutrient cycling [101].

Considering the complexity and multifaceted applications of perlite in environmental remediation, agriculture, and construction, the integration and development of artificial intelligence (AI) are becoming increasingly essential for determining optimal parameters related to its use. AI technologies can process vast amounts of data and identify patterns that are not readily apparent through traditional analytical methods. In the context of perlite, AI can assist in modeling its behavior under various environmental conditions, predicting its interactions with different contaminants, and optimizing its properties for specific applications. For instance, machine learning algorithms can analyze soil and plant data to determine the most effective perlite compositions for enhancing plant growth under stress conditions such as salinity, drought, or heavy metal exposure. In environmental engineering, AI can help simulate the long-term impacts of perlite use on soil health and ecosystem dynamics, enabling researchers to assess potential risks and benefits more accurately. Moreover, AI can facilitate the development of advanced perlite-based materials by predicting how modifications at the nano or macro scale might influence their sorption capacities, mechanical strength, or durability. This predictive capability accelerates innovation and reduces the need for extensive trial-and-error experimentation. Similar AI-driven approaches have already been employed in estimating parameters for other materials, including anthropogenic materials: fly ash, slag, and recycled concrete aggregates [112,113,114,115,116]. The successful application of AI in these contexts highlights its potential utility in advancing perlite research and applications.

6. Conclusions and Future Directions

While perlite offers numerous benefits, there are scenarios where its use may not be suitable or practical. Expanded perlite’s porous nature makes it susceptible to moisture absorption, rendering it less ideal for applications with continuous exposure to water or damp conditions. In large-scale construction projects, the cost and logistics of sourcing sufficient quantities of perlite may be prohibitive compared to more widely available construction materials. Additionally, in seismic zones, structures made from perlite concrete may require additional reinforcement to meet strength and safety requirements. Despite these limitations, perlite remains a valuable material with a wide range of applications in various industries, particularly where its lightweight, insulating, and non-toxic properties are advantageous. Proper evaluation, engineering analysis, and consideration of project-specific requirements are essential when determining perlite’s suitability for a particular application. There is a need for scientific research to educate users on the rational use of expanded perlite, including its benefits, best practices, and proper handling.

Based on the information presented in this review, several directions with the greatest potential for the use of perlite in future research can be identified (

Table 2. Directions with the greatest potential to use perlite for further research.

1—Environmental Engineering in Horticulture
Greatest Potential	The Reason for the Position in the Ranking	Possible Application Hazards	The Biggest Research Gap
Hydroponic substrates, production, and biofilters for the methane emission treatment	Effective for plants on green roofs, tomato seedlings, and soilless culture in commercial crop production. Extends greenhouse lifespan, allows recycling of used substrates, and improves nutrient and water management. Use of siderophore-producing microorganisms in perlite-containing soil helps plants combat heavy metal toxicity. Toxicological studies suggest that perlite has relatively low toxicity.	Sorption of heavy metals in perlite depends on experimental conditions such as pH, cation exchange capacity of soils, metal concentration, ligand concentration, competing ions, and particle size. Heavy metals are non-biodegradable and can lead to bioconcentration, biomagnification, and bioaccumulation in living organisms, causing various illnesses and disorders.	Further research is needed to optimize plant growth in perlite under different conditions, such as heat stress, salinity, drought, and heavy metal action. Lack of comprehensive, long-term environmental impact assessment research should focus on evaluating the extended environmental effects of using perlite as a growth medium, especially considering potential cumulative impacts and changes in soil properties over an extended period.
2—Environmental Engineering in Animal Husbandry
Greatest Potential	The Reason for the Position in the Ranking	Possible Application Hazards	The Biggest Research Gap
As a feed additive	Studies indicate positive effects of perlite as a feed additive in animal husbandry. Specifically noted for enhancing enzyme activity in broiler chickens and improving egg quality in laying hens. It is used as litter in poultry houses, fillers, anti-caking agents, and adsorbent additives in veterinary preparations, pesticides, and fertilizers. Perlite demonstrates promise as an alternative control tactic for hard ticks. Effective in immobilizing and killing ticks without causing environmental degradation. A sorption complex containing perlite shows potential in reducing toxins in guppy aquarium fish. Suggests a possible preventive measure for food toxicosis in aquarium fish.	Although toxicological studies suggest that perlite has relatively low toxicity, it is regulated as a “nuisance dust” in most countries. Prolonged contact with perlite sand may contribute to the development of skin diseases, so protective measures are recommended for workers in contact with the substance. The introduction of microorganisms in perlite-containing soil may pose risks, especially if not managed properly. Adequate precautions should be taken to prevent the growth of harmful microorganisms. Fine perlite particles can become airborne during handling and processing. Prolonged inhalation of perlite dust may lead to respiratory irritation.	Lack of comprehensive research on the potential long-term health impacts on humans and animals exposed to perlite-containing products. Research should focus on monitoring and assessing the health outcomes of individuals, workers, or animals over extended periods of exposure to perlite, considering inhalation, dermal contact, and ingestion. Addressing this gap would provide a more thorough understanding of any chronic health risks associated with prolonged use or exposure to perlite-based materials in diverse settings, helping to establish appropriate safety guidelines and regulations.

).

Table 2 highlights key areas where perlite shows significant potential for future research and application, particularly in environmental engineering within horticulture and animal husbandry. In horticulture, perlite’s effectiveness as a growth medium in hydroponic systems, green roofs, and soilless cultures is emphasized. Its ability to support plant growth, extend greenhouse lifespan, and improve nutrient and water management makes it valuable for sustainable horticultural practices. Additionally, incorporating siderophore-producing microorganisms into perlite substrates can enhance plant resistance to heavy metal toxicity, further increasing its utility in agriculture.

Future research in horticulture should focus on optimizing plant growth in perlite under stress conditions such as heat, salinity, drought, and heavy metal exposure. Comprehensive, long-term studies are also needed to assess the cumulative environmental effects of using perlite, with a focus on soil properties and potential ecological changes over extended periods. Considering the complexity of these interactions, integrating artificial intelligence (AI) into perlite research offers transformative possibilities. AI can model plant–perlite dynamics under various environmental stresses, enabling precise adjustments to substrate compositions. By analyzing extensive soil and plant datasets, AI can predict optimal conditions for perlite use, facilitating data-driven improvements in agricultural practices. In the realm of animal husbandry, perlite offers significant benefits as a feed additive and in pest control. Its use has been shown to improve animal health and productivity while providing environmentally friendly pest management solutions. To fully leverage these advantages, extensive research is necessary to evaluate the long-term health impacts on humans and animals exposed to perlite-containing products, including potential respiratory and dermal effects. AI-driven technologies could also play a role here by simulating the long-term biological impacts of perlite exposure, aiding in the development of comprehensive safety protocols. Establishing appropriate safety guidelines and regulations based on scientific evidence will ensure the safe handling and use of perlite in animal husbandry.

In conclusion, the diverse applications of perlite offer significant benefits in both horticulture and animal husbandry, contributing to sustainable practices and environmental protection. However, challenges such as potential health risks, environmental impacts, and practical limitations require focused research efforts. By addressing identified research gaps—optimizing plant growth conditions, assessing long-term environmental and health impacts, and developing safety protocols—perlite can be used more effectively and safely. In addition, integrating artificial intelligence to analyze and optimize perlite’s applications in these areas has the potential to accelerate these efforts, reduce the cost of experimentation, and impact sustainability.