2.2.7. Antistatic Textiles

Due to increased moisture content, cellulose fibers like lyocell linen, viscose, cotton, etc. do not mount up the static charge. On the other hand, synthetic fibers like nylon are susceptible to the generation of static charge due to lower moisture regain. Consequently, several studies have been performed on the development of anti-static textiles by the incorporation of certain conducting nano-fillers (Memon et al., 2018, [148]). Titanium dioxide nanoparticle, nano-silver, zinc oxide nanoparticle, antimony-doped tin oxide, and silane nanosol can be used to provide anti-static ability in synthetic fibers (Zhang et al., 2009, [149]), (Hassan et al., 2019, [150]), (Hossain, M et al., 2013, [151]), (Yadav et al., 2006, [152]). Due to the fact that the aforementioned nanomaterials are conductive in nature, these materials dissipate static charges mount up on the surface of fiber.

### **3. Nanomaterials in Textile Industries—Environmental, Health, and Safety Concerns**

Textile material is considered to be our second skin for an entire day. We use textiles for aesthetic, protective, decorative, and several other applications. Most textile materials are in direct and prolonged contact with our skin. Consequently, the influence of carcinogenic and toxic substances that are available in textiles must be comprehensively examined. One of the most modern groups of prospective dangerous substances belongs to the group of engineered nanomaterials. The significance of engineered nanomaterials has been acknowledged by the textile sector, due to the fact that these materials have the ability to modify the chemical and physical properties of textile materials and textile fibers—improve water and stain resistance, enhance the capability of materials for absorbing dyes, and alter the wettability depending on surface roughness and surface energy. The aforementioned properties are beneficial for several non-woven and woven textiles like automobile interior fabrics, sportswear, protective clothing, and rainwear (Harifi et al., 2017, [153]), (Shalaby et al., 2020, [154]), (Yu et al., 2018, [155]), (Kausar et al., 2018, [156]). Still there are no adequate studies, however some literature reviews and scientific papers have focused on safety issues related to nanotextiles. Some of the recently published studies include the works by (Rovira eta al., 2019, [157]) and a recent chapter by (Montazer et al., 2018, [158]) in a book entitled Nanofinishing of Textile Materials. Nanotextiles can definitely cause risks for human health, safety, the environment, and sustainability (Kohler et al., 2014, [159]), (Geranio et al., 2009, [160]), (Lorenz et al., 2012, [161]). On the basis of the location of the integration of nanomaterials in textiles, they could be less or more exposed to external influences (Rather et al., 2020, [162]). There have been di fferent studies carried out for assessing the release of silver nanoparticle from antibacterial fabrics into artificial sweat (Wagener et al., 2016, [163]), (Kulthong et al., 2010, [164]), (Kim et al., 2017, [165]), (von Goetz et al., 2013, [166]), (Spielman et al., 2018, [167]), (Stefaniak et al., 2014, [168]), (Balakumaran et al., 2016, [169]), (Milosevic et al., 2014, [170]). (Wagener et al., 2016, [163]) studied the textile functionalization as well as its impacts on the discharge of silver nanoparticles into artificial sweat. Migration tests have been performed for four commercial textiles and for six lab-prepared textiles. Two of these laboratory-prepared textile signifies materials where silver nanoparticles were incorporated inside the textile fiber (composite), while the other laboratory-prepared textile consists of silver particles on the particular fiber surface (coating). The test results confirmed a lesser release of total silver from composites as compared to the surface-coated textile. The particulate portion found inside artificial sweat was noted to be less in the majority of textiles, confirming that the majority of the discharged silver is available as dissolved silver. Additionally, it can be noted that nanotextiles will not discharge more particulate silver, relative to the conventional silver textiles. Moreover, the results confirmed that the functionalization type is the significant parameter influencing the migration.

Despite the aforementioned reported works, attaining wide-ranging information on the risks associated with nanomaterials is still challenging. The aforementioned is because of the range of nanomaterials, manufacture techniques, nanoparticle shape, size, crystallinity, porosity, agglomeration and aggregation, and several other factors. Examination on the dangers associated with nanotextiles and nanofinishing techniques needs a complete understanding of the product's life-cycle (Figure 7). This take account of the fundamental properties of the nanomaterials, nanomaterial fabrication procedures, and di fferent application techniques utilized for imparting nanocomposites and nanoparticles on the textile substrates or insertion of nanoparticles into fiber formation processing, nanofinishing durability on the surface, storage/transportation of the treated textiles, ultimate product usage, the conditions in which the final product will be exposed to, and product recycling/disposal. Depending on the

utilization of the nanotextiles, the disposal of the product will influence soil, water, and commonly the environment, or straight skin contact of human causing threats on the health of a human with ultimate environmental effects. Nanomaterials could be accidentally discharged from the treated samples in the course of their lifetime or exposure of labors to the dangerous effects of nanomaterials might happen at the time of the fabrication process. The life cycle of the product and design of the product regulate the different environmental as well as health exposure situations. As an illustration, the engineered nanomaterials inadvertently discharged from geotextiles might possibly end up in soils, while the engineered nanomaterials involuntarily discharged from T-shirts might make direct contact with humans, finally entering wastewater. Therefore, recommending regulation based on the behavior and effects of nanotextiles needs complete product characterization based on particle stability, surface morphology, shape, porosity, size, chemical composition, as well as propensity to aggregation and agglomeration.

**Figure 7.** Life-cycle of nanotextiles. Reproduced from (Montazer et al., 2018, [158]).

### *3.1. Environmental Risks of Nanomaterials from Textile Industry*

A moderately larger fraction of engineered nanomaterials in textiles are assumed to be discharged into wastewater (for example till 20% for silver nanoparticles) (Cucurachi et al., 2019, [171]), (Patnaik et al., 2019, [172]). Nevertheless, the quantity of silver nanoparticles and other engineered nanomaterials accidently discharged into the environment depends greatly on the textile design utilized, particularly how the nanomaterials are incorporated within the textile fiber. Straight discharge of nanomaterials into the air by means of abrasion looks to be of a lesser significance (just 5%). Other flows of nanomaterials from textiles, for example, into waste incineration, are greater from a bulk perspective though, they probably result in just minimal discharges to the surroundings. Therefore, the textiles might constitute a significant source of nanomaterials released into aqueous systems and into soils by the biosolid utilizations. The evaluation of the environmental dangers is extremely dependent on the corresponding product life cycles and on the quantities of engineered nanomaterials manufactured globally. The durability (stability) of the nanomaterials existing in the textile depends on its fabric binding, the influences on the fabric in the course of its life-cycle (manufacture, utilization, disposal/recycling), which could harm the textile material or the bonding between the fibers and nanomaterial, mechanical stress (like pressure, strains), abrasion, temperature changes, high temperatures (till 225 ◦C in textile finishing), detergents (either during laundry or in textile processing), solvents (during dry cleaning or textile processing), water (washing, rain), body fluids (urine, sweat, and saliva), and ultraviolet radiation. The nano-biocomposite application can be a good substitute to a majority of artificial antibacterial agents because of their biodegradability, increased environmental compatibility, as well as non-toxic nature. Considering a life cycle method for studying the possibility of the release of silver nanoparticles from functionalized textiles, it is possible to find the significance of various phases to silver discharge over time. In a study by (Mitrano et al., 2016 [173]), three distinct lab-prepared nanofabrics were exposed to one or 10 washing cycles under various laundering conditions. It was noted that the total entire metal discharged differed remarkably on the nanoparticle incorporation as well as the washing pattern variant. The test results confirmed that the active landfill environment will not mobilize nanoparticles from the surface of the fabric as easily subsequent to washing relative to the unwashed textile. Increased release of nanoparticles from textile have been noted at the time of the life cycle's utilization phase instead of the disposal phase.

Despite the fact that nanotextiles have been observed to be e fficient in photocatalytic or the absorption degradation of pollutants from impure wastewaters, or the nanofibrous membranes could be employed as air/water filters, there have been several forewarnings in regards to the ecological dangers of nanomaterials. Due to the larger surface area of nanomaterials, these materials are extremely reactive to other materials while discharged during any stages of its life cycle. The aforementioned must be associated with both sides of danger and opportunity as the reaction of nanomaterials with other constituents might contribute to lesser toxicities, thus altering these materials from their unique properties. Conversely, these nanomaterials might carry other harmful materials, generating additional toxicity. If the aggregation/agglomeration of nanomaterials occurs, it is conceivable to separate the nanomaterials from the waste water e ffluent by filtration or sedimentation techniques. The consequence of sediments on the environment is not totally clear yet. The burning of sewage sludge was reported, even though the whole avoidance of the discharge of nanomaterials has not been demonstrated ye<sup>t</sup> (Som et al., 2011, [174]). Certain nanomaterials could be dissolved in the surroundings producing no consequence, whereas other solutions consisting of metals are extremely harmful to the surroundings. Magnetic separation approaches based on the manufacture of magnetic nanomaterials and their utilization on textile substrates were also established as a capable inexpensive technique for the separation of the nanomaterials from waste water e ffluents (Harifi et al., 2014, [175]). Fascinatingly, certain engineered nanomaterials might influence the environment less harshly than they might influence human health, whereas the case for some others is vice versa. The aforementioned is specifically true for carbon nanotubes.

The engineered nanomaterials have several benefits depending on the properties, such as less textile laundering because if their antibacterial properties or quick wound healing (Temizel-Sekeryan et al., 2020, [176]). From the analysis of the study by (Lorenz et al., 2012, [161]), four out of the seven silver nanotextiles leached a noticeable amount of silver (Figure 8). Neither the rinsing nor the washing solutions of textiles 1 to 3 contained any silver. In a study by (Piontek et al., 2018 [177]), the team analyzed two Life Cycle Assessment studies on the textile value chain and on the product-service systems. It is good review paper, where the authors presented their findings on the dependence of Life Cycle Assessment studies, lack of accessible information on chemicals, advantages because of the technological development in the area, the significance of the use phase of clothes, and sugges<sup>t</sup> additional routes of research in regards to user behavior as well as methodological development. Merging the conclusions of the two studies helped for the development of a method for conducting the Life Cycle Assessment studies on a product-service system based on existing research as well as research gaps. This could include the development of a method for assessing the environmental benefits when establishing a product-service system.

For the environment, the following criteria were established as critical for the determination of environmental fate as well as e ffects of engineered nanomaterials (Som et al., 2011, [174]): (1) Certain warning of dangerous e ffects at existing genuine exposure concentrations, (2) a propensity to be dissolved in water, leading to the vanishing of the engineered nanomaterials, and the development of dissolved metal ions, (3) a propensity for sedimentation or agglomeration under normal conditions, (4) destiny in wastewater facility, and (5) steadiness in the course of incineration. The aforementioned conditions comprise of consequences of engineered nanomaterial and the performance of these materials in ecological compartments as well as the technosphere. The dissolution of alumina nanoparticles, zinc oxide nanoparticles, and nano-silver in water enhances the harmful e ffects. However, the dissolution of nano-silicon dioxide reduces the harmful e ffects as it caused the vanishing of the nanomaterials and the dissolved silica is not dangerous at environmental concentrations. With the probable exemption of nanosilica, all other nanomaterials can agglomerate intensely in natural waters and are therefore detached from the water system and are less mobile. A majority of engineered nanomaterial seem to be separated in the course of wastewater treatment, but this is based on only limited accessible research, which have employed unrealistically higher concentrations of nanomaterials. A probable exclusion might be carbon nanotubes and silica where a lower separation rate was noted depending on functionalization. For the duration of waste incineration, the carbon-containing nanomaterials might probably be destroyed totally, while metal-oxide or metal particles might persist intact. In general, it can be concluded that mostly silver nanoparticles and zinc oxide nanoparticles could lead to a maximum risk to the environment, however the titanium dioxide nanoparticles also need to be additionally examined. From an environmental perspective and the present utilization of engineered nanomaterials like aluminum dioxide, silicon dioxide, carbon black, and montmorillonite probably cause no or little hazard to the environment (Black, 2013, [178]).

**Figure 8.** Quantity of silver released from the seven textiles at the time of washing as well as rinsing. The inset presents an expanded outlook of the lower concentration range. The percentage of total silver released is presented on top of the columns. bdl: Below detection limit. Reproduced from (Lorenz et al., 2012, [161]).

### *3.2. Health Risks of Nanomaterials from Textile Industry*

The exposure to engineered nanomaterials from textile materials could happen by means of several pathways: Skin absorption, inhalation, and ingestion (Sahu et al., 2017, [179]), (Alanezi et al., 2018, [180], (Murphy et al., 2020, [181]), (Yu, 2018, [182]), (Abdelrahman et al., 2020, [183]). Maximum exposure to nanomaterials arise for laborers in the textile industries because of continued and prolonged exposure to higher quantities of engineered nanoparticles (Torabifard et al., 2018, [184]). The most frequent routes for the engineered nanoparticle uptake are the skin as well as respiratory track. Subsequent to body entry, nanomaterial accumulates in the spleen, bon, kidney, and liver (Tavares et al., 2017, [185]). The hypothetical model of engineered nanoparticles (ENPs) pathway in the human body and its toxic and harmful effects are shown in Figure 9. Due to the aforementioned reasons, the toxico-kinetics of engineered nanomaterials are presently under numerous studies (de Jong et al., 2017, [186]). Due to the fact that the engineered nanomaterials are smaller than 100 nm, these materials could smoothly penetrate cells (Aryal et al., 2019, [187]). Even though the harmfulness of nanoparticles varies based on their properties (chemical composition, surface energy, charge, shaper, size, and others), they also depend on the living organisms and their diverse DNA covering ratios (Sukhanova et al., 2018, [188]). The major concern for nanoparticle exposure from textiles is by means of skin absorption. The skin is considered to be a superior absorptive material because of the rich supply of blood and tissue

macrophages, dendrites, lymph vessels, and various types of sensory nerve endings (Ramachandran, 2014, [189]). The paper by (Filon et al., 2016 [190]) reviewed and analytically assessed evidence on the significance of different skin adsorption paths for engineered nano-objects, nanoparticles, their aggregates as well as agglomerates.

**Figure 9.** Model of the transport of nanomaterials in human body. Reproduced from (Rezic et al., 2012, [191]).

Several studies have confirmed that nanomaterials can lead to adversarial toxic effects in living beings (Exbrayat et al., 2015, [192]), (Roberto et al., 2019, [193]), and DNA damage (Grumezescu et al., 2017, [194]). Studies on DNA damage have received more research attention because of associations with cancer, neurological diseases, and ageing. In the study by (Grumezescu et al., 2017 [194]), the damage of DNA caused by different nanomaterials will be evaluated with respect to DNA damage products, types as well as detection methods. The results of the study carried out by (Nallanthighal et al., 2017, [195]) sugges<sup>t</sup> that a human being with genetic polymorphisms as well as mutations in 8-Oxoguanine DNA glycosylase 1 might have enhanced susceptibility to silver nanoparticle-mediated DNA damage. The factors that regulate the possible toxicity of engineered nanoparticles are biodegradation, biodistribution, biocompatibility, inflammation, as well as interference with cells and a regular functioning of organs (Adabi et al., 2017, [196]). The aforementioned factors are associated with the reactivity, composition, shape, and size of the engineered nanoparticles.

The textiles are categorized on the basis of usage in products for babies, products with no direct skin contact, products with direct skin contact, and decorative materials. The boundaries for toxic as well as allergenic metals and chemicals differ according to the degree of fabric contact with the skin of a consumer and on heavy metal toxicity. Those limits do not involve the entire amount of compounds existing in the fabric, but the part that could be extracted (Yin et al., 2015, [197]). Analogous method must be developed for examining the harmfulness of nanoparticles on textiles, as their impact on the environment and human health is presently unpredictable. For now, humans are exposed to the emission of nanoparticles from textiles, textile industries, and textile laundries in a cycle we cannot monitor and control (Figure 10).

**Figure 10.** The discharge of nanoparticles (NPs) from textile materials and textile industry into surroundings and uptake by human body. Reproduced from (Yin et al., 2015, [197]).

Therefore, the dangerous effects of nanotextiles against human health and the environment have not been broadly demonstrated ye<sup>t</sup> and accessible data were extremely debatable, being contingent upon the stability, porosity, shape, size, dosage level, and end use of nanomaterials. Consequently, the obtainable reports are not much consistent and could not be compared. Further studies on the conceivable dangers in the utilization of nanofinishing in textile industries must be performed. An absence of guidelines for the control of nano-based treatments is acknowledged therefore, there might be greater concern of the supervisory establishments in the coming years. Ecolabeling is needed when nano-sized materials are included in textile clothing, particularly with direct human contact. Efforts to sugges<sup>t</sup> eco-friendlier fabrication steps utilizing green chemistry, a development of nanomaterials with lesser toxicity, utilization of in-situ preparation techniques resulting in lower effluent, as well as increased durability of the nanomaterials bonded to the textile substrates will also be broadly made in forthcoming studies.

### **4. Approaches for Assessing the Nanomaterial Toxicity**

The nanomaterial toxicity examinations might be carried out using in vivo (live) organisms, like rodents, fishes, microcrustaceans, and several other animals or/and cell cultures (in vitro). Different normalized toxicological examinations are obtainable for measuring the natural response of a living organism to a chemical. On the other hand, there is no standard existing for the assessment of nanomaterial toxicity, which impedes the evaluation of results as well as understanding about its toxicity. A majority of research carried out up to now are revisions of standard procedures utilized for other materials (Ju-Nam et al., 2008, [198]). Even though certain nominal associations of assays are recommended, (Drasler et al., 2017, [199]) defined that there exists no typical assessment protocol because of the extensive range of physico-chemical properties that the nanomaterials could contribute.

Animal experiments are highly prognostic for human effect however there are restrictions, primarily due to the biochemical and physiological dissimilarities among the species. Furthermore, there exist an increasing legal and public demand that morally supports the replacement of animal analysis for substitutes not based on in vivo testing. Novel concepts of testing are based on approaches with the primary culture of human cells as well as permanent cultures of cell lines, due to the fact they provide reliable, cheap, and efficient results (Drasler et al., 2017, [199]). In the following section, we discuss certain major evaluation techniques, developed both in vitro and in vivo, for properly characterizing nanomaterial toxicity.
