**2. Textile industry and its environmental impact**

The global textile industry generates notable environmental impacts through the phases of raw material production, fiber, yarn and garment manufacturing, and garment use. The rise of global population and improved living standards have resulted in consistent increase in the production and consumption of textiles and fibers in the past few decades. According to the Global Fashion Industry Statistics, the world population was 7.84 billion in 2021 [4]. Despite the fact that the global apparel and footwear market has been affected by the COVID-19 pandemic and shrunk to \$1.45 billion by −18.1% in 2020, the industry grew by 18% in 2020–2021, to \$1.71 billion dollars. The global apparel retail market is expected to witness a 7.5% growth in 2021–2022 period and a 6.1% growth in 2022–2023 period.

Textiles generally count on petrochemical products, and fashion accounts for up to 10% of global carbon dioxide output. Polyester, which is a form of plastic derived from oil, has experienced an explosive growth and overtaken cotton in the textile production. Garments made from synthetic fibers such as polyester are the main prime source of microplastic pollution, which harms mainly the marine life [5, 6]. In Europe, clothing is the 4th most environment polluting category after food, housing, and transport industries. The way people dispose unwanted clothes has also changed, and about 87% of the total fibers used for clothing are ultimately incinerated or sent to a landfill. Only a small fraction is recycled. Fashion brands either destroy unsold products or send piles of them to landfills across the Global South.

#### **2.1 Estimating the environmental impact of textile processing**

In order to identify the environmental impacts caused by the long supply chain of textiles and to control them, there are various environmental standards applicable to textile products. This environmental information is related to the life cycle of a product and to each step of its manufacturing line. There are many important concepts related to environmental sustainability, and life cycle assessment (LCA) is the most important and common technique for assessing the overall environmental impact of a product, process, or service [7]. LCA is based on the ISO standards 14,040:2006 and ISO 14044:2018, which outline the processes required to carry out the study [8–10].

LCA comprises four major phases, as defined by ISO, which are [11].

*Life-Cycle Assessment as a Next Level of Transparency in Denim Manufacturing DOI: http://dx.doi.org/10.5772/intechopen.110763*

1.definition of goal and scope,

2.life cycle inventory (LCI) analysis,

3.life cycle impact assessment (LCIA)

4.life cycle interpretation

The analyses require collection of data of the inventory substances, the emissions, and resources, involved in the product life cycle and are performed using specific software tools with;

data provided directly from companies and/or collected through audits; data gathered from previous studies (LCA studies, literature); and data from databases such as Ecoinvent, ELCD [12].

The effects of resources consumed and emissions released are detailed in the LCIA step which comprises the selection of impact categories such as depletion of abiotic resources, climate change, human toxicity, acidification, eutrophication, ecotoxicity, photo-oxidant formation, stratospheric ozone depletion, land use, water depletion, depletion of minerals, and use of fossil fuels. There are two different approaches to derive characterization factors namely, midpoint and endpoint approaches. In the midpoint approach, category impacts are translated into environmental topics such as climate change, acidification, water use, fossil depletion, freshwater eutrophication, etc. In the endpoint approach, the indicators are grouped into damage categories, including resources, ecosystems, and human health.

The midpoint indicators are calculated based on the data of relevant inventory data. The endpoint, on the other hand, assesses the environmental impact tracking to the end of the impact chain. Environmental impact indicators of LCA method are given in **Figure 1** [12].

#### **Figure 1.**

*Environmental impact indicators of LCA (as adopted from [12]).*

A number of methods are available to quantify life cycle impacts [7, 13]. ReCiPe is one of the most recent and updated impact assessment methods available to LCA users. The method addresses 18 environmental concerns at the midpoint level and then collects the midpoints into a set of three endpoint categories [14]. CML method, created by the University of Leiden in the Netherlands in 2001, is a database that contains characterization factors for life cycle impact assessment (LCIA) [15]. The method is divided into baseline and non-baseline characterization methods, the former being the most common impact categories used in LCA. The impact assessment method implemented as CML-IA methodology is defined for the midpoint approach. In LIME-3 methodology, there are nine impact categories (climate change, air pollution, photochemical oxidants creation, water consumption, land use, mineral resource consumption, fossil fuel consumption, forest resource consumption, and solid waste) and four endpoints (human health, social assets, biodiversity, and primary production) for characterization. The conjoint analysis for weighting was conducted in all G20 countries [16]. TRACI is another environmental impact assessment tool that provides characterization factors for LCIA, industrial ecology, and sustainability metrics. The potential impacts of inputs and releases on specific impact categories are quantified in common equivalence units. Ozone depletion, climate change, acidification, eutrophication, smog formation, human health impacts, and ecotoxicity are the included impact categories in TRACI.

Resource uses of fossil fuels are also characterized [17]. For the characterization of human and ecotoxicological impacts of chemicals USEtox model, endorsed by UNEP's (the United Nations Environment Program) Life Cycle Initiative, provides midpoint and endpoint characterization factors for human toxicological and freshwater ecotoxicological impacts of chemical emissions in life cycle assessment. Main output is a database of characterization factors including exposure, effecting parameters, etc. [18]. A free web-based biodiversity broadcasting tool, BioScope, calculates the biodiversity footprint of products, companies, and investments provides businesses and financial institutions with a fast and simple indication of the main impacts their supply chains and financial products have on biodiversity [19].

These methods are linked to the software programs used in LCA. LCA software packages calculate the potential environmental impacts in a transparent way, based on inventory data. However, depending on the activity, whether the software has access to the right database needs to be checked. The differences among LCA softwares are categorized by Bach based on the following [20, 21]:


A set of criteria for qualitative comparison of LCA software tools was also presented by Silva et.al as; software origin and version, dataset format, user interface, LCA result presentation, uncertainty/sensitivity analysis of results, support facilities for users, positive and negative modeling aspects, and other relevant aspects [22].

SimaPro, GaBi, Umberto, and Open-LCA are some of the most popular and widely known tools used for LCA. A broad list of tools is available in the LCA resources directory of the European Commission's website [23]. GaBi and Simapro programs were introduced in the early 90s and are regarded as the earliest softwares. Following them, Umberto was developed to address material assessment. Today, the softwares have evolved into LCA expert tools based on elaborate information [24–27]. The topics covered by different LCA softwares are diverse and it is important to consider the particularities of the softwares when selecting an appropriate LCA tool.

In a study conducted in order to assess whether the use of different softwares namely, SimaPro and GaBi, can cause a difference for the LCA results used for modeling a product system or doing an impact assessment, differences were identified in particular for the implementation of the impact assessment methods. It appeared that the observed differences came primarily from differences/errors in the different databases of the softwares [28].

In another study in which a gate-to-gate product system (particleboards production in Brazil) was assessed with the same functional unit using GaBi, openLCA, SimaPro, and Umberto NXT, the modeling principles, hotspots, and impacts for each software tool compared in. Acidification, climate change, ecotoxicity, human toxicity, and photochemical ozone formation from the ILCD/PEF method were the selected midpoint impact categories. It was identified that up to 22.7% more impacts were calculated by SimaPro to acidification, and up to 66.7% more impacts to photochemical ozone formation than compared to other software tools. Thus, depending on the software tool a user chooses, LCA results showed variations [22]. LCA software tools are also widely used for textile products.
