Cotton denim jeans are widely known to be among the dirtiest textiles available in the market. Denim jeans consume a significant amount of water, chemicals, and energy during their entire existence, from cultivation to disposal. This literature review examines the environmental impacts of denim production across four important phases: cotton cultivation, raw material processing, finishing, and disposal using conventional and organic methods. The environmental impact is classified into four areas using the life cycle assessment software openLCA 2.0.2. The four impact categories are: global warming, water consumption, freshwater ecotoxicity, and ozone formation in terrestrial ecosystems. Cotton cultivation makes use of a disproportionate number of chemicals (around 25 percent of the world's insecticides). Denim fabric manufacturing consumes 34, 38, 23, and 5 percent of total energy throughout the spinning, chemical process, weaving phase, and other operations, respectively. Besides, consumer use phase is the most resource consumed phase. People frequently discard or burn clothes, contributing to vast amounts of waste and harming the environment by emitting greenhouse gases. Cotton cultivation and conventional raw material processing produce the highest greenhouse emissions and use the most energy. Organic approaches emit 12 percent fewer emissions than conventional approaches. The conventional approach has a bigger environmental impact.