Pollution in the fashion industry impact on the environment, the natural crop growing fibers also have been contributing to pollution through the form of agriculture. Cotton production requires a large amount of pesticides and water use. Cotton is considered the world's dirtiest crop because it uses 16% of the world's pesticides. Two of the main ingredients in pesticides are nitrates and phosphates. When the pesticides leak into stream systems surrounding the cropland the nitrates and phosphates contribute to water eutrophication. Water eutrophication is an environmental phenomenon that causes a depletion of oxygen when the nutrient overload from pesticides causes a boom in plant growth and
Eutrophication especially immobile bottom dwellers die off. In extreme cases, anaerobic conditions ensue, promoting growth of bacteria such as "Clostridium botulinum" that produces toxins deadly to birds and mammals. Zones where this occurs are known as dead zones. Eutrophication may cause competitive release by making abundant a normally limiting nutrient. This process causes shifts in the species composition of ecosystems. For instance, an increase in nitrogen might allow new, competitive species to invade and out-compete original inhabitant species. This has been shown to occur in New England salt marshes. In Europe and Asia, the common carp frequently lives in naturally Eutrophic