Exposure to environmental conditions, wind and waves decrease the stability of plastics and causes fragmentation to occur. It is posited that a major part of the degradation process begins on land, as plastics travel along rivers and waterways they are constantly washed onto the riverbanks, increasing exposure to UV radiation and heat, becoming brittle, breaking down into small fragments and re-entering the aquatic environment. . However, the fragmentation of larger items of plastics is not the only source of microplastics in the environment, as the direct release of primary microplastics through industrial spillage, wastewater systems and microbeads used in cosmetics contribute significantly to the accumulation of microplastics in the marine environment. .