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A large portion of marine debris consists of plastic particles, including nurdles, pre-production microplastic resin pellets typically under in diameter found outside of the typical plastic manufacturing stream and an intermediate good used to produce plastic final products; microbeads from cosmetics; and the breakdown products of plastic litter. Plastic particle water pollution is also referred to as mermaids' tears. Approximately 60 billion pounds (27 million tonnes) of nurdles are manufactured annually in the United States.〔(Heal the Bay | The Pacific Protection Initiative | AB 258: Nurdles )〕 One pound of pelletized HDPE contains approximately 25,000 nurdles (approximately 20 mg per nurdle). ==Environmental impact== Nurdles are a major contributor to marine debris. During a three-month study of Orange County beaches researchers found them to be the most common beach contaminant. Nurdles comprised roughly 98% of the beach debris collected in a 2001 Orange County study.〔("Adopted Marine Debris Resolution" )〕 Waterborne nurdles may either be a raw material of plastic production, or from larger chunks of plastics. A major concentration of plastic may be the Great Pacific garbage patch, a growing collection of marine debris known for its high concentrations of plastic litter. Nurdles that escape from the plastic production process into waterways or oceans have become a significant source of ocean and beach plastic pollution. Marine life is severely threatened by these small pieces of plastic: the creatures that make up the base of the marine food chain, such as krill, are prematurely dying by choking on nurdles. Nurdles have frequently been found in the digestive tracts of various marine creatures, causing physiological damage by leaching plasticizers such as phthalates. Nurdles can carry two types of micropollutants in the marine environment: native plastic additives and hydrophobic pollutants absorbed from seawater. For example, concentrations of PCBs and DDE on nurdles collected from Japanese coastal waters were found to be up to 1 million times higher than the levels detected in surrounding seawater.〔Mato Y: "Plastic resin pellets as a transport medium for toxic chemicals in the marine environment", "Environmental Science & Technology" 35(2), pages 318–324, 2001〕 Plastic microbeads used in cosmetic exfoliating products are also found in water. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Plastic particle water pollution」の詳細全文を読む スポンサード リンク
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