Plastic has the drawback of not being easily decomposed in nature. This drawback has become clear and is becoming a cause for concern for humanity. A team from the Medical University of Vienna in Austria has announced a report on microplastics in the ocean. After analyzing the feces of eight people aged 33 to 65 from eight countries, they found that tiny “microplastics” were present in all eight countries, including Japan. The global average amount ingested by one person is estimated to be up to about 54,000 pieces per year. According to animal research, it can be absorbed in the digestive tract and enter the bloodstream and lymphatic system. Research on how much intake will affect health is not yet sufficient, and further investigation is needed.
In the mid-19th century, a dream material was born to replace natural resins such as lacquer and amber. That was plastic. It is strong and light, and its use has spread to food storage containers and clothing. Plastic was one of the key players in creating the culture of mass production and mass consumption. This plastic is widely used, so the amount of waste is also large. According to the United Nations Environment Program, about 430 million tons of plastic are produced every year. Of that, about 353 million tons become garbage. The disposal of used plastics around the world is a problem. In particular, the problem of finely broken plastic pieces causing marine pollution is a problem.
Human beings are not sitting idly by and watching the marine pollution caused by plastic. Plastics derived from plants are called “biomass plastics (plant resins)”. Biomass plastics are attracting attention because they have a light environmental impact. Unlike plastics made from petroleum, they decompose over time. The problem is the price. The difficulty is that they are about 1.5 to 5 times more expensive than petroleum-based plastics. General plant resins are made from starch such as corn and sugar cane, which are used as food and feed. Polylactic acid (PLA), the raw material for biomass plastics, requires about 1.5 tons of starch per ton. This is equivalent to 47,000 ears of corn. From the standpoint of food security, there are voices criticizing the scarcity of food grains as industrial raw materials. In response to these criticisms, there is a growing movement to use inedible plant materials for plastics.
