日本申请了近10年，美军正式回复：不同意

Core Viewpoint - Japan's request to investigate pollution sources at U.S. military bases in Okinawa has been formally rejected by the U.S. military, despite concerns over elevated levels of per- and polyfluoroalkyl substances (PFAS) detected in local water bodies [1][3][5]. Group 1: Background and Context - Since 2016, Okinawa Prefecture has made four requests to enter U.S. military bases to investigate pollution sources, all of which have gone unanswered until now [3]. - On December 19, the Japanese Ministry of Defense communicated to Okinawa that the U.S. military has officially declined the request for an investigation [1][3]. Group 2: Reasons for Rejection - The U.S. military cited a lack of scientific evidence proving that the military bases are the source of the contamination, and noted that there is no unified standard between Japan and the U.S. for determining whether water and soil samples are contaminated [3][5]. Group 3: Health and Environmental Concerns - PFAS are a group of thousands of chemical substances that are difficult to degrade and can accumulate in humans and the environment, often referred to as "forever chemicals" [5]. - The U.S. Centers for Disease Control and Prevention (CDC) has indicated that these substances may lead to various health issues, including kidney cancer, testicular cancer, and elevated cholesterol levels [5]. Group 4: Local Response and Future Actions - Okinawa's environmental department has stated that experts have concluded that the U.S. military bases are likely sources of the pollution, and the prefecture will continue to seek access to conduct investigations [5].