Apple (AAPL.NASDAQ), the world’s biggest technology company, admitted that some of its supply chain plants in China have polluted the local environment, Caixin reported. In a meeting between the company and Chinese environmental activists on November 15, Apple acknowledged that 15 of its local suppliers had polluted their surroundings through “excessive emissions” and failed to track wastewater pollution. However, the company did not say which companies were involved and pledged to improve standards without detailing how it would do so. The admission comes after months of accusations by environmental groups, which Apple previously responded to by saying that it was committed to “the highest standards of social responsibility.” The latest meeting appears not to have satisfied some activists: “In the term of information transparency, Apple has still not done enough,” said Li Bo, secretary general of Friends of Nature, an environmental protection organization.