CHINA IS POSTING inspectors to monitor dairy companies and imposing new rules to improve accountability among milk suppliers, as it moves to restore consumer confidence after tainted baby formula sickened tens of thousands of children. Authorities detained six people on Sunday for allegedly selling melamine, an industrial chemical that has been used to adulterate milk. The arrests were in the northern city of Hohhot, a major dairy-production base. Dozens of people, including government officials, have been detained since the public last month was informed of the widespread contamination. Chinese regulators intend to "make a substantial change in the production and distribution of dairy products," said Wang Yong, director of China's General Administration of Quality Supervision, Inspection and Quarantine, according to the state Xinhua news agency. More than 5,000 inspectors have been sent to monitor dairy production nationwide. Companies are being made to perform an expanded number of tests on raw milk