Growth in China's exports and imports slowed in September, official data showed Thursday, as domestic tightening measures and turmoil in the United States and Europe hit demand. Exports rose 17.1 percent year on year to $169.7 billion, compared with a rise of 24.5 percent in August, the customs agency said in a statement. Imports expanded by 20.9 percent to $155.2 billion in September, compared with an increase of 30.2 percent in August.