A total of 13,200 tons of imported waste mixed up with imported garbage was inspected and returned by Ningbo in 2017, topping all other Chinese ports, according to the Ningbo Entry-Exit Inspection and Quarantine Bureau, China News reported.

The bureau says that a total of 42,200 tons of imported waste to be used as raw materials worth $4.71 billion were inspected by the port, among which 13,200 tons was mixed up with illegally imported garbage worth $20.12 million. The waste was all returned by the port.

The main reason for the large number is that overseas shippers are not familiar with China’s policy and laws on the import of waste as raw materials and their efforts to reduce relevant sorting costs, so that they usually turn a blind eye on waste exports to China.

Developed countries including the U.S., the Netherlands, Germany, and Canada create the most industrial waste each year. China, as the world’s largest importer of waste that could be used as raw materials, might be affected if the countries do not carefully sort out their waste.