nitrite content a big issue in China?

In China, there are reported cases that pregnant women suffered from miscarriage after consuming blood bird nest for few months. Besides there are other health issue related to bird nest (especially blood bird nest) consumption.
Due to cumulative reported cases, the Chinese authorities investigated the issue and came to a conclusion that the nitrite content in the bird nest is the root of the problem. Therefore, the China Government put a ban on the import of bird nest from Malaysia pending the resolution of nitrite content.
The China Government insists to have zero nitrite content in bird nest, which to the bird nest industrialists are impractical to achieve. It could be achieved at a cost and thus pushing up the bird nest prices. Whether it is essential to eradicate the nitrate/nitrite content at all in bird nest is an issue for the China Government and Malaysian Government to resolve.
In fact, nitrate also presents in the drinking water. As a reference, the U.S Environment Protection Agency sets Maximum Contaminant Levels (MCL) for nitrogen in public drinking water systems. The MCL for nitrates is 10 milligrams per liter whereas nitrites one milligram per liter. These figures may be used as a yardstick to resolve the nitrite content issue.