China exports $30 billion a year in agricultural and drug products to Asia, Europe and North America from ports like this one in Shanghai.

But simmering beneath the surface is a thornier problem that worries Chinese officials: how to assure the world that this is not a nation of counterfeits and that “Made in China” means well made.

Already, the contamination has produced one of the largest pet food recalls in American history, heightening global fears about the quality and safety of China’s agricultural products. And evidence has also shown that China exported fake drug ingredients, threatening to undermine the credibility of another booming export.

Still, few trade experts believe that China’s export boom is going to slow anytime soon. China’s shipments of vegetables and seafood have been soaring in recent years. And many importers say they would rather work with Chinese companies to raise safety levels than switch suppliers. China is also negotiating with the United States and the European Union to have them accept Chinese poultry products. That move is opposed by American and European poultry farmers, who are using the pet food scandal to press their case.

“If you bring chicken in here from China, you don’t know what that chicken ate, and I think that’s dangerous,” said Lucius Adkins, president of the United Poultry Growers Association.