U.S. corn farmers in 11 states have filed class action lawsuits accusing Syngenta Corporation of causing them more than $1 billion in losses by releasing genetically-engineered corn seeds to China before Beijing approved the seeds and agreed to import them.

Beginning in November 2014, China began rejecting U.S. corn shipments containing Syngenta, depressing the overall market price for the grain, resulting in farmers losing in excess of $1 billion, The Wall Street Journal reported.

“Syngenta has caused damages to U.S. farmers, grain handlers and exporters,” one of the Syngenta corn class action lawsuits alleges. “Syngenta’s conduct in marketing, distributing and selling unapproved corn seed violates the legal standards of the marketplace because the primary market risk falls on U.S. farmers, grain handlers and exporters, not on Syngenta.”

Grain exporters such as Cargill Inc., Archer Daniels Midland Co. and Trans Coastal Supply Co. filed the first GMO corn class action lawsuit against Swiss-based Syngenta after Chinese grain inspectors detected Syngenta in cargoes and turned away shipments, according to The Wall Street Journal. Dozens of farmers followed, according to Reuters. The Syngenta GMO class action lawsuits have been consolidated in a Kansas federal court.

The farmers are seeking damages for the dip in corn future prices, which dropped by 18 percent in 2014, a second hit from 2013 when prices plummeted by 40 percent. Before the Syngenta issue, 2014 had been forecasted as a good year for corn futures.

“Corn production is of crucial economic importance to the United States,” the Corn GMO lawsuits state. “The U.S. is ranked first in the world in total corn production and exports a significant amount of its production.”

Reuters reported on Feb. 2, 2015, that China has since approved imports of Viptera corn, though Cargill’s chief executive officer maintains that the rejections that began in November 2013 caused the company a lot of financial damage.

Syngenta began selling Viptera corn seed to U.S. farmers in 2011. The company’s website touted the Chinese approval in a statement from Ponsi Trivisvavet, president of Syngenta Seeds.

“This is great news for U.S. farmers,” Trivisvavet said. “Agrisure Viptera has been in strong demand for years because it offers corn growers incredible protection against the broadest spectrum of above-ground corn pests including corn earworm, black cutworm and Western bean cutworm.”

Genetically engineered foods have been a touchstone of controversy for many years. Critics allege that GMO foods are not nutritionally comparable to their natural counterparts. According to the Center for Food Safety, studies have shown that genetically engineered foods can pose serious risks to farmers, human health, domesticated animals, wildlife and the environment.

Syngenta officials, according to The Wall Street Journal, maintain that the GMO corn class action lawsuits are without merit and insist that the company “has been transparent about the approval process for the GMO corn in question, known as Viptera.”