UPDATE: An energy group responds to the article by The Nation. Click here to read the article.

Scientists have been unable to diagnose the reason why livestock near oil- and gas-drilling zones across the country are sick and dying.

The Nation reports scientists believe chemicals used in drilling and hydrofracking operations are poisoning animals nearby, but a direct cause has not been determined.

In 2009, cattle from a North Dakota ranch adjacent to a drilling site experienced weight loss from 60 to 80 pounds in a week. The animals were unable to produce milk for their calves and were limping on swollen legs.

Cattle from the ranch were infected and their tails mysteriously dropped off. The owner of the ranch, Jacki Schilke, lost five of the cattle. The remaining livestock have recovered, but she’s not selling them because she’s concerned with the safety of the meat they’d produce.

A report of 24 case studies earlier this year showed farmers in six shale-gas states owned livestock who were exposed to fracking chemicals in water or air and experienced neurological, reproductive and acute gastrointestinal problems. The report was challenged by the fracking industry as farmers involved in the study were not identified.

Michelle Bamberger, an Ithaca, N.Y., veterinarian who co-published the report, is concerned if animals affected by fracking chemicals enter the food supply.

“They live in areas that have tested positive for air, water and soil contamination. Some of these chemicals could appear in milk and meat products made from these animals,” Bamberger told The Nation.

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