Paraquat, one of many pesticides that can't be used in Europe but is sold in the United States and elsewhere, has been linked to Parkinson's disease in a growing body of research. The [paraquat factory in Huddersfield, England] recently celebrated its centennial. Paraquat [is] one of the world's most enduring weed killers - but not one that can be purchased in ... Britain or across the Channel in the rest of the European Union. So it will be sent to the United States, or another part of the globe that still allows paraquat to be sprayed on weeds. Now regulators in the United States are grappling with a wave of research linking paraquat to ... Parkinson's disease. In a recent ... regulatory filing, the Environmental Protection Agency said, "There is a large body of epidemiology data on paraquat dichloride use and Parkinson's disease." The agency is weighing whether to continue allowing the chemical to be sprayed on American cropland, although a decision is not expected until 2018. In the meantime, many of the nations that ban paraquat and other chemicals whose use is contentious still allow them to be manufactured as long as they are exported to faraway fields. Even the government of China, a nation not known for environmental regulation, said in 2012 that it would phase out paraquat "to safeguard people's lives." As Europe and China move away from paraquat, its use is rebounding in the United States. That is particularly true for soybean fields, where the number of pounds used is up more than fourfold over the past decade.