Atrazine is an organic compound that is a widely used herbicide. Atrazine is used to kill weeds, primarily on farms, but has also been used on highway and railroad rights-of-way. It may wash from soil into streams or groundwater where it will stay for a long time, because breakdown of the chemical is slow in water. The EPA now restricts how atrazine can be used and applied; only trained people are allowed to spray it. Its use is controversial due to its effects on nontarget species. Atrazine was banned in the European Union (EU) in 2004 because of its persistent groundwater contamination. Its endocrine effects, possible carcinogenic effect, and epidemiological connection to low sperm levels in men has led several researchers to call for banning it in the US. Individuals may be exposed by drinking water from wells that are contaminated with the herbicide. The EPA has set a maximum amount of atrazine in drinking water of 0.003 milligrams of atrazine per liter of drinking water (0.003 mg/L). The recommended treatment method for removal of atrazine from drinking water is a Reverse Osmosis System.