sentences:  In 2013, the European Union and a few neighbouring countries restricted the use of certain neonicotinoids; in 2018, the EU banned the three main neonicotinoids (clothianidin, imidacloprid and thiamethoxam) for all outdoor uses.Several states in the United States have also restricted usage of neonicotinoids out of concern for pollinators and bees.The precursor to nithiazine was first synthesized by Henry Feuer, a chemist at Purdue University, in 1970;
  
  Shell researchers found in screening that this precursor showed insecticide potential and refined it to develop nithiazine.