A neurologist studying an unidentified brain disease affecting dozens of New Brunswick residents is urging the Canadian government to conduct environmental tests for the herbicide glyphosate. On Jan. 30, Dr. Alier Marrero sent a letter to New Brunswick’s chief medical officer and the chief federal public health officer outlining lab tests that showed “clear signs of exposure” to glyphosate and other herbicides, according to the letter obtained by the Guardian. Marrero, who identified 46 of the 48 cases of the unknown illness, wrote some patients referred to him are in “advanced stages of clinical deterioration and near end of life.” …New Brunswick’s forestry department has used glyphosate for generations, usually spraying it from small planes or helicopters, to control the growth of trees and other foliage. The herbicide is also used in agriculture and industrial practices such as for clearing vegetation around power lines.