OTTAWA — An influential research article that claimed a popular weed-killer was safe has been retracted 25 years after it was published, prompting environment groups in Canada to ask the federal government to review the science on glyphosate use. Health Canada said Thursday that its decision to approve glyphosate will not be affected by this development. Last week, the journal Regulatory Toxicology and Pharmacology retracted a paper published in 2000 that concluded the herbicide glyphosate, the main ingredient in Roundup, is safe for humans. …The retraction notice cited documents made public through litigation in the US that suggest employees of Monsanto may have helped write the article without proper acknowledgment. …Health Canada said in a written statement that “the retraction of this review does not affect our previous review conclusions” because the department also independently evaluated the primary data sources used in the 2000 review paper.