Reuters reports that a large long-term study on the use of the weed killer glyphosate by agricultural workers in the U.S. has found no firm link between exposure to the pesticide and cancer, scientists said earlier this month.

Published in the Journal of the National Cancer Institute, the study found there was no association between glyphosate, the main ingredient in Monsanto’s popular herbicide RoundUp, “and any solid tumors or lymphoid malignancies overall, including non-Hodgkin Lymphoma and its subtypes.”  

The research is part of a large and important project known as the Agricultural Health Study, which has been tracking the health of tens of thousands of agricultural workers, farmers and their families in Iowa and North Carolina. Since the early 1990s, it has gathered and analyzed detailed information on the health of participants and their families, and their use of pesticides, including glyphosate.