Monsanto is now the target of a class action lawsuit against them for the sale of roundup, due to cancer studies of its active ingredient.
Roundup is, apparently, known to not be safe, due to its active ingredient, for people with recurring contact with treated crops (such as agricultural and construction workers).
Actually, it's just suspected not to be safe; And if carcinogenicity were to be demonstrated (which it has not yet been), then that would be a characteristic it shared with a host of other substances, including some that are explicitly marketed for human consumption, such as coffee and wine.
The existence of a lawsuit is not evidence of anything other than that someone decided that they might be able to win a lawsuit; And a court of law is not a laboratory - court rulings can and do fly in the face of reality.
Roundup is not particularly dangerous - it's safer than many things nobody worries about at all. That that's not the end of the discussion, merely shows how dreadfully bad human beings are at reasoning. Monsanto are targeted because they have become an arbitrary symbol of an ill-defined feeling amongst a section of society that technology and corporate power are somehow 'evil'. By doing so, activists are kicking themselves in the ass - Corporations that are not Monsanto, and hazardous chemicals that are not Glyphosate, are able to 'fly under the radar' because of all the FUD thrown up by ignorant morons who think that Monsanto is the anti-Christ.