Virtually nil.

Farmers (and employees certified/licensed to apply sprays) generally only spray in favourable conditions. Eg. Calm conditions where the output doesn’t go beyond a few meters of the intended swath. Given the cost, it makes little financial sense to waste it on non-target plants.

And while nearly any pesticide/herbicide/fungicide will tell you to suit up and use a respirator, it’s usually because of the (often petroleum derived) volatiles used in the mixture to ensure stability and proper spreading rather than the active ingredient itself.

Glyphosate (RoundUp) for example interacts with a biochemical pathway that doesn’t even exist in humans, yet still suffers from the legacy and cultural entrenchment of a paper that has since been refuted and retracted. The infamous “roundup causes cancer” paper where the author used lines of lab rats that were (intentionally, for use in cancer studies) genetically predisposed to developing tumours.

The volatiles evaporate and break down rapidly, which is why a freshly sprayed field will have an odd aroma for several hours after application. Meanwhile these sprays come with a PHI (post harvest interval), whereby if a producer is following laws and regulations, the active ingredient itself is virtually undetectable at the time of harvest due to UV/heat/microbial degradation.

PHIs are determined empirically by testing sprays across environments and conditions for years before certification, then still including a buffer period to account for outlier conditions where a chemical may persist beyond what was observed.

Because people see "wear standard PPE" in an MSDS and think "it's unsafe if you're not wearing a hazmat suit!" and not "this is safe." Here's the MSDS for good old table salt: https://fscimage.fishersci.com/msds/21105.htm

Quoting the PPE section:

> Personal Protective Equipment

> Eyes: Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA's eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166.

> Skin: Wear appropriate protective gloves to prevent skin exposure.

> Clothing: Wear appropriate protective clothing to prevent skin exposure.

> Respirators: A respiratory protection program that meets OSHA's 29 CFR 1910.134 and ANSI Z88.2 requirements or European Standard EN 149 must be followed whenever workplace conditions warrant respirator use.

This is table salt. The thing you keep in a salt shaker on your kitchen table. If even this has "wear PPE" in its section on what to wear for PPE, then you can infer that literally every single chemical will at least advise you to wear something.

Because we need to feed billions of people. Because doing that more efficiently not only saves labour and lives of people who would starve otherwise, but also land as we don't need as much of it, so it can be forests and grasslands and steppe [1]. Currently the most efficient way to grow plants on a massive scale requires using herbicides.

As we need herbicides for industrial agriculture, herbicides need to be judged against other herbicides, not in isolation. Glyphosate is fairly benign compared to other herbicides (compare to [2] for example), it's not "shit".

[1] In fact we are likely past peak agricultural land use https://ourworldindata.org/peak-agriculture-land

[2] https://labelsds.com/images/user_uploads/Atrazine%204L%20SDS...

See people complaining about the rising food prices, just due to increasing labor costs. Definitely won’t be politically popular to make farming even more expensive.