Well, not always. In the district of Blaye in the Bordeaux region recently an entire school class was taken to hospital after having exhibited symptoms of poisoning, which apparently were due to a wine producer spraying his vineyard nearby.
The wine producer used a common and permitted product to spray against fungal diseases. But the investigation showed that the spraying was done without adequate safety precautions. The investigation also showed that the symptoms exhibited by the children are consistent with the effects that this fungicide can have on people, if used incorrectly.
Read more about this at lavigne-mag.
There are of course rules for how and when you can spray your vineyard. Most important is the rule that forbids any spraying when the wind blows over a certain wind speed. Additionally, the wine producer has to make sure that his sprayer is very precise and well adjusted; he should have hedges or other protective barriers, respect certain times of spraying and so on.