You should seek the advice of Ryan Rogers here, he has extensive sous vide/low temp slow cooking experience on the pro side (including sous vide + smoking) and knows of the various potential health concerns.
That said, I've fooled around with a rube goldberg sous vide contraption myself, and work at or around those temps, and have not gotten sick. That is purely anectdotal and not scientific of course, so all I can offer is that, in my own experience, I have not sickened or poisoned myself, my family, or my guests, on a half dozen or so occasions. What I have learned is that it is worth consulting and sticking to the time/temp guidelines, rather than winging it, as you may have some substandard results when it comes to texture of the final cooked meat, etc.
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