Exposed beverages were forbidden by the rabbis because they feared that snakes would have drunk from them, and left behind venom. But now when snakes are not found amongst us, it is permitted.
צריך ליזהר שלא לאכול בשר ודג ביחד מפני שקשה לצרעת: הגה וכן אין לצלות בשר עם דג משום ריחא מיהו בדיעבד אינו אסור (ארוך כלל ל"ט דין כ"ה):
He should wash his hands between meat and fish, and eat dipped bread in between, to wash his mouth. Hagahah: And some says that there is no concern for this unless he cooks and eats eats them togther, but to each them one after the other there is not concern. And the custom is not to wash ones mouth and hands between, but still one should eat and drink something. Since this fulfills kinuach and hadachah
One needs to be careful from human sweat, since all human sweat is deadly poison, except for sweat of the face
One must refrain from putting coins in one's mouth, lest it's covered with dried saliva of those afflicted with boils. He should not put the palm of his hand in his arm pit, lest his hand touched a metzorah or a harmful poison. He should not put a loaf of bread under his armpit, because of the sweat. He should not put a cooked item or drinks under the bed, since an evil spirit rests on them. He should not stick a knife in an esrog or a radish, lest one fall on its edge and die. Hagah: Similarly, he should be careful of all things that cause danger, because danger is stricter than transgressions, and one should be more careful with an uncertain danger than with an uncertain issur. They also prohibited to go in a dangerous place, such as under a leaning wall, or alone at night. They also prohibited to drink water from rivers at night or to put one's mouth on a stream of water and drink, because these matters have a concern of danger. It is the widespread custom not to drink water during the equinox, and the early ones wrote this and it is not to be changed. They also wrote to flee from the city when a plague is in the city, and one should leave at the beginning of the plague and not at the end. And all of these things are because of the danger, and a person who guards his soul will distance himself from them and it is prohibited to rely on a miracle in all of these matters.
It is prohibited to eat food and drinks that a persons soul is disgusted by, such as drinks and food that have vomit or feces mixed with them, and rotten moisture and things like this. It is assur to eat and drink from dirty vessels that a person's soul is disgusted by them, like bathroom vessels and glass vessels that they let blood into. And he should not eat with dirty hands and on dirty vessels, since all of these fall into the prohibition of "Do not make your souls abominable"
An animal that is in danger of dying, even though it is permitted to eat when slaughtered, people who are careful are strict on themselves not to eat it. Hagah: An animal that a rabbi ruled to [permit] out of logic,but the law is not explicitly found [in books] to permit that it is permitted, and person who is careful for his soul will not eat from it.