These are all questions that arise from time to time from people who are considering living in a container.
The internet abounds with articles expressing concern for the health risk of noxious chemicals leaching from the floor boards and being a hazard to health. I have lived in a shipping container for quite some time now. A subscriber asked my thought about this. Here is how I replied to him.
"I considered the principle of outgassing. The floor is 25mm ply, treated with chemicals to make it unpalatable to infestation and rot. The underside coated in tar, to waterproof the container. I suspect the years would diminish the vapour that may or may not be given off. Our house is as ventilated as any, and in summer more so. We have underlay and carpet over the top. I suspect my diet, exercise regime, tobacco habits, alcohol consumption, and decisions made behind the wheel of a car will have vastly more impact on my longevity than my wooden floor. I respect those who think otherwise. My car emits carbon monoxide in sufficient quantity to kill a human, though we drive in congested cities. I suspect life is a risk and we all get to choose level of acceptable risk."
His reply was equally pragmatic, and he said he would "put a coat of clear coat over the floor and not worry, my paint is probably toxic anyway "