I was hoping I wouldn't have to line the bags, as I assume that will shorten the lifetime (plus then I'm back to having to bring plastic bags). I haven't really given much thought to hygiene, I'll mostly use it for dry food and the idea was just to wash it after I've used it. Do you know in which way the chemicals can be harmful? After all, it's not like I will use it every day, I'm maybe out hiking 30-40 days a year. Maybe it's not really harmfuk unless you get loads of it into your system over extended periods of time or something? Food grade would be brilliant, but I couldn't find anyone who actually sold it. Do you know if there is some sort of spray or something out there?