Here is a write up I did several years ago. there may be things now that are considered fine that aren't on this list but this is a good rule of thumb for plastics.
there are 3 types of food safe plastics commonly available on the market.
1. HDPE (high density polyethylene, recycle code 2) is the most common because of its rigidity. Pretty much all 5 gallon buckets are made of it. it is also what the large brute containers are made from. i use these in my restaurant to store flour sugar ect. and can be bought at any commercial food service suppliers and from home depot and lowes with caution. it is important to note that NOT ALL HDPE is food safe however. this is because as it is molded a release agent is sometimes used in the manufacturing to make it easier to remove from the mold. many are toxic.
2. LLDPE or LDPE (linear low density polyethylene, recycle code 4) it is less rigid. Most of your rubbermade containers are made from it. we use these in the restaurant to mix and hold things like coleslaw and large batches of orzo salad ect. these can be bought from commercial food service suppliers home depot and lowes and have little risk of not being food safe they are however less rigid (think of a bucket you use to put fall leaves into) and mat not be the best for long term storage because of the possibility of becoming deformed. i find containers that use this plastic personally as its cheap and easy to find ans because of its flexability it doesnt have the same mold release issues HDPE has. but i do worry about them breaking.
3. PP (polypropylene, recycle code 5) it might be hard to find a large container made of PP. it is mostly used in those little brown bottles that your prescription pills came in and the disposable ziploc containers with the blue lids that have taken over your kitchen. the issue with PP is The Environmental Working Group classifies polypropylene as a low to moderate health hazard. they state "two substances found to leach from polypropylene labware - an antimicrobial chemical known as quaternary ammonium and a plastic softening agent called oleamide" this might be only because PP is used in some makeup as an ingredient.
the other plastics i would not use though they are in many bottles one finds food in is PETE (polyethylene terephthalate recycle code 1) as it is known to leach BPA over long periods. and OTHER (other recycle code 7) this really speaks for it self. it is anything that does not fit in the other categories. it could be ok but you cannot know.
finally vinyl (PVC recycle code 3) strangely not considered food safe due to the use of phthalates to soften the plastic. many companies are using non-phthalate plasticizers since 2010 so it may be changed at some point.
thats what I found. my curiosity was piqued for both the hobby and my work (a few years ago when the #7 plastic ban happened due to bpa)as my restaurant is "hippie Friendly" ( that just made me LOL for real) anyway thats what i found i hope it helps
