Sunlight exposure of packaged food items

It is common to see some of eatables,  groceries in packets outside of shops or adjacent to glass walls of malls. Also, we see water, beverages in plastic bottles exposed to sun. Same will be transported in open trucks from manufacturers to distributors to retail outlets. And, they get exposed to sun, releasing micro particles into the packed contents. We consume same, unknowingly. 

In olden days, or, even some people now also,  purchase groceries in bulk meeting half yearly or annual requirements,  clean at home, store in steel containers or jute bags with needm leaves to prevent insects / germs and use which seems a good practice avoiding plastic.