Some of these campaigns are so strong that cities (like San Francisco in 2007) and states (California might well follow the example of San Francisco) are getting into the act, banning, or making stores charge money for disposable plastic bags (charging customers for plastic bags is something that was taking place in Tokyo, when I was living there in the 1980s).
However, I think that public consciousness about the implications of reusing a plastic bag has not moved past the framing of "helping the environment": people aren't washing their reusable bags. For the same reason that you would want to wash your cutting board after use, or your counter-tops, you should wash out the reusable grocery bags: because biology happens. What, exactly, does Umlud mean by this statement? Well, "out of sight, out of mind" is rarely a good way to live one's life, especially when "invisible" activities are taking place (remember, "invisible" doesn't mean "inconsequential). In this particular case, the invisible activity is the growth of microbial life that is feasting on the small pieces of microscopic residue being left behind after you are done using your bag in your shopping trip.
However, according to this piece, many people are unaware of this problem:
"consumers are alarmingly unaware of these risks and the critical need to sanitize their bags on a weekly basis."Of course, one way of changing this is the method suggested by the researchers: to use labeling. However, I think that the problem goes beyond the power of what a label can accomplish. Until the idea in people's minds that reusable plastic bags cannot be used in the same way as disposable plastic bags (i.e., you have to wash a reused item), people's attitudes won't change significantly; or not in the direction that some might want. Indeed, back-sliding (moving away from using reusable plastic bags and returning to using disposable plastic bags) is a possibility, especially as people view this "new necessity" as an onerous task (as opposed to something that they should have been doing in the first place).
The question, therefore (at least to me), is how to incorporate the implications of "re-use" into shopping bags from the very beginning. Perhaps this might be an issue only with re-usable "plastic bags", and not so much with cloth "tote bags" (i.e., the material of the bag changes how people think about and take care of the bag). Perhaps it might be an issue with the rigidity of the bag (i.e., paper-bag-like, rigid reusable plastic bags are more difficult to turn inside out for cleaning by hand or in a machine than soft, pliable plastic bags). Or maybe it is an issue of how people conceive of the importance of something that is "plastic" (and therefore potentially "disposable") than for something that is not. (This last point is more than somewhat ironic, since plastics are orders-of-magnitude less biodegradable than natural fibers, such as cotton, and yet plastic items are usually seen as being more disposable than items made with natural fibers.)
At a larger scale, the statement "biology happens" is appropriate, not just for raising the awareness of bacterial growth in reusable plastic bags, but also in getting people to think about the longer-term consequences of actions. For example, "biology happens" whenever one follows a particular hunting management or fishing management plan, either in raising the number of stock of deer or salmon (as the DNR did in the 1980s and 1990s), or dealing with the impact of having raised the number of stock of deer or salmon (as the DNRE is doing right now). "Biology happens" when Chicago decided to connect Lake Michigan to the Mississippi River via a canal in order to minimize disease outbreaks due to sewage (i.e., bacterial growth) contamination of drinking water. Biology continues to happen in the form of using that channel as an avenue for colonization (a.k.a. "invasion") by foreign species (biology also happened when foreign species, brought in for aquaculture, find themselves suddenly in a major river system, thanks to a large-magnitude flood). In other places, "biology happens" by creating strains of microbes and weeds that are resistant to the antibiotics and herbicides that we apply to our bodies and our fields (it's called natural selection, people) -- and will continue to happen as we apply more and more "anti-bacterial" soap and hand sanitizer to ourselves and our environments.
However, the concept of "biology happens" in the above cases -- and countless more -- fall outside the realm of what many people think about, or (if they do consider them) deem important enough to do something about. The concept of "out of sight, out of mind" is a strong one, even though the processes of biology -- once understood -- are quite visible, and the direction of the outcomes are somewhat predictable.