There's been some recent discussion on line lately on whether the move to re-useable grocery bags (you know, like our parents/grandparents used) may be bad for our health. This has escalated this month following a paper examining the increase in C. difficile enterocolitis cases in San Francisco. A Slashdot article by theodp "Are Plastic Bag Bans Making People Sick?" nicely summarises what's been happening:-
"A paper by Wharton's Jonathan Klick and Joshua Wright suggested that San Francisco's eco-friendly ban on plastic bags might actually be killing people. Klick and Wright found that food-borne illnesses in San Francisco increased 46% after the bag ban went into effect in 2007, with no such uptick in neighboring counties. Most likely, the authors concluded, this was due to the fact that people were putting their food into dirty reusable bags and not washing them afterward. But Tomas Aragon, an epidemiologist at UC Berkeley and health officer for the city of San Francisco, begs to differ, arguing that in order to establish a link between the bag ban and illnesses, the authors would have to show that the same people who are using reusable bags are also the ones getting sick. Aragon offers an alternative hypothesis for the recent rise in deaths related to intestinal infections, noting that a large portion of the cases in San Francisco involve C. difficile enterocolitis, a disease that's often coded as food-borne illness in hospitals which has become more common in lots of places since 2005, all around the U.S., Canada, and Europe (for yet-unexplained reasons). 'The increase in San Francisco,' he suggests, 'probably reflects this international increase.'"
The closing comments in a letter from Tomas Aragon, puts it well:
"Finally, the idea that widespread use of reusable bags may cause gastrointestinal infections if they are not regularly cleaned is plausible. However, the hypothesis that there is a significant increase in gastrointestinal foodborne illnesses and deaths due to reusable bags has not been tested, much less demonstrated in this study. It would be a disservice to San Francisco residents and visitors to alarm them by claiming that it has been. It could be useful, however, to remind people to use safe food-handling practices, including maintaining the cleanliness of everything they use to transport, handle, and prepare food."
In May 2009,the state I live in was the first in Australia to ban on lightweight, checkout-style plastic bags, though the even thinner bags for fruit and vegetables are still allowed. I haven't heard of any associated increase in illnesses, though of course plastic bag manufacturers did argue the cleanliness issue prior to the ban being implemented. There have also been complaints by checkout operators about being handed disgustingly dirty bags to pack, so here too, it seems the vast majority of people don't wash or replace their bags when they become soiled. Some supermarkets here offer to put your meat purchases into a plastic bag and I try to remember to grab plastic bags from the fruit and veg section to further enclose my meat purchases.