We are about two weeks away from a Toronto mandated charge of a nickel for a plastic bag in all stores in the city. Many supermarkets, including Metro, Loblaws and Sobey's, have already instituted the policy in advance of the June 1st deadline. And some across the province have followed suit.

Shoppers have been advised to bring their own bags or buy one of the reusable cloth kind, available for about 99 cents at every grocery checkout. But now those who make the plastic tote sacks are fighting back with a study they say shows those so-called 'green bags' aren't all they're cracked up to be.

The Canadian Plastics Industry Association hired two independent labs to study the reusable gear. Their findings: 64 per cent of so-called eco-friendly bags were contaminated by some level of bacteria.

Forty per cent tested positive for yeast or mould, and some had levels of coliform and fecal bacteria inside.

Scientists compare it to similar perils involving kitchen counters and raw meat, where contamination from the latter source can spread germs to the former. And the more waterproof the reusable bag is the worse the peril becomes, the research suggests.

It's especially aggravated if there's some contamination, like a spill from eggs or meat or if the bag is used to carry things like diapers, which could be transferred to food later put in the sack.

Why doesn't that happen with regular plastic bags? Analysts say they're only reused once or twice and that doesn't give the bugs time to accumulate or spread.

The World Wildlife Fund calls the study interesting but says it doesn't negate the need to reduce the use of plastic, which doesn't biodegrade and is a serious long term pollution threat that's not going away. They suggest washing the reusables occasionally will end the problem once and for all.

Loblaws, which is one of the chains that offers the cloth bags in question, adds that the protective wrapping on food products - ironically often made out of plastic - will keep them from becoming contaminated with anything.

Ontario's Environment Ministry is looking into the findings

Plastic bag recycling tips