Reading Beyond the Spin

One of the best books I have ever read was Trust Us, We're Experts: How Industry Manipulates Science and Gambles with Your Future by Sheldon Rampton and John Stauber. If you want to know how industry-hired public relations firms use science to influence (or spin) public opinion, then this is the book for you. Why science? Because the general public, myself included, tends to shy away from the scientific and is easily convinced by quantitative "facts."

I recently came across what appears to be a perfect example of questionable science being used to influence consumer habits.

On May 19, 2009, the Environment and Plastics Industry Council, the shill representing the Canadian Plastics Industry, published a scientific study which concluded "swab-testing demonstrates that single-use plastic shopping bags and other first use carry bag options are more hygienic than reusables" (reusables = cloth or any other type of reusable shopping bags). I should also add that only 25 bags were actually tested. Not exactly a large-scale study.

The study also concluded that the "test findings clearly support concerns that reusable grocery bags can become an active microbial habitat and a breeding ground for bacteria, yeast, mold and coliforms."

Okay, so according to the study, we're not supposed to use reusable shopping bags because they are not as hygienic as the new bags we get in the store. It appears from these conclusions that reusable shopping bags are breeding grounds for bacteria, yeast, mold and coliforms.

Sorry, I don't know what "coliforms" are. Sounds pretty sciencey though, doesn't it? And if we break the word down we have "coli," as in E-coli. Scary stuff...

Luckily, I had a chance to read a critique of the study by Dr. Ben Chapman, Assistant Professor at North Carolina State University. He had this to say about coliforms in the study.
...coliform isn't an indicator of really anything in a shopping bag. It's a great indicator of water quality, but not great for food (coliforms are all over the place, including on produce). And mean relatively nothing.

In addition, the study found that "64% of the reusable bags were contaminated with some level of bacteria, and close to 30% had elevated bacterial counts higher than 500 CFU/ml considered safe for drinking water."

I chose this last sentence because initially it, too, caused me to shy away from science. However, I found it odd to compare the bacterial counts in shopping bags with those in water. After all, we don't drink our shopping bags, and presumably, most of the things going into the shopping bag are already wrapped in some form of packaging. In other words, we don't put unwrapped raw meat into the bag, so what is the problem?

I also have to admit that I was stumped by the CFU/ml unit of measure. Now, just what was it measuring?

Dr. Chapman had this to say in reference to CFU/ml,


The lack of real data is probably why it was reported in CFU/ml (a water measurement -- pretty hard to tell what a ml of a shopping bag represents). The most telling data was that no generic E. coli or Salmonella was found.

(By the way, CFU is an acronym for Colony Forming Units. This expresses the number of viable microbial cells per millilitre.)

So what does this all mean?

According to Dr. Chapman, it means that we should regularly wash and dry our shopping bags, and use single-use plastic bags to wrap our meat, which most of us do anyway.

It seems that the Environment and Plastics Industry Council is using science and some scare tactics to get consumers to go back to using single-use plastic bags.

And by reading beyond the intended spin of this study, we can see that a large enough number of consumers have opted for reusable shopping bags and that the Canadian Plastics Industry is feeling the pinch.

To read the Environment and Plastics Industry Council's press release and study click here.
To read Dr. Chapman's blog post on the Environment and Plastics Industry Council's study click here.

2 comments:

C.McKane | May 25, 2009 at 7:33 PM

It's good to see someone dig a little deeper. I think whenever a study proves something many (myself included) automatically assume that it's infallible. Of course, when it's not a neutral party doing the study (ie. plastics studying their threat, cloth) it does raise a flag.

I buy the reusable bags all the time, but always end up using them as totes, storage and rarely for food shopping, but I used to work at a grocery store and saw (& smelt) some pretty rank bags. Washing them once in awhile would probably be a smart idea ;)

AKAmamma | May 28, 2009 at 9:23 PM

We have the same problem. No shortage of shopping bags in this house.

I've been told that the trick is to keep one in your car, at work, in your purse, etc. That way you never are without.

I just found out that Dr. Chapman is following me on Twitter. I hope he lets me know if he comes across another study involving questionable science.
Thanks for dropping by.

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