If there’s one thing that really annoys most people about politicians, it’s when they take advantage of a situation to score political points without thinking things through. One recent example is the feel-good proposal to ban or tax plastic grocery bags, supposedly to help preserve the environment.

These proposals are gaining ground because they provide political “cover” for generating revenue, allow politicians to claim they’re “doing something green,” or both. But like many ideas that sound good at first, we should never forget the Law of Unintended Consequences.

Ah yes, that pesky little law. We’ve seen it before.

According to the Wall Street Journal, we saw it as 50 million preventable deaths occurred after pressure from environmentalists resulted in a ban on DDT. We saw it as people switched to trans fat-laden margarine after pseudo-experts demonized butter. We see it in the huge cleanup projects that are now required after some activists thought dumping tires into the oceans in the early 1970s would help sea life. And we saw it in my last column, as a nationwide ban on horse slaughter has actually increased horse abandonment and suffering.

We’re already seeing some of the unintended consequences of banning or taxing plastic bags.

Taxes and bans will drive consumers toward reusable grocery bags. But this might not be such a good thing.

According to recent testing commissioned by the Center for Consumer Freedom, a nonprofit organization that I manage, a significant number of reusable bags are tainted with excessive levels of lead. The bags we tested had lead levels as high as 697 parts per million. That’s nearly seven times the level allowed under the “Toxics in Packaging” model law on the books in 19 states.

These weren’t just knock-off brands, either. Some of the most lead-laden bags came from stores like CVS, Bloom and Giant. One bore the logo of the Oregon Ducks football team.

Further, a recent study from the University of Arizona found that more than half the bags it tested came up positive for fecal coliform bacteria, and 12 percent tested positive for E. coli. This is probably because more than half the people who carry their groceries home in reusable bags have never washed them.

The environmental benefits of switching to reusable bags are also questionable. Almost 3 billion of these bags have been imported into the U.S. since 1999, according to data from the U.S. International Trade Commission. That’s almost 10 bags for every man, woman and child.

Why so many? “Reusable” bags often aren’t actually reused.

According to one survey in San Francisco, where disposable plastic bags are already banned, 58 percent of shoppers forget to take their reusable bags to the store. When you consider that each reusable bag has 28 times the carbon footprint of its disposable counterpart — and that researchers recommend wrapping meat in disposable plastic bags to avoid those nasty bacteria — you can see just how shaky the supposed environmental benefit really is.

Here in Washington, D.C., the city council has already imposed a tax on disposable plastic bags. So every trip to CVS and every take-out dinner can cost an extra nickel. The city government has already pulled in $2 million — although the former mayor proposed funneling the money to pay street sweepers instead of an Anacostia River clean-up fund, as initially promised.

And what of the reusable bags that the D.C. government puts its logo on? They tested positive for excessive lead, too (142 parts per million).

Let’s put it plainly: This effort to supposedly help the environment might actually do more harm than good. People who want to change their lifestyles to consistently use — and wash — their reusable bags will do so. But most of us don’t want to do it when given the option, or even when having the “option” forced upon us.

Enough is enough with these solutions in search of problems. If you’re looking for something positive to do, it’s pretty simple: Recycle, whether it’s a bag or a bottle. Don’t litter. Plant a tree or two. And encourage your friends to follow suit. It’s better for the environment than trashy policymaking.

Rick Berman is President of the public affairs firm Berman and Company. He has worked extensively in the food and beverage industries for the past 30 years. To learn more, visit http://www.BermanCo.com.