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I have a tower of shame of reusable shopping bags stacking up in the corner of my pantry. My collection started honorably. In the early days of Oahu’s ban on single-use plastic bags, I bought reusable totes at the supermarket when I forgot to bring a cloth bag from home.

Then retailers and nonprofits started giving out for free totes with their logo printed on them to promote their products and causes.

Pretty soon friends — eager to get rid of their own reusable totes — started passing them on to me as gift bags containing jars of homemade mango chutney, or leaving them behind at the house after using them as carriers for wine contributions to potlucks. My stack started to multiply exponentially.

On Sunday, I pulled out all the bags from every closet and trunk of the car to take a few pictures for this column and shamefully discovered I have 35 of them.

It doesn’t make me feel any better about my bag collection to know that shoplifters apparently love the totes. Tina Yamaki, president of the told me that shoplifting has skyrocketed since the launch of reusable bags. She told me that when I called her to ask what retailers think about the reusable totes.

Thieves sneak merchandise off the shelves then stash it in a reusable bag so they can claim the goods were bought at another store if they’re nailed by store security, Yamaki said.

My friend Laurie Carlson agrees that reusable bags are lurking everywhere. “Everybody has got a hundred of them, hiding away under their bed. At first the bags seemed like a good idea, but … ?”

She’s right. You have to wonder. Is this environmentally friendly — hoarding cloth and polypropylene bags — having too many of them to regularly reuse?

Conventional wisdom says the reusable bags help the environment but only if you use them many, many times, not if you make a collection of them. Or worse, throw them in the trash.

Turns out the supposedly virtuous reusable shopping bags have their environmental benefits but also a big downside. Everyone knows the upside of reusable bags: they don’t litter like flimsy, single-use plastic bags made of fossil fuel that easily fly into the streets, wash into the ocean and get stuck up in trees, some even getting jammed up in machinery.

If they they end up as litter, the thin plastic bags do not biodegrade. And over time, they break into small pieces known as microplastics that can end up in the stomachs of marine animals or in the soil or the air.

But litter aside, the interesting fact is results in less carbon emissions waste than paper bags and the reusable bags of cloth and polypropylene we now carry out of stores instead of conventional plastic bags.

Paper bags are biodegradable and easier to recycle than single-use plastic bags. Also, they are handy for composting. But according to a , paper bags would have to be reused at least three times to neutralize the carbon producing effects required to make them. Paper production calls for enormous amounts of water, chemicals and fertilizers, and it causes deforestation of carbon sequestering trees.

Nonwoven polypropylene bags are a common kind of reusable tote sold at supermarkets and given away for free to promote products.

It takes less energy to create these bags made of a durable plastic than cotton bags. They are recyclable and sometimes made with recycled products themselves. For example, the are made from recycled plastic bottles.

According to the British study I cited earlier, the polypropylene bags have to be reused at least 11 times to put them on a par with single-use plastic bags when it comes to the amount of energy used for their production.

Cotton reusable bags are the most energy intensive to produce of the reuseable bags, requiring large amounts of water, chemical fertilizers and pesticides to protect cotton crops from insects. It’s . You can’t put cotton cloth into the recycling bin. Textile depositories in the business of repurposing cloth are difficult to find.

The British study found that a person would have to use a cotton tote at least 131 times to make up for the global warming potential of its production cost. And to make up for its even more intensive production cost, an organic cotton bag would have to be used many more times to equal .

The benefit of cotton bags is they are sturdy and machine washable, which is an advantage because when they are used to carry produce, meat and fish.

To be clear here, shoppers are not entirely to blame for the proliferation of reusable bags. Stores like Whole Foods Market keep creating new and ever cuter totes such as the Hawaii-themed bags that tourists and locals alike eagerly snap up.

And certain totes gain a street cred beyond their shopping bag purpose such as the graphic bags of the New Yorker Magazine and the canvas bags of famous clothing designers. The stylish totes become must-have items, almost like designer handbags.

And to defend reusable bags, even though they cost more energy and resources to create than conventional plastic bags, they have greatly reduced litter according to environmentalist Stuart Coleman. Coleman was Hawaii manager of the Surfrider Foundation for 12 years during which he conducted more than 150 beach cleanups.

He says besides cigarette butts, plastic bags were the most common littler they picked off beaches but today the lightweight, fly away bags are mostly gone.

Now that I have dragged out all of my totes from the corners where they were hidden, the shock of seeing the pile is prompting an environmentally friendly act. I will donate all of them to thrift shops except for the six bags I like the most. Six bags are really enough for anyone to own.