The debate about the environmental impact of plastic straws has gone global, and so have inaccurate and unverified statistics about the little suckers.

The original bad-straw-stat sin was the claim that Americans use 500 million straws a day, a number that popped up in just about every news article, blog post, or government press release on the topic before Reason revealed that its source was a small phone survey by a nine-year-old.

This revelation sparked some mea culpas from National Public Radio, The New York Times, and other outlets that cited it (although the National Park Service, CNN, and San Francisco politicians still use it from time to time), but these sadly came too late to prevent the bad stat from infecting the debate abroad.

When city government employees in Vancouver decided to gauge Canada's use of plastic straws in the run-up to that city's straw ban, they merely imported the 500 million figure and then adjusted it for our northern neighbor's population.

This was only slightly less rigorous than what has been going on in the United Kingdom.

Back in April, when the British government announced plans to prohibit plastic straws, it did so on the basis that that country's citizens use an intolerable 8.5 billion straws a year. Government press releases cite the figure, as do countless environmental groups, and media reports.

Then the BBC investigated. Apparently, the figure comes from the waste management consultancy Eunomia. Eunomia—appropriately named after the Greek goddess of legislation—arrived at this figure by taking the anti-straw group Straw Wars' estimate for how many straws McDonald's uses every day, looking up the E.U.'s statistics on what percentage of the fast food industry consists of McDonald's, and then "multiplying up" to get to 8.5 billion.

On top of that, Straw Wars' estimate of how many straws McDonalds's uses turns out to be twice as high as the company's own figures.

8.5 billion, incidentally, was only supposed to be an estimate of straw use at fast food restaurants, not everywhere, a fact that got lost in transmission as other groups picked the number up. Eunomia has an estimate for total British straw use too—about 42 billion a year. But its methodology there is questionable too.

To get the figure, Eunomia looked at market data on the aggregate weight of straws consumed in the E.U. each year, then divided that number by each member state's GDP. This is obviously going to inflate estimates of richer countries' straw consumption, since the number of straws a country uses is going to plateau pretty quickly as they get wealthier. (If you got a 20 percent pay increase, do you think you'd use 20 percent more straws?)

Then there is Australia's ubiquitous straw stat, whose origins are a total mystery.

This was discovered by the Australian Broadcasting Corporation after it aired a documentary, Waste Wars, that said the country uses 10 million straws a day. When a viewer asked where that figure came from, the network found itself unable to answer. The number nonetheless turns up not just on television but in government press releases and on environmentalist websites. And even without a good count of how large the purported problem is, some Australian senators are pushing for the country to ditch plastic straws by 2023.

The fact that dubious numbers keep surfacing in the straw debate suggests that activists are at best unconcerned with the trade-offs involved in their anti-straw crusade. So does their defensive hand-waving when confronted with the bad stats.

Take Peter Allan of the Australian group Sustainable Resource Use, who told the Australian Broadcasting Corporation, "I think it's important we get good data but in the end I think we can say with this there's enough consumption and enough of it is superfluous that it's worth focus."

Or take Milo Cress, the kid who gave us that 500-million-straws-a-day figure. He told USA Today, "Why I use this statistic is because it illustrates that we use too many straws. I think if it were another number, it still illustrates the fact that there is room for reduction. That's really my message."

If we're going to ask people to give up a convenience—or in the case of disabled people, a necessity—and impose new costs on businesses, you shouldn't wave away such a basic question.