If the environmental movement drew up a Most Unwanted list for 2018, the plastic drinking straw surely would land near the top. More than a dozen cities and California banned or limited plastic straws. The corporate giants Starbucks and Disney led a long roster of companies that promised to do the same. A list of luminaries — from football’s Tom Brady, to rock’s Mick Jagger, to former first daughter Chelsea Clinton — embraced the #StopSucking campaign against single-use straws. Environmentalists hope the movement will stir a larger conversation about runaway plastics pollution. Straw bans alone — which have been criticized for not truly reducing waste — will barely dent the flood of plastic spewing into the environment each year. The most often repeated estimate of the amount of plastic spilling into the oceans is 8.8 million tons a year. That’s the equivalent of five grocery bags full of plastic along every foot of coastline in 192 countries, according to researchers. Other studies show that the synthetics increasingly find their way not just into fish, sea turtles and whales, but into human beings. “We are beginning to understand the impact on human health,” said John Hocevar,...