ON JULY 30th Canada’s Conservative government announced it intends to ban the use of microbeads in personal-care products. The Netherlands has already imposed an unofficial ban on them, which should be in effect by the end of 2016. What are these horrid little things? Microbeads are very small synthetic plastic particles, each of them perfectly spherical. None are more than five millimetres (5mm) across, and most are only 1mm or smaller; they look like grains of sand. The most common sorts are made from polyethylene and polypropylene. These are used in everything from cancer research and HIV treatment to flat-panel televisions and the jumbo screens in stadiums. But what really worries the Canadians, and a growing number of scientists and environmentalists everywhere, is the use of microbeads in products like toothpaste, soap and facial scrubs and exfoliants.

When these goops and gunks go down the drain, so do the microbeads. The trouble is they are too tough to dissolve and yet too small to be caught by the filters in water-treatment plants. So they are discharged into natural water systems, where they do untold damage. New York alone flushes about 19 tonnes of microbeads down its drains every year. They can absorb toxic agents along the way. Wild critters often mistake them for food. Ingested microplastics can block up their guts and lead to starvation. Worse, from a human point of view, chemicals can be gobbled up with the microbeads and so work their way up the food chain. Microbeads have already been found in the flesh of fish caught for human consumption.

Scientists at Environment Canada, a department of the national government, reviewed more than 130 scientific papers, consulted experts and concluded that microbeads should be added to the national list of toxic substances. This would give Canada the authority to regulate the sale, manufacture and import of microbeads. It won’t happen right away however. Three days after his microbeads announcement, Stephen Harper, Canada’s prime minister, called an election for October 19th. But both the main opposition parties have called for a ban too, so something should happen whichever party wins. The trickier point might be the government’s plan to align its policy with America’s.

The United States does not have anything so clear as a federal ban. Most of the action has taken place at the state level, starting with the states that share coastlines along the Great Lakes, which sit on the border between Canada and the United States. Eight states have passed banning legislation and 17 have bills pending. In June 2014, Illinois became the first state to pass a bill against microbeads, though many experts think it did not go far enough. They see it as an unwholesome compromise: Illinois’s rule only bans some microbeads, allowing the use of biodegradable ones. Those are also plastic, though they can be broken down under laboratory conditions. It is not clear whether they would actually biodegrade on, say, the bottom of Lake Michigan. States with more ambitious proposals on the table, including New York and California, are calling for companies to substitute all microbeads with natural alternatives, like seeds, husks or shells.

While lawmakers split hairs—which can be as thin as 0.05mm or thinner—many manufacturers of personal-care products are independently taking action against microbeads.

Procter & Gamble has made a commitment to phase them out. Loblaws, the largest food retailer in Canada, has said it will stop making them by 2018 (or sooner, presumably, if the law demands it). Colgate-Palmolive stopped using them in 2014 and Unilever phased out the last of its microbeads in January 2015. Johnson & Johnson (J&J) says it will have eliminated the use of polyethylene microbeads by the end of 2017. J&J has already begun reformulating some products to use jojoba wax, extracted from a shrub native to the deserts of North America.

Correction: This article was changed slightly on August 5th 2015, to reflect the fact that Colgate-Palmolive had already removed microbeads from its products.