Polystyrene foam, sometimes incorrectly referred to as “styrofoam,” is neither biodegradable nor compostable in any viable sense.

Environmentalists and others maintain that due to lightweight design, foam clamshell food-service containers and cups can easily drift away from waste collection systems and accumulate on land and in water, and can leach toxins. The products — made with non-renewable fossil fuels and synthetic chemicals — can do harm to birds and marine life, ranging from fish and turtles to seals and whales.

This seems reason enough to ban the stuff. Maui was the first county in the islands to do so. Its prohibition on the sale and use of polystyrene food containers took effect last week. Hawaii island is slated to follow suit in July. And Honolulu’s City Council is now weighing a proposal that would put in place a ban taking effect on Jan. 1, 2020.

That’s also the start date for the last phase of Honolulu’s single-use plastic bag ban — when a complete prohibition on all single-use plastic bags 10 mils or less in thickness kicks in. Customers at groceries and other businesses will then have to purchase or provide their own reusable bags.

Oahu’s phased-in approach to a flat-out ban on checkout plastic bags is a laudable move for environmental protection, although it lags behind effective laws already up and running on neighbor islands. We’re seeing a similar slow pace in the push toward banning ubiquitous foam takeout containers on Oahu.

The latest proposal to be weighed by the City Council, Bill 92, would ban vendors from using polystyrene containers when serving prepared food, and in packaging of meat, eggs, bakery goods and other foods. However, it would allow for a city enforcer, the Department of Environmental Services, to grant exemptions for businesses demonstrating undue hardship.

The pros and cons echo those debated six years ago, when Hawaii became the first state nationwide in which each county had a plastic-bags ban on the books. Holding the most weight for both types of ban is the argument for environmental gains. Much of the opposition is tied to the price tag for going green.

In the case of foam containers, opponents say vendors should not be forced to shell out for a more expensive option, which could lead to job cuts or higher-priced takeout food; and that businesses should be free to make their own selection of government-approved food-grade products.

For the past five decades, the U.S. Food and Drug Administration has permitted the use of polystyrene for food service products. However, due to environmental concerns, since 1990, Honolulu has limited restaurant use of foam containers to those that do not contain chlorofluorocarbons.

A report issued last month by Honolulu Auditor Edwin Young concluded that a ban on foam containers on Oahu would negatively affect some smaller businesses, and is “unlikely to effectively reduce the overall amount of litter and its harm to the environment.”

The report’s take on the environmental upshot is puzzling. Even if the quantity of litter remains, if polystyrene is replaced by Earth-friendly materials, such as natural starches and recycled fibers, that’s a gain. The report also rightly noted one less-complicated strategy for protecting our land and waters would be stepped-up enforcement of littering statutes.

It’s apparent that the need for a polystyrene ban is more pressing on neighbor islands, where the stuff ends up in landfill space that is, of course, tightly limited in an islands-based economy. Honolulu’s waste collection system bypasses the landfill to deliver all of its polystyrene materials to HPOWER, where it’s burned as an inexpensive source for fuel.

The waste-to-energy facility in Kalaeloa produces up to 10 percent of Oahu’s electricity. To that, environmentalists have countered that compostable containers have a much higher fuel value when incinerated, and don’t release toxic ash and smoke.

The city auditor’s report included a survey of polystyrene foam bans in dozens of cities and counties nationwide. The approaches range from a complete plastic ban in Seattle — single-use foam food containers, plastic utensils, straws and bags are prohibited — to one that bars the presence of polystyrene from beaches and parks in Miami.

In San Diego, the government purchase of polystyrene containers is outlawed. That’s a step in the right direction that Hawaii could quickly take. It’s already in place at the University of Hawaii at Manoa’s food establishments. Campus eateries have been foam-free for several years, thanks, in part, to a student-led initiative.

Efforts to impose a statewide foam container ban have stalled in the Legislature. So, as with the plastic bags issue, our counties are to be commended for taking action based on environmental foresight.

Ditching the containers that durably hold ever-popular hot and cold meals and snacks is no easy task. Still, long-term benefits for Hawaii’s environmental health outweigh cost bumps and perceived inconvenience.