That's what they told me in school, too.

But then I got out in the real world, and noticed plastics just falling apart all around -- including stuff that is not intended to fail and which is otherwise still within its useful life.

Like: One year, I bought some used pickle buckets from a local burger joint to use as planters. Within 6 months, they were falling apart: It was easy to break them apart in chunks with my bare hands.

Or the plastics used for cars: They often eventually turn brittle and fall apart, whether interior or exterior. Plastic lenses on USDM cars turn foggy and useless; some types of wire insulation disintegrate. (If we want to talk about environmental cost, can we also talk about the impact of building a new car?)

In some areas, we once used polybutylene water pipes. These tended to fail and damage homes. There was even a billion-dollar lawsuit about it in the 1990s. It was not good.

Meanwhile, a red Solo cup or a plastic drinking straw, once landfilled, will be there a very long time -- but eventually, they will also decompose.

And the UHMW cutting boards I use in my kitchen will probably outlive my grandchildren's grandchildren before they start falling apart on their own accord.

Plastic isn't always forever, even though some people seem fond of saying that it is. Plastic isn't necessarily cheap, either, even though "cheap plastic" is a common expression -- some plastics are very expensive and resoundingly durable (and there's only partial overlap of these two qualities on a Venn diagram).

The truth is somewhere in the middle, but is rather nuanced and variable and difficult to pin down in absolutes.

But plastic (as a noun) does, broadly speaking, have the material property of being plastic (as an adjective).

You have to put UV and temperature stabilizers in plastics to prevent them from breaking down outside. The sun is merciless and destroys everything in time.

Your buckets would have lasted longer if you had painted them with outdoor housepaint or outdoor water- or oil-based urethane, because those coatings contain uv stabilizers.

>Plastic isn't always forever

But molecularly, plastic is around forever. A wooden bucket will eventually breakdown to not be wood at all anymore. Products made from plastic is not what lasts forever, the plastic itself is.

I meant decomposable by bacteria.

It's trivial to make plastics that break, but then you have many microplastics which again don't decompose.

The breakage isn't even infinite, as the particles grow smaller, the shear resistance grows and it stops splitting, and again nothing decomposes it further

So decompose =/= break.