Okay, this post kind of fractalled into multiple conversation threads, thank you to everyone who participated! I learned a lot.
First, PVA, the skin of laundry pods, is a plastic. Yes, it dissolves in water (under selected conditions). But it doesn't go away. On this planet, there is no "away":
"Dissolve does not mean disappear. Salt is technically soluble in water, but if you pour a bunch of salt in a glass of water, you very much taste it. Itβs still there."
https://plasticoceans.org/pva-detergent-pods-gone-but-not-forgotten/
"In order for #PVA to #biodegrade, special PVA-adapted microbes need to be added at high levels and for long durations. Currently, most water treatment facilities do not sufficiently treat PVA in water, and therefore poses a series of environmental and safety concerns. "
Also:
"the production of PVA film involves heavy environmental and safety burdens in carcinogenic toxins, ozone depletion, acidification, eutrophication, and fossil fuel depletion."
https://dirtylabs.com/blogs/the-dirt/ask-dr-pete-are-laundry-pods-and-sheets-really-sustainable
"In order for #PVA to #biodegrade, special PVA-adapted microbes need to be added at high levels and for long durations. Currently, most water treatment facilities do not sufficiently treat PVA in water, and therefore poses a series of environmental and safety concerns. "
Also:
"the production of PVA film involves heavy environmental and safety burdens in carcinogenic toxins, ozone depletion, acidification, eutrophication, and fossil fuel depletion."