-"nobody possibly uses their cotton bags 7000x - cotton is so much worse than plastic"
-"everything we do is bad for the environment (pick your poison!), AND the greenies who love cotton and organic are literally the WORST" 2/n
>Plastic bags aren't that bad in some environmental aspects
>Paper and reusable and recycled plastic are also pretty good bag materials
>Organic can be worse for the environment (due to reduced yield)
>Apparently Danes consume, per year, the equivalent of 63 cotton bags in textiles. So one could easily compensate for one cotton bag simply w/ one less t-shirt. 4/n
I was surprised by the order of magnitude & looked into the Life Cycle Assessment (LCA) study that was the source of this number.
The LCA was commissioned by the Danish Ministry of Environment & written by researchers at @DTUtweet. LCA is a way to compare cradle-to-grave impacts, on an apples-to-apples basis. But environmental impacts are complicated. Some things are really hard to compare! 7/n
Cotton: farming, agricultural & textiles chemicals, fertilizer productn & run-off, transportation, textiles production.
Plastic: oil extraction, refining, plastics manufacturing (but a lot less material is processed bc plastic is weight&volume-efficient). 8/n
Use a cotton bag once/week for a year & it will have "paid off". We're talking abt nice cotton cloth bags, not the thicker plastic ones. 13/n
But 7100x of a miniscule number can still be miniscule. They cld both be really harmless! I suspect LDPE (plastic bag) has a tiny O3 impact, & so % diff seems large 14/n
Also, I am certain that uncertainty dominates the estimates of life cycle O3 impact data that resulted in this point estimate of 7100x. 15/n
Cotton vs. LDPE: 1000x for freshwater & terrestial eutrophication. 67-400x for PM, ionising radiation, terrestial acidification, marine eutrophication, freshwater ecotoxicity, cancer, non-cancer toxicity, photochemical ozone formation. 16/n
Minor Problem #1: I've always found these particular impact categories controversial. Water & resource consumption can be added up, but impacts can vary widely depending on where and how. 18/n
Again, this is very different from "7000x" or even the average number, 840x, which equally weights all the impact categories discussed. 19/n
Plastic bags aren't that bad, in many ways, considering the choices, BUT cotton isn't that bad either, particularly if you use it something like 50+ times, and then it can be better in many ways for the environment.
Beware false precision - think in orders of magnitude.
Be numerate - 7000x of a miniscule number can also be a miniscule number. 29/n Good takes: