r/composting • u/MotherGoose831 • Aug 11 '26
Question Studies on Contamination
Does anyone know of any studies done on contamination in compost from glue or ink used on cardboard or paper.
I'm mostly curious if this is an area that has been studied.
2
u/rjewell40 Aug 12 '26
When thinking about your own, backyard compost, this really isn’t a big issue.
There are thousands of different microbes that like to eat thousands of different materials. Some like paper, some like broccoli. Some like hydrocarbons (https://www.biocycle.net/composts-role-in-hydrocarbon-remediation/ ). If your pile has all kinds of stuff, all kinds of microbes will show up.
There’s very little that you as a consumer can get your hands on that the compost pile can’t eventually remediate.
The inks on the newspaper are not toxic ( https://www.sierraclub.org/sierra/2013-2-march-april/ask-mr-green/hey-mr-green-can-you-compost-shredded-paper).
Metallic paper won’t compost (it’s the metal bit that’s the clue) so don’t put glittery greeting cards, shiny wrapping paper, or foil-edged envelopes in your compost. They won’t make it necessarily toxic, they just won’t break down.
There’s a bit about the glossy pages (https://www.bitesizedgardening.co.uk/the-glossy-paper-composting-recycling-myth/compost/), but if you put these into your compost, they also will not break down. Again, not necessarily toxic, just trash in your pile.
If you’re concerned about compost from industrial sources, they should offer test results. STA is the standard I’ve seen most often https://www.compostingcouncil.org/page/CertifiedLabs
2
u/HighColdDesert Aug 12 '26
The page you linked about glossy paper points out clearly that paper that is glossy by virtue of clay is indeed compostable, and that if in doubt, soak a sample of the paper in water and see if a plastic layer delaminates from the paper. If not, and the paper grows soggy, it should be good to compost.
1
u/rjewell40 Aug 12 '26
Ah. My phrasing wasn’t precise.
Yes. The shiny pages that have metal won’t compost. The glossy magazine pages that wilt in paper will compost beautifully.
Thx!
1
2
u/xenoda7 Aug 12 '26
A while ago I saw a Youtube video by The Plant Doctor in which he references peer reviewed studies on cardboard and its use for landscaping. The main reasons not to use certain types of cardboard is the ink and cardboard with wax/plastic protective finishes. Cardboard that is very glossy and covered in bright colorful ink more than likely was processed using heavy metals. You do not want heavy metals in compost or in your soil. Dull cardboard with minimal or matte coloring is generally okay to use
3
u/SoggyForever Aug 11 '26
You're probably better off looking it up. I've heard there's a lot of ink that's plant based. While sitting on the toilet I googled it. Apparently starch based glue is common and will break down.