PLA

Cleared for food contact. FDA accepted the first polylactide food-contact notification (FCN 178) in 2002 for all food types under conditions of use B through H, which extend to boiling-water sterilization, and a second (FCN 1926) in 2018 excluding infant formula and human milk; NatureWorks also declares compliance with EU plastics regulation 10/2011. That is a food-contact notification, not GRAS status, so descriptions of PLA as "FDA GRAS" are wrong. The live question is particle release, and the number everyone quotes is misattributed: the "billions of particles per bag" figure comes from a 2019 study of nylon and PET bags, and Germany's federal risk institute (BfR) rejected that study's sample preparation, counting 5,800 to 20,400 particles per bag against the reported 2.3 million and finding most of them oligomers rather than microplastic. The PLA-specific work is more modest: a 2023 study measured roughly one million PLA nanoplastics released per tea bag, with no significant cytotoxicity to intestinal cells at 100 ug/mL over 48 hours and only slight, short-lived barrier disruption. The honest position is that a PLA tea bag does shed nanoplastic into the cup, that the quantities are far below the numbers usually cited, and that no health effect has been demonstrated at those doses.

The least heat-tolerant plastic in common consumer use. NatureWorks lists a heat distortion temperature of 55C (ASTM E2092) for its general-purpose grade and states that the grade is designed for applications with heat deflection temperatures below 49C/120F. That is under a dishwasher cycle, a hot car dashboard and a fresh cup of coffee, which is why PLA cutlery and cold cups warp against anything genuinely hot. Regulatory clearance does cover hot fill and boiling-water sterilization, so the limit here is physical rather than a migration one - the item deforms long before it becomes unsafe.

On packaging, look for "PLA", "polylactic acid", "Ingeo", "plant-based", "compostable", or a seedling logo; where a resin code is stamped at all, PLA falls under #7. A dead-clear rigid cold cup that dents under a fingernail and creases white is usually PLA rather than PET. In tea, any "silky" woven pyramid is plastic mesh - PLA, nylon or PET - and a plain paper bag can still carry a PLA heat-seal thread, so a stitched, folded or string-and-tag bag is the only reliably plastic-free format. Ask a tea brand two questions: is the bag heat-sealed and with what, and is the compostability certification the industrial EN 13432 / ASTM D6400 route or a home-compost scheme.

Single-use in practice. It is not dishwasher-safe, it will not survive a hot drink twice, and it embrittles slowly with UV and humidity even in storage.

Industrially compostable, and nothing else. BPI's commercial criteria call for disintegration at 58 +/- 2C over up to 84 days and biodegradation at the same temperature over six months; a home-compost scheme does exist (25 +/- 2C, 180 days and 12 months), but PLA is not typically certified to it. Outside that heat the material is effectively permanent - PLA textiles showed no sign of degradation after 428 days in natural seawater in a 2023 study, while cotton and lyocell controls disappeared in roughly 35 days. There is no curbside recycling route for PLA in North America and it is a contaminant if it reaches the PET stream, so without access to an industrial composter a PLA tea bag ends up in the same bin as a nylon one.