ASTM International, formally the American Society for Testing and Materials is a non-profit organization founded in 1898. ASTM has offices around the world. They develop and publish technical standards for a wide range of materials, systems, products, and services.
ASTM International plays no role in requiring or enforcing compliance with any of its standards. While the standards are voluntary, some countries including the US, have laws that reference certain ASTM standards. Balloons fall under the classification of toys. Toys sold in the United States must meet the safety requirements of ASTM F963 - Standard Consumer Safety Specification for Toy Safety.
We are not the manufacturer of any of our products. To the best of our knowledge, the manufacturers we work with have done independent tests, to make sure every balloon manufactured meets the requirements of ASTM F963.