Plastic resists decomposition because its carbon bonds are as chemically stable as those in crude oil, remaining virtually unchanged for millions of years.

Plastics are synthetic polymers derived primarily from hydrocarbons found in fossil fuels like crude oil and natural gas. During polymerization, exceptionally strong covalent bonds form between carbon atoms. These bonds resist both chemical and biological degradation because they rarely occur in such concentrated forms in nature.The stability of these bonds is comparable to organic matter trapped in the Earth's crust for millions of years. Most microorganisms lack the specific enzymes needed to break these long, complex chains into smaller molecules for energy. While some bacteria, such as Ideonella sakaiensis (discovered in 2016 at a recycling facility in Japan), have evolved to metabolize PET plastic, they remain the exception rather than the rule.According to the Environmental Protection Agency (EPA) and marine research studies, a standard plastic water bottle can take up to 450 years to decompose in the ocean. Even then, plastic typically fragments into smaller pieces called microplastics rather than fully returning to organic components. This molecular resilience explains why an estimated 8.3 billion metric tons of plastic have been produced since the 1950s, with the vast majority still existing in some form today.