Supposedly eco-friendly cups are still coated with a thin layer of plastic, which scientists have discovered can leach chemicals that harm living creatures.
Leaching chemicals isn’t just a problem when paper cups are littered—it can begin when a cup is used. In 2019, a research group from India filled paper cups with hot water to see if plastic particles or chemicals were released. “What came as a surprise to us was the number of microplastic particles that leached into the hot water within 15 minutes,” Anuja Joseph, a research scholar at the Indian Institute of Technology in Kharagpur, wrote in an email. On average, there were 25,000 particles per 100 ml cup. The researchers also found traces of harmful chemicals and heavy metals in the water and plastic lining, respectively.
A recently published study shows that paper cups can be just as toxic as conventional plastic ones if they end up littered in our natural environment. Seemingly eco-friendly paper cups are coated with a thin layer of plastic to keep their contents from seeping into the paper, and this lining can emit toxic substances.
“Reusable” cups aren’t necessarily much better when it comes to leaching, as they are often made of plastic; heat and wear accelerate leaching, and acidic drinks like coffee absorb chemicals more easily. The carbon footprint of reusable plastic cups is also disputable: A reusable cup has to be used between 20 and 100 times to offset its greenhouse gas emissions compared to a disposable one, according to some estimates. Blame the high amount of energy needed to make the reusable cup durable and the hot water needed to wash it. That said, a reusable plastic cup at least has the potential to last longer and is easier to recycle.