The answer: when the product gets dumped in a landfill.
Stateside boffins say that, contrary to popular perception, it would often be better for the planet if people avoided using biodegradable products compliant with the recommended US government guidelines.
This is because biodegradable wastes — for instance cardboard cups, “eco friendly” disposable nappies, various kinds of shopping and rubbish bags etc — often wind up in landfill, where they will degrade and emit methane. Methane is, of course, a vastly more powerful greenhouse gas than CO2, so it is seen as important to prevent it getting into the atmosphere.
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The answer, according to Barlaz, is to get away from the idea that rapid decomposition is always a good idea — especially on things which won’t be recycled much but will probably wind up in landfill, for instance disposable nappies, fast-food packaging etc.
“If we want to maximize the environmental benefit of biodegradable products in landfills,” Barlaz says, “we need to both expand methane collection at landfills and design these products to degrade more slowly — in contrast to FTC guidance.”
