Neppure le buste per la spesa usa e getta in bioplastica si degradano rapidamente nell'ambiente. Lo hanno verificato i ricercatori dell'Università britannica di Plymouth, che hanno pubblicato uno studio sulla rivista scientifica Environmental Science & Technology.
Dopo tre anni nel suolo o nell'acqua di mare, i sacchetti possono essere ancora così "stabili" che non si strappano, anche se contengono più di due chilogrammi di peso. All'aria aperta, poi, le buste di tutti i materiali si riducono in frammenti, che finiscono ovunque, spiegano gli scienziati.
"Questa ricerca solleva una serie di domande su cosa il pubblico può aspettarsi quando qualcosa è descritto come biodegradabile", spiegano i ricercatori, che sottolineano la necessità di norme ad hoc per i materiali biodegradabili. "Per molti aspetti una busta riutilizzabile è un'alternativa migliore alla degradabilità".
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