In fact, they may threaten the secondary recycling of petroleum-based plastics, owing to possible contamination during sorting of mixed streams. And critics have expressed concern about the environmental impact of corn and other crops grown for industrial purposes, such as plastics and ethanol production, not to mention the potential effects on global food prices.
但生物塑料并不是塑料废物管理的万灵丹。事实上，它可能威胁基于石油的塑料的二级循环，因为在混合使用过程中会出现污染。批评者还担心以工业目的（如塑料和乙醇产品）种植的玉米和其他作物会带来环境问题，更不用说对全球粮食价格的潜在影响了。