Compostable plastics are generally starch-based materials that are considerably more expensive than conventional plastics, while intrinsically being weaker due to their chemical properties. Moreover, compostable standards only relate to the degradation of compostable plastics under industrial composting conditions; under home composting conditions or the open environment, their degradability is considerably lower.
Given that the UK Environmental Agency’s Life Cycle Analysis of carrier bags indicates that the primary factor to minimise the environmental impact of plastics is its re-use, the intrinsically reduced physical strength of compostable plastics means that they are not environmentally-friendly since they are not amenable to repeated re-use.
