COMPOSTABLE

The right to use the mark of conformity "COMPOSTABLE" on compostable plastic bags is granted only to the manufacturer/distributor that demonstrates that their product conforms with specific performance attributes and adheres to the parameters for "compostability" as set out in the BNQ document, Compostable Plastic Bags - Certification Program (BNQ 9011-911/2007) as published in September 2007.

It is important to be aware that "compostable" and "biodegradable" are not equivalent. Similarly, "disintegration" cannot be used interchangeably with either of these terms.

The definitions established for the purpose of the program are as follows:

Biodegradation: degradation caused by biological activity especially caused by enzymatic action leading to a significant change in the chemical structure of a material.

Compostable: said of that which is capable of undergoing biological decomposition in a compost site such that the material is not visually distinguishable and breaks down into carbon dioxide, water, inorganic compounds and biomass at a rate consistent with known compostable materials.

Disintegration: the physical breakdown of a material into very small fragments.

The key distinguishing features between the terms reflects time and end result.

In the definitions for both biodegradation and disintegration, there is no reference to time nor the type of physical and chemical quality attributes associated with the material's change.

Three additional definitions of note in the document are:

Degradation: an irreversible process leading to a significant change in the structure of a material, typically characterized by a loss of properties (eg. integrity, molecular mass or structure, mechanical strength) and/or by fragmentation. Note: degradation is affected by environmental conditions and proceeds over a period of time comprising one or more steps.

Compost: solid mature product resulting from compost

Composting: managed process of bio-oxidation of a solid heterogeneous organic substrate including a thermophilic phase.

Compostable plastic bags must be compatible with the dynamics involved in the composting process and not detract from the physical and chemical quality of the end product, compost.

In Canada, for a plastic bag to claim compostable, it must:

•   disintegrate by at least 90% within 84 days of the composting process
•   biodegrade by at least 60% or 90% into carbon dioxide depending on the type of polymer used
•   biodegrade within 180 days or 360 days depending on the test used
•   have no ecotoxicological effect greater than 10% on the germination rate of seeds and vegetation   biomass rate