’Degradable' bags are completely different from bio-degradable bags. They are made of similar plastic to normal carrier bags, and in addition they contain a small amount of mineral/chemical additive. This additive is also sometimes known as a brittling agent.
The additives speed up the fragmentation of the bag. Most of the products using the label Degradable plastic degrade as result of physical and chemical impact (fracture into smaller pieces of plastic).
Natural biological activity is not a significant part of the degradation of these products and the process is too slow to earn the classification Biodegradable or Compostable (the biological degradation will typically take many years).
The manufacturers usually give a timescale for how long the bag will take to break down. However the timelines given by the various manufacturers have been highly disputed if the bag is in less than perfect conditions (i.e out blowing round in the environment rather then in controlled lab with perfect test conditions).
Some case studies have shown the colder and darker the conditions the longer it takes for the products to break down. The products rely on the amount of moisture, humidity, light and heat. Obviously all of these factors in any environment are variable.
Degradable bags are known as Oxo-degradable, Photo-degradable or Hydro-degradable. Environmentally speaking these prefixes are irrelevant as none of these materials have ever been certified as compostable (biodegradable).
Depending on the company the additive varies in what chemicals/ minerals are used, companies even use sawdust.
However some additives used as brittling agents by certain manufacturers have been proven in independent studies to be heavy metals such as Lead, Zinc or Cobalt or "transient metals" such as magnesium chloride.
Degradable bags can cause trouble with the recycling of other plastics. Degradable bags aren't meant to be recycled (although some claim they are safe to do so). The Government funded Waste and Resources Action Programme does not think they are recyclable and has issued a guidance note recommending such additives are not used in packaging (carrier bags are officially classified as packaging).
Many recycling firms also have some grave concerns about this happening due to the general public lack of knowledge in this field and know that these products will inevitably end up being mixed in to the material that is sent to recyclers.
Andrew Green is the director of environmental affairs for BPI, Britain's largest recycler of plastic materials. "Our concerns on degradable materials entering the waste stream is that they could break down once turned into new products. This would be bad enough if large volumes of bin-liners degraded before they were used, but it is clearly an even bigger concern for our damp proof membranes and damp proof course products - which protect houses and buildings against moisture and gas vapours - and are intended to last!" (Quoted from the channel four website) website.
The additives speed up the fragmentation of the bag. Most of the products using the label Degradable plastic degrade as result of physical and chemical impact (fracture into smaller pieces of plastic).
Natural biological activity is not a significant part of the degradation of these products and the process is too slow to earn the classification Biodegradable or Compostable (the biological degradation will typically take many years).
The manufacturers usually give a timescale for how long the bag will take to break down. However the timelines given by the various manufacturers have been highly disputed if the bag is in less than perfect conditions (i.e out blowing round in the environment rather then in controlled lab with perfect test conditions).
Some case studies have shown the colder and darker the conditions the longer it takes for the products to break down. The products rely on the amount of moisture, humidity, light and heat. Obviously all of these factors in any environment are variable.
Degradable bags are known as Oxo-degradable, Photo-degradable or Hydro-degradable. Environmentally speaking these prefixes are irrelevant as none of these materials have ever been certified as compostable (biodegradable).
Depending on the company the additive varies in what chemicals/ minerals are used, companies even use sawdust.
However some additives used as brittling agents by certain manufacturers have been proven in independent studies to be heavy metals such as Lead, Zinc or Cobalt or "transient metals" such as magnesium chloride.
Degradable bags can cause trouble with the recycling of other plastics. Degradable bags aren't meant to be recycled (although some claim they are safe to do so). The Government funded Waste and Resources Action Programme does not think they are recyclable and has issued a guidance note recommending such additives are not used in packaging (carrier bags are officially classified as packaging).
Many recycling firms also have some grave concerns about this happening due to the general public lack of knowledge in this field and know that these products will inevitably end up being mixed in to the material that is sent to recyclers.
Andrew Green is the director of environmental affairs for BPI, Britain's largest recycler of plastic materials. "Our concerns on degradable materials entering the waste stream is that they could break down once turned into new products. This would be bad enough if large volumes of bin-liners degraded before they were used, but it is clearly an even bigger concern for our damp proof membranes and damp proof course products - which protect houses and buildings against moisture and gas vapours - and are intended to last!" (Quoted from the channel four website) website.
