us and the environment

The question we get asked most often is “are your bags biodegradable?”. You would think there would be a simple answer to this question, but the answer is more complicated than most people imagine. For example, the location where something degrades can determine what it turns into. Our bags are oxo-degradable, which means that above ground, in the presence of oxygen and sunlight they degrade to carbon dioxide and water at a similar rate to cornstarch bags. However, we have chosen to use oxo-degradable bags, not because of how they degrade above ground, but how they behave below ground. Because the reality is that the vast majority of dog poo bags end up in landfill. And in offering a product, we believe our responsibility extends beyond the point of our bags being placed in a rubbish bin. This is where things become more complicated. Because when you place biological material in a landfill, it can be very bad for the Planet.

Here is an explanation as to why we use HDPE (high density polyethylene) bags rather than cornstarch. In an ideal world, everyone would have a compost heap in their back yard. Unfortunately, there are reasons why most people don’t attempt to compost dog poo. And it’s not necessarily a lack of space, laziness, or the ick factor. Dog poo contains pathogens and if not handled properly can spread nasty diseases around the neighbourhood. In order to kill these pathogens, a temperature of 60 degrees Celsius needs to be achieved and maintained. This means your compost heap requires constant attention. If you presently use cornstarch bags for dog poo pick up and they are not breaking down quickly in your compost heap, it is probably an indication that optimum temperature is not being maintained, because cornstarch also requires prolonged temperatures of 60 degrees in order to breakdown. If not composted, a cornstarch bag takes around the same amount of time to break down in the environment as an HDPE bag (between 18 to 24 months on land – longer in seawater).

So, why do we use HDPE rather than cornstarch. The answer is that presently, because of all the above, the vast majority of dog poo bags end up in rubbish bins and go to landfill. If you landfill a cornstarch bag, it will eventually break down. Unfortunately that is not as good as it sounds because, due to the absence of oxygen, the bag and its contents will degrade anaerobically. This produces methane, which is terrible for the environment. It has an atmospheric heating capacity 30 times that of CO2. So, landfilling a poo in a cornstarch bag increases its effect on Global Warming by 3,000%. Using an HDPE bag (which is impervious to water, essential for the degradation process) sequesters the carbon contents of the poo, taking it out of the carbon cycle. You can think of it as reverse coal mining.  Landfilling is an emotive issue, but for the foreseeable future, some of our waste will continue to be buried. However, the first thing we should be removing from our landfill waste stream is biodegradable material because, if it degrades there, every last scrap of it turns to methane. If you want to offset your pet’s carbon footprint, we recommend you hire a green waste bin which is collected by a commercial composter. You can save up to 4 tonnes CO2e per household per year by diverting all your green waste and kitchen scraps to commercial composters. Unfortunately, one of the things they won’t presently accept is dog poo. So, in the meantime, if you don’t have a home compost bin, we recommend you continue to use HDPE bags.

Is Methane really that important?