A non-stick chewing gum that will wash easily off concrete surfaces could save authorities millions, claim researchers. Amidst a new 鈥減lague鈥� of gum litter in areas with smoking bans, they say their product could spell the end of sidewalks covered in chewing gum 鈥渃ud鈥� and cut city cleanup costs.
People chew gum for all sorts of reasons 鈥� to pass the time or freshen up their breath, for example. In fact, hunter-gatherers appear to have enjoyed this pleasure back in the Stone Age, and recent studies have even suggested that chewing gum can improve memory performance.
Recently, as a result of smoking bans in places such as Ireland and the UK, people have turned to gum to help them kick their cigarette addiction. Consequently, gum sales have skyrocketed, says Kerry Page of Straight plc, a company based in Leeds, UK, that sells special chewing-gum disposal bins and helps recycle the collected cud into construction materials.
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But the increased popularity of chewing gum has left an unpleasant mark on the cityscape 鈥� namely it increases the amount of cud that ends up stuck to the sidewalk. Page notes that some places in Ireland saw as much as a 30% increase in gum litter once the country鈥檚 smoking ban went into effect.
Sales surge
The problem of 鈥済um pollution鈥� has 鈥渓ong been considered a plague in Britain,鈥� says Page. Removing just one wad of gum from the pavement can cost anywhere from 10 pence ($0.20) to as much as 拢1.50 ($3.00), she adds. In the late 1990s, the UK government estimated that it spent over 拢150 million a year to clean up chewing gum. Page suspects that number has 鈥済one up massively鈥� with the recent surge in chewing gum sales.
Terence Cosgrove at the University of Bristol, UK, says he and his colleagues have come up with a solution to this sticky situation. They have designed a special gum ingredient that repels the cud from dry surfaces, such as concrete.
The researchers came up with the new ingredient they call 鈥淩ev7鈥�, by linking up two compounds already found in products such as toothpaste and various cosmetics. One of the compounds is attracted to water, while the other is repelled by water.
Rev7 works, says Cosgrove, because the water-loving regions of the ingredient migrate to the outside of the chewing gum in a person鈥檚 mouth. As a result, if it is spat onto the sidewalk, it is not attracted to the dry concrete.
Chewing the cud
In preliminary trials, developers chewed the gum 鈥� which comes in both mint and lemon flavours 鈥� for 20 minutes and then stuck it onto paving slabs. Two days later, they found that rain had washed away the gum, but the cuds of traditional chewing gum they had placed as controls remained stuck to the surface.
A second test on the gum suggests that it will disintegrate if left in water for a few months 鈥� which could mean it would naturally disappear from surfaces over time. Cosgrove鈥檚 team placed a regular piece of gum in a container of water and their non-stick gum in another container. After seven weeks, the traditional gum remained intact, but the Rev7 gum had broken into small fragments resembling the snowflakes inside a 鈥渟nowglobe鈥�.
Cosgrove has now helped start a company, called , to market the non-stick product, now called 鈥淐lean Gum鈥�, and hopes it will become available in 2008. 鈥淚t has a good chew and it certainly holds together in the mouth,鈥� he says of the product, which he presented at the BA Festival of Science in York, UK, this week.
