Plastic are persistently present in our daily consumable items for examples contact lenses. Contact lenses are regularly prepared from a mixture of acrylic glass, silicones and fluoropolymers that permits companies to create a softer plastic material which permits oxygen to pass through to the eye.
Scientists have known for years that plastic pollution can exacerbate climatic and health hazards, but our understanding of their connection has evolved significantly in recent years.
Contact lenses use in eye usually serve the same corrective purpose as conventional glasses, but are lightweight and virtually invisible – many commercial lenses are tinted a faint blue to make them more visible when immersed in cleaning and storage solutions. Cosmetic lenses are deliberately colored for altering the appearance of the eye.
It has been estimated that about 125 million people use contact lenses worldwide (2%), including 28 to 38 million in the United States and 13 million in Japan. The types of lenses used and prescribed vary markedly between countries, with rigid lenses accounting for over 20% of currently-prescribed lenses in Japan, Netherlands and Germany but less than 5% in Scandinavia. People choose to wear contact lenses for various reasons. Many consider their appearance to be more attractive with contact lenses than with glasses on eye. Contact lenses are less affected by wet weather, do not steam up, and provide a wider field of vision. They are more suitable for a number of sporting activities.
Every year, worldwide a number of consumers were using contact lenses for their vision needs and for their fashion demands. After specific time period their consumption date expired and they disposed of in simple garbage bin or flush out in washrooms. Recent research conducted in American university proved that Americans flush 2.6 to 2.9 billion contact lenses down the drain. By accumulation this litter and studying how it persists in this environment, the study provides the first estimate of the potential burden of micro plastics. There’s been a lot of research done on single-use, lower-value plastics such as straws, plastic bags, however no one has yet looked at how these everyday medical devices may contribute to pollution in our soil and waterways.
To apprehend how lenses break down in sewage, Rolsky and his colleagues placed the corrective lenses in wastewater treatment tanks filled with hungry microorganisms. The team left the lenses in this potion for 14, 96 or 172 hours the typical range of time waste may spend in such facilities but they discovered the lenses used in eye had only started to degrade a little after 172 hours in this environment.
Researchers in the study suggests that in the US at least, around 14 billion lenses (15-20% ) are thrown away, amounting to around 200,000kg (441,000lb) of plastic waste every year. Pakistan and other under developing countries lack such consumption data.
Much of the waste water material ends up as a digested sludge which is then often spread on farmland. The Rolsky and his colleagues estimated that about 13,000kg of contact lens plastic ends up dumped in this manner.
“Contact lenses persist during water treatment, they become part of sewage sludge,” Prof Rolf Halden, from the Centre for Environmental Health Engineering at Arizona State told BBC News. “We know that whatever’s in sludge can make its way into runoff from heavy rains, back into surface water and that is an outlet to the oceans; there is the potential of these lenses being taken on quite a journey.”
The researchers are concerned that this poses an ecological risk in food web and food cycles and may allow the accumulation of persistent toxic pollutants in vulnerable organisms such as worms and birds. “If earthworms munch the soil and birds nourish on it, then that slugged plastic make the same journey as is done by plastics debris in oceans, they are incorporated by biota that are also part of the human food chain,” said Prof Halden.
To work out the impact of waste water plants on these materials, the researchers exposed five polymers in contact lenses to anaerobic and aerobic micro-organisms commonly found in these treatment facilities. Lenses are not generally reprocessed, although one of the largest manufacturers Bausch + Lomb introduced a programme last year.
The authors of the study say that lenses used in eye should be recycled where this is possible, but if not they should be disposed of by putting them in with other solid, non-recyclable waste. “The simple solution to this issue is for people not to put the lenses down the sink or shower or toilet!” said Prof Halden.
“They are a real improvement in quality of life and are a justified use of plastic, so if we decide as a society that we want to use plastic for these purposes, we should also present the consumer with the chance to get rid of these materials in a responsible fashion.”