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영어로 읽는 과학기사 Several years ago, a song with the lyrics, “Have you done disinfecting laundry?” became a hot topic of conversation. It was a jingle for a commercial advertising for Samsung Electronics’ nano-silver washing machine. This commercial added to the stress of many people, with some critics saying “It constitutes intentional ‘noise marketing’, as the ad repeatedly played the song with the lyrics, “Have you done disinfecting laundry?””
A bigger problem however was not the jingle that angered the public, but the nano-silver washing machine itself. Several countries, including the U.S. and several European nations, raised issue with the environmental harmfulness of nano-silver.
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| ▲ Nano-silver has extensively penetrated our daily lives through its disinfecting ability, but controversy lingers over its harmfulness. | A nano-silver washing machine refers to a washing machine that adopts a new laundry method in which silver particles melted in water penetrates laundry to disinfect germs. The concern that was raised at that time was that the silver particles that were broken into fine pieces would be emitted into the air or water streams, causing chemical reactions. As a growing number of voices expressed worries that it might kill beneficial bacteria or microorganisms and disrupt the ecosystem, the U.S. Environmental Protection Agency classified silver nano as a harmful substance(agricultural chemical).
The controversy over nano-silver products did not end with the debate over washing machines. With the marketing of diverse silver nano products for daily life that promote their capacity to disinfect, controversy has been mounting further. Such products include toothpastes, baby bottles, and air conditioners.
No specific standards in place on nano-silver products despite heated controversy
As the controversy continued, the Korea Food and Drug Administration commissioned the Korea Conformity Laboratory to conduct animal tests on the toxicity of inhaled nano-silver particles. The tests showed that a white mouse that inhaled high density nano-silver particles for 90 days developed inflammatory cell tumors in the lung, while abnormal conditions were also spotted in its liver tissue as well. Commenting on these experiments, the manufacturers said, “There is no problem as long as nano-silver is used as a material for products, and is not directly inhaled”
Amid this situation, the academic community has yet to clarify its position on the harmfulness of nano-silver. Paradoxically, the reason for this problem is the “smallness” of nano technology, which is the very reason for the technology existence. Generally, nano particles measure one 1 billionths of a meter, and cannot be clearly checked for side-effects through conventional safety inspection methods. This is because there are not many cases of validation as to what impact such extremely tiny nano particles have on the environment.
Though nano products are already widespread in our daily lives despite such controversy, consumers remain anxious about their safety due to a lack of clear-cut safety standards.
Another problem is that there is no single government agency that is in charge of overseeing all nano-silver products because the products in the market are so diverse. It is difficult to impose unified regulations because different agencies oversee different products, with industrial products related with nano silver overseen by the Ministry of Knowledge Economy, and cosmetics and food managed by the Korea Food and Drug Administration.
Problem lies not in silver itself, but in size of particles
However, a Korean research team recently identified the fundamental reason that nano-silver products induce toxicity, drawing keen attention.
The research team, led by Prof. Chung Jin-ho at Seoul National University, discovered that the size of the particle, not the silver itself, can cause toxicity and trigger cardiovascular disease. The study was published in the early online edition of Nanotoxicology(July 6).
In an animal test, the research team found that the size of nano particles measuring 50 to 100nm increases calcium in platelet cells, and exposes specific phosphatides(PS) of the platelet membrane. This can prompt the condensation of platelets split off from the body, and ultimately induce cardiovascular disease.
The researchers said that if the shape of nano particles is changed or their size adjusted like micro silver, it can regulate calcium density within platelet cells, and suppress the ｅxpression of specific PSs. Prof. Chung said, “Studies on the safety of nano materials are a major issue that the academic community should address” In explaining the significance of his research, he added, “Through our study, we have laid the foundation to apply our findings in diverse ways in the development of nano materials that are harmless to the human body and safe to use”
Nano technology, a future growth engine, has become an indispensible technology for humans, as it is being extensively used in diverse areas that encompass the clothing, medicine, semiconductors, textile and aerospace sectors. Will the latest study present a blueprint in the quest to develop nano silver products that are harmless to the human body? It remains to be seen whether nano technology will overcome its side-effects and emerge as a true breakthrough of science and technology.
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저작권자 2010.08.09 ⓒ ScienceTimes
