Part 7. Problems, issues (including hazards) and implications associated with using nanomaterials

Doc Brown's Chemistry Revision Notes  NANOCHEMISTRY

Nanoscience - Nanotechnology - Nanostructures

Alphabetical keyword index for the nanoscience pages : Index of nanoscience pages : boron nitride * Buckminsterfullerenes-bucky balls * carbon nanotubes * fat nanoparticles * fluorographene * fullerenes * graphene * health and safety issues * liposomes * nanochemistry * nanomaterials * nanoparticles * nanoscale * nanoscience * nanosize-nanosized-particles * nanostructures * nanotechnology * nanotubes * problems in nanomaterial use * silver nanoparticles * safety issues * sunscreens-sunblockers * titanium dioxide

See also A general survey of materials - natural & synthetic, their properties & uses

Part 7. Problems, issues & implications associated with using nanomaterials

• There is no doubt that nanochemistry is providing materials scientists and chemists with incredibly useful atomic and molecular structures with a wide range of ingenious applications.

  • However, like all new discoveries and their applications to the world of science and technology, their very novel nature of these new materials raises various issues and examples are discussed below, but not in any particular order.

  • Potential hazard issues include cell damage in the body and unintended pollution-catalytic effects in the environment.

  • The effect of nanoparticles on the body is difficult to predict and not easily understood and the long-terms effects on our health and well-being are quite unknown.

    • Therefore any new nanomaterial must be carefully tested to ensure it is safe to use and minimise the risks.

    • Therefore, should it not be the duty of manufacturers to indicate on the label any product containing nanoparticles? This allows consumer choice.

    • There is some concern the products containing nanoparticles are being used in commercial products before being thoroughly tested for health and safety issues.

    • Neither do we know what the long-term effects might be.

    • Will nanoparticles be blown or washed away into the environment? What might this affect?

• Since the properties of nanoparticles are not as well known or as easily predicted there are worries that nanoparticles may have
  undiscovered harmful side-effects if e.g. they breathed in or orally ingested, so there way well be health and safety issues which are not yet fully understood and how thoroughly are these new materials tested for unwanted side effects.

  • Nanoparticles are small enough to be absorbed by the skin so could cause irritation.

• Nanoparticles have a very large surface area compared to their volume, so they are often able to react very quickly e.g. silver nanoparticles. This makes them useful as catalysts to speed up reactions BUT ...

  • However, there is also the possibility that they might speed up reactions in living things in unpredictable ways, perhaps causing illness or death.

  • Silver particles kill bacteria, but they may kill 'good' non-bacterial cells or 'good' bacteria if silver nanoparticles are inhaled or ingested.

  • Breathing in ANY fine or tiny solid particles can cause irritation in the lungs and potentially cause lung damage and cancer e.g. coal miners, quarry workers etc. can all get diseases like silicosis, emphysema, cancer from breathing in fine dust particles.

  • How safe are the new sunscreens that contain nanoparticles?

  • Can the nanoparticles be absorbed by the body i.e. through the skin and cause irritation or other effects on cells?

  • We don't really know yet whether nanoparticles can cause cell damage in or on your body?

  • Can nanoparticles washed away with commercial products like suncreams cause any environmental damage and get into food chains?

  • Nanoparticles of silver can be used in deodorants, but can they do us harm if we breathe them in?

• Nanoparticles readily re-aggregate i.e. club together, so chemical/physical systems must be devised to keep them apart to retain their nanoscale properties.

• Nanomaterials are more costly to produce compared to more traditional materials but as their variety of applications and wider use increases, greater quantities are produced, and, according to normal economic principles, their unit cost of production should decrease, hence their price decreases.

• So there are genuine risks and uncertainties in using the 'fruits' of nanotechnologies which are usually presented in a positive way in the media because of their exciting potential and novel applications.

  • Therefore all the benefits, risks and drawbacks of new developments in material science such as carbon nanotubes should be carefully evaluated.

  • There are genuine health concerns and toxicity regulations are difficult apply as the properties of nanomaterials depend on the size of particles.

  • In truth, there must be unknown health effects because ALL new materials have NEW health risks.

  • There is concern that the human immune system may be defenceless against particles on the nanoscale.

  • This poses responsibilities for the nanotechnology industries, which in turn, raise political issues e.g. the for informed public education and debate and for the public to be involved in policy discussions  (I see absolutely no evidence of this at all in 2011 in the UK).

  • Who should decide whether particular directions in research are pursued and associated research funding priorities.

Some problems associated with agriculture

• Chemicals in the form of tiny nanoparticles have been shown to spread throughout a crop plant and affect growth and soil fertility.

• The agricultural use of  nanoparticles is increasing in agriculture but their environmental impact is not well understood and the effects are not just from the use of nanoparticles in agrichemicals, but from other environmental sources too.

• Nanoparticles present in exhaust gases from motor vehicles and some fertilisers have been shown to affect soybean growth and the health of soil the crops are grown in. Soybean is a crop of huge commercial importance and is the world's 5th largest crop and is the largest source of natural edible oil and plant protein.

  • Bacteria in the roots of soybean (a legume) help the absorption and production of essential nutrients.

    • Legume plants have roots that can nitrogen 'fixing' bacteria

  • Zinc oxide and cerium oxide nanoparticles have been shown to affect soybean plant growth, though the effect is small in the presence of low levels of these nanoparticles.

    • Cerium oxide has been shown to completely inhibit the plants ability to fix nitrogen in the roots.

    • Zinc oxide nanoparticles are toxic to mammalian cells grown under laboratory conditions but their effects on passing through food chains is unknown.

  • Zinc and cerium compounds can build up in the plants with potentially damaging effects.

  • Zinc oxide is a common component in the cosmetics industry and ends up as a contaminant in the solid waste from sewage treatment and this product is used as an organic fertiliser.

  • Cerium oxide is used in some diesel fuels to improve combustion efficiency and reduce carbon/hydrocarbon particulate emissions.

• The nanoparticles have been shown to harm bacteria important for plant growth, though their effects are relatively small, how the plant is affected is not fully understood.

• In the agricultural science community there is concern that widespread long-term use of nanoparticle may spread into the environment with unforeseen effects on plants and animals (including implications for the health of humans too!)

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These revision notes on problems and hazards associated with the use of nanoparticles should prove useful for the new AQA, Edexcel and OCR GCSE (9–1) chemistry science courses.

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