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Nano Toxicity Risk Merit Attention

Written By krishna on Saturday, August 27, 2011 | 11:54 PM

Developing countries overlook the potential risks of nanoparticles and structures like carbon nanotubes

Developing countries forging ahead with nanotechnology need regulation and research into local risk patterns, say Alok Dhawan and Vyom Sharma.

Nanotechnology, the science of manipulating tiny particles less than 100 nanometers in diameter, has found many applications in consumer products, biomedical devices, drug delivery agents and the industrial sector.

In the consumer sector alone, more than 30 countries are manufacturing some 1,300 nanotech-based products, including textiles, food packaging, cosmetics, luggage, children's toys, floor cleaners and wound dressings. The number of such products has increased five-fold in the last five years.

But this rapid growth has also raised concerns about the potential for adverse effects on human health and the environment. Although research on harm remains inconclusive, developing countries that embrace nanotechnology should not overlook possible risks and must regulate products that contain nanoparticles.

Special properties, possible harm

Their small size gives nanoparticles some unusual physical properties, as they have a larger ratio of surface area to volume than bigger particles. This can also make them biologically more active. For example, when gold, usually an inert material, is converted to a nano-form, it acts as a catalyst for chemical reactions owing to high surface reactivity.

This suggests that nanoparticles may interact differently with biological systems, compared with larger particles, and could reach further into the body.

People can be exposed to nanoparticles either directly, such as through nano-based drugs and topically applied cosmetics or sunscreens, or indirectly, for example by inhalation during synthesis of nanoparticles.

A number of studies have documented in vitro and in vivo toxicity of exposure to nanoparticles. Evidence suggests they can induce DNA damage, reactive oxygen species, damage to cellular organelles and cell death.

And a study published in the European Respiratory Journal in 2009 claimed that seven Chinese workers developed severe lung damage after inhaling polyacrylate nanoparticles produced in their printing factory — the first time that a link was made between exposure to nanoparticles and human illness. [1]
Risk on the agenda…

There is currently no mandatory consumer labelling of nanomaterials as potentially hazardous in any country. But governments and scientific bodies in the developed world — including the Royal Society, United Kingdom, and the US Environmental Protection Agency (EPA) — are taking note of the potential hazards and have set up committees to formulate risk assessment guidelines.

For example, under existing regulations, the EPA is proposing rules requiring those that manufacture, import or process two chemical substances — multi-walled and single-walled carbon nanotubes — to submit a notice with information that would help it monitor health or environmental risks.

Similarly, washing machines using silver nanoparticles at the end of the wash cycle are being evaluated by the US government for their environmental safety. In 2005, concerns about toxic effects on microbe populations prompted the temporary withdrawal of a washing machine using silver nanoparticles in Sweden.

The US EPA has already decided to regulate products containing silver nanoparticles, which are used widely in consumer products and have anti-bacterial properties.
…while developing countries lack guidance

But developing countries still lack awareness of the potential hazards of nano-based consumer products, and only a few guidance documents are available in the public domain.

A company in India already claims to be the world's largest manufacturer of nanotech-based fabrics. Many other companies that synthesise nanoparticles — for use in cosmetics, for example, or water filtration devices — are emerging in countries such as China and India.

Framing regulations and guidelines for the synthesis, use and disposal of nanomaterials is of great importance for the responsible development of nanotechnology in developing nations. International organisations and developed nations can assist them by sharing scientific data and technologies for assessing environmental and health safety.

And to control occupational exposures, the regulatory framework should include mandatory documentation of the nanomaterials developed and personnel involved, and training workers to take precautions.

Our institute, the Indian Institute of Toxicology Research, Lucknow, has recently published guidance on the safe handling of nanomaterials in research laboratories, a step in the right direction. [2]
Implications, not just applications

But the vast majority of government funding in developing nations is spent on research into the applications, rather than the implications, of nanotechnology.
For example, out of more than 200 research projects funded during 2001–10 by the Department of Science and Technology in India under its flagship Nano Mission programme, only one was directly related to nanoparticle toxicity studies (and was awarded to our institute).

As a result, scientists may fail to identify any impacts of nanotechnology that are specific to populations or the use of a product in poor countries — patterns of environmental distribution and exposure could be different in developing nations.
Current research on nanotoxicity does not take into account how different local environments and populations can influence risk. People in developing countries may be more prone to adverse effects of nanoparticles because of underlying health conditions and malnutrition. Moreover, genetic susceptibility to toxic effects varies in diverse ethnic groups and geographical areas.

The scientific community needs to identify these information gaps before developing regulations and standard methodologies for nanotoxicity assessment.
Alok Dhawan is principal scientist and Vyom Sharma is a senior research fellow at the Nanomaterial Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow, India.

[1] Song, Y. et al. Exposure to nanoparticles is related to pleural effusion, pulmonary fibrosis and granuloma. European Respiratory Journal 34, 559–567 (2009)
[2] Dhawan, A. et al. Guidance for safe handling of nanomaterials.Journal of Biomedical Nanotechnology 7, 218–224 (2011)

Alok Dhawan and Vyom Sharma

25 August 2011

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