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OCR GCSE Chemistry A · J248
OCR J248 · C2.3j Check the specification (PDF) (opens in a new tab)
Nanoparticles are extremely small particles, about 1–100 nanometres across. Their small size gives them a large surface area compared with their volume. This can make a nanoparticulate material behave differently from a lump of the same substance. A useful property can therefore bring a possible risk too: a nanoparticle may interact with its surroundings in ways that larger particles do not.
There is concern that some nanoparticles could be breathed in or could pass into cells. If they reach parts of the body where they can interact with living tissue, they might cause damage. Their large exposed surface can also make some nanoparticulate materials effective catalysts. Inside the body, such particles might catalyse unwanted reactions that produce harmful substances. These are possible mechanisms of harm, not claims that all nanoparticles do this.
Nanoparticles may also leave a product and enter the environment. For example, particles in sun cream could wash off the skin. Whether this causes harm depends on the material, how much is released and what it encounters.
Nanoparticulate titanium dioxide is used in sun cream because it blocks ultraviolet light while appearing colourless on skin. That benefit does not remove the need to consider possible exposure and harm. Modern nanoparticulate materials have not been used for very long, so some long-term risks are difficult to determine. Scientists must investigate particular materials and uses rather than assume that all nanoparticles are either safe or dangerous.
Some nanoparticles may be inhaled or enter cells. Their large surface area may allow unwanted reactions; particles released from products may also affect the environment.
These are possible effects, not properties of every nanoparticle. Consider the material and route of exposure alongside its benefits. Long-term risks can be difficult to establish because many modern nanoparticulate materials have not been used for long.
Use cautious language: a possible risk is not proof that every nanoparticle is harmful.
Link each risk to a reason, such as small particles being inhaled or entering cells, or their large surface area allowing unwanted reactions.
Distinguish a material’s useful property from a possible unwanted effect when weighing benefits against risks.
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Nanoparticle
A particle with a dimension of about 1–100 nanometres; one nanometre is one billionth of a metre.
Surface area to volume ratio
The amount of a particle’s exposed surface compared with the space it occupies.
Risk
The possibility of harm, taking account of both what a material might do and whether people or the environment are exposed to it.
Put your knowledge into practice — try past paper questions for Chemistry A
Nanoparticle
A particle with a dimension of about 1–100 nanometres; one nanometre is one billionth of a metre.
Surface area to volume ratio
The amount of a particle’s exposed surface compared with the space it occupies.
Risk
The possibility of harm, taking account of both what a material might do and whether people or the environment are exposed to it.