Does Nanotechnology Pose a Threat to Our Health?
When you hear the term “Nanotechnology” a vast number of images such as tiny submarines in blood streams seeking out cancer cells and lightweight materials ten times as strong as steel come to mind, but the most recent advances in the field are much more subdued. Most of the nanotechnology being created in labs around the world are nothing more than tiny particles of simple elements such as copper or gold, the only difference between these nanoparticles and their more common counterparts is theirs size.
Nanoparticles vary in size from 1-2500 nanometers; on the smaller end of this spectrum are the “superfine” nanoparticles with a particle size of 100 nanometers or less. Little is known about how organisms will react when exposed to these particles, some of which could potentially be harmful. We have seen many examples throughout history of manmade or mass produced chemicals having an adverse effect on the environment through bioaccumulation and amplification; the build-up of a substance through the food web. Large harmful amounts of chemical end up in the systems of higher carnivores, our main food sources. The best example of this is the contamination of our waters from mercury, a poisonous metal which has bioaccumulated in large game fish such as salmon and tuna. Could potentially harmful nanoparticles be headed on the same path? Recently a study done by University of Kentucky’s department of plant and soil sciences has attempted test that theory. The team of researchers at the Tracy Farmer Institute for Sustainability and the Environment attempted in the first study of its kind, to trace and map the bioaccumulation of nanoparticles ranging from 20 nm to 55 nm in the common earthworm.
Because of waste management practices in many countries including Canada, the United States and the United Kingdom it is thought that nanoparticles from products are entering ecosystems in much higher concentrations than are naturally present. Earthworms provide the perfect test subjects for bioaccumulation of these particles as they are detritivores, one of the first organisms in the food web to come in contact with nanoparticles from waste water and sewage sludge. In the experiment, gold nanoparticles were synthesized in the lab and added to soil samples containing earthworms, at different concentrations. After the duration of the experiment the worms were then frozen and put through various tests including x-ray microspectoscopy. The team found that the worms exposed to higher concentrations of gold nanoparticle had a much higher level of bioaccumulation in the tissue surrounding the digestive tract. What didn’t seem to have any effect on uptake was particle size; worms had a slightly higher level of bioaccumulation of 50 nm than the 20 nm particles. Various other tests done on mice exposed to nanoparticles showed as well that particle size had no significance.
One might think the presence of gold nanoparticles in food sources is not much to be concerned about as gold is a relatively stable element and is very nonreactive, thus not posing an immediate threat to human health and the environment. But because of their size, nanoparticles seem to have many different effects than their larger counterparts, studies have shown that at different sizes and structures nanoparticles can become catalysts for all sorts of reactions even when on a larger scale these reactions would never take place. As well as catalyzing reactions nanoparticle have similar size and shape to some important biomolecules, this is why nanoparticle research for medical advancement is being done, as nanoparticles could target specific cells or bacteria. This may seem like good news but at the same time particles that escape into ecosystems and bioaccumulation could have many adverse biochemical interactions. The research done by the Tracy Farmer Institute shows nanoparticles can and do bioaccumulate in organisms and underlines the importance to proceed with caution as we develop new untested technologies meant to help us that could ultimately do the opposite.
Primary Article: http://pubs.acs.org/doi/full/10.1021/es101885w