Nanotechnologies and Food - Science and Technology Committee Contents

Examination of Witnesses (Questions 240 - 259)


Professor Ken Donaldson, Dr Qasim Chaudhry, Dr Jonathan Powell and Professor Michael Depledge

  Q240  Chairman: Just to be clear about the last point you made—many things that we inhale end up being swallowed in the end?

  Professor Donaldson: Absolutely, almost all of what we inhale, otherwise our lungs would be bunged up by now—after 60 years or so in my case—so it is cleared upwards all the time; and you swallow mucus containing particles all the time.

  Q241  Chairman: Regardless of what we ingest in food, we are ingesting a lot of material that is just floating around in the air around us, including soot?

  Professor Donaldson: Yes.

  Professor Depledge: I just wanted to return to the issue. You were saying about the intricacy of the debate that we were getting into, but I think if you want to think about really big problems that we face, ultimately if we want to devise toxicity tests for nanomaterials in foods, then I think we should think about the practicality of doing that because there are likely to be a myriad of different forms of nanomaterials in foods; some of which we put in deliberately; others which get there for reasons of environmental contamination and access to food. If you think about evaluating the toxicity of these various forms of nanomaterial and nanotubes, it would take years and years and years to get through the list. In terms of protecting the public, what happens in the meantime?

  Dr Chaudhry: I just want to add, in this whole scenario an independent industry body is missing which can look at the whole scenario of publications. Not every application of science here is going to give us any major concerns or any hazards or any risks. The body needs to separate those applications that have no or low risk, and those applications can go ahead: but because of the nanotechnology label everything seems to be static. For example, we know from our own experiments that nanoparticles hardly ever move from packaging material into food; so that application, as far as tests show, may not cause any risk to the consumer and can go ahead: but because of the nanotechnology label, companies are afraid of declaring that it is nanotechnology-derived. Even if we do not know about hazards or exposure or many other uncertainties, we can divide applications on the basis of whether nanoparticles are free, whether they are soluble, digestible or insoluble; and we can form those categories very quickly on a hypothetical basis, whether an area of application is going to be in the high risk category or in the low risk category. We have attempted that and I have a handout if you would like to look at that.

  Chairman: Perhaps you could leave that with the Committee clerk afterwards. I would like to move on now to Baroness Neuberger.

  Q242  Baroness Neuberger: We have been talking about persistence. I would really like to ask you what the state of knowledge is regarding the actual accumulation of nanoparticles in the body once we know we have been ingesting them? How do they accumulate? How many of them do we not get rid of which you have been talking about earlier?

  Dr Powell: The work we have done is purely around the gut and, again, around these larger nanoparticles, so generally upwards of 100 nm but not solely. We have shown that certain areas of the gut, the lymphoid tissue, does with increasing age accumulate these particles. Presumably they only represent a very small percentage of what has been taken up, so there probably is a clearance mechanism; but quite clearly accumulation does occur. As I also mentioned, we have been unable in any way to link that accumulation to any type of disease, disorder or impact upon health. We have not in our work looked beyond the gut in terms of accumulation, but I know others have and it may be some other members of the panel are better to answer that.

  Professor Donaldson: There is a body of work that has been done on model nanoparticles starting from various portals of entry: inhalation and injection into the blood predominantly; not much through the skin because they do not seem to pass very readily through the skin; and virtually nothing through the gut at the moment has been published at least. If you inhale nanoparticles they find their way to the blood. Something like a per cent or so of all the material that deposits in the lung will get into the blood—let us say a per cent—and that circulates round the body and accumulates in various organs at low levels. The liver is a good place for particles to stop in. The liver monitors the blood and it has cells that grab things in the blood and it grabs particles, so they are focussed in the liver. Nobody really knows what happens to them in the liver. Do they just remain there? If someone was to get a chronic exposure through food or a particle that did get into the blood, what would be the consequence of a lifetime's accumulation of such particles in the liver? Nobody knows that. There have been no long-term studies done to know the outcome of that. There is also evidence that they get into the brain at a low level from the blood as well, and into the bone marrow and some other organs. Again, it is hard to imagine what the clearance system would be from the brain but it is not like the lungs which have a clearance system; so it comes back to this issue that Professor Depledge has mentioned about the fact that there are unintended consequences when particles get to places where particles should not get because there is no system there to clear them.

  Q243  Baroness Neuberger: That actually comes back to Lord May's point, does it not? If you started explaining that and said what was not known, people might have quite good reason to get concerned; and we do not, from what you are saying, have a very adequate answer for them; we just do not know?

  Professor Donaldson: No, we do not know.

  Q244  Baroness Neuberger: Can I just add one other thing: we know that nanotechnology is used to encapsulate substances to make them more easily absorbed to target specific cells, organs or whatever. Do we think there may be some particular risks associated with that, so that you get exposure to certain substances from that kind of technology to too great an extent; or that they get through to some part of the body they would not normally go to; so either your liver or your brain?

  Professor Donaldson: Through medical uses.

  Q245  Baroness Neuberger: Yes, medical uses, with drugs, for instance.

  Professor Donaldson: That is very interesting and concerning to a particle toxicologist. For example, one of the widest uses of nanoparticles is to image the plaques, the coronary artery plaques that cause most people's deaths—most deaths are from cardiovascular diseases when this plaque, this lesion in the blood vessels near the heart, ruptures. To know when a plaque would rupture—it is called a "vulnerable plaque"—cardiologists would really like to know what a vulnerable plaque is. If you inject these iron nanoparticles into the blood, which are now licensed to be used and are used by cardiologists, they seem to localise to these plaques and you find them in the plaques if you section the plaques. The cardiologists can image these plaques using that methodology, and that is one reason they are used. That seems to me to be a really risky thing to do. One of the most powerful signals in the air pollution literature is that exposure to particles in the environment causes these plaques to rupture. It seems to me you are inviting disaster. It seems to be being used, and maybe it is a baseless concern, but to me it seems a considerable worry.

  Q246  Baroness Neuberger: It is only being used diagnostically. It is not being used for any form of treatment, is it?

  Professor Donaldson: No, it is not.

  Q247  Baroness Neuberger: Purely diagnostic?

  Professor Donaldson: There is also an idea that such particles can be used to deliver drugs to the plaques and to other places in the body. There seems to be considerable potential for the accumulation over time if the therapy went on and on. Clearly imaging only happens maybe once or twice; but for therapy you would give protracted treatment so you might get a long-term accumulation of nanoparticles in places and, as we have already said, you do not know what these places are, or the extent.

  Q248  Baroness Neuberger: The last thing I would really like to ask you, maybe you have already given us some of the answer: is there research being done into any of this, about what the short or the long-term effects will be?

  Professor Donaldson: The long-term I do not know. In Edinburgh we are doing some studies and the Department of Health has funded a student in our department to look at these superfine paramagnetic iron particles—to look at the effect that these might have. We have a mouse model that develops plaques and we are going to put these into the mouse model and see if they go to the plaques and if they cause the plaques to grow and become more likely to rupture and more vulnerable. I imagine there is other research as well but I do not know what that is.

  Dr Powell: We are undertaking research at MRC Human Nutrition Research both in terms of short-term effects of very small mineral nanoparticles; these are iron oxide and other oxide nanoparticles in gut cells; and we are also, however—and have been for a long time—undertaking long-term studies in terms of the effects of larger nanoparticles on the human gut tissue. That research is time-consuming. It takes a very long time to get the data but we have made good progress and I hope that within a year or so we will start to see the fruits of that labour. There is work going on but it is quite tricky work.

  Q249  Baroness Neuberger: Do you know of other institutions that are doing it?

  Dr Powell: Yes, we have now hooked up with two institutions in Germany who have both just started to work on the gut; but prior to that we knew of no other group, certainly within Europe, who was working on large or small nanoparticles and the gut; but we have just started to work with two in Germany, as I have mentioned.

  Q250  Lord Methuen: Do nanotubes feature at all in this discussion? I understand they are being used for some purposes; but are they relevant and might they come into this argument?

  Professor Donaldson: I do not think they are used in food.

  Dr Chaudhry: Their properties are such that they are no use in food. Their features are that they give huge tensile strength to whatever material they are put in; and also they are electrically conductive. These two features have nothing to do with food. They may find some use in food packaging but not in food per se.

  Q251  Lord Methuen: Do they form a risk if they are in packaging?

  Dr Chaudhry: If they are in the environment and they get into food as a contaminant or into the environment as a contaminant, yes, certainly. I think Professor Donaldson is best placed to answer that.

  Professor Donaldson: Even when you burn gas rings you make nanotubes—not very many, but it is surprising what has been found in the air when you burn gas rings. Most forms of combustion—even probably coal burning and wood burning—produces some degree of nanotubes, so it is not a new exposure. The workplace exposure to mg and µg/m3 of the stuff is probably fairly new. The concern has been that it has a particle hazard; it could be a harmful particle; but also they are long and thin like asbestos so they could behave like asbestos. There are two kinds of hazard associated with these materials. The question is: are people generally exposed to the particles, or to the long thin ones; because the dangers are different and the hazards are different for the two. Really it is a case where we need more exposure data. We really do not know what people are being exposed to in workplaces with this material. Certainly it has now increased to be one of the major products of the nanotechnology industry so it is being handled in tens of hundreds of tonnes in workplaces.

  Q252  Lord Haskel: Is there anything that we could learn from ecotoxicology about the dangers or the potential risks to humans of ingesting nanoparticles?

  Professor Depledge: I think we can look at this in a number of ways. First of all, I think the potential use of animal models is very valuable. There has been work done with lower organisms, which are easier to deal with in experimental situations. Of course some of the conditions in the guts of lower organisms are somewhat similar to those that are in humans, so there is a model organism kind of approach. There is a great deal to be learnt there. I think it is very important to understand what routes of contamination are possible for our food items. For example, if you like eating snails or if you like eating shellfish, some of which are filter feeding organisms, they are exactly the kind of organisms which are likely to take up nanomaterials from sediment or from water bodies, and they filter vast amounts of water and so may accumulate nanoparticles. Looking at contamination of food by nanomaterials involves ecotoxicological approaches to see which organisms are mostly likely to do that. Then there is the issue of food chain transfer. If you happen to be a top predator that eats lots and lots of shellfish, do the nanomaterials accumulate in fish and so on? I think those are very important points. The other thing I would mention is that, earlier this year, I attended a meeting in the USA at Rice University where they have a major centre for nanotechnology. The discussion there turned to the use of nanomaterials in agriculture. This was voiced by the experts attending that meeting as one of their greatest concerns. There may be ways of delivering pesticides attached to nanoparticles, or phosphates and nitrates and other fertilisers and so on, and also maybe agriceuticals and pharmaceuticals that are given to domesticated animals, cows, sheep and so on; and we have no idea, to my knowledge at least, of how these materials might get into the food products that we eat. I think there is some evidence from the literature that if you expose fungi to nanomaterials, they will take up certain kinds of nanomaterials. You can see the uptake of nanomaterials in the roots of plants. You can actually get nanomaterials into plants by spraying them on the leaves. Then of course the organisms eating those plants and fungi are likely to be subjected to those nanomaterials as contaminants. There is plausibility of uptake by those routes but actual evidence of uptake into humans and where it ends up in humans I think is absent at the moment, or I am not aware of it anyway.

  Q253  Lord Haskel: People have been eating snails for years, they have been eating shellfish for years, they have been using agricultural chemicals for years. If we have been ingesting nanoparticles from that source, we have been doing for hundreds or thousands of years. Can we take any comfort from that?

  Professor Depledge: I do not think so and the reason I do not think so is because you are quite right, we have been taking up nanoparticles by that route but we have not been taking up engineered nanoparticles by that route for long. Particular types of nanomaterials are engineered to do specific things. If something like nanomedicines were to become widely used in the future—and we have heard about nanoimaging materials and so on—one should be aware that these materials do end up in the environment, just as the pharmaceuticals that we use in our daily lives: antibiotics, analgesics and even cancer chemotherapy agents can be detected in British rivers having passed through sewage works and so on. If we ended up with that kind of issue with nanomedicines being delivered into rivers or being deposited in sewage sludge on fields, with the potential uptake into plants, again the plausibility of getting our nanomaterials excreted back again should be investigated, in my view.

  Q254  Lord Haskel: Is there any work going on to investigate this?

  Professor Depledge: Not to my knowledge at the moment, other than studies in the laboratory where a variety of fungi, plants, animals, bacteria are being exposed in laboratory tests in a very limited range of nanomaterials.

  Q255  Chairman: Could I just clarify in my own mind your comment about a possible accumulation in the food chain, rather like the story with DDT where it was concentrated in the top predators and that, in a sense, was the danger signal—the canary in the coal mine that warned us of the risk. Have there been studies of accumulation in higher predators in the food chain that perhaps consume molluscs or other invertebrates that may be the primary filter and absorbers?

  Professor Depledge: Not to my knowledge and at the meeting that I attended in the US where many of the experts were gathered together nobody mentioned that as an issue.

  Q256  Lord Methuen: What research has taken place into the health and safety risks associated with nanomaterials, and how much in the UK and how much worldwide?

  Professor Donaldson: There is a lot now. It is safe to say, though, that that is focused fairly much on the lungs and inhalation exposure. As I said, perhaps 10 or 20:1 against the skin and hardly at all for the gut. So in the UK there is funding from all the major research councils now, MRC, NERC and the EPSRC I think as well. The European Union FP7 has funded large studies, several of which I have been involved in. In the USA the Nanotechnology Programme is huge in NIOSH and in EPA. In Japan and Korea again they all have big programmes. There is a huge amount of ongoing research but it is focused very much on environmental exposures to the lung and I think increasingly in ecotoxicology.

  Q257  Lord Methuen: Are you worried about the lack of attention to what happens with food in the gut?

  Dr Chaudhry: There is one project call that has come out from the Food Standards Agency recently, which is very topical, which aims to study toxicokinetics; i.e. how these nanoparticles move out of the gut, where they go and what sort of toxic effects they have, but that project is still to be started and done. The funding call has just been announced.

  Q258  Lord Methuen: We have already talked about the range of these particles and how you know which ones to concentrate on. Is that not the real problem?

  Professor Depledge: I agree with you; I think it is a real problem. Currently there are in a broad sense something like 600 or 700 products on the market that contain nanomaterials, according to the Woodrow Wilson Center in the US, and they have been through standard toxicity testing, and we have some doubts about how well it works. I think there is a general consensus that conventional toxicity testing is not very useful, and so the OECD has set up a programme to develop new toxicity tests specifically designed to evaluate nanomaterials. They have chosen 14 model substances that are being investigated, two per country, and I think some of these model materials have not actually been taken up by anybody yet, but they are trying to develop full characterisation of these particles and also develop toxicity tests. To my mind, that will be of value but of limited value in the sense that we do not know that we are looking at the right kinds of nanomaterials and whether you can actually use 14 different representative nanomaterials from the myriad of different forms that have been produced I have some doubt.

  Lord Methuen: I find it quite frightening.

  Q259  Lord May of Oxford: I wanted to ask: is this general area of research one at which the UK is as well represented among the leaders as it is in many things? I have in mind the fact that if you look, for example, at some of the eastern European or the EU accession countries, they are very good at the physical sciences but not quite so at the cutting edge in life science because the mechanisms are less agile than those that have characterised the Scandinavian, Anglo and other countries? Some of the things that have happened in some of the research councils that are deliberately trying to identify applications and so on, I just wonder whether you feel these things are helping or hindering and just more generally what is the state of British facility in this area on the world stage?

  Professor Donaldson: If you take human toxicology, the UK has always punched above its weight in terms of particle toxicology historically because there was such a focus in the UK in the dusty industries and dusty trades. For instance, the Coal Board is the seat of particle toxicology in the UK and it was in Wales and it was in Edinburgh. That is why I am in Edinburgh because I went to work for the Coal Board first of all. I think the Coal Board was very important in driving forward in the UK particle toxicology and it took over the Asbestosis Research Council. That is not to say that there was not also a recognition of a particle toxicology problem in the US or in other places; there certainly was in Germany for instance a very famous history of particle toxicology. We have punched above our weight but there was not very much funding in the UK until relatively recently. We have kind of caught up but we were slow to get off the mark compared to America, definitely.

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