Nanotechnologies and Food - Science and Technology Committee Contents

Examination of Witnesses (Questions 214 - 219)


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

  Q214  Chairman: Good morning. I would like to start by welcoming our four witnesses today, as well as the members of the public sitting behind; to remind you that the proceedings today are being webcast so the public can observe what is going on; and also to draw the attention of members of the public to the information note which sets out members' declared interests; so we will not be declaring interests as we go through the questioning. I would like to kick off by asking each of our four witnesses to introduce themselves for the record. If there are any points you would like to make in a brief opening statement please feel free to do so. Perhaps I could start with Dr Powell and then go along the row?

  Dr Powell: I am Jonathan Powell from the Medical Research Council Human Nutrition Research Unit based in Cambridge. My area of expertise is minerals, particularly nanominerals in the gut.

  Dr Chaudhry: I am Qasim Chaudhry. I work for the Food and Environment Research Agency of Defra. I am a research scientist and we have been working on the safety of nanoparticles through human health and the environment.

  Professor Donaldson: My name is Ken Donaldson. I am Professor of Respiratory Toxicology in the University of Edinburgh, and I specialise in the harmful effects of inhaled particles on the lungs and the cardiovascular system.

  Professor Depledge: I am Michael Depledge. I am Professor of Environment and Human Health at the Peninsula Medical School in south-west Britain. I am a member of the Royal Commission on Environmental Pollution. As you may be aware, the Royal Commission conducted a study on novel materials, and in particular nanomaterials, over the last two years and I have been deeply involved in that particular study. I am an ecotoxicologist and have worked on nanomaterials in lower animals.

  Q215  Chairman: Thank you very much indeed. Perhaps I could kick off with an opening question of a fairly general nature and any of you might wish to respond to this. As you will understand, part of the focus of our inquiry is about possible or potential health and safety concerns relating to the use of nanomaterials and nanotechnologies in the food sector. You are all experts in this area and I wonder if you would like to express to us what you think are the potential health and safety concerns, and what evidence is available to address those?

  Dr Powell: I think we know quite a lot about the uptake of particles in the gut, in terms of the route of entry; and we know a reasonable amount about the likely cellular targets. We know very, very little about what happens once those particles meet those cells. We would certainly consider persistence to be important, so that were you to ingest a particle that was broken down in the gut lumen prior to meeting its cellular target, it would in our eyes have a toxicology related to its chemistry, i.e. the components, rather than to its nanoparticulate sizing. We do believe that more work needs to be done in terms of both nanoparticles and the larger nanoparticles or microparticles, i.e. those larger than 100 nm in diameter, in terms of what happens inside the gut.

  Dr Chaudhry: In our view there are two fundamental concerns about the health and safety of nanomaterials, and both relate to oral intake of food products that contain free nanoparticles that are insoluble, indigestible and that can translocate from the gut in particulate form to other parts of the body. Essentially that category of particles is of most concern. The first concern is the ability to cross cellular barriers, and there is scientific evidence for that. Cellular barriers prevent entry of larger insoluble particulate material; but nanoparticles, because of their very small size, can override that principle and potentially reach new targets in the body, for example the brain. The second concern is the potential effects of nanoparticles, and that will depend on the chemical nature of nanoparticles, as Dr Powell mentioned. If the chemicals that constitute nanoparticles are toxic then it can be perceived that they deliver toxic chemicals to new targets in the body where those chemicals would otherwise have not gone, had they not been in nanoparticle form. The other concern is that many nanoparticles have a reactive surface and they can interfere with cellular processes, for example oxygen metabolism, and this can lead to the emission of oxyradicals. This has been shown in a number of studies. This can lead to inflammatory reactions and oxidative damage. There are other concerns: for example, some nanoparticles or nanodelivery systems can carry harmful substances out of the gut into the blood circulation from where they can lead to other parts of the body. Another concern is about antimicrobial effects of some metallic nanoparticles; when ingested they can have a harmful effect on gut natural microflora, which can ultimately harm consumers' health.

  Professor Donaldson: As a non-specialist in terms of the gut, my main concern is that there is so little research on what is happening with nanoparticles in the gut; whereas there are fairly huge amounts of research funding pouring into Europe and the USA into the lungs, the inhalation hazard, and to some extent the skin, although less so. The research into the gut is much, much less. I do not think you can generalise from the effects of particles in the lungs or on the skin to the effects on the gut. The gut is a wholly different environment to me to these other situations in terms of the extremity of the conditions, for instances of acidity in the stomach. My main concern would be the lack of research in the non-generalisability of existing research to the gut.

  Professor Depledge: Just to add I think it is worth emphasising the diversity of nanotechnologies and the diverse nature of nanomaterials. It is very difficult, I think, to make general statements about nanomaterials: some are very reactive; some are not; some are very persistent; some are not. I think we need to focus on that. The second point concerns nanomaterials in food, some of them are put there intentionally, and some are unintentional occupants of food, as it were. I certainly agree with the idea that the amount of evidence available with regard to the effects of nanomaterials, delivered through food or in food, is very, very small indeed and there is an urgent need to conduct many more studies. I also think that we ought to consider plausibility. We know that some of these nanomaterials are designed to be highly reactive. We know that some of them have very highly reactive surface properties; and there are little bits of evidence which show that they can convert chemicals from one form into another: so it may not be the nanomaterial itself that is toxic but the role it plays in converting substances that are non-toxic to be toxic. There is a lot of plausibility that needs investigating.

  Q216  Chairman: When you look at the current developments in the use of nanotechnologies and nanomaterials in food in the evidence that both MRC and CSL submitted, you referred to various examples. Do those examples themselves trigger concerns about the lack of knowledge of toxicological effects and risk?

  Dr Powell: The examples I think you are referring to are those such as nano-silver, nano-silica and nano-clays. I believe those do trigger concerns, in particular that, as has already been mentioned, when a substance is nanosized, in doing so its major cellular interaction and biochemistry may be driven by its nanoparticulate nature. If that becomes the major characteristic that drives its reactivity, then there is no doubt that some of those materials will have different properties compared with bulk materials—and I think of nano-silica in particular. The other point to make is that, as a nanoparticle in the gut, there is always the possibility of picking up local soluble molecules onto the surface, such as bacterial toxins, and that those then become delivered with almost a Trojan horse effect into cells of the gut; and of course, as has been explained by Dr Chaudhry, with the possibility of dissemination to other organs as well.

  Dr Chaudhry: I think the main point is that if nanomaterials are solubalised, digested or degraded within the gut then they are of least concern, because then their properties or effects will be dependent on what sort of chemical composition they had, i.e. what chemical constituted the nanoparticle. The main concern is on insoluble, indigestible, non-degradable nanoparticles than can survive mechanisms in the gut and can come out of the gut.

  Q217  Chairman: From the point of view of a toxicologist, I wonder if you might think that particular groups of consumers would be more at risk than others? If there were a risk would you think, for example, young children or elderly people would be more at risk? I think one of the points the MRC made in its evidence is that the way the body responds to free nanoparticles is an immunological response. I think that is what you said. Bearing that in mind, would you expect particular population subgroups to be more or less susceptible?

  Professor Depledge: I have certainly read one study—I say one because it emphasises the scarcity of information—which involved rats and looking at the uptake of iodine labelled polystyrene microspheres of more than 50 nm. They have demonstrated uptake of these microspheres. It was suggested in that particular study that people, or animals with inflammatory bowel disease of one form or another, would be at greater risk. I am not aware of any other evidence.

  Professor Donaldson: I think there is maybe one case where the lung data might come to hand here. Certainly in the human lung the adverse susceptibility to particles is greatly enhanced in those people who have inflammatory conditions of the lung, asthma and COPD especially. If you have inflammation already in your airways then the effect of the particles are worse. That is very strong data to support that. One would imagine that the gut would be exactly the same. The effect of particles in the gut may be much worse in someone who has got some inflammation in their gut.

  Dr Powell: I can add to that in two forms: firstly, that gut permeability is enhanced in the presence of certain disease, including chronic diarrhoea; and there is good evidence that small particles or large molecules will have enhanced permeability under these conditions. The second point to make is to pick up on Professor Donaldson's point, which is that we have looked in inflamed cells from patients with inflammatory bowel disease; we have challenged them with particles and we have shown that they will have enhanced pro-inflammatory effects; again, I stress this is ex vivo, and there is little or no data as far as I know in vivo.

  Dr Chaudhry: There is no evidence in scientific terms but nanoparticles may act as seeds for crystallisation of certain chemicals, but this has been shown in test tube experiments. Concerns have been raised that if nanoparticles get into, for example, the kidney and the kidney is inflamed, they might act as seeds for calcification there; but there is no scientific evidence for that.

  Q218  Lord Haskel: Could I just put the layman's question: if you do get some nanoparticles in your gut and they have the reaction you describe, what can you do about it? Is there an antidote, or something like that?

  Dr Chaudhry: I think, depending on the chemical nature of nanoparticles, they may not cause toxicity there and then. If they are excreted from the body, metabolised, broken down, that is another story because they will be eliminated from the body. The concern is if they become lodged into the cells and tissues and remain there and get accumulated over time and what sort of effects they may have. We are not talking about immediate effects; we are talking about medium to long-term effects.

  Professor Donaldson: Jonathan would know better than me, but if we go back to the situation where someone has an inflammatory bowel condition and he already takes some medication, they would take more of it more often, I would imagine; which is the case with asthma and air pollution; people use their asthma medication more when the air pollution is high. You would make the same argument, one would imagine.

  Professor Depledge: The point I would like to make is I think this demonstrates what I was saying earlier about plausibility. You can imagine scenarios of what might happen, but we are operating in an area of profound ignorance. Certainly we do not have a comprehensive understanding; I am not sure we have any real understanding of what would happen in those circumstances and whether you could pull nanomaterials out. It is actually extremely difficult to find the nanomaterials in the first place

  Q219  Earl of Selborne: I would like to ask our toxicologists today how they would define nanotechnologies and nanomaterials from a toxicological point of view?

  Professor Donaldson: There is an immediate problem there because the standard definition (which has been considered and thought about extensively by various nomenclature committees which Qasim has sat on) that a nanoparticle is a particle with one dimension at least less than 100 nm or 0.1 of a micron, there is no toxicological basis whatsoever for that. The idea that a 102 nm particle is safe and a 99 nm particle is not is just plain daft, it does not work that way. It is a sliding scale: we may talk later on about surface area, but as particles get smaller their surface area per unit mass increases; and it is surface area that interacts with biological systems. You can talk about smallness as well, but surface area matters a lot in terms of delivering harm.

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