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Meat and Fish

Animal physiology is very similar, not too rarely actually identical, to that of humans. So, when animals eat something containing solid, non-biodegradable particles, as already illustrated, part of them are captured by organs and tissues without any possibility to exit The inevitable consequence is that, when those animals become our food, they introduce those pollutants into our body.

Silver is used as a pesticide, and silver particles can be found on hay and other vegetables used as animal feed. Because of that, detecting them in meat is no surprise at all. But what may be somewhat more worrisome, other particulate matter can also be found in homogenised baby food (Fig. 5.5).

Baby food. As is the case with many other meat-based food products, baby homogenised food can also contain solid and inorganic particles

Figure 5.5 Baby food. As is the case with many other meat-based food products, baby homogenised food can also contain solid and inorganic particles. Their origin can be identified both in the raw material (i.e., in the meat and in the residues which the mincing process leaves). In the images shown, the presence of a cubic titanium particle is rather unusual, the sample we analysed being a product of an important brand, and it is clear that controls are not carried out even from official sources which should guarantee safety.

Mad cow brain. The analysis of different samples of mortadella, a very common sausage both in Italy and worldwide

Figure 5.6 Mad cow brain. The analysis of different samples of mortadella, a very common sausage both in Italy and worldwide (where in many circumstances is known under other names), showed how that meat contains steel microparticles.

Quite illegally, there are circumstances in which the flour or the animal meal with which cattle were fed was mixed with exhaust motor oils in order to form a blend and a bolus which could be swallowed without chocking. That oil contains particles coming either from its additives or from the friction between piston and cylinder. Therefore, those pollutants were thus introduced into the animal's organism, including the brain, where they caused serious disturbances to the nerve transmission which works on an electrical basis.

The micro- and nanoparticles in the photographs (Fig. 5.6) belong to the brain of a cow which was ill with bovine spongiform encephalopathy (BSE). The steel-based particles (iron-chromium-nickel) have as a probable origin the residues of the rubbing of mechanical parts of engines lubricated with the used oil which was then added to the feed. The other particles could come from both lubricant additives and from the corpses of other animals transformed into feed.

The reason of that presence is due to processing. To be finely chopped, meat should be frozen, and the processing is performed with blades which quickly lose their sharpness. This involves the loss of residues of the metal the blades are made of and metal particles enter the mixture of minced meat (Fig. 5.7).

Italian sausage

Figure 5.7 Italian sausage. The large particle was photographed in a sample of mortadella, the Italian sausage known abroad under different names. The presence of these metallic residues is due to the wear of the blades with which the frozen meat is minced.

Fish, too, are far from being exempt from particulate pollution.

Mercury is the most universally known among the poisons present infish, particularly big-sized predatory fish like tuna, and the so-called Minamata disease is a tragic example of what that metal, in that case as methylmercury released by a chemical factory, accumulated for decades in the fish and shellfish eaten by the local population. It must be remembered that pollution by particles is different from that caused by atoms or molecules, and when particles, molecules and atoms are present together, it is difficult or utterly impossible to predict the result in terms of toxicity (Fig. 5.8).

Anchovy sample. An increasing quantity of waste ends up in the sea, often coming from rivers and, therefore, from areas which can be geographically distant from the sea

Figure 5.8 Anchovy sample. An increasing quantity of waste ends up in the sea, often coming from rivers and, therefore, from areas which can be geographically distant from the sea. A part of this waste is in the form of micro-and nanoparticles which are excellent markers for pollution because they enter the fish tissue without undergoing transformations as it can happen for many organic substances. In this case, these are iron-based particles which, as evidenced by the spherical shape, come from combustion. The fish analysed was an anchovy.

Technically speaking, foraminifera are members of a phylum or class of amoeboid protists most of which are marine. One of their characteristics is the production of a shell (a ‘test’) in which they live made of calcium carbonate or agglutinated sediment particles. Like many other very simple beings, foraminifera can represent the base of the food chain (or, better, the food pyramid), and for that reason, they are particularly important, because, if the base is altered, the whole structure is affected in a negative way. When foraminifera live in polluted water, they are malformed with serious difficulties to reproduce. Incidentally, the carbon of the shell comes from the C02 dissolved in the water in equilibrium with that present in the atmosphere according to Henry’s law. Hence the function of air ‘scrubbers' of foraminifera (Fig. 5.9).

Healthy and contaminated foraminifera. (a) A healthy foraminifer, (b) a malformed foraminifer and (c) a polluting, spherical particle (white arrow) which is composed of sulphur and iron

Figure 5.9 Healthy and contaminated foraminifera. (a) A healthy foraminifer, (b) a malformed foraminifer and (c) a polluting, spherical particle (white arrow) which is composed of sulphur and iron.

Particles, especially secondary ones, are the carriers of a number of organic pollutants. Most of them are soluble in fats, and for that reason, they can be found in meat, milk and its derivatives, and eggs. It is important to note that many of those pollutants have a half-life of several years and, as a consequence, remain for a long time in the organism. As already mentioned, part of them, for example, dioxins, are eliminated more quickly by nursing mothers through the milk babies are fed with. Needless to say, the infant will necessarily be exposed to the toxicity of those substances.

Pollution from sparkling candles

Figure 5.10 Pollution from sparkling candles.

Sparklers are small fireworks emitting sparks, mounted on chopsticks which are used very often, especially by children, on the occasion of parties, and it is also customary to stick them on cakes. To obtain sparks, it is essential to include metals in the composition, each of which gives a different effect. The titanium which we detected in the spark fragments in the case we analysed serves to give the sparks a rich white colour (Fig. 5.10). As it is obvious, those very small metal fragments are inhaled and, if the sparkler is used on a cake, are ingested.

Decorating food, especially sweets, with coloured powders is a very common practice. The image is about a powder sold as gold, but in reality, there is no trace of that metal (Fig. 5.11). The particles, almost all of a rather coarse size, are made up of silicon, aluminium, titanium, potassium and iron. It can be assumed that most of these particles are eliminated in the faeces, but it is also necessary to consider how the gastrointestinal walls allow the passage to much larger particles than it is for those which pass through the respiratory system. It should also be added that it is not at all improbable that these indigestible particles, like titania shown in Fig. 5.12, exert an inflammatory action, thereby making the walls even more permeable.

Titanium dioxide (titania) nanoparticles to make white icing for cake design

Figure 5.12 Titanium dioxide (titania) nanoparticles to make white icing for cake design.

Engineered Particles in the Food

As already mentioned, nanoparticles behave in a way which is often different from that of the same material at the macroscale, and with increasing frequency, industry takes advantage of those characteristics. They are used as colouring (e.g. candy coating) and thickening agents in processed food (e.g. mayonnaise), and there are fruits, for example, bananas, which are coated with engineered nanoparticles to retard their spoilage. Nanoparticles are used to purify water (e.g. silver), as anti-caking, clarifiers and gelatinforming agents (e.g. alumino-silicates) and in packaging to protect food against UV light and prevent the growth of microbes or detect microbial contamination.

As to silver, nanoparticles are now widely used in domestic equipment to filter drinking water in order to avoid bacterial contamination, for packaging, in toothbrushes and in toothpaste, deodorants, medical bandage, etc.

They are also incorporated in polymer-based packaging from which they can be released into food in concentrations increasing according to storage duration. Silver nanoparticles with diameters of 22, 42, 71 and 323 nm were fed to mice at 1 mg/kg over a 14-day period. A size-dependent distribution pattern was found among different organs. The particles smaller than 100 nm were detected in the brain, liver, kidneys and testes, while the largest particles were not seen there. The amount of silver discovered in the brain, lungs and testes was roughly inverse to the particle size [3].

As to alumino-silicate clays, it is known for a long time that they can perturb normal nutrition via their sequestration of minerals and possibly other nutrients. The effect is beneficial to animals which occasionally ingest them to be able to gain nutritional benefit from food which contains toxins, but very little is known about chronic effects on the human organism.

Titanium dioxide is probably the material most nanoparticles added to food are made of, and it is hard to tell how much of it we ingest daily. Those particles are not soluble in water and have three natural forms: rutile, anatase and brookite. Rutile and anatase particles are used to produce pigment-grade material for the colouring of some foods and may be coated with various materials (aluminium, silicon or polymers) to enhance their technological properties. Those coatings are made because they modify the reactions between the surface of the titanium dioxide particles and the matrix where they are mixed, resulting in lower aggregation and a better dispersion possibility (Fig. 5.13).

Cluster of titania nanoparticles found in a stomach cancer patient

Figure 5.13 Cluster of titania nanoparticles found in a stomach cancer patient.

Nanoparticles are also used in food supplements as addition of iron and trace elements. Their bio-availability, however, is, to say the least, very doubtful. Bio-availability, defined here as the rate and extent to which a component of a food can be used by the organism, varies from individual to individual and, in the same subject, depends on his/her occasional state of health. In any case, many inorganic, insoluble particles cannot be degraded and stored or immediately made available to metabolism. So, the element listed in the label is actually there but, at least in some circumstances, is useless when not harmful at all.

Unfortunately, the current international rules do not distinguish clearly between particles and the same material in bulk. Therefore, when the quantitative limits for inorganic pollutants exist, they are considered on materials whose size and, consequently, whose behaviour is utterly different from its micro- and, more in particular, nanoform. Until this truism is entered in the concepts used by legislators, not only will the confusion remain, but we will be in a constant state of legally ignored risk. The immediate consequence is the use of nanoparticles in an increasing number of products, unfortunately including food.

The attitude of producers towards nanoparticles is rather contradictory, probably depending on the market approach which the manufacturer (or the distributor) intends to give to the product. There are instances where a content of nanoparticles is reported in the label and nanoparticles are actually there. In other circumstances, instead, no nano, though attested by the producer, but larger particles are present (it should be remembered that nanoparticles have a great tendency to agglomerate). Yet, in other cases, the chemistry declared is not the one detected by the analysis as is the case of gold or silver, declared by the manufacturer but in fact not always present. And, finally, there are nanoparticles which are actually contained in the product, but no notice is given. For some time, there are marketed products labelled as particle-free as a proof that people grow more and more suspicious towards nanoparticles and that neither lawmakers nor producers have managed to make the least clarity in this regard. As has often happened in other circumstances, even science looks uncertain, but it must be considered that the vast majority of what is done in terms of research is financially supported by industry. The consequences are the doubt and the actual possibility, as history teaches us, of biased results, great confusion in data interpretation and delays in official and universally accepted understanding of facts which, objectively, do not seem to leave room for conflicting interpretations.

Not only ingredients but also how food is prepared can be critical. Non-stick containers used to cook food are growing more and more popular. Their inside surface is coated with polytetrafluoroethylene, perfluorooctanoic acid or similar matrices. No matter what they are made of, in those matrices, mineral micro- and nanoparticles are often dispersed, giving an attractively shiny appearance to the pot or pan. All the containers we tested in our laboratory showed that those particles come off easily, going to pollute the food, even if the surface looks intact (Fig. 5.14).

Strictly speaking, chewing gum is not a food, but is often used the same way as a confectionery such as candies. In some types of those products, solid micro- and nanoparticles with an abrasive function are added. The chewing movement will partially clean the teeth from food debris, but many particles are ingested by swallowing saliva.

As previously mentioned, there are no reasonable laws, not to mention controls, ruling, even if only for the sake of prudence, the use and the presence of particles. As a matter of fact, in this way, manufacturers are free to act as they want, adding particles (be they micro or nano) either boasting their presence or being silent about it, while consumers remain without reliable information, withoutthe possibility to choose among a great variety of products and without protection.

Non-stick pan. The pan's fluoride-based non-stick layer matrix containing mineral micro- (aluminium silicate) and titania (titanium dioxide) nanoparticles

Figure 5.14 Non-stick pan. The pan's fluoride-based non-stick layer matrix containing mineral micro- (aluminium silicate) and titania (titanium dioxide) nanoparticles.

 
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