Watson Food Chemical Safety

Volume 1: Contaminants
1. Auflage 2001
ISBN: 978-1-85573-632-0
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 336 Seiten

Reihe: Woodhead Publishing Series in Food Science, Technology and Nutrition

Chemical contaminants in food, from pesticides and veterinary drug residues to contamination from food packaging, are a major concern for the food industry. Written by a distinguished international team of contributors, this authoritative collection describes the main chemical contaminants, their health implications, how they contaminate food products, methods of detection and how such contaminants can be controlled. - Describes the main chemical contaminants of food, their health implications, how they contaminate food products, methods of detection and how such contaminants can be controlled

Autoren/Hrsg.

Watson, David

Inhaltsverzeichnis

1;Front Cover
;1
2;Contaminants;4
3;Copyright Page
;5
4;Table of Contents;6
5;Contributors;12
6;Chapter 1. Introduction;16
6.1;1.1 Background;16
6.2;1.2 Pesticides;17
6.3;1.3 Veterinary drugs;19
6.4;1.4 Persistent environmental chemicals;21
6.5;1.5 Processing contaminants;22
6.6;1.6 Migration from materials and articles in contact with food;23
6.7;1.7 Naturally occurring toxicants;23
6.8;1.8 Control measures;24
6.9;1.9 Current and future trends;26
6.10;1.10 Dedication and acknowledgement;26
6.11;1.11 References;26
7;Part I: Analytical methods;28
7.1;Chapter 2. Risk analysis;30
7.1.1;2.1 Introduction;30
7.1.2;2.2 Hazard identification in the food supply chain;31
7.1.3;2.3 Dose-response characterisation;34
7.1.4;2.4 Exposure analysis;36
7.1.5;2.5 Risk evaluation;43
7.1.6;2.6 Methods for risk management;44
7.1.7;2.7 Future trends in risk analysis;47
7.1.8;2.8 Sources of further information and advice;50
7.1.9;2.9 References;50
7.2;Chapter 3. Analytical methods: quality control and selection;52
7.2.1;3.1 Introduction;52
7.2.2;3.2 Legislative requirements;53
7.2.3;3.3 FSA surveillance requirements;56
7.2.4;3.4 Laboratory accreditation and quality control;56
7.2.5;3.5 Proficiency testing;62
7.2.6;3.6 Analytical methods;68
7.2.7;3.7 Standardised methods of analysis for contaminants;72
7.2.8;3.8 The future direction for methods of analysis;76
7.2.9;3.9 References;77
7.2.10;Appendix: Information for potential contractors on the analytical quality assurance requirements for food chemical surveillance exercises;79
7.3;Chapter 4. Molecular imprint-based sensors in contaminant analysis;86
7.3.1;4.1 Introduction;86
7.3.2;4.2 The principles of molecularly imprinted polymer-based techniques;88
7.3.3;4.3 The development and application of MIP-based sensors;91
7.3.4;4.4 Case studies: contaminant analysis;94
7.3.5;4.5 Future trends;99
7.3.6;4.6 Sources of further information and advice;101
7.3.7;4.7 Acknowledgements;102
7.3.8;4.8 References;103
7.4;Chapter 5. Bioassays in contaminant analysis;106
7.4.1;5.1 Introduction;106
7.4.2;5.2 Dioxins and the DR-CALUX bioassay;107
7.4.3;5.3 The use of bioassays for other groups of compounds;115
7.4.4;5.4 Future developments;117
7.4.5;5.5 Acknowledgements;117
7.4.6;5.6 References;117
8;Part II: Particular contaminants;122
8.1;Chapter 6. Veterinary drug residues;124
8.1.1;6.1 Introduction;124
8.1.2;6.2 Control of veterinary products in the UK;127
8.1.3;6.3 Chemical substances commonly used in veterinary medicines;132
8.1.4;6.4 Surveillance for veterinary drug residues;147
8.1.5;6.5 Analytical methods employed in drug residues surveillance;149
8.1.6;6.6 Results of surveillance for veterinary drug residues in the UK (1998);153
8.1.7;6.7 Potential effects on human health of veterinary drug residues in food;158
8.1.8;6.8 Current issues relating to residues of veterinary drugs in food in the UK;159
8.1.9;6.9 Summary;161
8.1.10;6.10 Further reading;162
8.2;Chapter 7. Inorganic contaminants in food;163
8.2.1;7.1 Introduction;163
8.2.2;7.2 Metals and metalloids;165
8.2.3;7.3 Nitrate and nitrite;178
8.2.4;7.4 References;180
8.3;Chapter 8. Environmental organic contaminants in food;184
8.3.1;8.1 Introduction;184
8.3.2;8.2 Aromatic hydrocarbons;186
8.3.3;8.3 Polycyclic aromatic hydrocarbons;187
8.3.4;8.4 Dioxins and PCBs;190
8.3.5;8.5 Chlorinated hydrocarbons;197
8.3.6;8.6 Phthalic acid esters;199
8.3.7;8.7 Endocrine disrupters;200
8.3.8;8.8 References;201
8.4;Chapter 9. Chemical migration from food packaging;208
8.4.1;9.1 Introduction;208
8.4.2;9.2 Chemical migration and the main factors that control it;210
8.4.3;9.3 The range and sources of chemicals in food packaging that pose a potential risk;214
8.4.4;9.4 Research on health issues;220
8.4.5;9.5 Regulatory context;221
8.4.6;9.6 Migration testing;224
8.4.7;9.7 Case studies;227
8.4.8;9.8 Suggested further reading;232
8.5;Chapter 10. Pesticides;233
8.5.1;10.1 Introduction;233
8.5.2;10.2 Monitoring pesticides in food;240
8.5.3;10.3 High risk groups;243
8.5.4;10.4 The UK’s approach to pesticide surveillance;244
8.5.5;10.5 Findings from the UK pesticide monitoring scheme;246
8.5.6;10.6 Human exposure monitoring;249
8.5.7;10.7 Should we ban pesticides?;251
8.5.8;10.8 References;251
8.6;Chapter 11. Mycotoxins;253
8.6.1;11.1 Introduction;253
8.6.2;11.2 Health implications of mycotoxins;256
8.6.3;11.3 Analytical methods;261
8.6.4;11.4 Application of HACCP systems to reduce mycotoxin presence;265
8.6.5;11.5 Prevention and control of mycotoxins;268
8.6.6;11.6 Conclusion and future trends;271
8.6.7;11.7 References;272
9;Part III: Regulation;276
9.1;Chapter 12. The international regulation of chemical contaminants in food;278
9.1.1;12.1 Introduction;278
9.1.2;12.2 The nature of international regulation: Codex Alimentarius;280
9.1.3;12.3 Decision making and enforcement mechanisms;283
9.1.4;12.4 The Codex General Standard on Contaminants and Toxins in Food;286
9.1.5;12.5 Future trends;289
9.1.6;12.6 Sources of further information and advice;291
9.1.7;12.7 References;292
9.2;Chapter 13. The regulation of chemical contaminants in foodstuffs in the European Union;294
9.2.1;13.1 Introduction;294
9.2.2;13.2 Scientific advisory committees;295
9.2.3;13.3 Pesticide residues;297
9.2.4;13.4 Veterinary drug residues;299
9.2.5;13.5 Mercury and histamine in fishery products;302
9.2.6;13.6 Other chemical contaminants;303
9.2.7;13.7 Future trends;304
9.2.8;13.8 References;305
9.3;Chapter 14. Contaminant regulation and management in the United States: the case of pesticides;310
9.3.1;14.1 Introduction;310
9.3.2;14.2 Pesticide regulation in the US;312
9.3.3;14.3 Regulatory monitoring of pesticides in the US;313
9.3.4;14.4 Managing pesticides in foods in the US;316
9.3.5;14.5 Improving the management of pesticides in foods;320
9.3.6;14.6 Future trends;325
9.3.7;14.7 Further information and advice;326
9.3.8;14.8 References;326
10;Index;329

Leseproben

2 Risk analysis
D.R. Tennant    Consultant, UK 2.1 Introduction
We all share the expectation that food will be safe to eat. However, the opportunities for food to become contaminated by chemicals at some stage in its production are legion. Nevertheless, incidents of chemical contamination are very rare and this is testimony to systems for risk assessment and risk management that are applied by food producers, processors and retailers. Any reliable system for assessing and controlling chemical risks must contain six key elements whose relationships are described in Fig. 2.1: Fig. 2.1 Food chemical risk assessment and risk management. 1. Hazard identification. It is necessary to be aware of what chemical contaminants might occur in a particular foodstuff and the nature of the harmful consequences to human health that might be associated with them. 2. Dose–response characterisation. Different chemicals will be associated with different toxicological end-points and the risk of any individual experiencing toxicity is related to the dose that they receive. Very often it is possible to identify a dose level below which the probability of anyone experiencing an adverse effect is very low or zero. 3. Exposure analysis. The amount of any chemical that an individual is exposed to will depend upon the levels that occur in food and the amounts of those foods that are consumed. Different population groups will often have different levels of exposure and it is therefore necessary to identify such sub-groups. 4. Risk evaluation. If a dose level at which no adverse effects are experienced has been identified then it is necessary to identify any population sub-groups whose exposure might exceed that level. Risk evaluation should aim to quantify the level of risk that any such populations are exposed to. 5. Risk management. If any population sub-group has been identified as being potentially at risk then measures to control the risk must be assessed and introduced. Any benefits associated with the foods affected must be taken into account and the costs associated with alternative methods of control evaluated. 6. Risk communication. Where there are potential risks associated with chemical contaminants in food other interested parties, in particular any sub-groups particularly affected, must be informed. The remaining sections of this chapter will provide detailed information about each of these six steps. However, specific strategies for risk assessment and management may need additional elements, depending on the nature of the hazard, the foods in which it may occur and other specific conditions. 2.2 Hazard identification in the food supply chain
Chemical contamination can occur at any point in the food chain from the field through to the point of consumption (Fig. 2.2). Once contamination has occurred it is usually expensive and technically difficult to remove it. Processing may further complicate the situation, by concentrating the contaminant in a particular fraction such as vegetable oil. It is therefore vital to identify all potential sources of contaminants in order to prevent contamination from occurring. Fig. 2.2 Opportunities for chemical contamination in the food chain. 2.2.1 Primary food production
In the field, soil can sometimes be a significant source of contamination. For example, in areas of mineralisation, heavy metals may occur naturally at elevated levels in soils. If there has been mining activity in the past this can exacerbate the problem by the spreading of mine spoil at the surface. Animals, particularly cattle, which tend to tug at forage rather than biting it, can ingest significant amounts of soil and metals can accumulate in tissues such as the liver. Plants may also take up elements from the soil that can accumulate in edible parts. Where mineral workings drain to the sea, metals can precipitate where chemical conditions change in estuarine environments. Shellfish caught from such estuaries may also have elevated levels of heavy metals. Soils may also become contaminated with industrial pollutants or with agricultural chemicals. For example, fields located close to industrial plants such as incinerators or metal smelters can gradually accumulate residues of combustion products and other chemicals from the fall-out from smoke plumes. Organo-chlorine pesticides, which are now largely banned, can persist in soils for many years and nitrates used in fertilisers can accumulate in soils which, under certain growth conditions, can result in high levels in certain crops. Animal feeds appear to be particularly vulnerable to chemical contamination. Chemical hazards associated with fungal toxins (mycotoxins) were first identified when poultry were adversely affected. Mycotoxins such as aflatoxins and ochratoxins were found to be carcinogenic and to occur at low levels in a variety of plant and animal-derived foods. Many national authorities have taken steps to control the levels of mycotoxins in food. On occasions, animal feed has been suspected of deliberate contamination. Incidents involving contamination of animal feed by industrial by-products such as polycylic aromatic hydrocarbons (PAHs) and combustion products such as dioxins are not uncommon. A problem with animal feed is that there is sometimes inadequate control over the provenance of feed constituents. For example, spent cooking oil from food-processing plants is a legitimate feed component. Unfortunately, the temptation for the unscrupulous to dispose of other unwanted oils in this way is too great for some. In many cases such adulterants are probably diluted to such an extent that they are undetectable by conventional chemical analyses. Nevertheless, they may still represent a long-term cumulative hazard to consumers of products from animals fed on such material. 2.2.2 Food processing
It is often necessary to process food before it is suitable for human consumption. Grain must be ground into flour, milk churned into butter, barley and hops brewed into beer, for example. Simple contamination might arise from direct contact with containers and tools used in food processing if they are not made from suitable materials. Machinery lubricants and coolants sometime leak and they can find their way into food. 2.2.3 Retailing and consumption
Foods are frequently packaged before being put on sale and constituents of the packaging or inks, dyes and glues used in packaging present the potential for migration into food. During transport, food and other materials can become inadvertently intermingled thus presenting a further hazard. In the home there are further potential hazards such as contamination from storage vessels and cooking containers and utensils. The process of cooking can alter food so that new chemical substances are formed. Cooking meat so that it is well browned (for example by roasting, grilling or frying) can produce heterocyclic amines, which are potentially carcinogenic. Hazards can occur right up to the point of consumption. For example, ceramic glazes with a high lead content can be leached out by acidic foods such as wine. 2.2.4 Hazard characterisation
Once potential hazards have been identified the nature of the hazard must be characterised. Initially the nature of any toxicological damage should be identified. For example, cadmium, which can be present at high levels in certain soils and sediments, can cause damage to the kidneys, whereas polycyclic aromatic hydrocarbons, which are pollutants produced by high-temperature combustion, are carcinogenic. The time-scale over which contaminants can exert an adverse effect is also of importance. For carcinogens such as PAHs and mycotoxins, it is the long-term cumulative dose that is most important. Conversely for organophosphorus pesticide residues, one meal might be sufficient to cause some inhibition of the cholinesterase enzyme. 2.3 Dose–response characterisation
The severity of any adverse effect associated with a chemical contaminant is usually directly related to the dose. Severity can be measured as the degree of damage to an individual or the probability of being affected, or a combination of these effects. For a substance that causes tissue damage such as cadmium, increasing the total dose will tend to increase the degree of damage to the kidneys as measured by the loss of proteins in the urine. For carcinogens, where just one molecule has the theoretical ability to induce a tumour, increasing the dose increases the probability that an individual will contract a tumour. In either case there may be some threshold level below which no effects are observed. 2.3.1 Thresholded end-points
For many substances the body’s own mechanisms for de-toxification and repair mean that low doses of some chemicals can be tolerated without experiencing any adverse effects. However, once a certain threshold has been exceeded then the degree of adverse effect is related to the dose. The highest dose at which no adverse effects are observed in the most susceptible animal species is identified at the No Observed Adverse Effect Level (NOAEL). The NOAEL is used as the basis for setting human safety standards for contaminants,...