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63 Processing-related changes in food
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Symposium S7. Risk assessment in food: examples
the cultures with UV irradiation. With both agents, no suppression of basal apoptosis was observed. The suppression of apoptosis with TCDD coincided with an attenuated increase of the tumor suppressor protein p53 observed upon UV irradiation. Furthermore, TCDD treatment resulted in a marked hyperphosphorylation of p53. The fact that almost identical concentration-response curves were obtained for the phosphorylation of p53 and the induction of cytochrome P450(CYP)1A-catalyzed 7-ethoxyresorufin O-deethylase (EROD) activity indicates that p53 phosphorylation after TCDD treatment is mediated by the aryl hydrocarbon receptor (AhR) signalling cascade. With tumor-promoting ‘non-dioxinlike’ polychlorinated biphenyls inhibition of UV-induced apoptosis was also observed. A comparative study investigating the effects of various concentrations did not reveal, however, a clear correlation between the suppression of apoptosis and the induction of CYP2B-catalyzed 7-pentoxyresorufin O-dealkylase (PROD) activity. In summary, inhibition of UV-induced apoptosis with liver tumor promoters is observed in rat hepatocytes in culture. Hyperphosphorylation of key proteins of apoptosis including p53 seems to play a critical role in this effect.
S7 Risk assessment in food: examples 63
PROCESSING-RELATED CHANGES IN FOOD
A. Tritscher. Department of Quality and Safety, Nestlé Research Center, Lausanne, Switzerland Many types of food processing techniques have been employed throughout human history, e.g. heat treatment, freezing, acidification, hydrolysis, fermentation, salting etc. The main purpose of these treatments is to ensure the microbiological and chemical safety of products and to increase storage times, but also to improve texture and flavour. The growing consumer demand for healthy and nutritious, convenient food, which is as fresh and ’low-processed’ as possible, is a key driver for new developments in food processing. In the case of ’Novel Processes’, according to EU legislation, the effect of the process on the product has to be carefully evaluated, if possible in comparison with traditional processing techniques. As example for an approved novel process the high pressure pasteurization of fruit preparations is explained. A number of scientific studies were conducted to prove that a given product treated by this new process is as safe as the conventionally processed product. Although designed for beneficial purposes, several processing techniques may also lead to formation of potentially harmful compounds in the foods. One example is the formation of 3monochloropropanediol (3-MCPD) in a variety of industrially and domestically produced foods in the presence of fat and chloride (salt). MCPD is considered a non-genotoxic carcinogen, and the EU Scientific Committee on Food has established a tolerable daily intake (TDI). Highest levels of MCPD have been detected in hydrolyzed vegetable protein and soy sauce and regulatory limits have been established for these products. The second example is the formation of acrylamide in certain high heat-treated foods. This new finding has raised considerable concern, since acrylamide is considered a genotoxic carcinogen. Acrylamide is also known to cause neurotoxicity in humans (occupationally), and reproductive toxicity in experimental animals. Neurotoxicity and reproductive toxicity may only occur at higher exposure levels, however dose-response relationships and mechanistic information regarding carcinogenicity are lacking, thus precluding the assessment of health risk from acrylamide exposure through food. State-of-the-art knowledge on acrylamide will be reviewed. 64
ASSESSING HUMAN SAFETY OF FOODS PRODUCED BY BIOTECHNOLOGY
Trish Malarkey. Syngenta Biotechnology Inc. Research Triangle Park, North Carolina, USA Biotechnology was used in the first generation of so-called ‘GM’ crops to provide growers with complimentary and sometimes al-
ternative crop management solutions to pesticides. Selected host genes or genes identified from other plants or non-plant sources are modified or transferred to a crop plant. The new or altered protein expression resulting from these modifications confer on the plant a desired physiological trait, such as resistance to particular herbicides or insect pests. Second generation modifications provide traits such as enhanced nutritional or health-promoting characteristics that are of benefit to consumers. The following are the commonly raised concerns about possible implications for human health. • Inherent toxicity of the novel gene and their products • The potential to express novel antigenic proteins or alter levels of existing protein allergens. • The potential for unintended effects resulting from alterations of host metabolic pathways or over expression of inherently toxic or pharmacologically active substances. • The potential for nutrient composition in the new food occur differing significantly from a conventional counterpart. Foods produced using biotechnology are subjected to far greater levels of scrutiny than foods produced by traditional plant breeding techniques. The accepted analytical, nutritional and toxicological methods employed to support this scrutiny and to assess and assure that a ‘GM’ food is a safe and nutritious as its ’non-GM’ counterpart will be discussed. The challenges associated with identifying unintended effects in whole GM foods and the promise new (proteonomics/genomic) technologies offer opposite traditional toxicity testing paradigms will be critically appraised. 65
CRITERIA FOR RISK ASSESSMENT OF BOTANICAL FOOD SUPPLEMENTS
R. Walker. School of Biomedical and Life Sciences, University of Surrey, Guildford, Surrey, United Kingdom The increasing use of botanical food supplements with perceived health benefits has raised concerns among scientific and regulatory communities. There have been occasional cases of intoxication from such products as a result of misuse, misidentification of the botanical species or contamination with extraneous plants. Consequently, risk assessment of botanical products requires that they are adequately specified with regard to identity and composition. The sources of botanical supplements vary from staple food plants to herbals used in traditional medicine and the supplement may consist of the whole plant, extracts thereof or more purified components and this variability poses problems in adopting a generic approach to their risk assessment. Factors that determine the nature and extent of toxicological testing required to characterize hazard and assess possible risks include: nature and complexity of the supplement, prior knowledge of human consumption of the product or its source material, the likely magnitude of human exposure and its nutritional impact, and the intended physiological/beneficial effects. Generally, for herbs or complex extracts, it is not possible to make a risk assessment on the basis of a single active component as there may be more than one of toxicological significance and matrix effects also may affect factors such as bioavailability. Nevertheless, studies on single components may be useful in elucidating potential interactions. Because the consumption of botanical supplements is intended to produce physiological effects, there may be a need to distinguish a No Observed Effect Level from a No Observed Adverse Effect Level and the margin of exposure between that required to produce the desired effect and the upper safe level may be smaller than is customarily adopted for food additives and contaminants. In this regard, human efficacy studies including observations for possible adverse side effects may help in determining the adequacy of the margin of exposure. In relation to these considerations, a decision tree developed at a Workshop organized by ILSI Europe in May, 2002 will be presented to assist in determining the extent of data requirements based on the nature of the product
Symposium S7. Risk assessment in food: examples
the cultures with UV irradiation. With both agents, no suppression of basal apoptosis was observed. The suppression of apoptosis with TCDD coincided with an attenuated increase of the tumor suppressor protein p53 observed upon UV irradiation. Furthermore, TCDD treatment resulted in a marked hyperphosphorylation of p53. The fact that almost identical concentration-response curves were obtained for the phosphorylation of p53 and the induction of cytochrome P450(CYP)1A-catalyzed 7-ethoxyresorufin O-deethylase (EROD) activity indicates that p53 phosphorylation after TCDD treatment is mediated by the aryl hydrocarbon receptor (AhR) signalling cascade. With tumor-promoting ‘non-dioxinlike’ polychlorinated biphenyls inhibition of UV-induced apoptosis was also observed. A comparative study investigating the effects of various concentrations did not reveal, however, a clear correlation between the suppression of apoptosis and the induction of CYP2B-catalyzed 7-pentoxyresorufin O-dealkylase (PROD) activity. In summary, inhibition of UV-induced apoptosis with liver tumor promoters is observed in rat hepatocytes in culture. Hyperphosphorylation of key proteins of apoptosis including p53 seems to play a critical role in this effect.
S7 Risk assessment in food: examples 63
PROCESSING-RELATED CHANGES IN FOOD
A. Tritscher. Department of Quality and Safety, Nestlé Research Center, Lausanne, Switzerland Many types of food processing techniques have been employed throughout human history, e.g. heat treatment, freezing, acidification, hydrolysis, fermentation, salting etc. The main purpose of these treatments is to ensure the microbiological and chemical safety of products and to increase storage times, but also to improve texture and flavour. The growing consumer demand for healthy and nutritious, convenient food, which is as fresh and ’low-processed’ as possible, is a key driver for new developments in food processing. In the case of ’Novel Processes’, according to EU legislation, the effect of the process on the product has to be carefully evaluated, if possible in comparison with traditional processing techniques. As example for an approved novel process the high pressure pasteurization of fruit preparations is explained. A number of scientific studies were conducted to prove that a given product treated by this new process is as safe as the conventionally processed product. Although designed for beneficial purposes, several processing techniques may also lead to formation of potentially harmful compounds in the foods. One example is the formation of 3monochloropropanediol (3-MCPD) in a variety of industrially and domestically produced foods in the presence of fat and chloride (salt). MCPD is considered a non-genotoxic carcinogen, and the EU Scientific Committee on Food has established a tolerable daily intake (TDI). Highest levels of MCPD have been detected in hydrolyzed vegetable protein and soy sauce and regulatory limits have been established for these products. The second example is the formation of acrylamide in certain high heat-treated foods. This new finding has raised considerable concern, since acrylamide is considered a genotoxic carcinogen. Acrylamide is also known to cause neurotoxicity in humans (occupationally), and reproductive toxicity in experimental animals. Neurotoxicity and reproductive toxicity may only occur at higher exposure levels, however dose-response relationships and mechanistic information regarding carcinogenicity are lacking, thus precluding the assessment of health risk from acrylamide exposure through food. State-of-the-art knowledge on acrylamide will be reviewed. 64
ASSESSING HUMAN SAFETY OF FOODS PRODUCED BY BIOTECHNOLOGY
Trish Malarkey. Syngenta Biotechnology Inc. Research Triangle Park, North Carolina, USA Biotechnology was used in the first generation of so-called ‘GM’ crops to provide growers with complimentary and sometimes al-
ternative crop management solutions to pesticides. Selected host genes or genes identified from other plants or non-plant sources are modified or transferred to a crop plant. The new or altered protein expression resulting from these modifications confer on the plant a desired physiological trait, such as resistance to particular herbicides or insect pests. Second generation modifications provide traits such as enhanced nutritional or health-promoting characteristics that are of benefit to consumers. The following are the commonly raised concerns about possible implications for human health. • Inherent toxicity of the novel gene and their products • The potential to express novel antigenic proteins or alter levels of existing protein allergens. • The potential for unintended effects resulting from alterations of host metabolic pathways or over expression of inherently toxic or pharmacologically active substances. • The potential for nutrient composition in the new food occur differing significantly from a conventional counterpart. Foods produced using biotechnology are subjected to far greater levels of scrutiny than foods produced by traditional plant breeding techniques. The accepted analytical, nutritional and toxicological methods employed to support this scrutiny and to assess and assure that a ‘GM’ food is a safe and nutritious as its ’non-GM’ counterpart will be discussed. The challenges associated with identifying unintended effects in whole GM foods and the promise new (proteonomics/genomic) technologies offer opposite traditional toxicity testing paradigms will be critically appraised. 65
CRITERIA FOR RISK ASSESSMENT OF BOTANICAL FOOD SUPPLEMENTS
R. Walker. School of Biomedical and Life Sciences, University of Surrey, Guildford, Surrey, United Kingdom The increasing use of botanical food supplements with perceived health benefits has raised concerns among scientific and regulatory communities. There have been occasional cases of intoxication from such products as a result of misuse, misidentification of the botanical species or contamination with extraneous plants. Consequently, risk assessment of botanical products requires that they are adequately specified with regard to identity and composition. The sources of botanical supplements vary from staple food plants to herbals used in traditional medicine and the supplement may consist of the whole plant, extracts thereof or more purified components and this variability poses problems in adopting a generic approach to their risk assessment. Factors that determine the nature and extent of toxicological testing required to characterize hazard and assess possible risks include: nature and complexity of the supplement, prior knowledge of human consumption of the product or its source material, the likely magnitude of human exposure and its nutritional impact, and the intended physiological/beneficial effects. Generally, for herbs or complex extracts, it is not possible to make a risk assessment on the basis of a single active component as there may be more than one of toxicological significance and matrix effects also may affect factors such as bioavailability. Nevertheless, studies on single components may be useful in elucidating potential interactions. Because the consumption of botanical supplements is intended to produce physiological effects, there may be a need to distinguish a No Observed Effect Level from a No Observed Adverse Effect Level and the margin of exposure between that required to produce the desired effect and the upper safe level may be smaller than is customarily adopted for food additives and contaminants. In this regard, human efficacy studies including observations for possible adverse side effects may help in determining the adequacy of the margin of exposure. In relation to these considerations, a decision tree developed at a Workshop organized by ILSI Europe in May, 2002 will be presented to assist in determining the extent of data requirements based on the nature of the product