Food contaminants risk assessment

The characterisation of health hazards of food contaminants, the assessment of the occurrence of undesirable compounds in food and the estimation of the dietary intake are key issues in the risk assessment. In 2000, the European Commission published a White Paper on Food Safety, which underlined the importance of ensuring the highest possible standards of food safety and proposed a new approach to achieve them. Recently, PFCs have gained increased scientific and socioeconomic interest as emerging environmental contaminants due to the unique combination of persistence, toxicity and environmental prevalence. Risk assessment of the dietary exposure to PFCs, however, is hampered by the lack of sufficient data about the occurrence of these contaminants in food. 

Chemical contaminants are usually not reduced or removed by processing steps. Chemical risks must preferably be controlled as early as possible in the agri-food chain. Food color additives (Section 7.1.3) are chemical compounds and are considered potential risks. Therefore a safety evaluation is part of the approval of a food colorant before its use is acknowledged by legislation (see also Section 7.1.6). This section explains the principles of risk assessment and includes an example of such an assessment of a specific food colorant. 

For human health risk assessment, it is necessary to elaborate realistic scenarios. Knowledge of real scenarios where the contaminant is emitted to the environment will help to obtain information about the fate and transport of the contaminant once emitted to the environment and the route of exposure for the human beings living in this scenario of concern. There are different types of exposure, i.e., direct, indirect (as is the case of food contaminated by the air, water, or soil contaminated by the emission), occupational exposure, and consumer goods coming from outside the scenario of concern. Depending on the objective of the study, it will be necessary to consider in the exposure assessment one or more types of exposure. 

This chapter provides a comprehensive examination of the current knowledge of drinking water and food contamination by PFCs and their bioaccumulation in humans, with special attention given to the fundamental role chemical analysis played in the evaluation of these compounds sources, levels, exposure and risk assessment. 

In the EU until 2003, the European Commission s Scientific Committee for Food (SCF) performed safety evaluations of food additives and contaminants. This task has now been taken over by the EFSA. EFSA s risk assessments and other scientific work are undertaken by its Scientific Committee and nine scientific Panels, each responsible for a different aspect of food and feed safety. The scientific work is also supported by external Scientific Expert Working Groups, each specializing in a specific subject (EFSA 2006). 

Chapter 5 of the document reviews the UFs used by UK Government departments, agencies, and their advisory committees in human health risk assessment. Default values for UFs are provided in Table 3 in the UK document with the factors separated into four classes (1) animal-to-human factor, (2) human variability factor, (3) quality or quantity of data factor, and (4) severity of effect factor. The following chemical sectors are addressed food additives and contaminants, pesticides and biocides, air pollutants, drinking water contaminants, soil contaminants, consumer products and cosmetics, veterinary products, human medicines, medical devices, and industrial chemicals. 

For a risk assessment, see Evaluation of Ethyl Parathion as a Toxic Air Contaminant, California Department of Food and Agriculture (1988). 

Many countries do not have the expertise and funds to conduct risk assessments of food additives and contaminants. JECFA performs a critical function in providing these risk assessments, and many countries use evaluations from JECFA to establish national regulatory programs for food additives and contaminants. 

A threshold also exists for quantal dose responses as well as graded, i.e., there will be a dose below which no individuals respond. However, the concept of a threshold also has to be considered in relation to the variation in sensitivity in the population, especially a human population with great variability. Thus, although there will be a dose at which the greatest number of individuals show a response (see point B in Fig. 2.5), there will be those individuals who are very much more sensitive (point A in Fig. 2.5) or those who are much less sensitive (point C in Fig. 2.5). This consideration is incorporated into risk assessment of chemicals such as food additives, contaminants, and industrial chemicals (see below). 

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. 

For food safety purposes the overriding aim is that food contamination should be reduced to the lowest practicable level, bearing in mind the potential costs and benefits involved. Since it is difficult to establish cause and effect relationships following long-term (chronic) exposure at low concentrations, it may be necessary to base action on prudence rather than on proven harm to health. However, if this approach is to maintain the confidence of both consumers and producers of food, a rational evaluation of all relevant information is required so that the balance between the risks and benefits of veterinary drugs can be assessed. Information on the incidence of potentially harmful drug residues is fundamental to this cost-benefit analysis so too is the consumption of the commodities involved (particularly for susceptible consumers or those consumers who eat more). Account must also be taken of the potential fall in food production if a drug is controlled or prohibited, and also the animal health and welfare implications that may result from the restriction of an animal medicine for which there may be no effective alternative. 

The risk to health from chemicals in food can be assessed by comparing estimates of dietary exposure with recommended safe levels of exposure. For most metals and other elements, these are the Provisional Tolerable Weekly Intakes (PTWIs) and the Provisional Tolerable Daily Intakes (PTDIs) recommended by the Joint Expert Committee on Food Additives of the Food and Agricultural Organisation of the United Nations and the World Health Organisation International Programme on Chemical Safety (JECFA). The European Commission s Scientific Committee on Food has established other relevant safe levels. These are Acceptable Daily Intakes (ADIs) for chemicals added to food, and Tolerable Daily Intakes (TDIs) for chemical contaminants. The use of the term tolerable implies permissibility rather than acceptability. All the above recommendations are estimates of the amount of substance that can be ingested over a lifetime without appreciable risk, expressed on a daily or weekly basis as appropriate. 

The human health risk assessment was conducted based on exposure estimates from two most relevant exposure pathways, namely dietary intake of POPs from food consumption and inhalation intake of airborne POPs contaminants. The potential intake of POPs from drinking water (considered to be a relatively minor exposure pathway) was not taken into account due to lack of relevant local data necessary for their estimation. 

Results of human health risk assessment indicated that there was no unacceptable inhalation nor dietary chronic/carcinogenic risk of toxicological concern associated with a lifetime exposure of Hong Kong residents to the current level of POPs contamination in the local environment and locally consumed foods. 

We are working with the Food Quality Control Department of the Ministry of Health to study the contamination of OCPs and PCBs in local fish and chickens. This project is in line with our current effort to assess the health risk arising from consumption of food contaminated with POP chemicals. The health risk assessment of POPs through dietary intakes project involved analyses of OCPs and PCBs in various foodstuff, initially raw materials which will be extended to cooked food. Unfortunately, we do not currently have the capability to analyze PCDD/PCDF in our laboratory but there are two high resolution mass spectrometers in the country that are capable of analyzing PCDD/PCDF. National and international collaborations will definitely improve the country capacity to monitor POPs not only those listed in the Stockholm Convention but other toxic chemicals found in the environment. 

FDA (U.S. Food and Drug Administration). 1990. Carcinogenic risk assessment for dioxins and furans in fish contaminated by bleached-paper mills. Report of the Quantitative Risk Assessment Committee. Washington, DC Food and Drug Administration. 

The Food Standards Code [10] is the main regulatory instrument which controls the quality of food, contaminant levels, approved additives, processing aids, sanitisers and disinfectants and these standards are performance based. If a chemical or a group of chemicals is covered by a food standard then they must only be used in food in accordance with the standard. However, if a chemical is not mentioned in a standard, then this does not preclude its use in food. For a new chemical not previously used in food production, it would be necessary for the supplier to undertake a detailed risk analysis of the product to demonstrate its safety and suitability. The assessment would need to consider both the toxicological profile of the chemical and the levels of human exposure that are likely to arise from residues in food. 

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