REGULATORY ASSESSMENT OF THE RISKS OF FOOD ADDITIVES

IV. REGULATORY ASSESSMENT OF THE RISKS OF FOOD ADDITIVES

A. Determination of Safe and Effective Quantities for Foods

For some additives, especially vitamins and minerals, the quantity added to a finished food product may not be sufficient to achieve an intended health benefit. Some foods that are commonly consumed by the majority of the population may be supplemented with various vitamins or minerals. A single serving of a fortified food may not provide the same health benefit as regular consumption of a fortified food. For example, iodine is added to table salt to provide a regular source of this important mineral. Table salt is regularly consumed by most Americans, and iodine is often lacking in typical diets. The determination of a beneficial, yet safe, quantity of iodine to add to table salt must consider the typical consumption of salt over the lifetime of the consumer.

While a food additive may provide a benefit to a processor or a consumer when used as intended, the use of an inappropriate quantity may be deleterious to the food or to the consumer. If an additive is used in excess to process a product, then the desired effect may not be achieved, or else there may be an undesirable quality defect attributed to the product. For example, if an artificial sweetener such as aspartame is added to a beverage in a high concentration, then the product may be too sweet and rejected by consumers. Or an excessively high concentration of a chemical additive may lead to an acute illness or injury to the consumer, such as can occur with sulfiting agents. People who are sensitive to additives containing sulfur, especially those with asthma, are at a greater risk to suffer an allergic reaction to high levels of sulfites. Safety determinations of additive use should consider the effects of accidental or intentional consumption of a high quantity of an additive that is beyond its prescribed use level. Toxicological principles for assessing the safety of food additives have been developed (FDA, 1993).

Also an additive may be injurious to health when consumed in moderate doses over extended time periods. When the risks or benefits of food additive use are considered, estimation must be made of the long-term or lifetime consumption of the additive. These substances may have cumulative effects on health, may interact with other biological or chemical compounds in the body, or may elicit different responses in consumers of differ- ent ages or health status.

B. New Additive Approval

The U.S. Food and Drug Administration determines if new additives will be permitted for food use, or if existing additives can be used in additional food products or for new functions (FDA, 1998b). Usually, a commercial company will ask the FDA to approve a The U.S. Food and Drug Administration determines if new additives will be permitted for food use, or if existing additives can be used in additional food products or for new functions (FDA, 1998b). Usually, a commercial company will ask the FDA to approve a

C. Risk Assessment

The determination of the appropriate uses and concentrations of additives to allow in foods can be a complex process. Directly or indirectly added additives may have a demonstrated usefulness to a food processor or consumer, but they may also have harmful toxicological effects when consumed in excess quantities or by sensitive population groups. To deter- mine if a food additive can become a health hazard to the consumer, the inherent toxicity of the additive and the typical consumer consumption or exposure must be estimated. Both the short-term and the lifetime cumulative exposures should be considered since some additive uses may result in acute or chronic effects detrimental to health. To protect individuals from the possible adverse effects of these substances, studies to assess the risk of exposure to chemical residues should be performed. The basic components of a risk assessment include hazard identification, dose-response assessment, exposure assessment, and risk characterization (NRC, 1980, 1983; Winter and Francis, 1997).

Hazard identification is the process where specific chemicals are causally linked to the exhibition of particular health effects. These may include illnesses, birth and develop- mental defects, and reproductive abnormalities. Also it must be determined if consumption of a chemical could lead to the development of cancer. Cancer usually develops after long-term exposure to a carcinogenic substance. Other adverse health effects may be ob- served after a short-term or high-level exposure to an additive. In other words, the use of some additives may only be hazardous when consumed in specific quantities.

A dose-response assessment is used to predict the relationship between human expo- sure to the chemical and the probability of adverse effects. For carcinogens, it is assumed that no threshold level of exposure may exist, which implies that carcinogens may be hazardous when consumed in any quantity. For noncarcinogenic hazards, toxic effects will not generally be observed until a minimum, or threshold, dose is reached. Toxicology studies may be designed to identify the dose just above the threshold where effects are seen (lowest observed effect level [LOEL]) and the dose just below threshold at which no effects are seen (no observed effect level [NOEL] or no observed adverse effect level [NOAEL]). Often, an uncertainty factor has been applied to the NOEL to give a value known as the acceptable daily intake (ADI). This term may be expressed as the acceptable chemical exposure per amount of body weight per day. The ADI is usually calculated as either the NOAEL divided by 100, when the the NOAEL is derived from animal studies,

WHO, 1987). The decision to incorporate a specific quantity of an additive should consider not only the ADI level, but also the minimum amount that is deemed necessary to achieve

a desired technical effect. Exposure assessment is necessary to predict the likely amount of human exposure to an additive. For many foods and food additives it can be difficult to determine how much may be consumed by a particular population and how consumption varies among individuals. Some population subgroups may be exposed to greatly different quantities of food additives. Food consumption patterns vary greatly due to consumer age, gender, ethnicity, socioeconomic status, health status, and so on. Additionally, the quantity of additives present in some foods may be a known or unknown quantity, or could vary greatly. While the concentration of many food additives may be known or relatively con- stant, the quantity of indirect additives or pesticide residues that remain on food at the time of consumption may vary considerably and be difficult to predict.

Risk characterization describes the origin, magnitude, and uncertainties of estimates of the health risk. Considerations for evaluating the overall risk of using a food additive must include whether it has specific hazardous properties, a prediction of the likelihood of adverse effects based on exposure, and an estimation of the amount of exposure. For noncarcinogens, risk characterization typically relates the estimated exposure to the ac- ceptable daily intake. Exposures at the level of the ADI represent a very low risk. Increas- ing chemical exposures above the ADI would result in an increasing risk or increased probability of an adverse health consequence. For carcinogens, estimated cancer risks are obtained by multiplying exposure estimates by cancer potency factors. This practice often results in numerical cancer risks that may describe the frequency of people (e.g., 1 in 1 million) who would be expected to develop new cancers after long-term exposure to the food additive. Due to the considerable uncertainties and wide ranges of data used to esti- mate risks, a risk characterization should include qualitative evaluations of risk (Winters and Francis, 1997).