Use of food additives in relation to their safety

101 Toxic Food Ingredients

101 Toxic Food Ingredients

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Food additives have been used since prehistoric times to maintain and improve the quality of food products. Smoke, alcohol, vinegar, oils, and spices have been used for more than 10,000 years to preserve foods. These and a small number of other chemicals, such as salts, copper, and chalk, were the major food additives used until the time of the Industrial Revolution. Since then many changes in food manufacturing and food distribution have taken place as a result of urbanization, the decrease in opportunity for individual families to grow their own food, and the increase in the consumer's demand for a broader food assortment and a higher quality of food. Also, food had to be produced on a larger scale. Distribution over long distances involves a longer span of time between production and consumption. Further, food needs to be stored in warehouses and shops, and also at home. In addition, convenience foods require extensive preservation.

Processed food is more perishable than the individual food components themselves. This can be overcome by the use of food additives. Without these, the food choice would be limited, many food products would be prohibitively expensive, and much food would be wasted. Also, food-related poisonings would occur more often. All these factors together have led to an increased use of additives in food, particularly since the 1950s. More than 2500 different chemicals are now in use. Apart from the consumption of salt and sugar, which are also important preservatives, the yearly additive consumption per capita in the early 1960s was estimated to exceed 3 lbs. However, the demand for new, tasty, convenient and nutritious foods continued to increase. In the US, where this development is most pronounced, the additive consumption per capita has increased from 3 to 9 lbs per year. Besides being beneficial, the use of food additives may also involve adverse health effects which can be either indirect or direct. Indirect effects are concerned with unbalanced diets and direct effects with potential toxicity.

The indirect health effects of additives are the opposite of some of their beneficial effects. The use of additives has led to a wider food assortment, but also to an increased availability of food with a low nutrient content. This type of food (so-called junk food) can be (and often is) consumed as dietary substitute for more nutritious food. Obviously, educational programs are needed to alert consumers to the need for a balanced diet.

The direct effects include short-term as well as long-term toxic effects. Short-term effects of additives are unlikely because of the low levels at which they are applied. On the other hand, hypersensitivity has been attributed to additives, even if they are used at legally acceptable levels. Further, little or no data are available on the health risks from the daily intake of combinations of additives.

Toxicological problems after long-term consumption of additives are not well-documented. There is no conclusive evidence for the relationship between chronic consumption of food additives and the induction of cancer and teratogenic effects in humans. Results of animal studies, however, have suggested that the use of certain additives involves safety problems. Most of these additives are now banned.

Nowadays, food additives undergo extensive toxicological screening before they are admitted for use. However, the majority of additives already in use are believed to be safe for the consumer at the levels applied in food, even though they have not been examined toxicologically. The substances involved are of natural origin and traditionally have been in use since the early days of food processing. Many additives that are used by the consumer in preparing food in the natural matrix, e.g., pectin as thickener, egg yolk as emulsifier, tomato juice as flavor enhancer, and lemon juice as antioxidant, are used in the food industry in a purified form.

The search for new and safer additives to replace debatable ones, and for processing techniques that require fewer additives, continues.

5.2.1 Colorings

Colorings are used to improve the overall attractiveness of food.

Food colors may be of natural as well as synthetic origin. About 50 colors of natural origin and their derivatives are in use, including chlorophylls (green), carotenoids (yellow, orange, and red) and anthocyanins (purple). They have all been toxicologically evaluated. This section deals with synthetic colorings only.

Synthetic colorings are superior to natural pigments in tinctorial strength, brightness, and stability. After the discovery of the first synthetic dye in 1856, a wide variety of colorings became rapidly available. By the end of the 19th century, 80 colorings were in use. In the first decade of this century, most of these substances were prohibited by law on the basis of their composition and purity.

The toxicology of synthetic food colorings was not given any attention until the early 1930s, when 4-dimethylaminoazobenzene was found to be carcinogenic. This dye was used to color butter and margarine yellow, hence its name "butter yellow." Since then other dyes have proved to be toxic and, as a consequence, have been banned from addition to food. Currently, only 9 synthetic colorings are allowed in the US and 11 in the EU. The majority belong to the class of the azo dyes. A few typical examples are discussed below: amaranth and tartrazine.

Amaranth, (trisodium 1-(4-sulfo-1-naphthylazo)-2-naphthol-3,6-disulfonic acid) has been approved for use as food color in several countries, including the member states of the EC. It is a water-soluble red dye.

HO SO3Na

NaO3S

NaO3S

HO SO3Na

Amaranth SO3Na

In many long-term studies on carcinogenicity, amaranth has been found to be safe. It is used in food products, such as packaged soup, packaged cake and dessert mix, and canned fruit preserves. In the USA, however, amaranth is no longer in use. The reason for this is the development of tumors in rats fed on a diet containing 3% amaranth.

Tartrazine (5-hydroxyl-1-(p-sulfophenyl)-4-(p-sulfophenylazo)pyrazole-3-carboxylic acid) is a yellow food coloring.

Tartrazine is widely used in foods, such as the packaged convenience foods mentioned above, smoked fish, chewing gum, sweets, beverages, and canned fruit preserves. The dye has undergone extensive testing, and was found to be harmless in experimental animals. However, various types of allergic reactions are attributed to tartrazine. As little as 0.15 mg can elicit an acute asthmatic attack in sensitive persons. The average daily intake of tartrazine is estimated at 9 mg/kg body weight in the US, while the ADI is 7.5 mg/kg body weight.

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