FOOD ADDITIVES AND FOOD CONTAMINANTS

Today nearly 80 000 chemicals are used for several purposes with an increase in number. At the beginning of 20th century, few thousands of chemicals had been used, mostly from natural sources. But it should be considered that casual use of chemicals in industry is a huge threat for human health and the environment. After 1960's, developments in toxicology and risk assessment applications provided safety in usage of chemicals.

CHEMICALS IN FOOD

• Nutrition facts: Carbohydrates, proteins, lipids, minerals, vitamins
• Chemicals with no nutritive value: Natural chemicals in food, food additives, food contaminants

FOOD CONTAMINANTS
Contaminants are substances that have not been intentionally added to food. These substances may be present in food as a result of the various stages of its production, packaging, transport or holding. They also might result from environmental contamination.
Chemical Contaminants in Food

1. Pesticide residues (residues of agricultural drugs used during production of fruits and vegetables)
2. Environmental contaminants (Pollution as a result of reflection of environmental pollutants to foods directly or enhanching with mechanisms such as bioconcentration) chlorine (Polychlorodiphenils, Dibenzodioxins, Dibenzofurans)
3. Mycotoxins (Aflatoxins, Patulin)
   • Pesticides (DDT, Aldrin, Lindan, Dieldrin, Endrin,Chlordan)
   • Metals (Lead, Cadmium, Mercury)
   • Radionuclids (Cs-137, Sr-90)
   • Organic compounds with chlorine (Polychlorodiphenils, Dibenzodioxins, Dibenzofurans)
4. Chemical pollutants produced by chemical reactions
   (N-Nitrozo compounds)
5. Veterinary drugs
6. Pollutans produced by migration from packaging materials (Plastifians, Monomers)
7. Pollutans produced by cooking (Poysyclic aromatic hydrocarbons, pyrolise products, acrylamide)

FOOD ADDITIVES

1. Shelf-life prolongers by keeping quality (Preservatives)
   • Antimicrobials (nitrite, benzoic acid, sorbic acid, sulphur dioxide...)
   • Antioxidants (BHA, BHT, propil gallate...)
2. Preparing and cooking property developers
   • pH regulators (acetic acid, propionic acid, calcium carbonate...)
   • Anticaking agents (magnezyum oksit, magnezyum karbonat, silikon dioksit...)
   • Emulsifiers (lecithin, mono and diglycerides...)
   • Stabilizers, thickeners (calcium acetate, calcium carbonate...)
3. Aroma, taste, flavor and color developers
   • Flavours (aroma substances)
   • Flavour enhancers (MSG, inisitol)
   • Colourings (tartarazin, kurkumin, annotto, b-karoten...)
   • Artificial sweeteners (aspartam, saccharin, asesulfam K,
     neoherperidin DC...)

Agreement and Permission for the use of Food Additives
Protection of human health is the basic aim during the permission period for the use of food additives. Food additives is a very special and important group of chemicals. People may expose to these substances all over their lives willing it or not. As a result, food additives is a chemical substance group under high control for the protection of human health. 

First step in the permission of a food additive is the determination of the substance amount where effects are observed on test animals or not. Toxicity is defined as the damage of chemical substances on the organism. Toxicity is a multi-dimensional effect. All toxicity possibilities are investigated by giving the chemical to the test animal (mostly rodents such as mice and rats) at different doses. The unit of the dose is mg/kg. In other words test substance in mg per living weight of test animal in kg. In toxicity tests there are average 100 test animals, at least 10 animals, for one dose group. 3000 test animals are used for a chemical substance in toxicity tests. These tests are applied in laboratories through the rules of Good Laboratory Practice determined by international foundations.

Toxicity Studies
1. Toxicokinetic Studies
Absorbtion, distribution, biotransformation and excretion properties of the additive is observed. The events from intake to excretion is shortly defined as ADME.
2. Toxicity Tests

• Acute Oral Toxicity Study

• Single exposure, or multiple doses within 24 hours
• To determine adverse effects from acute (short term) exposure
• Rodent species (rat or mouse) usually used

• Short-term Feeding Studies

• Duration less than one month, usually 28 days
• Determination of dose range to be tested in longer-term studies
• Dermination of target organs of the test chemical

• Subchronic Oral Toxicity Studies

• Duration 90 days to 12 months
• At least 3 dose levels

• 20 rodents each sex per dose group, or
• 4 dogs each sex per dose group

• Provide information on toxic effects on target organs from daily dose throughout time period

• Chronic Oral Toxicity Studies

• Longer than one year duration
• Determine most chronic effects and dose-response relationships
• Often can assess carcinogenic potential of the proposed food additive

• Developmental Toxicity and Teratogenicity Studies (Oral)

• Rodent species
• Multigenerational, to determine effects on reproduction, and offspring
• Effects on gonadal function, estrous cycles, mating behavior, conception, and partutition are assessed.
• Incidence of congenital malformations (birth defects) is assessed.
• Can often be combined with chronic feeding studies and carcinogenesis bioassay

• Carcinogenesis bioassay

• Two species
• Observe test animals over life span for the development of cancer

Oral, dermal, and inhalation routes of administration

Determination of doses safe for People
National/international scientific committees meet to evaluate toxicity test results and obtain safe use values. If the chemical substance had been used for a long time, then epidemiologic data obtained from human groups are used additionally. In summary, toxicity test values and epidemiologic data are used for the determination of the amount of the each chemical.
NOAEL (mg/kg): No Observed Adverse Effect Level
NOAEL (No Observed Adverse Effect Level) is the first value obtained from the toxicity test results data. In other words test animals have taken the food additive over the 70-80% of their life period and at NOAEL dose no adverse affects are observed.
NOAEL value is divided by safety factor (usually 100) to reach the dose which is safe for people. In other words 100 times lower dose than the dose which does not cause any adverse affects in test animals is accepted as safe for people. ADI (Acceptable Daily Intake) is the dose safe for people.

Calculation of Food Contaminant Residues In Foods

The difference of MPI is that the value is calculated per individual, not per human health as in calculation ADI. In calculations average human health is assumed as 60 kg.

Reference
http://www.turktox.org.tr/gida/fr.1-link.htm
http://ec.europa.eu/food/food/chemicalsafety/contaminants/index_en.htm
http://extoxnet.orst.edu/faqs/additive/toxtest.htm

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