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Preservative

A '''preservative''' is a natural or synthetic chemical compound|chemical that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by microbial growth or by undesirable chemical changes.

Preservatives in wood

Preservatives may be added to wood to prevent the growth of fungi as well as to repel insects and termites. Typically arsenic, copper, chromium, borate, and petroleum based chemical compounds are used. For more information on wood preservatives, see timber treatment, lumber, and LOLO-E

Preservatives in foods

Preservative food additives can be used alone or in conjunction with other methods of food preservation. Preservatives may be ''anti-microbial preservatives'', which inhibit the growth of bacterium|bacteria and fungus|fungi, or ''antioxidants'' such as oxygen absorbers, which inhibit the oxidation of food constituents. Common anti-microbial preservatives include calcium propionate, sodium nitrate, sodium nitrite, sulfites (sulfur dioxide, sodium bisulfite, potassium hydrogen sulfite, etc.) and EDTA|disodium EDTA. Antioxidants include BHA and BHT. Other preservatives include formaldehyde (usually in solution), glutaraldehyde (kills insects), ethanol and methylchloroisothiazolinone. The benefits and safety of many artificial food additives (including preservatives) are the subject of debate among academics and regulators specializing in food science and toxicology.

Natural food preservation

Natural substances such as edible salt|salt, sugar, vinegar, and diatomaceous earth are also used as traditional preservatives. Certain processes such as Frozen food|freezing, pickling, Smoking (cooking)|smoking and salting (food)|salting can also be used to preserve food. Another group of preservatives targets enzymes in fruits and vegetables that continue to metabolize after they are cut. For instance, citric acid|citric and ascorbic acids from lemon or other citrus juice can inhibit the action of the enzyme phenolase which turns surfaces of cut apples and potatoes brown. Caution must be taken, however, since FDA standards do not currently require fruit and vegetable product labels to accurately reflect the type of preservative used in the products.

Health concerns

Some modern synthetic preservatives have become controversial because they have been shown to cause respiratory or other health problems. Some studies point to synthetic preservatives and artificial coloring agents aggravating ADD & ADHD symptoms in those affected.“Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomized, double-blinded, placebo-controlled trial”, ''The Lancet'', Sept 20071997 Graduate Student Research Project conducted at the University of South Florida. Richard W. Pressinger M.Ed. Older studies were inconclusive quite possibly due to inadequate clinical methods of measuring offending behavior. Parental reports were more accurate indicators of the presence of additives than clinical tests. "Food Additives May Affect Kids' Hyperactivity", ''WebMD Medical News'', May 24, 2004 Several major studies show academic performance increased and disciplinary problems decreased in large non-ADD student populations when artificial ingredients, including preservatives were eliminated from school food programs. "A different kind of school lunch", ''PURE FACTS'', October 2002The impact of a low food additive and sucrose diet on academic performance in 803 New York City public schools, Schoenthaler SJ, Doraz WE, Wakefield JA, ''Int J Biosocial Res.'', 1986, 8(2); 185-195 Allergenic preservatives in food or medicine can cause Anaphylaxis|anaphylactic shock in susceptible individuals, a condition which is often fatal within minutes without emergency treatment.

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