Food contamination refers to the presence in food of harmful chemicals and microorganisms which can cause consumer illness. This article addresses the chemical contamination of foods, as opposed to microbiological contamination, which can be found under
Foodborne illnessFoodborne illness is any illness resulting from the consumption of contaminated food....
.
A separate issue is
genetically modified foodGenetically modified foods are foods derived from genetically modified organisms. Genetically modified organisms have had specific changes introduced into their DNA by genetic engineering, unlike similar food organisms which have been modified from their wild ancestors through selective breeding ...
, or the presence in foods of ingredients from genetically modified organisms, also referred to as a form of food contamination.
Impact
The impact of chemical contaminants on consumer health and well-being is often apparent only after many years of prolonged exposure at low levels (e.g. cancer). Chemical contaminants present in foods are often unaffected by thermal processing (unlike most microbiological agents). Chemical contaminants can be classified according to the source of contamination and the mechanism by which they enter the food product.
Agrochemicals
Agrochemicals are chemicals used in agricultural practices and animal husbandry with the intent to increase crops and reduce costs. Such agents include pesticides (e.g. insecticides, herbicides, rodenticides), plant growth regulators, veterinary drugs (e.g.
nitrofuranNitrofurans are a class of drugs typically used as antibiotics or antimicrobials. The defining structural component is a furan ring with a nitro group.Members of this class of drugs include:* Furazolidone, antibacterial* Furylfuramide...
, fluoroquinolones,
malachite greenMalachite green, also called basic green 4 or victoria green B, is a toxic chemical primarily used as a dye. When diluted, it can be used as a topical antiseptic or to treat parasites, fungal infections, and bacterial infections in fish and fish eggs...
,
chloramphenicolChloramphenicol is a bacteriostatic antimicrobial originally derived from the bacterium Streptomyces venezuelae, isolated by David Gottlieb, and introduced into clinical practice in 1949...
), and
bovine somatotropinBovine somatotropin is a protein hormone produced in the pituitary glands of cattle. It is also called bovine growth hormone, or BGH. Monsanto Company, a U.S.-based corporation, first synthesized the hormone in large quantities using recombinant DNA technology and marketed it as "POSILAC"...
(
rBSTRBST or rBST may refer to:* Randomized binary search tree, a computer data structure* Rare Breeds Survival Trust, a UK charity* Recombinant bovine somatotropin , a synthetic growth hormone controversially used in dairy farming...
).
Environmental contaminants
Environmental contaminants are chemicals that are present in the environment in which the food is grown, harvested, transported, stored, packaged, processed, and consumed. The physical contact of the food with its environment results in its contamination. Possible sources of contamination are:
Air: radionuclides (
137CaesiumCaesium or cesium is the chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of , which makes it one of only five metals that are liquid at or near room temperature...
,
90StrontiumStrontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...
), polycyclic aromatic hydrocarbons (PAH).
Water:
arsenicArsenic is the chemical element that has the symbol As, atomic number 33 and atomic mass 74.92. Arsenic was first documented by Albertus Magnus in 1250. Arsenic is a notoriously poisonous metalloid with many allotropic forms, including a yellow and several black and grey forms...
,
mercuryMercury , also called quicksilver or hydrargyrum , is a chemical element with the symbol Hg and atomic number 80...
.
Soil:
cadmiumCadmium is a chemical element with the symbol Cd and atomic number 48. The soft, bluish-white transition metal is chemically similar to the two other metals in group 12, zinc and mercury. Similar to zinc it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
,
nitrateIn inorganic chemistry, a nitrate is a salt of nitric acid with an ion composed of one nitrogen and three oxygen atoms . In organic chemistry the esters of nitric acid and various alcohols are called nitrates.-Chemical properties:...
s,
perchloratePerchlorates are the salts derived from perchloric acid . They occur both naturally and through manufacturing. They have been used as a medicine for more than 50 years to treat thyroid gland disorders. They are also used as an oxidizer in rocket fuel and explosives and can be found in airbags...
s.
Polychlorinated biphenyls (
PCBPolychlorinated biphenyls are a class of organic compounds with 1 to 10 chlorine atoms attached to biphenyl, which is a molecule composed of two benzene rings. The chemical formula for PCBs is C12H10-xClx, where x = 1-10. PCBs were widely used for many...
) , dioxins, and polybrominated diphenyl ethers (PBDE) are ubiquitous chemicals, which are present in air, water, soil, and the entire biosphere.
Packaging materials:
antimonyAntimony is a chemical element with the symbol Sb and atomic number 51. A metalloid, antimony has four allotropic forms. The stable form of antimony is a blue-white metalloid. Yellow and black antimony are unstable non-metals...
,
tinTin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead, like the two possible oxidation states +2 and +4...
, lead,
perfluorooctanoic acidPerfluorooctanoic acid , also known as C8 and perfluorooctanoate, is a synthetic, stable perfluorinated carboxylic acid and fluorosurfactant. One industrial application is as surfactant in the emulsion polymerization of fluoropolymers. PFOA has been produced since the 1940s in industrial synthesis...
(PFOA),
semicarbazideIn organic chemistry, semicarbazide is a derivative of urea, where NH2 on one side has been replaced with H2NNH2 hydrazine, yielding H2NNHCNH2....
,
benzophenoneBenzophenone is the organic compound with the formula 2CO, generally abbreviated Ph2CO. Benzophenone is a widely used building block in organic chemistry, being the parent diarylketone.-Uses:...
, isopropylthioxanthone (ITX),
bisphenol ABisphenol A, commonly abbreviated as BPA, is an organic compound with two phenol functional groups. It is a difunctional building block of several important plastics and plastic additives...
.
Processing/cooking equipment:
copperCopper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity. Pure copper is rather soft and malleable and a freshly-exposed surface has a pinkish or peachy color...
, or other metal chips, lubricants, cleaning and sanitizing agents.
Naturally occurring toxins:
mycotoxinA mycotoxin is a toxic secondary metabolite produced by an organism of the fungus kingdom, including mushrooms, molds, and yeasts. The term 'mycotoxin' is usually reserved for the toxic chemical products produced by fungi that readily colonize crops...
s,
phytohaemagglutininPhytohaemagglutinin is a lectin found in plants, especially beans. PHA actually consists of two closely related proteins, called Leucoagglutinin and PHA-E...
, pyrrolizidine alkaloids,
grayanotoxinGrayanotoxin is a toxin found in rhododendrons and other plants of the family Ericaceae. It can be found in honey made from their nectar and cause a very rare poisonous reaction called grayanotoxin poisoning, honey intoxication, or rhododendron poisoning...
,
mushroomA mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus, hence the word mushroom is most often applied to those fungi that have...
toxins, scombrotoxin (
histamineHistamine is a biogenic amine involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by basophils and by...
),
ciguateraCiguatera is a foodborne illness poisoning in humans caused by eating marine species whose flesh is contaminated with a toxin known as ciguatoxin, which is present in many microorganisms living in tropical waters...
, shellfish toxins (see
shellfish poisoningThere are four syndromes called shellfish poisoning, which share some common features and are primarily associated with bivalve molluscs . These shellfish are filter feeders and, therefore, accumulate toxins produced by microscopic algae, such as dinoflagellates and diatoms, and cyanobacteria. For...
),
tetrodotoxinTetrodotoxin is a potent neurotoxin with no known antidote. There have been succesful tests of a possible antidote in mice, but further tests must be carried out to determine efficacy in humans...
, among many others.
Banned pesticides, carcinogens
There are many cases of banned pesticides or carcinogens found in foods.
- Greenpeace
Greenpeace is a non-governmental organization for the protection and conservation of the environment. Greenpeace uses direct action, lobbying and research to achieve its goals. Greenpeace has a worldwide presence with national and regional offices in 46 countries, which are affiliated to the...
exposed in 2006 in China that 25% of surveyed supermarkets agricultural products contained banned pesticides. Over 70% of tomatoes that tested were found to have the banned pesticide LindaneLindane, also known as gamma-hexachlorocyclohexane, , gammaxene, Gammallin and erroneously known as benzene hexachloride , is an organochlorine chemical variant of hexachlorocyclohexane that has been used both as an agricultural insecticide and as a pharmaceutical treatment for infestations of lice...
, and almost 40% of the samples had a mix of three or more types of pesticides.Fruits were also tested in this investigation. Tangerines, strawberries and Kyofung grapes samples were found contaminated by banned pesticides, including the highly toxic MethamidophosMethamidophos is an organophosphate insecticide.Crops grown with the use of methamidophos include some Latin American rice. Many nations use methamidophos on crops, including developed nations such as Spain, US, Japan, and Australia.-Toxicity:...
. These fruits can also be found in Hong Kong market. Greenpeace says there exists no comprehensive monitoring on fruit produce in the Hong Kong as of 2006.
- In India, soft drinks were found contaminated with high levels of pesticides and insecticides, including lindane, DDT
DDT is one of the most well-known synthetic pesticides. It is a chemical with a long, unique, and controversial history....
, malathionMalathion is an organophosphate parasympathomimetic which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity....
and chlorpyrifosChlorpyrifos is a toxic crystalline organophosphate insecticide that inhibits acetylcholinesterase and is used to control insect pests. Trade names include Brodan, Detmol UA, Dowco 179, Dursban, Empire, Eradex, Lorsban, Paqeant, Piridane, Scout, and Stipend...
.
- Even Quality Assurance International
Quality Assurance International is a U.S.-based international organic certification company that is authorized by the United States Department of Agriculture as “a USDA-accredited certifying agent that operates globally to certify organic operations to National Organic Program standards.” It is...
, a USDA certified organization, in July 2008 QAI had mistakenly certified as organic powdered ginger produced in China, which tests showed was contaminated with the banned pesticide AldicarbAldicarb is a carbamate insecticide with structural formula: 2-methyl-2-propanal O-oxime. Aldicarb is the active substance in Temik pesticide, which is effective against thrips, aphids, spider mites, lygus, fleahoppers, and leafminers but is primarily used as a nematicide...
.
- News of Formaldehyde
Formaldehyde is a chemical compound with the formula CH2O. It is the simplest aldehyde. Formaldehyde also exists as the cyclic trimer trioxane and the polymer paraformaldehyde. It exists in water as the hydrate H2C2. Aqueous solutions of formaldehyde are referred...
, a carcinogenA carcinogen is any substance, radionuclide or radiation that is an agent directly involved in the promotion of cancer or in the increase of its propagation. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...
was found in Vietnamese national dish, PhoPHO may refer to:* Primary Health Organisation* Potentially Hazardous Object...
, broke in 2007 Vietnam food scareThe 2007 Vietnam food scare was a food scandal, which exposed contaminated food. Among the issues were formaldehyde in noodles of the national dish, Pho, banned pesticides in vegetables and fruit, and toxic soy sauce.-History:...
. Vegetables and fruits were also found to have banned pesticides. "Health agencies have known that Vietnamese soy sauceSoy sauce , soya sauce or is produced by fermenting soybeans with the molds Aspergillus oryzae and Aspergillus soyae along with roasted grain, water, and salt. Soy sauce was invented in China, where it has been used as a condiment for close to 2,500 years...
, the country's second most popular sauce after fish sauceFish sauce is a condiment that is derived from fish that have been allowed to ferment. It is an essential ingredient in many curries and sauces. Fish sauce is a staple ingredient in Filipino, Vietnamese, Thai, Lao, and Cambodian cuisine and is used in other Southeast Asian countries...
, has been chock full of cancer agents since at least 2001," thundered the Thanh Nien daily. "Why didn't anyone tell us?" The carcinogen in Asian sauces is 3-MCPD3-MCPD or is carcinogenic and highly suspected to be genotoxic in humans, has male anti-fertility effects, and is a chemical byproduct which may be formed in foods, the most commonly found member of chemical contaminants known as chloropropanols.It's primarily created in foods by protein...
and its metabolite 1,3-DCP, which has been an ongoing problem before 2000 affecting multiple continents.
- 2005 Indonesia food scare
The 2005 Indonesia food scare was a food scare in 2005 in Jakarta, Indonesia, when the government found that 60% of noodle shops in the capital had been serving noodles laced with formaldehyde, a known carcinogen. Noodles in the 2007 Vietnam food scare also had the same contaminant, and the...
, carcinogenic formaldehyde was added as a preservative to noodles, tofu, salted fish, and meatballs.
- 2008 Chinese milk scandal
The 2008 Chinese milk scandal was a food safety incident in the People's Republic of China involving milk and infant formula, and other food materials and components, adulterated with melamine....
.
Hair in food
Many people consider hair in food to be particularly unpleasant, however there are certain risks to be considered such as choking and repulsion induced vomiting. There are also considerations of contaminants on the hair itself such as waxes or other hair products that may cause problems. It is claimed sometimes that it does not usually pose any serious health risk, but in other cases it is claimed that it does pose a health risk.
For example, people working in the food industry are required to cover their hair. Also, when people are served food which contains hair in restaurants or cafes, people may complain to the manager. Despite this, it is not valid ground to
sue-As an acronym:* the IATA airport code for Door County Cherryland Airport in Sturgeon Bay, Wisconsin* the fictional book series "A Series of Unfortunate Events"* Dassault Super Étendard , a French aircraft-carrier-borne strike fighter...
the restaurant in the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
but in the United Kingdom it breaks the regulations of the UK Food Safety Act 1990 and is known to cause food poisoning and people can sue for this. In one case a supermarket considered banning a man with a beard working there. In such cases there exists protection for food workers who have facial hair, which is called 'snood'.
The cause of people's disgust with hair in food could be that hair is not easily digestible and is the wrong shape for being processed in the body. Hair in food was often a common cause of complaint from people eating food, before the introduction of complete capture hairnets.
Also, sometimes protein from human hair is actually used as a food ingredient, in bread and other such similar products. Such use of human hair in food is forbidden in
IslamIslam Islam Islam ( al-’islām,
[There are ten pronunciations of Islam in English, differing in whether the first or second syllable has the stress, whether the s is or , and whether the a is pronounced as in father, as in cat, or (when the stress is on the i) as in the a of sofa...]
. Historically in
JudaismJudaism is a set of beliefs and practices originating in the Hebrew Bible , as later further explored and explained in the Talmud and other texts...
finding hair in food was a sign of bad luck.
Processing contaminants
Processing contaminants are generated during the processing of foods (e.g. heating,
fermentationFermentation in food processing typically is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. A more restricted definition of fermentation is the chemical conversion of sugars into ethanol...
). They are absent in the raw materials, and are formed by chemical reactions between natural and/or added food constituents during processing. The presence of these contaminants in processed foods can not be entirely avoided. However, technological processes can be adjusted and/or optimized in order to reduce the levels of formation of processing contaminants. Examples are: nitrosamines, polycyclic aromatic hydrocarbons (PAH),
heterocyclic aminesHeterocyclic amines, also sometime referred to as HCAs, contain both heterocyclic and amine groups. While some heterocycles are amines themselves, the amines indicated in the name are those attached to the heterocyclic ring....
,
histamineHistamine is a biogenic amine involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by basophils and by...
,
acrylamideAcrylamide is a chemical compound with the chemical formula C3H5NO. Its IUPAC name is 2-propenamide. It is a white odourless crystalline solid, soluble in water, ethanol, ether and chloroform. Acrylamide is incompatible with acids, bases, oxidizing agents, iron and iron salts...
,
furanFuran, also known as furane and furfuran, is a heterocyclic organic compound. It is typically derived by the thermal decomposition of pentose-containing materials, cellulosic solids especially pine-wood. Furan is a colorless, flammable, highly volatile liquid with a boiling point close to room...
,
benzeneBenzene, or benzol, is an organic chemical compound with the molecular formula C6H6. It is sometimes abbreviated Ph–H. Benzene is a colorless and highly flammable liquid with a sweet smell and a relatively high melting point...
,
trans fatTrans fat is the common name for unsaturated fat with trans-isomer fatty acid. Trans fats may be monounsaturated or polyunsaturated but never saturated.Unsaturated fat is a fat molecule, containing one or more double bonds between the carbon atoms...
, monochloropropanediol (MCPD),
semicarbazideIn organic chemistry, semicarbazide is a derivative of urea, where NH2 on one side has been replaced with H2NNH2 hydrazine, yielding H2NNHCNH2....
,
4-hydroxynonenal4-Hydroxynonenal, or trans-4-hydroxy-2-nonenal or 4-HNE or HNE, , is an α,β-unsaturated hydroxyalkenal which is produced by lipid peroxidation in cells...
(4-HNE), and
ethyl carbamateEthyl carbamate is a substance first prepared in the nineteenth century. Structurally it is an ester of carbamic acid, i. e., ethyl carbamate as shown...
. There is also the possibility of metal chips from the processing equipment that requires metal detection. In many conveyor lines, the line will be stopped, or when weighing the product with a
Check weigherA checkweigher is an automatic machine for checking the weight of packaged commodities.It is normally found at the offgoing end of a production process and is used to ensure that the weight of a pack of the commodity is within specified limits. Any packs that are outside the tolerance are taken...
, the item can be rejected for over- or underweight as well as detection of very small pieces of metals.
Emerging food contaminants
While many food contaminants have been known for decades, the formation and presence of certain chemicals in foods has been discovered relatively recently. These are the so-called
emerging food contaminants, e.g.
acrylamideAcrylamide is a chemical compound with the chemical formula C3H5NO. Its IUPAC name is 2-propenamide. It is a white odourless crystalline solid, soluble in water, ethanol, ether and chloroform. Acrylamide is incompatible with acids, bases, oxidizing agents, iron and iron salts...
,
furanFuran, also known as furane and furfuran, is a heterocyclic organic compound. It is typically derived by the thermal decomposition of pentose-containing materials, cellulosic solids especially pine-wood. Furan is a colorless, flammable, highly volatile liquid with a boiling point close to room...
,
benzeneBenzene, or benzol, is an organic chemical compound with the molecular formula C6H6. It is sometimes abbreviated Ph–H. Benzene is a colorless and highly flammable liquid with a sweet smell and a relatively high melting point...
,
perchloratePerchlorates are the salts derived from perchloric acid . They occur both naturally and through manufacturing. They have been used as a medicine for more than 50 years to treat thyroid gland disorders. They are also used as an oxidizer in rocket fuel and explosives and can be found in airbags...
,
perfluorooctanoic acidPerfluorooctanoic acid , also known as C8 and perfluorooctanoate, is a synthetic, stable perfluorinated carboxylic acid and fluorosurfactant. One industrial application is as surfactant in the emulsion polymerization of fluoropolymers. PFOA has been produced since the 1940s in industrial synthesis...
(PFOA), monochloropropanediol (MCPD),
4-hydroxynonenal4-Hydroxynonenal, or trans-4-hydroxy-2-nonenal or 4-HNE or HNE, , is an α,β-unsaturated hydroxyalkenal which is produced by lipid peroxidation in cells...
and (4-HNE).
Safety and regulation
Acceptable Daily IntakeAcceptable daily intake or ADI is a measure of the amount of a specific substance in food or drinking water that can be ingested over a lifetime without an appreciable health risk...
(ADI) levels and tolerable concentrations of contaminants in individual foods are determined on the basis of the "No Observed Adverse Effect Level" (NOAEL) in animal experiments, by using a safety factor (usually 100). The maximum concentrations of contaminants allowed by legislation are often well below toxicological tolerance levels, because such levels can often be reasonably achieved by using good agricultural and manufacturing practices.
The establishment of ADIs for certain emerging food contaminants is currently an active area of research and regulatory debate.
External links