Additives and contaminants 2 - Principle of food chemistry

Additives and contaminants 2 - Principle of food chemistry

Other Additives In addition to the aforementioned major groups of additives, there are many others in- cluding clarifying agents, humectants, glazes, polishes, anticaking agents, firming agents, propellants, melting agents, and enzymes. These intentional additives present consider- able scientific and technological problems as well as legal, health, and public relations challenges. Future introduction of new addi- tives will probably become increasingly dif- ficult, and some existing additives may be disallowed as further toxicological studies are carried out and the safety requirements become more stringent. INCIDENTAL ADDITIVES OR CONTAMINANTS Radionuclides Natural radionuclides contaminate air, food, and water. The annual per capita intake of natural radionuclides has been estimated to range from 2 Becquerels (Bq) for 232 Th to about 130 Bq for 40 K (Sinclair 1988). The Bq is the International System of Units (SI) unit of radioactivity; 1 Bq = 1 radioactive disintegration per second. The previously used unit of radioactivity is the Curie (Ci); 1 Ci = 3.7 x 10 10 disintegrations per second, and 1 Bq = 27 x 10~ 12 Ci. The quantity of radiation or energy absorbed is expressed in Sievert (Sv), which is the SI unit of dose equivalent. The absorbed dose (in Gy) is multiplied by a quality factor for the particu- lar type of radiation. Rem is the previously used unit for dose equivalent; 100 rem = 1 Sv. The effective dose of Th and K radionu- clides is about 400 |nSv per capita per year, with half of it resulting from 40 K. The total exposure of the U.S. population to natural radiation has been estimated at about 3 mSv. In addition, 0.6 mSv is caused by man-made radiation (Sinclair 1988). Radioactive Fallout Major concern about rapidly increasing levels of radioactive fallout in the environ- ment and in foods developed as a result of the extensive testing of nuclear weapons by the United States and the Soviet Union in the 1950s. Nuclear fission generates more than 200 radioisotopes of some 60 different ele- ments. Many of these radioisotopes are harm- ful to humans because they may be incor- porated into body tissues. Several of these radioactive isotopes are absorbed efficiently by the organism because they are related chemically to important nutrients; for exam- ple, strontium-90 is related to calcium and cesium-137 to potassium. These radioactive elements are produced by the following nuclear reactions, in which the half-life is given in parentheses: p- p- 90 Kr(BBsCC) ^ 90 Rb(IJmIn) ^ 90 Sr (28 y) P- p- 137 I (22 sec) ** 137 Xe (3.8 min) *• 137 Cs (29 y) The long half-life of the two end products makes them especially dangerous. In an atmospheric nuclear explosion, the tertiary fission products are formed in the strato- sphere and gradually come down to earth. Every spring about one-half to two-thirds of the fission products in the stratosphere come down and are eventually deposited by precip- itation. Figure 11-6 gives a schematic out- line of the pathways through which the fallout may reach us. Previous page Among the radioisotopes that can be taken up in the food chain, the most significant as internal radiation hazards are barium-140, cesium-137, iodine-131, iodine-133, stron- tium-89, and strontium-90. 131 I is chemically similar to ordinary iodine and, therefore, accumulates in the thy- roid gland. It has a half-life of eight days and is a beta-gamma emitter. Because milk is produced year round and is consumed within one half-life, the presence of this isotope in milk was a major concern during the atmo- spheric testing period in the early 1960s. 137 Cs has a half-life of 29 years and, because of its chemical similarity to potas- sium, accumulates in muscle tissue. 137 Cs may cause several types of cell damage, including genetic damage. It is not retained in the body for a long time. 137 Cs is a gamma emitter. 90 Sr has a half-life of 28 years and is a beta emitter. This isotope collects in the bones because of its chemical similarity to calcium. It can result in bone cancer and leukemia. Children are very sensitive to this isotope because they require large amounts of cal- cium for bone formation and as a result deposit relatively more 90 Sr. They also face a longer life span, which is important because radiation effects are cumulative. In 1964, the rate of fallout of 90 Sr was about 40 pc/day/m 2 . Total intake of 90 Sr dur- ing that period was about 40 pc/day/person in some Western countries. Because about 3,000 m 2 of arable land are required to pro- duce food for one person, the total amount of 90 Sr deposited on that surface was estimated to be 120 nc per day. This means a reduction of about 3000-fold, indicating a highly effec- tive barrier mechanism. The amount of radioactivity gradually diminished after the United States and the Soviet Union ceased their atmospheric test programs. Emergency measures for decontaminating essential food items such as milk have been developed. Such procedures use ion-exchange methods to remove radioisotopes (Glascock 1965). The distribution of radioactive fallout in the environment and therefore in foods is nonuniform. The distribution is influenced by latitude; most of the fallout comes down between 30° and 60° latitude (Miettinen Figure 11-6 Pathways of the Transfer of Nuclear Fallout to Humans MAN INGESTION WASTES ANIMALS ANIMAL PRODUCTS FORAGE CROPS IRRIGATION FISH SHELLFISH WATER WATER SOIL PRECIPITATION FALLOUT NUCLEAR TEST AIR EXHALATION 1967). Because the fallout comes down with precipitation, precipitation is a major factor. In addition, uptake by plants is influenced by soil type. Wiechen (1972) found that the 137 Cs content of milk from a small herd of cows averaged 26 pc per kg when the ani- mals grazed on an area of sandy soil but increased to 244 pc/kg when they were trans- ferred to moorland. The primary contamina- tion level of the two soil types was 280 and 262 pc per kg, respectively. The higher trans- fer rate of 137 Cs in the moorland soil-grass- milk chain was the result of the low potas- sium content of this soil (180 mg/kg versus 720 mg/kg in sandy soil) and, to a lesser extent, different mobilities of Cs and K in the various soils. Lindell and Magi (1965) found a general similarity between precipitation distribution and distribution of 137 Cs levels in milk. In Sweden, the lowest levels of the iso- tope 90 Sr were found for the island of Got- land, which has low precipitation and a soil rich in calcium. Johnson and Nayfield (1970) reported a case of true selective concentration of 137 Cs. They found that high levels of 137 Cs in game animals from the southeastern United States resulted from their feeding on mushrooms in wooded areas. Common gill mushrooms (Agaricaceae) from these areas had 137 Cs levels as high as 29,000 pc/kg wet weight, with a mean of 15,741 pc/kg. These elevated levels occurred without similar concentration of potassium-40. White-tailed deer in these regions had 137 Cs levels ranging from 250 to 152,940 pc/kg body weight. The 1986 nuclear reactor accident at Cher- nobyl in the Soviet Union distributed radio- active fallout over most of Western Europe and the rest of the world. In addition to short- term problems with radionuclides of short half-life, there are ongoing concerns in coun- tries far removed from the source of the con- tamination. In the United Kingdom there are concerns over the contamination of sheep, whose levels still exceed the interim limit of 1,000 Bq/kg; bentonite is being used experi- mentally to reduce Cs uptake from grazing. In addition to the Chernobyl accident, there have been nuclear reactor accidents at Windscale in the United Kingdom in 1957 and at Three Mile Island in the United States in 1979. Low-level emissions from nuclear reactor plants apparently are not uncommon. Pesticides Contamination of food with residues of pesticides may result from the application of these chemicals in agricultural, industrial, or household use. Nearly 300 organic pesticides are in use, including insecticides, miticides, nematocides, rodenticides, fungicides, and herbicides. The most likely compounds to appear as food contaminants are insecticides, of which there are two main classes—chlori- nated hydrocarbon insecticides and organo- phosphorous insecticides. The chlorinated hydrocarbon insecticides can be divided into three classes—oxygen- ated compounds, benzenoid nonoxygenated compounds, and nonoxygenated nonben- zenoid compounds (Exhibit 11-3) (Mitchell 1966). In addition to the pesticide com- pounds, there may be residues of their metab- olites, which may be equally toxic. Two important properties of the chlorinated hydro- carbons are their stability, which leads to per- sistence in the environment, and their solubility in fat, which results in their depo- sition and accumulation in fatty tissues. The structure of some of the chlorinated hydro- carbon insecticides is given in Figure 11—7. Aldrin is a technical compound containing about 95 percent of the compound Exhibit 11-3 Classes of Chlorinated Hydrocar- bon Insecticides Class I—Oxygenated Compounds • Chlorobenzilate • Methoxychlor • Dicofol • Neotran • Dieldrin • Ovex • Endosulfan • Sulfenone • Endrin • Tetradifon • Kepone Class II—Benzenoid, Nonoxygenated Compounds • BHC • Perthane • Chlorobenside • TDE • DDT • Zectran • Lindane Class III—Nonoxygenated, Nonben- zenoid Compounds • Aldrin • Mirex • Chlordan • Strobane • Heptachlor • Toxaphene Source: From L.E. Mitchell, Pesticides: Prop- erties and Prognosis, in Organic Pesticides in the Environment, R.F. Gould, ed., 1966, Ameri- can Chemical Society. l,2,3,4,10,10-hexachloro-l,4,4a,5,8,8a-hexa- hydro-exo-1,4-£rafo-exo-5,8-dimethanonaph- thalene. It has a molecular weight of 365, formula C 12 H 8 Cl 6 , and contains 58 percent chlorine. Residues of this compound in ani- mal and plant tissues are converted into dieldrin by epoxidation. The epoxide is the stable form and, thus, it is usual to consider these compounds together. Dieldrin contains about 85 percent of the compound 1, 2, 3, 4, 10, 10-hexachloro-6, 7- epoxy-1, 4, 4a, 5, 6, 7, 8, 8a-octahydro-exo-l, 4-endo-exo-5,8-dimethano-naphthalene (HEOD). It has a molecular weight of 381, formula C 12 H 8 Cl 6 O, and contains 56 percent chlorine. DDT is a technical compound that contains about 70 percent of the active ingre- dient pp'-DDT. In addition, there are other isomers, including op'-DDT, as well as related compounds such as TDE or rhothane. The insecticide pp'-DDT is 1,1,1-trichloro- 2,2-di-(4-chlorophenyl) ethane, formula C 14 H 9 Cl 5 . It has a molecular weight of 334.5 and contains 50 percent chlorine. Residues of DDT in animal tissue are slowly dehydro- chlorinated to pp'-DDE, which may occur at levels of up to 70 percent of the original DDT. It is usual to combine DDT, DDE, and TDE in one figure as "total DDT equiva- lent." Heptachlor contains about 75 percent of 1,4,5,6,7,10,10-heptachloro-4,7,8,9-tetrahyro- 4,7-methyleneindene, formula C 10 H 5 Cl 7 . It has a molecular weight of 373.5 and contains 67 percent chlorine. In animal and plant tis- sues, it epoxidizes to heptachlor epoxide, which is analogous in structure to HEOD (dieldrin). Although relatively stable, the organochlo- rine pesticides undergo a variety of reactions that may result in metabolites that are as toxic or more toxic to mammals than the original compound. An example is the effect of ultraviolet light on DDT (Van Middelem 1966). Under the influence of ultraviolet light and air, 4,4'-dichlorobenzophenone is formed. Without air, 2,3-dichloro-l,l,4,4-tet- rakis-(p-chlorophenyl)-2-butene is formed. The latter may be oxidized to 4,4'-dichlo- robenzophenone (Figure 11-8). In mamma- lian tissue, 2,2-bis (p-chlorophenyl) acetic acid (DDA) is formed by initial dehydrochlo- rination of DDT to DDE, followed by hydrolysis to DDA (Figure 11-9). The organophosphorous insecticides are inhibitors of cholinesterase and, because of their water solubility and volatility, create less of a problem as food contaminants than the chlorinated hydrocarbons. A large num- ber of organophosphorous insecticides are in use; these can act by themselves or after oxi- dative conversions in plants and animals (Exhibit 11-4). The water solubility of these compounds varies widely, as is indicated by Table 11-6. The organophosphorous insecti- cides may be subject to oxidation, hydroly- Figure 11-7 Structure of Some Chlorinated Hydrocarbon Pesticides HEPTACHLOR EPOXIDE HEPTACHLOR pp 1 -DDE pp 1 -DDT ALDRIN DIELDRIN TDE (RHOTHANE) ENDOSULFAN sis, and demethylation (Figure 11-10). Thio- phosphates may be changed to sulfoxides and sulfones in animals and plants. In animal products, chlorinated hydrocar- bon residues are predominantly present in the lipid portion, organophosphates in both lipid and aqueous parts. In plant materials, the residue of chlorinated hydrocarbons are mostly surface bound or absorbed by waxy materials, but some can be translocated to inner parts. Extensive research has demon- strated that processing methods such as washing, blanching, heating, and canning may remove large proportions of pesticide residues (Liska and Stadelman 1969; Farrow et al. 1969). An illustration of the removal of DDT and carbaryl from vegetables by wash- ing, blanching, and canning is given in Fig- ure 11-11. It has been reported (Farrow et al. 1969) that 48 percent of DDT residues on spinach and 91 percent on tomatoes are removed by Figure 11-9 Dehydrochlorination and Hydrolysis of DDT to DDE and DDA in Mammals. Source: From C.H. Van Middelem, Fate and Persistence of Organic Pesticides in the Environment, in Organic Pesticides in the Environment, R.F. Gould, ed., 1966, American Chemical Society. Figure 11-8 Decomposition of DDT by Ultraviolet Light and Air. Source: From C.H. Van Middelem, Fate and Persistence of Organic Pesticides in the Environment, in Organic Pesticides in the Environ- ment, R.F. Gould, ed., 1966, American Chemical Society. UV Light Air Absent UV Light air DOT ooe DOA Exhibit 11-4 Classification of Organophospho- rous Insecticides Aliphatic Derivatives • Butonate • Mevinphos • Demeton • Mipefox • Dichlorvos • Naled • Dimefox • Phorate • Dimethoate • Phosphamidon • Dithiodemeton • Schradan • Ethion • Sulfotepp • Malathion • Tepp • Methyl demeton • Trichlorofon Aromatic (Cyclic) Derivatives • Azinphosmethyl • EPN • Carbophenothion • Fenthion • Diazinon • Methyl parathion • Dicapthon • Parathion • Endothion • Ronnel Source: From L.E. Mitchell, Pesticides: Prop- erties and Prognosis, in Organic Pesticides in the Environment, R.F. Gould, ed., 1966, Ameri- can Chemical Society. washing. Elkins (1989) reported that wash- ing and blanching reduced carbaryl residues on spinach and broccoli by 97 and 98 per- cent, respectively. Washing, blanching, and canning reduced carbaryl pesticides on toma- toes and spinach by 99 percent. Although this pattern of removal generally holds true, Peterson and colleagues (1996) have pointed out that there are exceptions. Pesticides may accumulate in one part of an agricultural product. Friar and Reynolds (1991) reported that baking does not result in a decline in thi- abendazole residues in potatoes, and Elkins Table 11-6 Water Solubilities of Some Organophosphorus Insecticides Insecticide (ppm) Carbophenothion 2 Parathion 24 Azinphosmethyl 33 Diazinon 40 Methyl parathion 50 Phorate 85 Malathion 145 Dichlorvos 1000 Dimethoate 7000 Mevinphos °o Source: From L.E. Mitchell, Pesticides: Properties and Prognosis, in Organic Pesticides in the Environ- ment, R.F. Gould, ed., 1966, American Chemical Soci- ety. et al. (1972) found that thermal processing does not result in a reduction of methoxy- chlor residues on apricots. Sometimes pro- cessing may cause a chemical to degrade, producing a compound that is more toxic than the original one. The dietary intake of pesticide chemicals from foods is well below the acceptable daily intake (ADI) levels set by the FAOAVHO (Table 11-7). In recent years, severe restric- tions on the use of many chlorinated hydro- carbon pesticides have been instituted in many areas. As a result, the intake of these chemicals should further decrease in future years. Dioxin The term dioxin is used to represent two related groups of chlorinated organic com- pounds, polychlorinated dibenzo-/?-dioxins (PCDD) and polychlorinated dibenzofurans Figure 11-10 Oxidation, Hydrolysis, and Demethylation Reactions of Organophosphorous Insecti- cides. Source: From L.E. Mitchell, Pesticides: Properties and Prognosis, in Organic Pesticides in the Environment, R.F. Gould, ed., 1966, American Chemical Society. DDT Tomatoes Green beans Spinach Potatoes CARBARYL Tomatoes Green Beans Spinach Percent removal (dry basis) Figure 11-11 Removal of Pesticides DDT and Carbaryl by Washing, Blanching, and Canning. Source: From R.P. Farrow et al., Canning Operations That Reduce Insecticide Levels in Prepared Foods and in Solid Food Wastes, Residue Rev., Vol. 29, pp. 73-78, 1969. DEMETHYLATlON p- MrTFOPHtNOL DIETHYL THIOPHOSPMATE PARATHIOM HYDROLYSIS PARATHION PARA-OXON OXIDATION (PCDF) (Figure 11-12). A total of eight car- bon atoms in each molecule can carry chlo- rine substitution, which produces 75 possible isomers for PCDD and 135 for PCDF. These compounds are lipophilic, have low volatil- ity, and are extremely stable. They are also very toxic, although the toxicity of each iso- mer may vary widely. These compounds may exhibit acute toxicity, carcinogenicity, and teratogenicity (birth defects). They are ubiq- uitous environmental contaminants and are present in human tissues. PCDD PCDF Figure 11-12 Chemical Structure of Polychlorinated Dibenzo-/?-dioxins (PCDD) and Polychlorinated Dibenzofurans (PCDF) Current value accepted 1969 Meeting Source: From J.R. Wessel, Pesticide Residues in Foods, in Environmental Contaminants in Foods, Special Report No. 9,1972, Cornell University. Table 11-7 Dietary Intake of Pesticide Chemicals Milligrams/Kilogram Body Weight/Day Pesticide Chemical Aldrin-dieldrin Carbaryl DDT, DDE, TDE Lindane Heptachlor-heptachlor epoxide Malathion Parathion Diazinon All chlorinated organics All organophosphates All herbicides WHO-FAO Acceptable Dally Intake 0.0001 0.02 0.01 (0.005) 1 0.012 0.0005 0.02 0.005 0.002 Average 1965-1969 0.00008 0.0005 0.0008 0.00005 0.00003 0.0001 0.00001 0.00001 0.001 0.0002 0.0001 Range (0.00006-0.00013) (None-0.0021) (0.0005-0.0010) (0.00002-0.00007) (0.00002-0.00005) (0.0001-0.0004) (0.000001-0.00001) (0.000001-0.00002) (0.0008-0.0016) (0.00007-0.00025) (0.00005-0.0001) The dioxins are produced as contaminants in the synthesis of certain herbicides and other chlorinated compounds, as a result of combustion and incineration, in the chlorine bleaching of wood pulp for paper making, and in some metallurgical processes (Startin 1991). Dioxins first attracted attention as a contaminant of the herbicide 2,4,5-trichloro- phenoxyacetic acid (2,4,5-T). The particular compound identified was 2,3,7,8-TCDD, which was for some time associated with the name dioxin. This compound was present in substantial concentration in the defoliant "Agent Orange" used by U.S. forces during the war in Vietnam. The various isomers, also known as conge- ners, vary in toxicity with the 2,3,7,8-substi- tuted ones being the most toxic. Humans appear to be less sensitive than other species. Dioxins can be generated from chlorine bleaching of wood pulp in the paper- and cardboard-making process. This can not only lead to environmental contamination but also to incorporation of the dioxins in the paper used for making coffee filters, tea bags, milk cartons, and so forth. Dioxins can migrate into milk from cartons, even if the cartons have a polyethylene plastic coating. Un- bleached coffee filters and cardboard con- tainers have been produced to overcome this problem, and there have also been improve- ments in the production of wood pulp using alternative bleaching agents. The FDA guide- line for dioxin in fish is 25 parts per trillion (Cordle 1981). Dioxin is considered a very potent toxin, but information on harmful effects on humans is controversial. Polychlorinated Biphenyls (PCBs) The PCBs are environmental contaminants that are widely distributed and have been found as residues in foods. PCBs are pre- pared by chlorination of biphenyl, which results in a mixture of isomers that have dif- ferent chlorine contents. In North America, the industrial compounds are known as Aro- clor; these are used industrially as dielectric fluids in transformers, as plasticizers, as heat transfer and hydraulic fluids, and so forth. The widespread industrial use of these com- pounds results in contamination of the envi- ronment through leakages and spills and seepage from garbage dumps. The PCBs may show up on chromatograms at the same time as chlorinated hydrocarbon pesticides. The numbering system used in PCBs and the prevalent substitution pattern are presented in Figure 11-13. Table 11-8 presents infor- mation on commercial Aroclor compounds. In the years prior to 1977 production of PCBs in North America amounted to about 50 million pounds per year. PCBs were first discovered in fish and wildlife in Sweden in 1966, and they can now be found in higher concentrations in fish than organochlorine pesticides (Zitko 1971). PCBs decompose very slowly. It is esti- mated that between 1929 and 1977, about 550 million kg of PCBs were produced in the United States. Production was stopped vol- untarily after a serious poisoning occurred in Japan in 1968. Large amounts are still pre- sent in, for example, transformers and could enter the environment for many years. Fed- eral regulations specify the following limits in foods: 1.5 ppm in milk fat, 1.5 ppm in fat portion of manufactured dairy products, 3 ppm in poultry, and 0.3 ppm in eggs. The tol- erance level for PCB in fish was reduced from 5 to 2 ppm in 1984. Although there has been a good deal of concern about the possi- ble toxicity of PCBs, there is now evidence that PCBs are much less toxic than initially assumed (American Council on Science and Health 1985). [...]... Range (ng/g) 17 -2 3 26 -4 1 20 - 120 11 -1 35 40 -2 6 0 1 2- 110 5- 32 8- 12 227 -1 000 5-1 5 Table 1 1-1 1 Mercury Levels in Atlantic Coast Fish Species Clam Cod Crab Flounder Haddock Herring Lobster Oyster Swordfish Tuna Hg Level Range (ppm) 0. 0 2- 0.11 0. 0 2- 0 .23 0.0 6-0 .15 0.0 7-0 .17 0.0 7-0 .10 0. 0 2- 0.09 0.0 8-0 .20 0. 0 2- 0.14 0. 8 2- 1.00 0.3 3-0 .86 Source: From E.G Bligh, Mercury in Canadian Fish, Can lnst Food Sd Technol... Rundschau 61: 23 7 -2 3 9 Hall, R.L 1975 GRAS: Concept and application Food Technol 29 : 4 8-5 3 Harwig, J., et al 1973 Occurrence of patulin and patulin-producing strains of Penicillium expansum in natural rots of apple in Canada Can Inst Food ScL Technol J 6: 22 -2 5 Havery, D.C., and T Fazio 1985 Human exposure to nitrosamines from foods Food Technol 39, no 1: 8 0-8 3 Homier, B.E 1984 Properties and stability of aspartame... result of industrial pollution Many water supplies contain asbestos fibers, which may become components of foods (especially beverages) An additional source of asbestos fibers may be asbestos filtration Table 1 1-8 Information on Aroclor Preparations Aroclor Aroclor 122 1 Aroclor 123 2 Aroclor 124 2 Aroclor 124 8 Aroclor 125 4 Aroclor 126 0 Aroclor 126 2 Aroclor 126 8 %CI 21 32 42 48 54 60 62 68 Average Number of. .. Science Publishers Ltd Institute of Food Technologists 1975 Naturally occurring toxicants in foods: A scientific status summary J Food Sd W: 21 5 -2 2 2 Institute of Food Technologists 1988 Migration of toxicants, flavors, and odor-active substances from flexible packaging materials to food Food Technol 42, no 7: 9 5-1 02 Johnson, W., and C.L Nayfield 1970 Elevated levels of cesium-137 in common mushrooms (Agaricaceae)... the rule Food Technol 50, no 5: 22 1 -2 2 3 Peterson, M.S., and A.H Johnson 1978 Encyclopedia of food science Westport, CT: AVI Publishing Co Inc Pontefract, R.D 1974 Ingestion of asbestos Can Res Dev.l,nQ 6: 21 Rhee, K.S., and LJ Bratzler 1968 Polycyclic hydrocarbon composition of wood smoke / Food Sci 33: 626 -6 32 Roberts, H.R., and JJ Barone 1983 Biological effects of caffeine History and use Food Technol... 39 3-3 99 Von Borstel, R.W 1983 Biological effects of caffeine Metabolism Food Technol 37, no 9: 4 0-4 7 Wagner, D.A., and S.R Tannenbaum 1985 In vivo formation of n-nitroso compounds Food Technol 39, no 1:8 9-9 0 Wiechen, A 19 72 Cause of the high Cs-137 content of milk from moorland Milchwissenschaft 27 : 82 84 Zabik, M.E., and MJ Zabik 1996 Influence of processing on environmental contaminants in foods Food. .. (ppb) Food Product Beef, chipped Cheese, Gouda Fish Herring Herring (dried) Salmon Sturgeon White Ham Frankfurters Pork roll Benzo Benzo (a )- Benzo (a )- Benzo (e )- (9M)anthracene pyrene pyrene perylene 0.6 2. 8 0.4 1.7 0.5 1.0 1 .2 0.4 1.0 1 .2 1.4 0.8 2. 8 4-MethylFluoranPyrene pyrene thene 3 .2 0.5 2. 6 3.0 1.8 3 .2 2.4 4.6 14.0 6.4 3.1 2. 2 1.8 2. 0 4.4 4.0 11 .2 3.8 2. 5 2. 0 Source: From J.W Howard and T... al and the FEMA Expert Panel 1996 GRAS flavoring substances 17 Food Technol 50, no 10: 7 2- 81 Somers, E., and D.M Smith 1971 Source and occurrence of environmental contaminants Food Cosmet Toxicol.9: 18 5-1 93 Spensley, PC 1970 Mycotoxins Royal Soc Health J 90: 24 8 -2 5 4 Startin, J.R 1991 Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzo furans, and the food chain In Food contaminants: Sources and. .. CT: AVI Publishing Co Chichester, D.F., and RW Tanner 1968 Antimicrobial food additives In Handbook of food additives, ed TE Furia Cleveland, OH: Chemical Rubber Co Clarkson, TW 1971 Epidemiological and experimental aspects of lead and mercury contamination of food Food Cosmet Toxicol 9: 22 9 -2 4 3 Collings, AJ 1971 The metabolism of sodium cyclamate In Sweetness and sweeteners, ed G.G Birch et al London:... treatment of foods Nahrung 12: 79 9-8 04 Gelardi, R.C 1987 The multiple sweetener approach and new sweeteners on the horizon Food Technol 41, no 1: 123 - 124 Glascock, R.F 1965 A pilot plant for the removal of radioactive strontium from milk: An interim report J Soc Dairy Technol 18: 21 1 -2 1 7 Grimmer, G., and A Hildebrand 1965 Content of polycyclic hydrocarbons in different types of vegeta- bles and lettuce . (a)- anthracene 0.4 1.7 0.5 2. 8 Benzo (a)- pyrene 1.0 0.8 3 .2 Benzo (e)- pyrene 1 .2 0.4 1 .2 Benzo (9M)- perylene 1.0 1.4 Fluoran- thene 0.6 2. 8 3.0 1.8 3 .2 2.4 4.6 14.0 6.4 3.1 Pyrene 0.5 2. 6 2. 2 1.8 2. 0 4.4 4.0 11. 2 3.8 2. 5 4-Methyl- pyrene 2. 0 Table . 17 -23 Herring Baltic States 26 -41 Apples United Kingdom 20 - 120 Apples New Zealand 11 -135 Pears Australia 40 -26 0 Tomatoes United Kingdom 12 -110 Potatoes United Kingdom 5- 32 Wheat Sweden 8- 12 Rice. 122 1 Aroclor 123 2 Aroclor 124 2 Aroclor 124 8 Aroclor 125 4 Aroclor 126 0 Aroclor 126 2 Aroclor 126 8 %CI 21 32 42 48 54 60 62 68 Average Number of Cl per Molecule 1.15 2. 04 3.10 3.90 4.96 6.30 6.80 8.70 Average