Stability of DDT in foods and feeds, transformation in cooking and food processing, removal during food and feed processing By
T. E.
ARCHER"'
Contents I. Introduction -----------------------------------------------------II. Stability in foods and feeds ---------------------------------------III. Transformations in cooking and food processing --------------------IV. Removal during food and feed processing --------------------------Summary ------------------------------------------------------------References ------------------------------------------------------------
29 29 30 32 34 35
I. Introduction
Since pesticides are widely used during the production of raw agricultural commodities, it is evident that pesticide residues may exist on these products at the time of harvest. Continuous surveillance of these residues is ongoing in the United States and throughout the world for the protection of the public health. This present discussion is limited to one pesticide, DDT, as to its stability in foods and feeds, transformation during cooking and food processing, and removal from food and feed whenever procedures allow. No exhaustive literature search was initiated; however, the references quoted are the most recent and are examples of research on the subject matter discussed. II. Stability in foods and feeds DDT may appear on food and feeds either by intentional application such as a direct spray or by unintentional contamination such as from drift of nearby applications, rainfall, particulate matter in the atmosphere, surface irrigation water, and many other environmental conditions. Whatever the route of contamination, DDT residues are rather stable and "' Department of Environmental Toxicology, University of California, Davis 95616.
© 1976 by Springer-Verlag New York Inc. F. A. Gunther et al. (eds.), Residue Reviews © Springer Science+Business Media New York 1976
30
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persistent. HELRICH et al. ( 1970) reported that early applications of DDT to lettuce will dissipate to a safe level, but that repeated applications will result in levels in excess of tolerances when the outer leaves are not removed. The California Department of Agriculture (ARCHER 1969) has found DDT residues in such animal feeds as alfalfa products, almond hull meal, apple pomace, grape pomace, and seed screenings. Tomato pomace is also known to contain DDT residues. Ladino clover seed crop screenings field-contaminated with DDT and its analogs were analyzed for these compounds in a composite sample and in 13 separate fractions of the composite sample (ARCHER 1970). The total residue for DDT and its analogs was 20 ppm. The residues were excessively high for use of the plant material as animal feed. Two fractions, representing 29% of the composite sample, contained 74% of the DDT. The fractions were ladino clover chaff which was 19% of the composite and contained 9.1 ppm of DDT and soil which was 10% of the composite and contained 5.8 ppm of DDT. DDT contamination of animal feed grains and forage crops has been discussed by CoLE et al. ( 1966). The DDT residues found by these workers were unintentional contaminants from the pesticides in the environment. ARCHER and CROSBY ( 1967) have also discussed residues of DDT found in field-contaminated alfalfa and the site of the residue on the plant material. It is well known that small quantities of DDT may be found in meat, milk, and poultry products (DuRHAM 1965, RAMSEY 1965). It is also recognized that DDT contained in and ingested with feed may accumulate in animal or poultry body tissues or be excreted in eggs or milk. Many workers have discussed the transfer of DDT from the feed to dairy animals or their milk ( LABEN et al. 1965, LABEN et al. 1966, CROSBY et al. 1967, WILLIAMS et al. 1964, BRowN et al. 1966, Wrrr et al. 1966). Processing raw milk into various products, including pasteurized milk, cream, butter, and cheese, distributed DDT according to the fat content, with its concentration remaining fairly constant in the fat (MANN et al. 1950). A change in structure in DDT occurred during drying of milk into powder but in general the finished products, other than dry whole milk, contained the same amount of insecticides as the raw milk when expressed on a fat basis (LANGLOIS et al. 1964). LISKA et al. ( 1964) have reported on the DDT residues resulting in eggs and tissues of chickens on rations containing low levels of DDT. MARTH ( 1965) has summarized information on residues of chlorinated pesticides in animals and poultry particularly as to the sources of contamination and levels of residues resulting from specific amounts of contamination.
III. Transformations in cooking and food processing Peeling is very effective in reducing residue levels: peaches, pears, apples, carrots, and potatoes are good examples. The ability of bases
Removal of DDT from foods and feeds
31
(GuNTHER 1947) and certain metallic ions such as iron (FLENNER 1946, GuNTHER 1947, LoRD 1948) to catalyze the decomposition of DDT could provide an avenue for changes in DDT residues during food processing. The baking of Hour into bread or cake removes a large proportion of DDT from cereal products processed into Hour (LEGGIER! 1950, ZEUMER and NEUHAUS 1953). This probably is due to pesticide volatilization; the bread crust was found to contain less than the center of the loaf, and cakes baked at lower temperatures retained more residues (LEGGIER! 1950). The effect of cooking on the DDT content of beef (CARTER 1948, CARTER et al. 1948) did not reduce the DDT levels substantially, although frying may have some effect. However, the trimming or removal of fat from the flesh represents a practical means of eliminating a major portion of the pesticide contaminant. Cooking methods and heating effects on DDT in chicken tissues have been discussed by RITCHEY et al. ( 1969). The tissue was cooked by baking, frying, steaming, and heating in closed containers. The amounts of DDT calculated on a dry-weight basis decreased during the cooking and heating operations. The concentration of DDE present remained fairly constant, but the TDE ( DDD) increased as the tissues were heated indicating that DDT was converted to TDE during the heating. However, the greatest losses occurred because of laaching rather than because of heat. Relatively high amounts of DDT, DDE, and TDE were found in the fat drippings. Comparison of the total amounts of residues occurred in those cooking procedures in which there were losses through leaching of fat. Observations have been made that DDT converts in part to TDE during canning at 250°F ( 121 oc) (FARROW et al. 1966). The conversion has been observed in spinach processed in plain tin plate, enameled tin plate, and glass containers. The TDE is evidently further decomposed to products not registered by the analytical methods ordinarily employed for organochlorine pesticides. Canning operations that reduce insecticide levels in prepared foods and in solid food wastes have been discussed (FARROW et al. 1969 a and b, ELKINS et al. 1968, LAMB et al. 1968 a, LISKA and STADELMAN 1969). Commercial canning operations often substantially reduce the level of pesticide residues remaining on the finished food product. Washing removes loose surface residues and major portions of polar compounds. Hot-water blanching increases pesticide removal and may hydrolyze substantial fractions of nonpersistent compounds; steam blanching is less effective. ~onpolar pesticides are frequently held tenaciously in the waxy layers of the peel of fruits and vegetables. Peeling and juice extraction operations usually result in almost complete removal of DDT. The pesticide remains in the solid waste resulting from these procedures. Thermal processing necessary to preserve low-acid foods results in the partial destruction of DDT. DDT is resistant to decomposition by composting of solid wastes resulting from peeling and screening operations.
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Potatoes grown in soil treated over a five-year period with DDT were harvested and prepared for serving by commercial canning and home preparative procedures (LAMB et al. 1968 b). Low concentrations of o,p'-DDT, p,p'-DDT, and p,p'-DDE were present at harvest. Commercial washing operations removed about 20% of the total DDT residue from potatoes and lye peeling plus washing removed about 94%. Commercial processing further reduced the residue to insignificant levels. During home preparative procedures, peeling removed more than 91% of the residue. There was no significant decrease from the original residue when potatoes with skins were boiled or pressure-cooked. BALDWIN et al. ( 1968) found that of the precooking treatments for apples, washing appeared to have little effect on the DDT and related residues, whereas washing, paring, and coring resulted in a marked reduction in the total pesticide residue. Cooking further reduced these residues. VIEL et al. ( 1966) washed apricots with a solution of water containing 0.0125% oxyethylenated oleocetyl alcohol and reduced the DDT residues by 28.5%. SAHA et al. ( 1970), studied the effects of simulated commercial vegetable oil processing techniques on the removal of DDT residues in rapeseed oil. Alkali-refining and bleaching had little or no effect on DDT in the oil. Deodorization of the oil by heating it in the presence of water vapor at 230° to 260°C and 6 mm of Hg for 4 hr removed 95 to 99% of the residue. Crude soybean and cottonseed oil were processed using simulated commercial processing procedures to determine if oil processing would remove chlorinated pesticide contaminants of either natural or fortified origin (SMITH et al. 1969). Representative samples of crude oil and products following each processing step were analyzed for pesticide contamination. Results indicated that alkali-refining or subsequent bleaching did not reduce chlorinated pesticide contamination. Deodorization, with or without hydrogenation, eliminated chlorinated pesticides. The results of this study indicate that normal commercial processing of crude vegetable oils for human consumption effectively removes any chlorinated pesticides which may be present in crude oils. It is hypothesized that chlorinated pesticide removal is achieved by volatilization during deodorization, which is supported by known volatilization characteristics, similarity of behavior in the pesticides studied, and absence of the pesticide or its conversion products in the finished oils, or both. IV. Removal during food and feed processing Several compounds have been fed to animals contaminated with organochlorine compound residues to increase intentionally the rate of elimination from the animals. These compounds were mineral oil, animal and vegetable fat, calcium salts, bentonite, ethoxyquin, thyroprotein, and vitamins A, D, and E. The effects of high-energy or low-energy rations on pesticide excretion have also been studied (MILLER 1967). Some of
Removal of DDT from foods and feeds
33
these materials helped to remove pesticides but the effects were not dramatic. A method (CooK and WILSON 1971) that is effective as an antidote for pesticide poisoning in cattle is a combination of activated carbon and phenobarbital feeding; this method proved successful in a large-scale field trial. Milk-drying processes at elevated temperatures remove substantial amounts of some persistent organochlorine insecticides ( STEMP and LISKA 1966, McCASKEY and LISKA 1967). These removals are primarily the result of codistillation with water vapor. Evaporated milk contained a higher proportion of residues while residues in condensed milk were only slightly lower than those in whole milk. Direct steam injection under a partial vacuum, a process for expelling volatile off-flavors, removed only small proportions of DDT from milk ( STEMP and LISKA 1966, LEDFORD et al. 1968). Ultraviolet light irradiation has been reported to lower some organochlorine residues in milk ( LI and BnADLEY 1967). A single irradiation of milk that was flowing over a surface cooler reduced the DDT content by 17% . STREET ( 1969) has recently completed a review of methods for the removal of pesticide residues from various plant and animal products as well as water and soils. Degradation of organochlorine pesticides with hydrogen peroxide has been studied ( HEKMA TI and BRADLEY 1971). When equal volumes of a 5 ppm solution of pesticide in 95% ethanol were mixed with a 0.06% solution of hydrogen peroxide at ambient temperatures, DDT was degraded 34%, DDE 4%, and TDE 0%. When 150 ml of pasteurized whole milk were contaminated with 10 ppm of a pesticide and when hydrogen peroxide was added to 0.03% and the mixture was stirred for 15 minutes, DDT was degraded 33.3%. The degradation of DDT and ODE by cheese has been reported (LEDFORD and CHEN 1969). After incubation for ten days, streptococci, micrococci, yeasts, and gram-positive rods isolated from several varieties of surface-ripened cheese were studied for degradation of 0.5 ppm of p,p'DDT and p,p'-DDE. Streptococci and micrococci did not alter the pesticide levels, and growth of the organisms was not inhibited by the pesticides. Brevilacterium linens cultures decreased the ODE and DDT concentrations and increased the amount of TDE. Geotrichum isolates reduced the level of both DDT and DDE significantly. Degradation by Geotrichum isolates was observed over a pH range of 5.5 to 8.5, with more degradation being observed at pH 8.5 than at 5.5. DDT and DDE degradation by Brevibacterium and Geotrichum may be present in certain types of surface-ripened cheeses. The intentional removal or decontamination of pesticides in such animal feeds as alfalfa hay, almond hull meal, and seed crop screenings has been reported (ARCHER and CROSBY 1969). Physical and chemical treatments of the feeds were investigated such as hot and cold water washing, organic solvent washing, warm air treatment with and without excess moisture, solvent vapor treatments, hot chemical washings, and
34
T. E.
ARCHER
commercial procedures for dehydration. When alfalfa green chops was rapidly dehydrated at inlet temperatures of 760° to 1,000°C and an outlet temperature of 127°C for 3 to 5 min in a revolving drum-type dehydrator, approximately 50% of the DDT and related organochlorine compound residues were removed. Oven heat removed approximately 34% of the residues of DDT and related organochlorine insecticides from alfalfa feeds containing 16.5% moisture. When the samples were saturated with water, removal increased to 86%. The same residues were removed almost completely by the vapors of various common solvents (water 86%, isopropyl alcohol 93%, benzene 97%, and pentane 73% (ARCHER and CROSBY 1968). The effect of ultraviolet light on DDT residues or alfalfa hay was reported by ARCHER ( 1969). Alfalfa containing high levels of DDT was air-dried in the dark, dried in sunlight, and dried under ultraviolet lamps. No changes occurred to the DDT in the dark treatment, except 49% of the original residue was lost during the drying process. On the fourth day of an ll-day exposure to ultraviolet lamps ( 2,537 A), TDE was formed from the DDT, but no change occurred with the DDE present; 67% of the total original residue was lost during the drying process. On the sixth day of the sunlight treatment, TDE was formed from the DDT, but no change occurred with the DDE present and 72% of the total original residue was lost during the drying process. Although at the time of harvest most foods and feeds may contain residues of DDT and related organochlorine pesticides, certain effects are produced on these residues during processing for consumption. Generally the residues are stable and persistent on the raw agricultural products; however, commercial and home preparative procedures either remove completely or decrease the DDT content in the processed materials. Heat, catalytic effects, pH, and other physical-chemical influences produce changes in these DDT residues so that either the pesticide is removed by volatilization, washing, or peeling or is degraded to innocuous or less toxic materials. These effects produce changes which makes the processed materials better marketable commodities. Summary DDT residues may be found in many sources of food and animal feeds. Although these residues may be of low levels, under certain conditions they can be persistent and stable. Specific commercial and home-preparative conditions can reduce and produce changes in the DDT levels present on most commodities. Several processes and procedures have been developed for the intentional removal or decontamination of DDT and other organochlorine compound residues on marketable human foods and animal feeds. Generally, these products are considered safe for human or animal consumption although it is extremely difficult to predict the effect of long-term exposure to even small amounts of pesticides.
Removal of DDT from foods and feeds
35
References ARCHER, T. E.: DDT and related chlorinated hydrocarbon residues on alfalfa hay exposed to drying by sunlight, ultraviolet light and air. J. Dairy Sci. 52, 1806 (1969). - - Toxaphene and DDT residues in ladino clover seed screenings. Pest. Monit. J, 4, 27 (1970). - - , and D. G. CROSBY: Extraction and location of selective chlorinated hydrocarbon residues in alfalfa hay. Bull. Envir. Contam. Toxicol. 2, 191 ( 1967). - - - - Removal of DDT and related chlorinated hydrocarbon residues from alfalfa hay. J. Agr. Food Chern. 16,623 (1968). - - - - The decontamination of animal feeds. Residue Reviews 29, 13 ( 1969). BALDWIN, R. E., K. G. SIDES, and D. D. HEMPHILL: DDT and its derivatives in apples as affected by preparation procedures; A pilot study. Food Technol. 22, 1460 (1968). BROWN, W. H., J. M. Wrrr, F. M. WHITING, and J. W. STULL: Secretion of DDT in milk by fresh cows. Bull. Environ. Con tam. Toxicol. 1, 21 ( 1966). CARTER, R. H.: DDT residues in agricultural products. Ind. Eng. Chern. 40, 716 (1948). - - , P. E. HuBANKS, H. D. MANN, L. M. ALEXANDER, and G. E. ScHOPMEYER: Effect of cooking on the DDT content of beef. Science 107, 347 (1948 ) . COLE, H., D. BARRY, and D. E. H. FREAR: DDT contamination of feed grains and forages in Pennsylvania. Bull. Envir. Contam. Toxicol. 1, 212 ( 1966). CooK, R. M., and K. A. WILSON: Removal of parathion residues from dairy cattle. J. Dairy Sci. 54, 712 ( 1971). CROSBY, D. G., T. E. ARCHER, and R. C. LABEN: DDT contamination in milk following a single feeding exposure. J. Dairy Sci. 50, 40 ( 1967 ) . DuRHAM, W. F., J. F. ARMSTRONG, and G. E. QUINBY: DDT and DDE content of complete prepared meals. Arch. Environ. Health 11, 641 ( 1965). ELKINS, E. R., F. C. LAMB, R. P. FARROW, R. W. CooK, M. KAWAI, and J. R. KIMBALL: Removal of DDT, malathion, and carbaryl from green beans by commercial and home preparative procedures. J. Agr. Food Chern. 16, 962 ( 1968). FARROW, R. P., E. R. ELKINS, JR., and R. W. CooK: Conversion of DDT to TDE in canned spinach. J. Agr. Food Chern. 14, 430 (1966). - - , E. R. ELKINS, W. W. RosE, F. C. LAMB, J. W. RALLS, and W. A. MERCER: Canning operations that reduce insecticide levels in prepared foods and in solid food wastes. Residue Reviews 29, 73 ( 1969 a). - - , F. C. LAMB, R. W. CooK, J. R. KIMBALL, and E. R. ELKINS: Removal of DDT, malathion, and carbaryl from tomatoes by commercial and home preparative methods. J. Agr. Food Chern. 16,65 (1969 b). FLENNER, A. L.: Catalytic decomposition of DDT. J. Amer. Chern. Soc. 68, 2399 (1946). GUNTHER, F. A.: Thermal decomposition of DDT and benzene hexachloride mixtures. J. Econ. Entomol. 40,874 (1947). HEKMATI, M., and R. L. BRADLEY, JR.: Degradation of organochlorine pesticides with hydrogen peroxide. Milchwissenschaft 26, 224 ( 1971). HELRICH, K., S. RACE, and J. REED: DDT residue disappearance from field sprayed lettuce. Bull. Envir. Contam. Toxicol. 5, 30 ( 1970). LABEN, R. C., T. E. ARcHER, D. G. CROSBY, and S. A. PEOPLES: Lactational output of DDT fed prepartum to dairy cattle. J. Dairy Sci. 48, 701 ( 1965). - - - - - - - - Milk contamination from low levels of DDT in dairy rations. J. Dairy Sci. 49, 1488 ( 1966 ) . LAMB, F. C., R. P. FARROW, E. R. ELKINS, J. R. KIMBALL, and R. W. CooK: Removal of DDT, parathion, and carbaryl from spinach by commercial home preparative methods. J. Agr. Food Chern. 16, 967 (1968 a).
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- - - - - - , R. W. CooK, and J. R. KIMBALL: Behavior of DDT in potatoes during commercial and home preparation. J. Agr. Food Chern. 16, 272 ( 1968 b). LANGLOIS, B. E., B. J. LISKA, and D. L. HILL: Effects of processing and storage of dairy products on chlorinated insecticide residues. J. Milk Techno!. 27, 264 ( 1964). LEDFORD, R. A., and J. H. CHEN: Degradation of DDT and DDE by cheese microorganisms. J. Food Sci. 34, 386 ( 1969). - - - - , and W. F. SHIPE: Effect of direct steam heating and vacuum treatment on levels of pesticide residues in milk. J. Dairy Sci. 51, 219 (1968). LEGGIER!, G.: DDT in bread and cakes made with disinfected flour. Ricerca Scientifica 20, 478 ( 1950). LI, C. F., and R. L. BRADLEY, JR.: Degradation of chlorinated hydrocarbon in fluid milk systems by ultraviolet light. J. Dairy Sci. 50, 944 ( 1967). LisKA, B. J., and W. J. STADELMAN: Effects of processing on pesticides in foods. Residue Reviews 29, 61 ( 1969). - - , B. E. LANGLOIS, G. C. MosTERT, and W. J. STADELMAN: Residues in eggs and tissues of chickens on rations containing low levels of DDT. Poultry Sci. 43, 982 (1964). LoRD, K. A.: Decomposition of DDT by basic substances. J. Amer. Chem. Soc. 42, 1657 ( 1948). MANN, H. D., R. H. CARTER, and R. E. ELY: The DDT content of milk products. J. Milk Food Techno!. 13, 340 ( 1950). MARTH, E. H.: Residues and some effects of some chlorinated hydrocarbon insecticides in biological materials. Residue Reviews 9, 1 ( 1965). McCASKEY, T. A., and B. J. LisKA: Effect of milk processing methods on endosulfan, endosulfan sulfate and chlordane residues in milk. J. Dairy Sci. 50, 1991 (1967). MILLER, D. D.: Effect of thyroprotein and a low-energy ration on removal of DDT from lactating dairy cows. J. Dairy Sci. 50, 1444 (1967). RAMSEY, D. S.: Facing the pesticide problem. Assoc. S. Agr. Workers Proc. 62, 118 (1965). RITCHEY, S. J., W. R. YouNG, and E. 0. EssARY: Cooking methods and heating effects on DDT in chicken tissues. J. Food Sci. 34, 569 ( 1969). SAHA, J. G., M. A. NIELSEN, and A. K. SuMNER: Effect of commercial processing techniques on lindane and DDT-14-C residues in rapeseed oil. J. Agr. Food Chern. 18, 43 ( 1970). SMITH, K. J., P. B. POLEN, D. M. DEVRIES, and F. B. CooN: Removal of chlorinated pesticides from crude vegetable oils by simulated commercial procedures. J. Amer. Oil Chemists Soc. 45, 866 ( 1969). STEMP, A. R., and B. J. LISKA: Effects of processing and storage of dairy products on telodrin and methoxychlor residues. J. Dairy Sci. 49, 1006 ( 1966). STREET, J. C.: Methods of removal of pesticide residues. Canad. Med. Assoc. J. 100, 154 ( 1969). VIEL, G., M. HAsCOET, and G. DuBROCA: The elimination of pesticide residues on apricots by washing before canning. Phytiat.-Phytopharm. 15, 41 ( 1966). WILLIAMS, S., P. A. MILLS, and R. E. McDOWELL: Residues in milk of cows fed rations containing low concentrations of five chlorinated hydrocarbon pesticides. J. Assoc. Official Agr. Chemists 47, 1124 ( 1964). WITT, J. M., W. H. BROWN, G. I. SHAW, L. S. MAYNARD, L. M. SuLLIVAN, F. M. WHITING, and J. W. STULL: Rate of transfer of DDT from the blood compartment. Bull. Environ. Contam. Toxicol. 1, 187 ( 1966). ZEUMER, H., and K. NEUHAus: The determination of contact insecticides. Getreide und Mehl3, 57 (1953). Manuscript received April 4, 1974; accepted May 9, 1975.
T. E.
ARCHER"'
Contents I. Introduction -----------------------------------------------------II. Stability in foods and feeds ---------------------------------------III. Transformations in cooking and food processing --------------------IV. Removal during food and feed processing --------------------------Summary ------------------------------------------------------------References ------------------------------------------------------------
29 29 30 32 34 35
I. Introduction
Since pesticides are widely used during the production of raw agricultural commodities, it is evident that pesticide residues may exist on these products at the time of harvest. Continuous surveillance of these residues is ongoing in the United States and throughout the world for the protection of the public health. This present discussion is limited to one pesticide, DDT, as to its stability in foods and feeds, transformation during cooking and food processing, and removal from food and feed whenever procedures allow. No exhaustive literature search was initiated; however, the references quoted are the most recent and are examples of research on the subject matter discussed. II. Stability in foods and feeds DDT may appear on food and feeds either by intentional application such as a direct spray or by unintentional contamination such as from drift of nearby applications, rainfall, particulate matter in the atmosphere, surface irrigation water, and many other environmental conditions. Whatever the route of contamination, DDT residues are rather stable and "' Department of Environmental Toxicology, University of California, Davis 95616.
© 1976 by Springer-Verlag New York Inc. F. A. Gunther et al. (eds.), Residue Reviews © Springer Science+Business Media New York 1976
30
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ARCHER
persistent. HELRICH et al. ( 1970) reported that early applications of DDT to lettuce will dissipate to a safe level, but that repeated applications will result in levels in excess of tolerances when the outer leaves are not removed. The California Department of Agriculture (ARCHER 1969) has found DDT residues in such animal feeds as alfalfa products, almond hull meal, apple pomace, grape pomace, and seed screenings. Tomato pomace is also known to contain DDT residues. Ladino clover seed crop screenings field-contaminated with DDT and its analogs were analyzed for these compounds in a composite sample and in 13 separate fractions of the composite sample (ARCHER 1970). The total residue for DDT and its analogs was 20 ppm. The residues were excessively high for use of the plant material as animal feed. Two fractions, representing 29% of the composite sample, contained 74% of the DDT. The fractions were ladino clover chaff which was 19% of the composite and contained 9.1 ppm of DDT and soil which was 10% of the composite and contained 5.8 ppm of DDT. DDT contamination of animal feed grains and forage crops has been discussed by CoLE et al. ( 1966). The DDT residues found by these workers were unintentional contaminants from the pesticides in the environment. ARCHER and CROSBY ( 1967) have also discussed residues of DDT found in field-contaminated alfalfa and the site of the residue on the plant material. It is well known that small quantities of DDT may be found in meat, milk, and poultry products (DuRHAM 1965, RAMSEY 1965). It is also recognized that DDT contained in and ingested with feed may accumulate in animal or poultry body tissues or be excreted in eggs or milk. Many workers have discussed the transfer of DDT from the feed to dairy animals or their milk ( LABEN et al. 1965, LABEN et al. 1966, CROSBY et al. 1967, WILLIAMS et al. 1964, BRowN et al. 1966, Wrrr et al. 1966). Processing raw milk into various products, including pasteurized milk, cream, butter, and cheese, distributed DDT according to the fat content, with its concentration remaining fairly constant in the fat (MANN et al. 1950). A change in structure in DDT occurred during drying of milk into powder but in general the finished products, other than dry whole milk, contained the same amount of insecticides as the raw milk when expressed on a fat basis (LANGLOIS et al. 1964). LISKA et al. ( 1964) have reported on the DDT residues resulting in eggs and tissues of chickens on rations containing low levels of DDT. MARTH ( 1965) has summarized information on residues of chlorinated pesticides in animals and poultry particularly as to the sources of contamination and levels of residues resulting from specific amounts of contamination.
III. Transformations in cooking and food processing Peeling is very effective in reducing residue levels: peaches, pears, apples, carrots, and potatoes are good examples. The ability of bases
Removal of DDT from foods and feeds
31
(GuNTHER 1947) and certain metallic ions such as iron (FLENNER 1946, GuNTHER 1947, LoRD 1948) to catalyze the decomposition of DDT could provide an avenue for changes in DDT residues during food processing. The baking of Hour into bread or cake removes a large proportion of DDT from cereal products processed into Hour (LEGGIER! 1950, ZEUMER and NEUHAUS 1953). This probably is due to pesticide volatilization; the bread crust was found to contain less than the center of the loaf, and cakes baked at lower temperatures retained more residues (LEGGIER! 1950). The effect of cooking on the DDT content of beef (CARTER 1948, CARTER et al. 1948) did not reduce the DDT levels substantially, although frying may have some effect. However, the trimming or removal of fat from the flesh represents a practical means of eliminating a major portion of the pesticide contaminant. Cooking methods and heating effects on DDT in chicken tissues have been discussed by RITCHEY et al. ( 1969). The tissue was cooked by baking, frying, steaming, and heating in closed containers. The amounts of DDT calculated on a dry-weight basis decreased during the cooking and heating operations. The concentration of DDE present remained fairly constant, but the TDE ( DDD) increased as the tissues were heated indicating that DDT was converted to TDE during the heating. However, the greatest losses occurred because of laaching rather than because of heat. Relatively high amounts of DDT, DDE, and TDE were found in the fat drippings. Comparison of the total amounts of residues occurred in those cooking procedures in which there were losses through leaching of fat. Observations have been made that DDT converts in part to TDE during canning at 250°F ( 121 oc) (FARROW et al. 1966). The conversion has been observed in spinach processed in plain tin plate, enameled tin plate, and glass containers. The TDE is evidently further decomposed to products not registered by the analytical methods ordinarily employed for organochlorine pesticides. Canning operations that reduce insecticide levels in prepared foods and in solid food wastes have been discussed (FARROW et al. 1969 a and b, ELKINS et al. 1968, LAMB et al. 1968 a, LISKA and STADELMAN 1969). Commercial canning operations often substantially reduce the level of pesticide residues remaining on the finished food product. Washing removes loose surface residues and major portions of polar compounds. Hot-water blanching increases pesticide removal and may hydrolyze substantial fractions of nonpersistent compounds; steam blanching is less effective. ~onpolar pesticides are frequently held tenaciously in the waxy layers of the peel of fruits and vegetables. Peeling and juice extraction operations usually result in almost complete removal of DDT. The pesticide remains in the solid waste resulting from these procedures. Thermal processing necessary to preserve low-acid foods results in the partial destruction of DDT. DDT is resistant to decomposition by composting of solid wastes resulting from peeling and screening operations.
32
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Potatoes grown in soil treated over a five-year period with DDT were harvested and prepared for serving by commercial canning and home preparative procedures (LAMB et al. 1968 b). Low concentrations of o,p'-DDT, p,p'-DDT, and p,p'-DDE were present at harvest. Commercial washing operations removed about 20% of the total DDT residue from potatoes and lye peeling plus washing removed about 94%. Commercial processing further reduced the residue to insignificant levels. During home preparative procedures, peeling removed more than 91% of the residue. There was no significant decrease from the original residue when potatoes with skins were boiled or pressure-cooked. BALDWIN et al. ( 1968) found that of the precooking treatments for apples, washing appeared to have little effect on the DDT and related residues, whereas washing, paring, and coring resulted in a marked reduction in the total pesticide residue. Cooking further reduced these residues. VIEL et al. ( 1966) washed apricots with a solution of water containing 0.0125% oxyethylenated oleocetyl alcohol and reduced the DDT residues by 28.5%. SAHA et al. ( 1970), studied the effects of simulated commercial vegetable oil processing techniques on the removal of DDT residues in rapeseed oil. Alkali-refining and bleaching had little or no effect on DDT in the oil. Deodorization of the oil by heating it in the presence of water vapor at 230° to 260°C and 6 mm of Hg for 4 hr removed 95 to 99% of the residue. Crude soybean and cottonseed oil were processed using simulated commercial processing procedures to determine if oil processing would remove chlorinated pesticide contaminants of either natural or fortified origin (SMITH et al. 1969). Representative samples of crude oil and products following each processing step were analyzed for pesticide contamination. Results indicated that alkali-refining or subsequent bleaching did not reduce chlorinated pesticide contamination. Deodorization, with or without hydrogenation, eliminated chlorinated pesticides. The results of this study indicate that normal commercial processing of crude vegetable oils for human consumption effectively removes any chlorinated pesticides which may be present in crude oils. It is hypothesized that chlorinated pesticide removal is achieved by volatilization during deodorization, which is supported by known volatilization characteristics, similarity of behavior in the pesticides studied, and absence of the pesticide or its conversion products in the finished oils, or both. IV. Removal during food and feed processing Several compounds have been fed to animals contaminated with organochlorine compound residues to increase intentionally the rate of elimination from the animals. These compounds were mineral oil, animal and vegetable fat, calcium salts, bentonite, ethoxyquin, thyroprotein, and vitamins A, D, and E. The effects of high-energy or low-energy rations on pesticide excretion have also been studied (MILLER 1967). Some of
Removal of DDT from foods and feeds
33
these materials helped to remove pesticides but the effects were not dramatic. A method (CooK and WILSON 1971) that is effective as an antidote for pesticide poisoning in cattle is a combination of activated carbon and phenobarbital feeding; this method proved successful in a large-scale field trial. Milk-drying processes at elevated temperatures remove substantial amounts of some persistent organochlorine insecticides ( STEMP and LISKA 1966, McCASKEY and LISKA 1967). These removals are primarily the result of codistillation with water vapor. Evaporated milk contained a higher proportion of residues while residues in condensed milk were only slightly lower than those in whole milk. Direct steam injection under a partial vacuum, a process for expelling volatile off-flavors, removed only small proportions of DDT from milk ( STEMP and LISKA 1966, LEDFORD et al. 1968). Ultraviolet light irradiation has been reported to lower some organochlorine residues in milk ( LI and BnADLEY 1967). A single irradiation of milk that was flowing over a surface cooler reduced the DDT content by 17% . STREET ( 1969) has recently completed a review of methods for the removal of pesticide residues from various plant and animal products as well as water and soils. Degradation of organochlorine pesticides with hydrogen peroxide has been studied ( HEKMA TI and BRADLEY 1971). When equal volumes of a 5 ppm solution of pesticide in 95% ethanol were mixed with a 0.06% solution of hydrogen peroxide at ambient temperatures, DDT was degraded 34%, DDE 4%, and TDE 0%. When 150 ml of pasteurized whole milk were contaminated with 10 ppm of a pesticide and when hydrogen peroxide was added to 0.03% and the mixture was stirred for 15 minutes, DDT was degraded 33.3%. The degradation of DDT and ODE by cheese has been reported (LEDFORD and CHEN 1969). After incubation for ten days, streptococci, micrococci, yeasts, and gram-positive rods isolated from several varieties of surface-ripened cheese were studied for degradation of 0.5 ppm of p,p'DDT and p,p'-DDE. Streptococci and micrococci did not alter the pesticide levels, and growth of the organisms was not inhibited by the pesticides. Brevilacterium linens cultures decreased the ODE and DDT concentrations and increased the amount of TDE. Geotrichum isolates reduced the level of both DDT and DDE significantly. Degradation by Geotrichum isolates was observed over a pH range of 5.5 to 8.5, with more degradation being observed at pH 8.5 than at 5.5. DDT and DDE degradation by Brevibacterium and Geotrichum may be present in certain types of surface-ripened cheeses. The intentional removal or decontamination of pesticides in such animal feeds as alfalfa hay, almond hull meal, and seed crop screenings has been reported (ARCHER and CROSBY 1969). Physical and chemical treatments of the feeds were investigated such as hot and cold water washing, organic solvent washing, warm air treatment with and without excess moisture, solvent vapor treatments, hot chemical washings, and
34
T. E.
ARCHER
commercial procedures for dehydration. When alfalfa green chops was rapidly dehydrated at inlet temperatures of 760° to 1,000°C and an outlet temperature of 127°C for 3 to 5 min in a revolving drum-type dehydrator, approximately 50% of the DDT and related organochlorine compound residues were removed. Oven heat removed approximately 34% of the residues of DDT and related organochlorine insecticides from alfalfa feeds containing 16.5% moisture. When the samples were saturated with water, removal increased to 86%. The same residues were removed almost completely by the vapors of various common solvents (water 86%, isopropyl alcohol 93%, benzene 97%, and pentane 73% (ARCHER and CROSBY 1968). The effect of ultraviolet light on DDT residues or alfalfa hay was reported by ARCHER ( 1969). Alfalfa containing high levels of DDT was air-dried in the dark, dried in sunlight, and dried under ultraviolet lamps. No changes occurred to the DDT in the dark treatment, except 49% of the original residue was lost during the drying process. On the fourth day of an ll-day exposure to ultraviolet lamps ( 2,537 A), TDE was formed from the DDT, but no change occurred with the DDE present; 67% of the total original residue was lost during the drying process. On the sixth day of the sunlight treatment, TDE was formed from the DDT, but no change occurred with the DDE present and 72% of the total original residue was lost during the drying process. Although at the time of harvest most foods and feeds may contain residues of DDT and related organochlorine pesticides, certain effects are produced on these residues during processing for consumption. Generally the residues are stable and persistent on the raw agricultural products; however, commercial and home preparative procedures either remove completely or decrease the DDT content in the processed materials. Heat, catalytic effects, pH, and other physical-chemical influences produce changes in these DDT residues so that either the pesticide is removed by volatilization, washing, or peeling or is degraded to innocuous or less toxic materials. These effects produce changes which makes the processed materials better marketable commodities. Summary DDT residues may be found in many sources of food and animal feeds. Although these residues may be of low levels, under certain conditions they can be persistent and stable. Specific commercial and home-preparative conditions can reduce and produce changes in the DDT levels present on most commodities. Several processes and procedures have been developed for the intentional removal or decontamination of DDT and other organochlorine compound residues on marketable human foods and animal feeds. Generally, these products are considered safe for human or animal consumption although it is extremely difficult to predict the effect of long-term exposure to even small amounts of pesticides.
Removal of DDT from foods and feeds
35
References ARCHER, T. E.: DDT and related chlorinated hydrocarbon residues on alfalfa hay exposed to drying by sunlight, ultraviolet light and air. J. Dairy Sci. 52, 1806 (1969). - - Toxaphene and DDT residues in ladino clover seed screenings. Pest. Monit. J, 4, 27 (1970). - - , and D. G. CROSBY: Extraction and location of selective chlorinated hydrocarbon residues in alfalfa hay. Bull. Envir. Contam. Toxicol. 2, 191 ( 1967). - - - - Removal of DDT and related chlorinated hydrocarbon residues from alfalfa hay. J. Agr. Food Chern. 16,623 (1968). - - - - The decontamination of animal feeds. Residue Reviews 29, 13 ( 1969). BALDWIN, R. E., K. G. SIDES, and D. D. HEMPHILL: DDT and its derivatives in apples as affected by preparation procedures; A pilot study. Food Technol. 22, 1460 (1968). BROWN, W. H., J. M. Wrrr, F. M. WHITING, and J. W. STULL: Secretion of DDT in milk by fresh cows. Bull. Environ. Con tam. Toxicol. 1, 21 ( 1966). CARTER, R. H.: DDT residues in agricultural products. Ind. Eng. Chern. 40, 716 (1948). - - , P. E. HuBANKS, H. D. MANN, L. M. ALEXANDER, and G. E. ScHOPMEYER: Effect of cooking on the DDT content of beef. Science 107, 347 (1948 ) . COLE, H., D. BARRY, and D. E. H. FREAR: DDT contamination of feed grains and forages in Pennsylvania. Bull. Envir. Contam. Toxicol. 1, 212 ( 1966). CooK, R. M., and K. A. WILSON: Removal of parathion residues from dairy cattle. J. Dairy Sci. 54, 712 ( 1971). CROSBY, D. G., T. E. ARCHER, and R. C. LABEN: DDT contamination in milk following a single feeding exposure. J. Dairy Sci. 50, 40 ( 1967 ) . DuRHAM, W. F., J. F. ARMSTRONG, and G. E. QUINBY: DDT and DDE content of complete prepared meals. Arch. Environ. Health 11, 641 ( 1965). ELKINS, E. R., F. C. LAMB, R. P. FARROW, R. W. CooK, M. KAWAI, and J. R. KIMBALL: Removal of DDT, malathion, and carbaryl from green beans by commercial and home preparative procedures. J. Agr. Food Chern. 16, 962 ( 1968). FARROW, R. P., E. R. ELKINS, JR., and R. W. CooK: Conversion of DDT to TDE in canned spinach. J. Agr. Food Chern. 14, 430 (1966). - - , E. R. ELKINS, W. W. RosE, F. C. LAMB, J. W. RALLS, and W. A. MERCER: Canning operations that reduce insecticide levels in prepared foods and in solid food wastes. Residue Reviews 29, 73 ( 1969 a). - - , F. C. LAMB, R. W. CooK, J. R. KIMBALL, and E. R. ELKINS: Removal of DDT, malathion, and carbaryl from tomatoes by commercial and home preparative methods. J. Agr. Food Chern. 16,65 (1969 b). FLENNER, A. L.: Catalytic decomposition of DDT. J. Amer. Chern. Soc. 68, 2399 (1946). GUNTHER, F. A.: Thermal decomposition of DDT and benzene hexachloride mixtures. J. Econ. Entomol. 40,874 (1947). HEKMATI, M., and R. L. BRADLEY, JR.: Degradation of organochlorine pesticides with hydrogen peroxide. Milchwissenschaft 26, 224 ( 1971). HELRICH, K., S. RACE, and J. REED: DDT residue disappearance from field sprayed lettuce. Bull. Envir. Contam. Toxicol. 5, 30 ( 1970). LABEN, R. C., T. E. ARcHER, D. G. CROSBY, and S. A. PEOPLES: Lactational output of DDT fed prepartum to dairy cattle. J. Dairy Sci. 48, 701 ( 1965). - - - - - - - - Milk contamination from low levels of DDT in dairy rations. J. Dairy Sci. 49, 1488 ( 1966 ) . LAMB, F. C., R. P. FARROW, E. R. ELKINS, J. R. KIMBALL, and R. W. CooK: Removal of DDT, parathion, and carbaryl from spinach by commercial home preparative methods. J. Agr. Food Chern. 16, 967 (1968 a).
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- - - - - - , R. W. CooK, and J. R. KIMBALL: Behavior of DDT in potatoes during commercial and home preparation. J. Agr. Food Chern. 16, 272 ( 1968 b). LANGLOIS, B. E., B. J. LISKA, and D. L. HILL: Effects of processing and storage of dairy products on chlorinated insecticide residues. J. Milk Techno!. 27, 264 ( 1964). LEDFORD, R. A., and J. H. CHEN: Degradation of DDT and DDE by cheese microorganisms. J. Food Sci. 34, 386 ( 1969). - - - - , and W. F. SHIPE: Effect of direct steam heating and vacuum treatment on levels of pesticide residues in milk. J. Dairy Sci. 51, 219 (1968). LEGGIER!, G.: DDT in bread and cakes made with disinfected flour. Ricerca Scientifica 20, 478 ( 1950). LI, C. F., and R. L. BRADLEY, JR.: Degradation of chlorinated hydrocarbon in fluid milk systems by ultraviolet light. J. Dairy Sci. 50, 944 ( 1967). LisKA, B. J., and W. J. STADELMAN: Effects of processing on pesticides in foods. Residue Reviews 29, 61 ( 1969). - - , B. E. LANGLOIS, G. C. MosTERT, and W. J. STADELMAN: Residues in eggs and tissues of chickens on rations containing low levels of DDT. Poultry Sci. 43, 982 (1964). LoRD, K. A.: Decomposition of DDT by basic substances. J. Amer. Chem. Soc. 42, 1657 ( 1948). MANN, H. D., R. H. CARTER, and R. E. ELY: The DDT content of milk products. J. Milk Food Techno!. 13, 340 ( 1950). MARTH, E. H.: Residues and some effects of some chlorinated hydrocarbon insecticides in biological materials. Residue Reviews 9, 1 ( 1965). McCASKEY, T. A., and B. J. LisKA: Effect of milk processing methods on endosulfan, endosulfan sulfate and chlordane residues in milk. J. Dairy Sci. 50, 1991 (1967). MILLER, D. D.: Effect of thyroprotein and a low-energy ration on removal of DDT from lactating dairy cows. J. Dairy Sci. 50, 1444 (1967). RAMSEY, D. S.: Facing the pesticide problem. Assoc. S. Agr. Workers Proc. 62, 118 (1965). RITCHEY, S. J., W. R. YouNG, and E. 0. EssARY: Cooking methods and heating effects on DDT in chicken tissues. J. Food Sci. 34, 569 ( 1969). SAHA, J. G., M. A. NIELSEN, and A. K. SuMNER: Effect of commercial processing techniques on lindane and DDT-14-C residues in rapeseed oil. J. Agr. Food Chern. 18, 43 ( 1970). SMITH, K. J., P. B. POLEN, D. M. DEVRIES, and F. B. CooN: Removal of chlorinated pesticides from crude vegetable oils by simulated commercial procedures. J. Amer. Oil Chemists Soc. 45, 866 ( 1969). STEMP, A. R., and B. J. LISKA: Effects of processing and storage of dairy products on telodrin and methoxychlor residues. J. Dairy Sci. 49, 1006 ( 1966). STREET, J. C.: Methods of removal of pesticide residues. Canad. Med. Assoc. J. 100, 154 ( 1969). VIEL, G., M. HAsCOET, and G. DuBROCA: The elimination of pesticide residues on apricots by washing before canning. Phytiat.-Phytopharm. 15, 41 ( 1966). WILLIAMS, S., P. A. MILLS, and R. E. McDOWELL: Residues in milk of cows fed rations containing low concentrations of five chlorinated hydrocarbon pesticides. J. Assoc. Official Agr. Chemists 47, 1124 ( 1964). WITT, J. M., W. H. BROWN, G. I. SHAW, L. S. MAYNARD, L. M. SuLLIVAN, F. M. WHITING, and J. W. STULL: Rate of transfer of DDT from the blood compartment. Bull. Environ. Contam. Toxicol. 1, 187 ( 1966). ZEUMER, H., and K. NEUHAus: The determination of contact insecticides. Getreide und Mehl3, 57 (1953). Manuscript received April 4, 1974; accepted May 9, 1975.
