Document Z8kemy9qb2Kb4zk1DjRbLox5O

POLYCHLORINATED BIPHENYLS (PCB'S) by John V. Shutze, Head Extension Poultry Science Department University of Georgia Athens, Georgia The. term PCS is new for most of the people in the poultry Industry. However, PCB's have been studied since 1881 and have been in extremely wide industrial use since 1930. The chemical properties which make PCB's desirable industrial materials are their excellent thermal stability, strong resistance to both acidic and base conditions, their resistance to oxidation and their general Inertness which makes them very stable, or Inactive, compounds. The most Important physical properties of the PCB's are: low vapor pressure (they have very high boiling points); low water solubility; a high dielectric constant (they will not conduct electricity except under extreme conditions). ' The largest single use of PCB's is related to their electrical proper* ties -- as eollant*lnsulatlon fluids in transformers. They ere used in ballasts for flourescent fixtures and plasticizers in electric wire and cables. Due to their thermal properties and fir* ** anc9 they arc used in high pressure hydraulic fluids, specialized lubricants, gasket sealers, and machine tool cutting oils. Other miscellaneous uses include: binders in epoxy paints, toughening agents In varnishes end waxes, adhesives, and carbon* leaa paper. The PCB property which has brought about the current situation in the poultry industry is its heat transfer usage. The USDA statement indicates that a shipment of Peruvian flah meal was being hear treated. The fluid PCB's were being used ae heat transfer materials when a leak developed in the heating chamber, which resulted in a contamination of the fish meal. Unknowingly. the fish meal containing PCB's moved into the feed trade. Various quantities of this meal have been located in 12 southeastern states. The source plant where this accident occurred has been closed and all existing fish meal has been seized. McCunc and Associates (1962) reported that PCB's were moderately toxic when fed at a level of 0.02% and caused high mortality and extensive pathology within 4 weeks at a dietary level of 0.04%. Gross pathology included hydro pericardium, hydroperitoneum, enlarged heart, liver and kidneys, and hemorrhage of internal organs. Microscopically the kidneys showed marked tubular dilata tion and numerous casts. Rohfcld and Associates (1971) reported the maximum tolerance oi PCB's containing 487. chlorine in the chick is approximately 50 ppm. Symptoms observed in the chick fed PCB's Included depressed weight gain, edema, gasping for breath, hyperpericardial fluid, Internal hemorrhaging, depression of secondary sexual characteristics and an increase in liver as percentage of body mons 047V5 17 weight. Several of these symptoms were present when levels of more than 20 ppm of PCB's were fed. Trout are aensitive to PCB's, however, dosages muse he more than 500 times higher than DDT to have the s'ame results. Observations by Shutte and uianes, (1971) under field conditions indicate that hatchabllity is markedly depressed when PCB concentration in the egg exceeds 2 ppm. One cosmerclal flock of light breeders attained approximately 207* hatchabllity when the eggs contained 1.6 ppm. Another flock 85% hatchabllity was attained when the eggs contained 1.2 ppm and body fat of the hens was 12 ppm. There appears to be an approximate ratio of 10:1 between the concentration of PCB's in the hen body fat and the egg. When the fertile eggs contain approximately 2.5 ppm, hatchabllity will be less than 0.5% Approximately 20V 30% of the chicks pip but are unable to emerge from the shell. A few embryos die all through the Incubation period but the majority die during the latter part. The livers of the dead embryos appear slightly swollen and blotchy in appearance and an occasional lesion may be present. Also in some embryos an accumulation of fluid may be seen in the pericardium. Feed consumption, agf .pp-arg fn K normal tn all mature and growing flocks of chickens and turkeys. Fertility has not been depressed in any of the flocks being monitored. Hydrocarbons such as PCB's, chlordane, dleldrin and DDT'have been shown to activate enzymes in the liver which transform estrogen and other compounds (DDT, dleldrin and certain drugs) into a more water-soluble form that Is readily eliminated from the body. Estrogen is involved in calcium metabolism and the presence of hydrocarbons In tissues has been suggested as the reason for soft shelled eggs among some wild birds. PCB's have received little _Mr>lno<eal research because of theit* excellent saiety record in wide usage. When routine pesticide analyses are made using gas-Tiquid chromatography, a standard laboratory procedure, ' PCB's will show up on the chromatogram similar to dleldrin, DDT, DDE, Aldrin and heptachlor oxide. Most laboratories now utilize procedures which separate the pesticides and PCB's. In tests conducted at the University of Cincinnati, Aroclor vapor (Monsanto trade name for PCB's) toxicity studies on guinea pigs, mice, rabbits, and rats showed no severe effects after 24-day exposure to 0.83 parts per million (ppm) for seven hours per day on 17 of those days. Even after more prolonged tests there were no severe effects from the Aroclor 1242. In the second study, three groups of beagles were fed Aroclor 1242, 1254, and 1260 respectively at a rate of 100 ppm in their diets. After three months no significant abnormal ities were noted. Based on the wj^eoccurrcnce and over 40 years of usage., _ it .is difficult to bellc.ve thaL Lhore_ is niw daneer. to the consumer. However, all products are being carefully monitored to insure that there will be less than 5 ppm PBC's in poultry meat and 0.5 ppm in eggs being used for human.consumption. Close cooper ation between the'State Poultry Federation, the USDA Consumer Protection Agency, HONS 047496 18 PDA, Associated poultry and egg Industries, and the Cooperative Extension Service will further Insure the marketing of wholesome products and the alleviation of the current problem. Poultrymen who suspect PCB contamination should submit samples of these materials to a reputable laboratory for analysis. Since limited laboratory facilities are available one should check with his ingredient suppliers to avoid test duplication of relatively expensive analysis. All feed and Ingredient handlers should follow the standard recommended feed quality control practice of maintaining samples of all ingredients and finished feeds for future reference. A list of laboratories with PCB determination capabilities Is available from the Department of Extension Poultry Science, University of Georgia, or U. S. Department of Agriculture, Washington, D. C. Methodology for Che performance of PCB analysis can be obtained from Mr. Paul Elliott, Chief, Chem. & Mlcrob. Br. Lab. Services Div., Room 604, C&MS USDA, Washington, D. C. 20250. Telephone No. 202-^88-4212. REFERENCES C. C. Gustafson, 1970, Environmental Science Technology 4:814. L. M. Reynolds, 1969, Bull. Environ. Contam. Toxicol. 4:128. R. N. Risebrough, 1968, Nature 220:1098. H. L. Hubbard, 1964, Encyckpedla of Chemical Tech. 2nd Ed. Interstate 5:289. E. L. McCune, 1962, Poultry Science 41:295. * ___ B. M. Rehfeld, 1971, Poultry Science 50:1090. HONS 047497