Document NjeV1doQRpmOmQn56jRQz46R

SUMMARY C? I'TFQRl'ATIQH OH THE POLYCHLORItATED BIPHZiiYL (PC3)-SILO PROBLEM This icsary on the PC3-coatecinatod silo problem was prepared from information provided and opinions expressed at a meeting held on November 27, 1972. The individuals attending the Beating were Lynn B. Willett, Ohio State University; lonald Kendlandt, University of Kentucky; George ?. Pries, ARS; Harry Geyer, XS: Everett Uarwlck, ARS; George Mcuntney, CSRS; and Cerald P. Combs, SIS. Moat of the infernation was provided by the first three, all of whoa have had extensive research or Extension experience with this problem. ' Conclusions 1. Host of the contaminated silos are located In Ohio, Kentucky, Indiana, Tennessee, and the adjacent areas of adjoining States. 2. Approximately $000 silos were built In which FCB-eontalnlng paint was used. 3. Residues of Pc3 is milk from ferns with these silos can he expected to exceed the TLA tolerance level of 2.5 ppm (fat basis). 1*. because of dilution with other milk, the problem presents no real hazard ' to the general public. 3. At the usual contamination levels, a member of a farm family consigning Its era milk over 3.5 years could consume approximately 50C milligrams of FC3*. ' This Is believed to ce the minimal amount which has produced clinical effects in man based on the Japanese experience wherein it was consumed over a much shorter period of time. 6. The cost of replacing a I4'x50' silo Is about $3400 if the hardware is . reused. 7. If PCB-contasicated milk i3 detected by a regulatory agency, the loss of feed and milk could involve an additional $$000. 3. The only counter measure known to be completely effective Is the replace ment of the contaminated silos. 9. Cleaning the silo ar.d rescaling with e water-base epoxy, hydraulic cement, or a furfuryl alcohol resin has been effective in short-term studies and would only cost abcut J400 to ~sOO. 10. Sand blasting, wire brushing, and high pressure water all are effective,* methods of cleaning silos,before resealing. HONS Q43968 8 11. An educational program carried out through State Extension Services la collaboration with producers and field men of producer groups Is ooasldared to be the most practical means of correcting this problem. 12. If PCB contamination could be Included under the Pesticide Indemnity Program or If milk could be collected for testing at the farm level, greater cooperation of local producers in eliminating this source of PCB contamination could be expected. Number and location of Silos ' The silo sealant "Cumar"* vas developed in the 1930s. It vas a private formulation developed and used by the Concrete Silo Company.2 In 1966 the assets of the concrete Silo Company vere divided among three successor companies, all of vhlch use the Cumar material. The successor companies vere the Michigan Silo Company, the Bloomfield Silo Company, and tbs Xontaagle Silo Company. The activities of the three companies 1 Cumar is the name of a coating used by several mldvestern silo companies and is responsible for meat. If not all, of the Aroclor-conterainated alios. This coating contains 70-lb Arodor 125I; and 20-lb Aroclcr 5460 par 47 gallons of paint. It should not he confused with Neville R-1-6A resin that has the same name. f 2, " There are discrepancies in the name of the original company depending CO the source of information. In some versions, the Michigan Silo co. vaa the original company. Its name vas changed to the Concrete Preducts Co. uhleh later divided into the three companies. MQNS 043969 N 3 cantered In Ohio, Indiana, Kentucky, and Tennessee. In addition to these States, it is known frem regulatory experience and from information supplied by the silo companies that the following additional States also have eontaninated silos: Michigan, Illinois, Alabama, Georgia, Horth ' Carolina, South Carolina, Pennsylvania, Maryland, West Virginia, Virginia, end flew Tork. Estimates of the number of contaminated silos built Since the 1966 reorganization are available fren the three coopanies. Michigan Silo has reported 108 sales of Cunar curing this period. Mounteaglc built 350 alios while Bloomfield built 2U5 silos in Kentucky during this period. n>e nunber of silos built by Bloomfield in other States during this period is not available. As nany es 1300 silos nay have been built by the three companies during this period. The records of silos built before 1966 were not available and it is our impression that they do not exist. Pries has estimated that about 5000 contaminated 3llos were built. This was based on the production of 10C0 ailos during the last It years. If 20 years are assured aa the period of active construction and the rate did not change, 5000 silos vould have been built. A Mounteagle representa tive bam also estimated that about 5000 to 6000 silos vere built by the present and predecessor companies. In 1970 the Baltlnore office of the Food and Drug Administration detected six farms in the Kartinsburg, We3t Virginia, area that had con taminated silos. All of these farms had Michigan silos built by the am# builder. Only one of these farms was on the list of sales by Michigan Silo after 1986. While the sample is small,. the numbers are consistent with the conclusion that about one contaminated silo in five vat built after i960. ' ' MONS 043910 It vu realised that some of the silos are not being used, have teen torn dovn, or are on farms other than dairy farms. Considering these points, it vas felt it would be helpful to perform a survey of ' individual Bilk samples in a given location in order to provide sore Information about these Questions. Such a survey is possible in a region Of Kentucky where 230 farms were shipping to a tingle cooperative. Because seme of the shippers have been detected with PC3 residues, the cooperative has been quite interested in checking all of the individual producers. With this study Pries and tfendiandt would hope to learn (a) the number of eilos that exist; (b) whether or not there are any other sources of contamination; (c) the cumber of silos built before 15co scampered to the number built after 1966; end (d) to determine if it is pesslbls for experienced individuals such as field sen of this company to determine before the analysis vhich of the farms are likely to be affected. ... .' . Significance of Residues The significance of the contaminated silos can be evaluated frem two viewpoints: as a possible health hazard to the general public end as a possible health and economic hazard to the dairyman end bis femily. The situation does not present a significant health hazard to the general public. Moat of the contaminated silos are dispersed and milksheds usually Include a large number of farms. It is unlikely that ary mixed ' Ilk supply will have significant ?C8 residues. This conclusion has been confirmed by FDA surveys. the significance of the problem for the individual farm femily say be considerably different. As a general rule, farms with these silos MONS 043971 'N . . . . 5. . produce nilk containing approximately 10 ppa PCB in the Bilk fat. Levela 8 to 3 times higher have been found in a fev cases. If the farm family drinks their own silk, a residue level of 10 ppa and consumptionof 1 liter per day vould provide an 0.5 gram Intake of PCB in 3-5 years. Short-tern . Intake of 0-5 gram PCB hes caused adverse effects in hunans. Long-term Intake is probably not as serious as the short-tern Intake because a larger portion of the dose will be excreted. However, the possible subacute affects of long-term Intake have not been evaluated. A second hazard to tha dairyman is aconcoic. The actionable level for PCB residues in nilk fat is 2.5 pja. Almost without exception, dairymen with these sllcs will be producing nilk with residues ebove the actionable level. If a dairyman is detected and removed frca the market, his financial loaaes vlll be substantial. The exact loss depends on a ntniber of factors ouch as size of operation, time of year, feeding program, to. .. . .' ' ' Three sources of loss are the silo, the allege In the silo, end the milk. Using s lk x 50 concrete-stave silo as an-example, replacement coat was estimated by Willett to be about $3*i00 if the hardware, roof, unloader, ate., could be reused. Cleaning and resealing could reduce this cost to 4k00 to $660., The loss of contaminated feed can be quite variable. Hie 1>ix50 foot Ho could contain as much as 160 tons of silage. If all of the silage ` wore loot, it could cost $3,000 to replace it vith hay even if one sod the low price of $50" per ton of hay. This cost vould be proportion ately less if sema of the silage had already been fed vhen the silo was detected. .. HONS 043972 . ..6 She value of the lost milk could easily be the most significant ltea. A lhxJO foot silo vould provide enough allege for half the dry matter intake f VO ecus for a 6-month period. If the dairyman lost his market and the initial concentration of residues vas 10 ppm, it vould require approximately 10 weeks to return to the market. Xf the 40 cows vere producing 30 pounds Of Bilk per day and the value of the milk vas $5.00 per hundred, the lost production vould he vorth about $b,000. When the covs are producing unmarketable milk, their body fat residues art also too high for sale as beef. Thus, the dairyman vould not he able to reduce his losses by selling the contaminated covs end replacing them with clean covs. .. ' Eliminating Residues . The most effective vay to remove the PC3 problem is to replace the silo. While this approach is the most effective, it is also the most expensive. It will probably cost the livestock producer In excess of $b000.00 to replace the silo. - - - . She results of a research program at the Ohio Agricultural Research and Development Center (0AKDC) have indicated that PCB residues can effectively he reduced in contaminated silos. These results have been achieved by carefully cleaning and recosting silos vith materials that fora a harrier betveen the silage tad the silo vail. She cost of cleaning and recoatlag a silo Is 'between 10 and lW of the cost of replacing the silo, depending on the type i of coating used. This research is nav being continued to determine if silage from these recoated silos can he safely fed without contaminating the milk sad alto to determine if the coating continues to he an effective barrier vhen the alio is used continually. '' HUNS 043973 fossil)ly the Dost important aspect of recoating e silo is the cleaning of the silo vails prior to applying the coating. Coatings will not be effective unless a clean and solid surface is prepared. Sandblasting is on Ideal scans to clean the silo, but the cost is greater than 505 of the replace- MSt eost. Dust oust also be controlled vben sandblasting is used to prevent vldespread contaaination. Alternatives to sandblasting are vlre brushing and high-pressure vater (500 psi). The vire brush method requires a great deal of labor. When high-pressure vater la used, the run-off must be controlled to prevent eanteaiaation of streezs or other parts of the farm. Under no circumstances should an organic (gasoline, etc.) solvent be used to dean the interior of silo. The solvent vould only serve to spread the PC3 contamination and could Interfere vith the bonding of a nev barrier coating. - Aesearch has provided information about some of the necessary properties of coatings if they ere to be used as effective barriers to PC3 residues. First, it should not contain a solvent in which the PC3 is sal- l&le. This type solvent vould dissolve the PCB from the silo vail and Mhe It part of the nev coating. A solvent-based coating nay make the contaaination nore severe than if no nev coating vos used. Second, the nev coating should provide a thick barrier betveen the contaminated silo vail and the silage. This neons that tvo or nore coats of the material are necessary. , .. - . * Three coating systems, of 12 tested, ore promising as a neans to cover the previously contaminated silo surface. These ere: a hydraulic cement1,3 1 hydraulic cement is not a sand and cement plaster but a special cement that forms a voter tight barrier. * Thoroteol* - Standard Dry Wall Products, Inc., Miami, Fin.. MOWS 043979 . .. . 8- with an acrylic bonder3, a water-based epoxy^, and a furfuryl alcohol resin? coating. Testing of these materials Is continuing to determine how long these coatings will continue to be effective barriers to PCB residues, when a alio is used continually. The aforementioned coatings, when applied to contaminated silos, reduced the level of PCB residue In the silage adjacent to the silo wall to less than 4.0 ppm (dry matter basis). Preliminary research results suggest that if the level of PCB in the silage adjacent to the wall Is less than 5.0 ppm, the milk produced by cows that consume silage from the silo will be less than 2.5 ppm (fat basis). Identification and Elimination of Contaminated Silos ' There are several points to consider before proposing methods of Identifying and eliminating contaminated silos. Tinder present circum stances, the dairyman may not be too concerned about checking his silo for contamination or correcting such a problem if he has had no difficulty marketing his milk. This situation could change rapidly if the producer realizes the potential danger to his family and the losses he would incur If regulatory agencies sampled milk at the farm level and found his to he contaminated.. 3. Acryl-60* - Standard Dry Wall Products, Inc., Miami, Ha. J, ~ 099 Epoxy* - Action Plastic, Inc., Charlotte, Michigan. >* 3 Sllsnxcrote* - Universal Cooperatives, Alliance, Chlo. * The uec of trade names 13 only to Identify the products used. The use Of these names Is not an endorsement of the products used nor meant to discriminate against similar products not mentioned. 043975 mqns 9 Shis situation alaost precludes the possibility that the Department OOulA become Involved in an active program of detecting contemlnated silos. If they were detected it would be necessary to report them to the regulatory agencies. It is doubtful if cany dairymen would be Interested in cooperating. The Department could probably only work in an educational roll presenttng the facts of the situation, the consequences of action or no action, and providing assistance in locating laboratories to perform analyses. The progrem could be cerrled out either through the Extension Service or through the fieldaen of processor groups. The letter possibility Is worth exploring because the fieldmen will be In contact with all producers rather than Just some aa is often the case with Extension. A second possible benefit from working through the processors is the possibility ' that there will be greater incentive to do something because the processors have an obligation to produce a vholesoce product. The situation could change drastically if one of two events occur. If regulatory agencies step up their activity, there will be greater advantage to the individual farmer to determine whether or not he has a contamination problem. As noted above, the cost of cleaning up e silo before detection by regulatory agencies is considerably less than the cost after a regulatory agency detects him. The second possible chance would be .s' . the inclusion of PC3 contamination under the pesticide indemnification program. If the dairyman foes not feel that it vill cost him a considerable leant of money, he will more likery determine if be has a problem. It should be noted that Monsanto Chemical Company has essmed partial HONS 043976 10 responsibility for the cost of cleaning a mnber of silos built since 1966. They have generally becoae Involved only after the detection by regulatory agencies. While this vlU not affect the old silos, it Is a natter that oould be explored further in any clean-up proposal. t i HONS 043977