Document peERk2p6oEq3wmJgOe77bRN6B

o\ SATES AMD ROUTES 0? TRANSPORT IH THE ENVIRONMENT Adal F, Saroflm Department of Chemical Engineering, Maaaachuaatt* Institute of Technology Ian c. T. Nlsbet ' Research Department, Massachusetts Audubon Society ABSTRACT The fragmentary Information on routes, rates of entry, and ultimate fate of FCB'o in the environment is reviewed with special reference* to Ivorth /varies and adjacent parts of the oceans. Until very recently,only a^veuiative in formation was available on production otr.tlstlce and on quantitative patterns of uoo. Monsanto Chemical Company has now relonsed figures ter total U. S. sales of PCB's, which peaked at 36,5C0 tons In 1970, and hat agreed to tarnish supplementary information In time for the Durham moating. VC3*s have been used primarily as dielectric, heat transfer, and hydraulic flwldo, particular ly where fire resistance is important, nud as plasticisers. Hirer uses, accounting for less than oix percent of sales, have included surface coatings and sealants, adhesives, printing inks, pesticide extender::, tticroenc;omtlatlon of dyes, and wax modifiers. Monsanto has recently restricted r.alcs of certain products based on considerations of either the possibility of contamination of fcod products or the inability to monitor or control pocsU ie losses ir. the environment. Sale of PCU*c for use ae plastici/ivr* *ml c.inor uccs presented above was dlsc0in.i2.aud in 1970. In udditior., r*lc heat fluid has been curtailed and, for tho?e applications which lead to food contamination, discontinued. Ae a consequence of thsee rasuren, U. S. sales of PCB's by !!onsanto have fAllen by almost 50 percont tc an estimated 10,600 tons in 1971. Concurrently with the control of sales Knnuanto is reducing the average chlorine content of PCB's and expects that tho pcrccntagA of PCD*s containing 5 to 9 chlorine atoms per molecule will decrease fro* 44 in 19C9 to 21 in 1972. Ae in the case of most industrial chcvlc&ls loss figures for FCB*a are practically non-existent. Some rough estimates of looses to the euviroa-wnr. havo been mode from the nature of application, end the physical. propercies of the PCB*a. These estimate* suggest that a large fraction of pr.E's manufactured to date arc eonflncQ-liigeaicd containerst cltbTr in active service or discarded in dumps. Major routes into the environment appear to ba Off'vaCerways ana estuaries, through scrappage or leakage. Losses to the at..-jti- phara by Incineration, vaporisation or co-dlstlllatlon era probably relatively minor. Ho major direct routes to the terrestrial environment have been identi fied, since the post use of PCB*s for pesticide formulations was small. Additional evidence on the accounts and routes of PCD1* In the environment Is provided by data on environmental occurrence of l'CD's, derived from both sparee measurements of PCB*a in water and Air, and more extensive measure ments on PCB residues and DDT/PC3 ratios encountered in the biota. The spatial distribution of both FCB levels and DDT/FC3 ratios are consistent with the postulate that the discharge of PCB's into the environment has b-:cn concentrated near industrial areas, and chc iueia. bu'w.c^cr.: tronojert V-- MONS 069636 2 bam aelnly through the movement of turface water* or water-borne particu late*. The occurrence of FCB'a In remote non-lndustrlal tltea suggests that a finite quantity of PCB'a have also been transported by air-borne particu late*. Co-dlatlllatlon or vaporisation la tentatively discounted at a major rout*, on the baala of the apparent lack of fractionation during transport in tha environment amongst the refractory Isomers of the Connercla1 product. FCB'* have been Identified In snow, rainwater, and air-borne particulates over Che continental U. S., but could not be detected In particulates carried from the Pacific over the California coast. Roughly ^p ton* per year of PCB'a Is estimated as an.upper limit for the annual deposits by air-borne particulates on~nflT continental~UT 5. Eatlirat'*~3~g?~ the total lnnut to the terrestrial environment, including "contribution by~lrrlaatlon waters, are two order* of magnitude lower than thoselfpr DOT. However, ob serve? '~Sb7?CB ratios In tarrestViai animala are generally lower than 10. The discrepancy Is so far unexplained. The amounts of PCB's stored In freshwater fish and discharged In eurface waters are relatively email. Tha total pf.g fmt.n, nf frhvin-r in Worth America la estimated to be of the order of tm end the amounts discharged with turface waters, estimated from data on DDT/PCB ratios In the blots, of the order of 100 tons. The estimate nf totel Input of J'CW'slnto the marine environment off the V. S. coasr from rivers and aawaga yludgeLa of the order of several hundred tons per~yef~.' IllghETy greater than the estimates for DOT. Direct Intro duction "to coastal waters, from industrial leaks, dumping of Industrial wastes and dredge spoils. Is of unknown magnitude, but probably accounts for locally high levels of PCB's and low DDT/PCB ratios in coastal animals, sspodslly on the Atlantic coaat. Farther offshore, DDT/rCB ratios are lower, consistent with the postulate t-hr u<dgBprd falloutl* a more lraportant route for DDT than for PCB'a, Tha major conclusion of the review Is that only s small fraction of the totel PCB production has entered tha biosphere. Of the remainder, part hse Been destroyed by Incineration, part Is lr. captive cs in heat exchanges or transformers, and part ha* accumulated In dumps or sediment* In shallow waters from which It is leached out at an unknown but probably slow rate. The flgurss presented In the review are baead on fragmentary evidence and ere speculative; they emphasise Che need for improved transport models for pollutants in the environment. '--- HONS 069*3?