Document 8R6kMKQ3B0jwRazp7xx1RRRda

Monsanto t ur>M N'Ml * LOCAMOS J.H. MAIHPBIZE, Huabon tAU 30th April, 1969. WUOJCCT 1 BIODEGRADATION OF AR0C10RS. Ni'MMNCt > TO : JHM/BJO'G. R*A* BAXTER1 Ru&bon* SCl R.A. Didgett, Ruabon. 1 have searched available literature (Water Poll. Abstracts eto.) for any references to work on the biodegradation of ohlorinated bi-phenyls and have so far been unsuccessful. There is however oonaider&ble published infoxmation on the techniques for studying the breakdown of other potentially toxic, water insoluble materials, and these X think could be adapted for work on Aroclore. Unfortunately, little evidence exists of any standardisation of taohnique amongst various workers, a fact which is commented on in the report of a U.5. oommittee published in 1967 (R.D. Swisher was a member). In the context of water pollution the report defines biodegradation aB "the conversion of chemical compounds to innoouous substances through the action of living organisms". Within this definition the following possibilities are Baid to exist* 1. Primary degradation - Biodegradation to the minimum extent necessary to ohange the identity of the compound. 2. Ultimate Biodegradation - Biodegradation to water oarbon dioxide, and inorganics. J. Aooentable Biodegradation - Biodegradation to the extent to remove some undesirable property e.g. toxicity. I have assumed that the immediate need ie to demonstrate that priaaxy breakdown of Aroclore oan ooour in nature, and that extensive study of the toxiolty of any degradation products should not be considered at this stage. No detailed teat procedures are given in the report but as general guidanoe it is stated that the following biological environments should be considered In a eearoh for active organisms. 1. Biologically populated surface waters. 2. Biological waste treatment facilities. (Activated Bludge, trickling filters) 5 Soil systems. An attempt to define a standard procedure for measuring biodegradability hae been made by Bunoh and Chambers2. Basically the procedure consists of inoculating a solution of the test material with Battled sewage in the presence Of buffer salts and essential minerals. Weekly sub cultures are made for three weeks, substrates being analysed for residual oontaminant 1LNHIBIT - WBP M-35 HONS 09769b Cont'd... TOWOLDMON0003309 WATER_PCB-00000331 I * -2- after each weekly period. Precautions are taken to ensure that concentrations are bolcm toxic levels initially and that removal due to meohanisns such ae adsorption is not interpreted as evidence of bio degradation. I think this method may be worth trying for initial screening of inocula from different sources but in the absenoe of any favourable results it will probably be necessary to attempt more long tern acclimatisation procedures. Our main problem will be to devise a method of Introducing the chlorinated bi-phenyls into any ohosen biological system. At the saturation concentration of 0.2 - 0.3 ppm. adsorptive effecteoould be the major reason for disappearance from solution. Faced with a similar problem when studying the breakdown of DOT Okey and Bogan^ dispersed the .insecticides in water using a non toxio wetting agent of low bio degradability. For long term studies the dispersed materials were added in graduated quantities to 13 litre reactors over a period of eix months. At the end of this period the entire reactor contents vers solvent extracted for analysis by infra red. A seoond method of adding very insoluble comp ounde to culture media is to prepare solutions in a volatile solvent e.g. Pet ether, which 1b removed by gentle warming before inoculum is added. If we are requested to undertake the study of Aroclor degradation I would propose that ws first use the standard procedure devised by Bunch and Chambers employing one of the methods mentioned above for introducing test materials into the culture vassels. If no evidenoe of breakdown is found we would then attempt Long term acclimatisation. For this I suggest we UBe the Okey and Bogan technique or possibly the type of perfusion units employed by John Mclver for his work on Ruabon effluent. Refs, 1. Jouxn. Water Poll. Control Fed. 33, 7, 1232 (July 1967) 2, " "" " " 39, 2, 181 (Feb 1967) 3. Proc. 11th Faoifio Northwest Industrial Waste Conference 1963 p.222. M0NS 097697 TOWOLDMON0003310 WATER_PCB-00000332