Document O1mkVqmKZwM57oqpbqD7Z8E7X

WRG VOOi-iOS *7 2180 MILVIA STREET, BERKELEY. CALIFORNIA 94701 MAILING ADORESS: P.O. BOX 772 Ms. Madeline Nelson c/o The San Francisco Bay Guardian 1070 Bryant Street San Francisco, California 94102 April 23, 1973 T,i,pnon (415) ms-a: l PLAINTIFFS EXHIBIT ^ f"4 'Wi"*vR< G-708 - Dear Ms. Nelson: I appreciate your sending me a copy of the April 25th issue of the Bay Area Guardian which contains your article on asbestos. You are cor rect when you quote me as being opposed to the use of sprayed asbestos for fire-proofing, but I would like to clarify my reasons for this and add some information to put the matter of air contamination in perspective. Four years ago, I did not think that asbestos should be banned until effective substitutes had been found. I believed then that the rigorous enforcement of measures to protect construction workers and to prevent dispersion of dust into surrounding streets would force the development and use of non-asbestos materials. In other words, that asbestos would be phased out. There has now been time to do this. MjrretsonrfOEmt supporting a bam is not "that the asbestos level in the air all around the city is now similar to the level right around construction sites." It is becausei(l) I am against putting ton*of. asbestos: Ink* building^ that must some day be demolished and (2) thr asbestos thatri* scattered about during actual construction contributes: unnecessaryjetircontamina tion of our environment which receives asbestos frost many sources * Thera amounts Introduced Into ventilation systems' that circulatmatr through* asbestos-coated spaces are small, but again they add-uimecosseriljr ta thu amounts of asbestos w* are all accumulating In our lungs* My remarks on ambient air standards were misinterpreted. The point I intended to convey was that basing controls on the numbers of fibers col lected in air samples near construction sites would probably not be ef fective and work practice standards would be preferable. The numbers would often be found to be lower than one would expect, and not too dif ferent upwind and downwind from construction sites. For example, we have measured airborne asbestos concentrations in downtown areas near buildings being sprayed and found from 9 to 77 fibers per liter upwind, 5 to 42 fibers per liter downwind. General ambient air In the Bay Area, not related ta construction- sitee; ranged from less than V to 12 fibers per lltetf. My position on ambient air standards remains that of the National Academy of Sciences panel two years ago, that "Analytic methods and epidemiologic data are not yet adequate for the development of an ambient air standard but emission controls are needed and appear to be feasible." This is es sentially the current approach of the Environmental Protection Agency. r  Ms. Madeline Nelson April 23, 1973 Page 2. 700140^ Our studies of the numbers of fibers in occupied buildings where asbestos had been used have shown the numbers to be low. In one such building, sprayed 4 years before our study with material similar to that in the Tishman building, air entering occupied areas contained from 0.2 to 2.7 fibers per liter, no higher than entry air from the outside. In another building sprayed one year before it was studied with a dif ferent material, there was evidence that fibers were being added during passage through the system, although no sample had more than 10 fibers per liter. It is important that people living and working in buildings where asbestos has been sprayed realize that the numbers are very small, at levels that have not been shown to be associated with a health risk. The proven effects of asbestos, such as lung cancer and mesothelial tumors, have largely been in workers who have had high exposures, com monly reaching many thousands of fibers per liter. We have found that the average exposures during the various jobs carried out by the Insu lating worker range from 2,600 to 8,900 fibers per liter, with individual counts over 60,000 fibers per liter. Household exposures can also be quite high, if dusty work clothes are carried home. There Is thus a great difference between occupational exposures and the small numbers of fibers': in our general environment. No one believes In inhaling any hazardous, substance unnecessarily but it is Important to keep dosages In perspective?) I have one other correction. My formal consulting relationship to the construction industry is with the Trustees of the Western States As bestos Health Plan, representing both unions and contractors. We advise both labor and management and try to provide both with objective informa tion on health hazards and their control. I realize that the foregoing may sound like quibbling comments that are unimportant in the face of the main issue, that of enforcing present regulations and developing new ones if the present ones are Inadequate. I don't want to weaken your main thrust of your argument, that this form of unnecessary exposure to asbestos should be eliminated, At the same time, I hate to see unwarranted anxiety and fear generated In the occupants of asbestos-sprayed buildings, whose exposures are so very low compared to those associated with occupational exposures. There are excellent reasons for believing that such low concentrations will not be associated with any detectable Increase in illness. Thanks again for sending me your article. Sincerely yours. WCC:jmm cc: Editor, San Francisco Bay Guardian 2*002*59