Document obKKYqK6477693J9JJ4jzjOo

SEC'S JUN 9i975 MOUNT SINAI SCHOOL OF MEDICINE of The City University of New York FIFTH AVENUE AND IOOTH STREET-NEW YORK, N.Y. 10019 Drparlment of Community !Mtdicint June 3, 1975 ^*0*D'* Mr. Roy J. Steinfurth, Administrator Insulators Health Hazard Program 511 Machinist Building 1300 Connecticut Avenue, N.W. Washington, D. C. 20036 Dear Mr. Steinfurth: Mr. W. C. Thurber of the Union Carbide Corporation visited with me on May 29th, to review problems associated with the spraying of texture spray materials. The background for the discussions were the wide apprehension among the construction trades concerning hazards found to be associated with the spraying of asbestos-containing materials into the air at worksites (as in structural fireproofing and soundproofing), and the belief held by some industry groups that the use of asbestos-content spray materials is a special case, not associated with the release of significant numbers of asbestos fibers into the worksite air, and therefore not to be equated with other spray procedures. Mr. Thurber has had intimate experience with the problem in his position as Product Manager - Asbestos for the Union Carbide Company, which supplies asbestos used in the formulation of spray materials. Recognizing that there is an immediate and natural reluctance to advocate uses of asbestos which are based upon the planned release of asbestos-content materials freely into the air, almost a priori, and that there could be considered that there waft a heavyxburden of proof on those who advocated such use, Hi> Thltrber presented data, based largely on dust counts undertaksafcby his company, which indicated that many uses of the materials (those tested) were associated with dust counts well within 03HA asbestos limits. Typical counts were sent to you in his letter of May 21, 1975. I found it difficult to fully evaluate the problem on the basis of the data made available to me. 1. On the basis of the experiences of our Laboratory with mixing of asbestos cements, I am not as sanguine as Mr, Thurber that the existence of work practices regu lations would ensure the safe use of dry-mix materials. UCC 010085 Mr. Roy J. Steinfurth -2- June 3, 1975 for preparation of the finished material. With asbestos cements, we found many practical pitfalls, little super vision and virtually no regulatory agency surveillance. 2. I recognize that it might be tedious and troublesome to obtain a significant number of dust counts to allow evaluation of the wide spectrum of potential exposures involved in the use of asbestos-content spray materials, subsequent manipulation of coated surfaces, cleanup and waste disposal. Nonetheless, one should not be asked to evaluate the dimensions of a problem for which data are Incomplete. For example, I have no way of knowing whether conditions which might obtain for one manufac turer* s material would hold for another nor whether the wide variety of field conditions which mark the construc tion industry would all be reflected in a limited number and spectrum of dust counts. Mr. Thurber discussed with me the possibility that some agencies such as the California State Department of Health might undertake an appropriate dust count study. If they should, I would hope that it would be sufficiently ex tensive to allow appropriate evaluation. If, because of scant resources or other reasons, it is fragmentary and of limited extent, it would not bring us much further. 3. It is of interest that sane types of asbestos used for the manufacture of asbestos-content spray coatings are much more "opened" than others with much of the material reduced to fibers and fibrils of fine dimension. While this may make for superb technical and commercial prop erties, it also makes it very difficult or impossible to count such fibers and fibrils with the optical micro scope; the fine material can often only be seen with electron microscopy. Thus, dust counts done for analysis of levels associated with use of spray coatings present a special problem. Without concomitant electron micros copy, dust counts limited to the optical microscope may give results very difficult to interpret since, in some circumstances, a much larger number than usual of fine fibers and fibrils will be present, and not enumerated. I would find it much easier to evaluate the asbestos fiber level in spray coating if some sample examination were also done with the electron microscope, as well as with the usual optical microscope. To repeat: spray coatings may present a special problem in view of the rather special kind of asbestos not infrequently used in the formulation of the materials. UCC 010086 Mr. Roy J. Steinfurth -3- June 3, 1975 As always, I found Mr. Thurber most knowledgeable concerning asbestos problems. Sincerely yours. IJS:jm \ UCC 010087