Document b3YZmb8MdyjyzL2Jweq6m9D6

FILE NAME: Raybestos-Manhattan (RBM) DATE: 1977 May 27 DOC#: RBM051 DOCUMENT DESCRIPTION: Letter from Hilton Lewisonn to RM Industrial Products Co. RE Limiting Asbestos Exposure to Workers with Lung Issues Hay 27, 1977 Dr. Joseph L. Goodman RM Industrial Products Co. Garoo St. & O 'Hear Ave. North Charleston* SC 29^06 Dear Joe: It Is ay personal opinion that a person with diaghosed asbestosis should not continue to work In an occupation which exposes his to asbestos dust containing respirable fibres. As long as there is any airborne asbestos dust In tto work environment, there may bo soma small risk to health. Having expressed ay personal opinion, I think that it night bo worth while to explore tho alternatives. Whoa dust concentration is hold constant tho prevalence of asbestosis is highest amongst those with the greatest duration of exposure. Asbestosis results because of accumulation of dust in the lungs ovsr a period of time. However, seaa of tho dust is removed frea the lungs by the normal clearance cechaaisas or by being dissolved in body fluids. Consequently, if it is assumed that none is removed and exposure is limited accordingly, a safety factor is thereby incorporated. In other words, if the present dust levels are such that they have not been associated with evidence of asbestosis in those exposed to them for a substantial period of tine, they 3re unlikely to aggravate the disease already present resulting froa prolonged past-exposuro to substantially higher levels held constant ever a period of time. The present standard of 2 fitrea/nl (100 fibre/nl years) proposes that one in 100 persons exposed to this concentration for 3 hours per day, **0 hours per week for 50 years will develop the earliest detectable clinical physical sign of bilatori-1 basal (pulmonary) rales. It could, therefore, be postulated that continued employment of already affected persons in occupations.where the dust counts are below 2 fibres/ol will not produco further lung cnanges. Coses which give sero respcoscs are never, in fact, known with absoiuto certainty since the sensitivity of measurements of response is limited. *acn person's dose-response line is different with a different threshold and a different slope. It is, bewevtr, ay personal oxpcrionco that asbestosis is a progressive condition even after removal from further exposure and I cannot bolleve that allowing an asbestosis sufferer to continue working in an asbestos exposed occupation, even if it ia below the present standard, will not in sooe way oxagcrate hia affliction. With regard to lung cancer, I believe that this ia highly correlated with the incidence of asbeatosis, but that it probably required smallor concentratlona over a longer period of time to cause it. The additional highly significant co-oarcinogenic effect of cigarette smoking makes it difficult to prognosticate in the case of a scokor. I believe that because of the association between lung cancer and asbestos exposure it would be unwlso to allow a person suffering from asbeatosis to continue to be exposed, even to low levels. It ia conceivable that asbestos accelerates the Last stage in a multi stage carcinogenic process. The attached paper by Julian Peto may be of interest to you. Mesothelioma of the pleura in persons solely exposed to chrysot'ile asbestos is very rare, nevertheless, the dose required to produce this disease appears to be far less than that required to produce lung cancer, especially when it occurs in the absence of asbeatosis. The doso induction period, however, is very long and may be 20-U0 years. It is unlikely that low levels of exposure after the diagnosis of asbestosis will continue for long enough to produce mesothelioca do novo, because of the cumulative dose already acquired. Nevertheless, bocause of the uncertainties involved and because I deprecate in creasing the lung burden of asbestos in a person already suffering lung damage from expostre to it, r:cy opinion is that further exposure should not be allowed. Medical surveillance of asbestos workers should aim at detecting the earliest biological effects of exposure in order to remove people from further exposure in the hope of preventing progression to the full-blown syndrome of asbestosis. I aa afraid that there is no? adequately documented epidemiologic evidence to consider which allows one to determine at vnat stage progression could be arrested by cessation of exposure. In my experience, asbestosis was certified in 50J of "suspected cases'* within a period of 3 years from date of first suspicion, even after removal from further exposure. I hepo I have managed to answer your question. The diagnosis of asbestosis is in your hand and, therefore, the final decision is yours ia tbo long run. Best wishes, Hilton C. Lewinsohn /as