Document rpx0Mjapmq0grDVX2zraKwbOE

August 16, 1976 Mr. S. Markham Personnel Manager Crown Cork & Steel Company Limited 7900 Keele Street Concord, Ontario L4K 1B6 CANADA Dear Mr. Markham: -- Thank you for your Interest In my talk at the last J.A.P.A. meeting In Toronto. The enclosed copy Is strictly a draft typed from,a very ooor tape. However, 1 believe it does convey the main thoughts on the Subject of health hazards and their measurement. Unfortunately, the slides on this subject could not be economically printed for the report. Should you have any questions, please contact me. Very truly yours* * LAK/pjw Leonard A. Krause, Sc.O. Director, Environmental Hygiene and Toxicology Department (draft copy of report entitled, "HEALTH HAZARDS AND THEIR MEASUREMENT".) OLI 4664 HEALTH HAZARDS AND THEIR MEASUREMENT For most of the occupational diseases that we recognize today, there is a cause and some effect consequence. This effect is usually singular, that is, a one type response. These responses have, over the years, resulted in the development of Threshold Limit Values (TLVs). These values are acceptable level limits for workers who are exposed for an 8 hour work day, each day. There are TLVs for over 400 compounds and new ones are being developed each year plus some of the old ones are being revised as we determine the effects of over exposure and establish safe or "no effect" levels. However, exposure to only one type of toxic material in the work place is more the exception than the rule. Exposure to several compounds is probably the more common phenomenon in industry. There may be a synergism of two chemicals. For instance, benzene exposures may be enhanced (more toxic) if toluene is in the same atmosphere. Exposure to lead fumes is serious enough, but it should be remembered that lead almost always has arsenic or cadmium as a contaminant. Both of these elements are very toxic materials. If this combination is inhaled, a most toxic effect ;Can result; the toxic effects have been compounded. If we examine the various dusts such as silica, we find situations where there are both asbestos fibers and silica in the same work environment. While there may be a lower safety limit for free silica exposure, the limit for safe exposure to asbestos is not really known. It is possible that there is no safe level. Complicating an already complex matter is the simple fact that the particle size of any of the inhaled vapors or dusts may alter the effects. Depending upon how far into the lungs the material can penetrate, will depend the response. OLI 4665 Page 2 The multiple effects of singular materials is well known; asbestos can cause pulmonary fibrosis as well as cancer of the lung, larnyx, stomach, etc. Radiation poisoning may produce blood anemias, fibrosis, and cancer. Vinyl chloride had been known to cause bone degeneration (acroosteolysis) in the hands; and now, we see even more severe cancer manifestations. Biological factors often influence the pathogenesis of diseases. Alpha-antitrypsin deficiency has been associated with some forms of emphysema. It has now been proposed that genetic defects may be the cause of some lung cancer response while not affecting others. Individual susceptibility along with industrial exposure may be a large factor in understanding why some people get a disease and others do not. Outside factors or exposures coupled with industrial exposures cause interactions which can be fatal. The use of carbon tetrachloride and drinking alcohol may increase the severity rate of developing hepatic cirrosis. Inhalation of isopropryl alcohol along with drinking ethyl \ alcohol can cause severe narcosis. Isopropyl alcohol is excreted as acetone which has narcotic-like effects. We know very little about such phenomena, but we are learning. The use of chemicals that produce urethane foams such as tolylene diisocyanate (TDI) have been known to cause sensitization in some people. The indications are now that there may be other materials in the work atmosphere which are necessary to create this sensitization reaction. In other words, two compounds are necessary before effects are seen. All of the common chlorinated solvents are under a heavy suspicion regarding their effects on human health. Under the correct conditions, they can breakdown to form phosgene, vinyl chloride, ethylene dichloride, allyl chloride, and a host of other chlor-compounds, all of which have OLI 4666 Page 3 very low exposure level limits compared to the original parent compound. Where the worker smokes on the job, small amounts of solvents or metal vapors drawn in through the cigarette can be converted to extremely toxic compounds. Feto-toxins We could discuss many toxic compounds and their effects on the workers. All of our standards are based on the adult worker. All have been based, in fact, on the adult, male worker. Our socio-ecomonic climate has and is changing rapidly. We now have the rightful obligation to offer equal employment opportunities to all people including, of course, females and persons who are handicapped. It is now established that the female adult has the guaranteed right to work anywhere that the male adult can work. In most instances, this does not present undue problems. Problems do arise if the female worker becomes pregnant. Many of the compounds that are used in industry are known to be feto-toxins. That is, at some level, they may cause mutagenic (genetic changes), teratogenic (abnormal tissues), or carcinogenic (cancer) effects to the unborn child. We do not know what the level is, thereby, placing an extreme burden on industry to either take the risks or to remove the female during the first trimester of pregnancy. We have gathered a list of compounds from the literature which have been reported to be feto-toxic. It is long, yet we do not know the precise levels which produce the adverse effects. We may never know. The risks appear to be greater the more we learn. Even noise may cause abortion in some females. There are new areas of concern constantly being discovered. Known causes are being reviewed and better techniques and approaches are being developed. OLI 4667 Page 4 It has been reported that selenium is emitted from the rectifiers of photoduplicating machines. Lead has been shown to cause chromosomal breaks in male cells, therefore, is being considered a teratogenic and mutagenic material. Tri valent chromium salts are being linked to cancer similar to hexavalent chromium. In addition to feto-toxicity, all of our standards are based upon 8 hours of exposure, 5 days per week. This allows for the 16 hours off the job, which is considered as time to clear the body of poisons and to return to normal. Unfortunately, many of our workers are now working double shifts, 16 hours of exposure, back to back. This is bad enough from a safety standpoint with reduced efficiency and increased accident rates; but the exposure levels have also indirectly increased by a factor of 2. This means that the overall exposure must be reduced by a factor of 3-4. For example, benzene at 25 ppm TLV, must be reduced to 6-8 ppm and not exceeded. Biological Measurements Since we are discussing hazards and measurements, it is only fitting we discuss measuring the biological system also. A close working relationship is necessary between the industrial physician and the industrial hygienist to obtain accurate results from this type measurement. A number of biological tests can be done which are indicative of the person's health and the effects of exposure long before we see signs of any outward manifestations. Obviously, if an employee comes down with lead poisoning, or mercurial ism, or a pneumonconiosis, it is too late. What we want to detect is extremely subtle changes. Changes which are not harmful to the individual, but which do tell us that some exposure has taken place and it is at a level which shows a biological response. 0LI 4668 Page 5 Electromyographic Measurements If a chemical is known to affect the nervous system in some way, at some exposure level, this detection can be made where the exposure is very low. For example, we know that elemental mercury can affect the central nervous system. What we do not know is at what level we begin to see this. How much exposure can an individual be subjected to without a manifestation, and are the present Threshold guides correct? Electromyographic measurements are taken by having the exposed worker lift a standard 15 lb. weight while sitting down and having electrodes attached to the muscles of his arm. Specific nerve impulses are generated and recorded on a tape. These tapes are fed into a computer and compared to other individuals of similar character ^axEBpi with the exception of the exposure to mercury. Any differences are indicative of a positive response to mercury. Along with this test, several agility tests are conducted to note the dexterity of the worker. Both blood and urine samples are also analyzed for mercury. When the total picture is put together, and all data analyzed, we can see any very minor neurological changes which might take place at a given exposure level. This type testing is now being considered for lead exposure, C$2 exposures, and possibly other areas where central nervous system involvement is noted. Respiratory Function Study A great many of the materials used in the chemical industry affect the lungs in some way. Ammonia, chlorine, TDI, solvents, many dusts, epoxy resins, amines, etc. all cause some difficulty in some people. But'just who these people are and when they complain, is it real, is not easy to OLX 4669 Page 6 determine. Some people are allergic. As a routine test, all new employees should be given a respiratory function test to determine the character of their lung capacity and vital , capacity as a part of pre-employment physical examination. This test should be given annually for those who work in suspected areas. Many gases cause irritation to the respiratory tract and result in difficult breathing. This in turn can affect the heart, causing it to work harder. These tests are simple ota and should be done routinely. Stress EKG' We recognize that heart disease is still the greatest incapacitator to all people. Normally, people having physical examinations are given what is called a resting EKG. This is fine - if all you do is rest. The newest concept is to test the heart under measured, controlled stress. The inclined walking tread is one way. This gives a measure of strain resistance the heart can take. It will show quickly is there is the slightest deviation from the normal rhythm. With this type physical examination, specific heart problems can be detected and safeguard the health of the employee. OLI 4670