Document oD1MQGMgOOJe85JDgebq5o8NR

Ai* d n is'aiu' Vm. Mi V-O Jfti January 16, 1964 Mr. Clifford H. Seymour Safety Director The Carborundum Company P.0. Box 337 Niagara Falls, New York Dear Mr. Seymour: We are pleased to enclose four signed copies of a report giving the results of the analysis of samples of dust collected during a visit to your plant on November 26th, 1963. We believe the report to be self-explanatory and we hope it is satisfactory for your purposes. Except for Table 2, the tables are the same as the ones sent to Mr. S. D. Mark, Jr., on December 11, 1963. Table 2 has been revised to include a count of the particles less than 2 microns in diameter. Sincerely yours, JC/meg Enclosures cc: Dr. Robert A. Kehoe J. Cholak Director, Division of Industrial Hygiene Technology KE Report Op ,an Environmental Survey, .of & Cut-off Operation at the Plant of the Carborundum Company, Niagara,Falla, Mow York Thin report given the results of analyses of particulate natter removed from the atmosphere while leaded, resin-bonded, abrasive, cut-off wheels were being used to cut rods of hot rolled steel* The tests were, conducted on November 26, 1563 in the testing laboratory, on the first floor of Building IP 1 of the Carborundum Compani in Niagara falls, Net-? York, Procedures Tests were carried out in duplicate with cut-off whe,, Is of three different formulations; a "lead-free" wheel, one containing 3 par cent of lead, and finally one in which the lead amounted to 12 per cent of the weight of the wheel. The abrasive wheels, 16 inches in diameter and 1/8 Inch thick, were enclosed in s' modified guard on an Allisen-Canpbell, cut-off machine and wore driven at a -speed of 3300 revolutions per minute by a 7 1/? HP motor, .lot rolled steel (C-1020) I s1/8 inches in diameter was chosen as the metal to be cut dry, and without the benefit of the exhaust ventilation available, in order to simulate the worst possible condition. Each wheel was operated for the period of time required to cut approximately 120 one inch pieces from the rod. Dust produced by the operation was collected during the entire time required to wake the 120 cute with the first (lead-free) test wheel, but In subsequent tests, the sir was sampled only during the periods of time required to cut 80 piece after the first 20 pieces had been -2 cut from the rods* Jk12 exhaust fans in the room were turned off and all windows and doors were kept closed during the cutting operations. Between tests with each type of wheel, the-room was aerated for a period of 15 to 20 minutes by turning: on the exhauat ventilation and opening the large doors to the outside located in one end-wall of the room* Dusts were removed from the air at the breathing xone of the operator and at -a distance of 12 feet from the machine, by electrostatic precipitation. The precipitator was set-up with the opening of the collector tube parallel to the oncoming particles generated by the cutting operation and about 12 inches fror.the nose of the operator* In addition to the sampler of dust collected by electro static precipitation, several sample of dust were removed fror the air, at the breathing zone of the operator, by filtration through paeer or.membrane filters* .The Freer gas operated "Unl^et* air sampler (Industrial Equipment Co*) fitted with a membrane filter snd sampling at a rate of 3 liters of air per tsinufce, collected dusts which could bo used-for the determination of the sizes of the particles and for chemical analysis* The membrane filter was set up in the same plane as the inlet of the electrostatic precipitator but 12 to 15 inches nearer to the cut-off machine* A two stage *respirable" dust sampler, consistin of a Union Model #230, cyclone, dust collector fitted to a Unlco #300 air simpler (Onion Industrial Equipment Corp*, Port Chester, Hew York) provided with a 3 inch diameter Whatman #31 filter paper disc, was also employed during .some of the teats* At a sampling - -a rat of approximately 8*5 ctfm, only these parfclcleo less than 1-2 microns in i*e reached the paper. This dust sampler, used only during the tests with the leaded abrasive cut-off wheels, was placed at the breathing one so that the air inlet was In the / saiae plane'a the inlets of the other two samplers, but was farthest away from the eut-of? machine, about 12 inches from, the electrostatic precipitator, ' Particulate, rsatfcer was remove a from the collector tubes of the electrostatic precipitator by wotting the inside vails of the tubes with -ethyl alcohol end rubbin.g off the particles by nseens of a rubber-tipped glass rod* The resulting; suspension was made up to h suitable volume with ethyl alcohol, and a small amount (a fraction of a milliliter) of the well shaken mixture was'then removed and examined by light field micros cory. and at & rmrnifi cation of 1000, to determine the distribution of particles of varied size. The mixture remaining was then placed in a 15 os*, vide mouth bottle, 2,5 inches in diameter and 5*5 Inches tall, with a rubber stopper containing a. siphon which extended to- within 1 inch of the bottom of the bottle. Alcohol was added to a height cf 3*3 ci-. above the end of the siphon tube, and the bottle was shaken to resuspend the particles* After standing 2 minutes and $2 seconds, the top 120 ml. of alcohol, containing only particles less than 10 microns in diameter, wore siphoned off. (A Practical Method for Particle Sie Separation of Atmospheric Dusts, Industrial-Hygiene Foundation, Pittsburgh, Pa., Feb, 1, 19^C.) This suspensin was taken to dryness, the residue was weighed and then was analysed for - k~ Its content of lead* The result of this type of analysis was then used to estimate the proportional distribution of the lead, as between the fine and coarse particles, in each sample of dust removed from the ail*. The particulate natter collected on the membrane filters on the Unijet equipment was first examined by light field microscopy to determine the frequencies of the occurrence of certain ranges of sites of particles, and then was analysed for its content of lead. -The filter papers used in the "respirable" dust sampler were analyzed only for their content of lead The cyclone sections of the two stage sampler were rinsed with alcohol and manipulated to remove the dusts which were also analysed for their content of lead. All determinations of lead were made by a colorimetric procedure tiRlwr dithisone* which is n method in regular use in the Laboratory. Hesuits ' In Table 1- are recorded the weights of rust* in the air, as collected by electrostatic precipitation only, the proportion (in per cent) of particles less than 10 microns in diameter, and the concentration of lead in'each entire sample, as well a that In the fraction made up of particles less than 10 'asIcrons in diameter. The frequencies of the occurrence of particles, within certain limits of size, in the material collected bf electrostatic precipitation or on membrane filters, while the leaded wheels were in use, are recorded in Table 2* ' KfF 0005379 Table 3 comparas the 'findings obtained by the analysis of samples collected simultaneously t>y the three different types of sampling equipment. The results of sedimentation tests made with samples collected by electrostatic precipitation during periods of use of the leaded, abrasive, cut-off wheel are tabulated in Table il. Di scusaion resin- d, leab-b earing. abrasive * cut-off wheels benefit cf ttrteqimt& exbau st venti latier; 5 of loan in the tir at th b r e s t b i n x e n the gener al work area, 12 feet from the h ware 2. ? to 15 times greafcer than the threshold limit reco?2jenoed for industrial operations (Table 1). When the exhaust ventilation of the cut-off machine was in operation, the dispersion of lead-bearinp dusts into the air was greatly reduced, as was indicated by the concentration of 0.1 r.;:. of lead per cubic j&eter of air, when a sample* was obtained durir," the operation of a wheel containing: 1? per cent of lead (sample 5, Tab le 1) * 'On- the average# 84 per cent of the particles of dust produced fey the use of the leaded, cut-off wheals- were smaller than 10 microns in diameter. The greater portion of the sir-borne lead was found in these finer dust particles. Particles of duct within this range in six averaged 75.0 per cent of the total lead; the findings varied from 60*5 per cent in a sas;ple collected 12 feet' from the cut-off smchlne, while a whel containing, 3 per cent of 0005380 KE - fe w 2a<S was being used, to 85 per cent of the total lead in the breathing cone of the operator during the use of a wheel containing 12 per cent of lead. The data in Table 2 indicate that scat of the particles dispersed into the air by th leaded wheels were below 10 microns in diatcoter, and that .the m & i & n diamtcrs of the particles in all of the snaplee were well below 5 1crons* Examination of the particles trapped on the membrane filters (3C and 8C) revealed that 8 per cent of the particles observed by light field microscopy were Sisaller than 5 microns in diameter, and .-that the median diaeetcr was considerably less than 1 sslcrcn in siae* Most of the particles wore spherical in shape, and there were many aggregates of these all part icier (this phenomenon is characteristic: of particles forming; metallic fumes) as may be soon from the data presented in Table 3* higher 'levels of concentration of lead were found In the dust collected on membrane filters, as compared with those found in dust collected by other cans* The higher values are probably due to the relative nearness of the *&;Vcrane sampler, to the source of the lead dust* The physical and chemical examinations of the particles deposited on the membrane, filters support the conclusion that the lead in the air was present mainly as fume* Such a result, we believe, can be' expected from the nature of the formulation of the wheel, the wear of the wheel, and the he*t generated in the cutting operation* Although the results obtained by the use of the three types of samplers reported in Table 3 are not strictly comparable k'E' 0005381 - ?- because of their different locations in the breathing zone relative to the cut-off Machine, and the different entrance velocities due to the different rates .of eeapling, they are consistent in showing that saoet of the lead in the air was represented by the smaller particles suspended therein* Of the three pieces of equipment employed in this investipation, only the "respirable" dust simpler directly separated the air-borne dust into so called "respirable" and "unrespirable" fractions. The device had beer* use by the A.K.C. with sowe success to study the inhalation of respirable uranium dioxide. (Llppmann, K. and Karris, 'W* R. "Size-Selective Samplers for Estimating "Respirable" Dust Concentrations" Health Rhys les, 6, 155, 1962.) Since the densities of lead and lead oxide are not too different from that of uranium, the equipment was `considered satisfactory for defcermlninr the quantities of lead which could roach the lungs. Fro theoretical considerations it was determined that BO per cent of the particles, of lead, 0.? microns in diameter and 50 per cent of those 1 micron in diameter would be collected on the filter and be representative of the Kites of particles which could reach the lungs* As was tienttoned earlier, approximately BO per cent of the particles deposited on the membrane filter were less than 2 microns in sise and only 2 per cent were greater than 5 microns in dlasseter (Table 2). Table h shows the distribution of the total lead between the fine and coarse particles. These data were obtained from the sedimentation studies in which the concentration of lead in the portion of the fine particles removed for analysis was used to calculate the amount of lead in the fine particles suspended at the 0005382 end cf 2 ninutes and lJ2 second in the total volume of ethyl alcohol used in the aedlaentatlon vessel The concentrations listen ere evidently on the lev side, since many fine particles accompanied tho coarse particles and were included In the latter f i n d i n g All of the evidence, therefore, points to the fact that the greater portion of the total lead present in the air is present in the fine particles and aessfc likely is present in the. air as fus-e. It Is also evident that gbrasive, cut-off wheels containinr lead will need to be onerated in equipment provided with adequate exhaust ventilation in order to collect the lead dusts and fumes produced In their use. Free The Ketterinp Laboratory in the Department of Preventive ftedicin and Industrial Health, Collere cf Medicine, Universi y of Cincinnati, Cincinnati, Ohio work am? Report brr; J. Cholak, Ch*E L. v* Schafer, E.S,{Ch.K.) D, Yeager, L#s. Approved Date: J-rmnrr? 15, 19t H e 00053S3