Document r6dKangomzLEdYnzZX2ZVkLR7

V Biochemical Research laboratory OFFICE COPY The Dow Chemical Company x o7 Noted E.E.D. H ' FEB 07 1958 EVALUATION OP CHEMICAL EXPOSURES RECEIVED BY R. R. SPENCER OF COATINGS TECHNICAL SERVICE, 433 BUILDING Pile: T2.1-1-45 (?) Chg.: 1219. Date: 1-22-58* By: .J. E. Peterson ST006828 PROBLEM THIS REPORT IS THE PROPERTY OF THE DOW CHEMICAL COMPANY Recently, R. R. Spencer has become 111. The Environmental Research Laboratory was requested to determine chemical exposures received by him, and to assess these data. i CONCLUSIONS 1. Exposures to airborne materials during the formulation, mixing, and calendering of vinyl asbestos tile In 433 Building were evaluated on 12-23-54 and on 1-15-58. Results of these evaluations are used to assess exposures received by R. R. Spencer during his work with this material. 2. Prom December 1953 to December 1954, R. R. Spencer worked with vinyl asbestos tile formulations, and In the course of that work was occasionally exposed to somewhat excessive concentrations of airborne asbestos. ST006829 ./' Biochemical Research laboratory T2.1-1-65 Page 2 During this period of time exposure to lead occurred, but his blood lead level on 3-7-55 was only 0.024 mg./lOO cc. blood, a normal figure. Exposures to cadmium during this period were to airborne concentrations of ''<.0.7 mg./m^" at intermittent periods. No effect is expected as a result of these exposures. 3. Prom the first part of 1955 to late 1956 Mr. Spencer worked mostly with latex in concrete, and exposures to vinyl-asbestos tile ingredients were reduced accordingly. 4. Prom the last part of 1956 until the present he has been working with vinyl-asbestos tile formulations in a supervisory t capacity. During this work he was probably exposed a maximum of 1-2 days per week to airborne dust concentrations of less than 3 mppcf of a material analyzing 20-30$ asbestos, less than 5$ SlOg, and about 0.02$ cadmium. No effect can be expected from such exposure. 5. If Mr. Spencer's difficulty is the result of chemical exposure, the c^usltlve agent is unknown at present. Further air analyses are to be made during a time when chlorinated polyethylene is used as the resin binder in the tile formulations. ST006830 y' Biochemical Research Laboratory T2.1-1-65 Page 3 PRESENTATION OF DATA R. R. Spencer has been 111 with a lung difficulty, and overexposure to chemicals encountered during the formulation, mixing, and calendering of vinyl-asbestos tile formulations was suspected to be the cause of his Illness. The Environmental Research laboratory was requested to determine and evaluate his exposures. On 12-23-54 an environmental survey of the vinyl-asbestos tile formulating operation was made by S. R. Johann; the results of this work were reported on 5-5-55 (Pile Number, T2.1-1-32). This survey found that air concentrations of "Inerts" (asbestos plus cu-ciu.T. carbonate), barium, and lead were too high for repeated 8-hour exposures, and even though exposures were not that prolonged, recommended the installation of local exhaust ventilation. Cadmium was determined In the air samples, but In all cases the amount present was below the limit of sensitivity of the analytical technique employed, leading to air concentration figures of "less than" 0.66 mg./m^ and "less than" 0.45 mg./m^. As a result of this Investigation several changes were made. First, the use of lead and barium compounds in the formulation was sharply curtailed. Second, operational techniques were changed so that each batch was completely formulated before mixing in the Banbury or Baker-Perkins machines, and mixing in these enclosed machines was always to be done prior to Biochemical Research laboratory T2.1-1-65 Page 4 Third, canopy hoods were Installed over the large 2-roll mill and over the calender, but not over the small 2-roll mill usually used for preliminary compounding of these formulations. Finally, the Building Products group recently moved into new quarters where a bench-type hood is always available to control dust from dry mixing. In connection with the environmental survey of December 1954, samples were taken for blood-lead determinations for the men involved on this project. R. R. Spencer's blood lead concentration was found to be 0.024 mg./lOO cc. of blood, a normal figure, indicating insignificant exposure to lead. The onner two men involved also had normal blood lead values. On 1-15-58 a second environmental survey of the vinyl-asbestos tile operations was made, partly to assess the value of indicated changes in reducing exposures of personnel, and partly to gain more insight into the chemical exposures that R. R. Spencer may have received recently. The ingredients used in vinyl-asbestos tile formulations have adhered quite well to the same basic recipe for over a year. ST00683I Biochemical Research laboratory T2.1-1-65 Page 5 ST00G332 The recipe Is as follows: Material Weight Ratio Resin May be chlorinated polyethylene or resin 2716, the copolymer of 15/6 vlnylldene chloride, 85# vinyl chloride. Dioctyl phthalate or trlcresyl phosphate 17.5 2.25 Monoplex S-38 An epoxidized oil purchased from Rohm and Haas. Metasap 624 Contains cadmium laurate Aluminium stearate Paraffin wax LeslmltCalcium carbonate No. 18 graining sand A very fine sand Tltanox RA50- Titanium dioxide Asbestos shorts, type 7M 2.25 1.5 0.1 0.1 39*8 12.5 5*0 19.0 > With the exception of dloctyl phthalate and monoplex S-38, which are liquids, all of these materials are dry powders, and normally are weighed Into a stainless steel mixing bowl In the open. This operation takes about 5 minutes. The mixing bowl Is then placed under a mixer within a hood, mixed for a few minutes, and then the two liquids are added. After further mixing, the batch (which Is still a dry powder) is poured into a paper bag held within the hood. STO06833 Biochemical Research laboratory T2.I-I-65 Page 6 When it is done* weighing and blending of the ingredients takes place at a maximum frequency of about 3-half-days per week; an average frequency is difficult to establish because two or three weeks may pass with no activity in this area at all. Mr. Spencer normally would be involved in about 10# of this work which is usually done by a lab technician. Dry powder from the paper bag is poured directly into the BakerPerkina or Banbury mixer - usually the Banbury. Here the material is forced into a heated mixing chamber with an air-powered ram and is mixed for about two minutes. The resulting mass is semiplastic* and is removed (sometimes with difficulty) from the mixer j and carried to the differential speed heated (200-300?.) 2-roll mill. On this mill it is further blended and occasionally marbilizing chips are added. Such blending may take from 2 or 3 minutes to a half-hour depending upon the difficulties encountered. After being thoroughly mixed on the 2-roll mill the plastic mass is carried to the calender (basically a cooler heated 2-roll mill) a few feet away. Here the material is squeezed to a pre-determined thickness by a pass through the rolls; the surface of the resulting strip is improved by a second pass through this machine. The strip of tile material is then cut into pieces of the' correct size for testing with a shear. From Banbury mixer to finished pieces of tile may take from 15 minutes to an hour or so for a single batch. Biochemical Research laboratory T2.1-1-65 Page 7 The maximum frequency of this job is about the same as for weighing and blending, 3 half-days per week, and again, an average frequency is almost Impossible to establish. For reasons of safety, two men always work together in these operations; Mr. Spencer has been associated with about 8o of this work since the latter part of 1956. On 1-15-58 several air analyses were made during vinyl-asbestos tile manufacture. Air sampling equipment used was the Bausch and Lomb dust counting microscope and the electrostatic precipitator. Results of these air analyses are presented In Table I. Samples 1-11 were taken with the B and L dust counting microscope and the concentrations are expressed in terms of millions of particles per cubic foot of air. (mppcf). Samples 12-14 were taken with the electrostatic precipitator, and normally concentrations would be expressed as milligrams of air contaminant per cubic meter of air (mg./nr^), but the samples were unfortunately of too short duration to obtain welghable quantities of dust. ST006034 Biochemical Research Laboratory T2.1-1-65 Page 8 Table I Description _____________ Dust Concentration, mppcf An air sample taken directly over a paper bag of dry materials shaken to produce dust. This sample was mainly to establish the size range of the airborne particles. Breathing zone sample as a paper bag of formulation was dumped into the Banbury mixer. Sample of fume from the hot semlplastlc mass as it was withdrawn from the mixer, not a breathing zone sample. Breathing zone of a man removing the semi-plastic mass from the Banbury mixer with steel picks. Breathing zone while working the material on`the 2-roll mill. Breathing zone while working the material on the 2-roll mill. Breathing zone of man as he put the material through the calender. Breathing zone while cutting the tile to size on the shear. Room air In the office. Breathing zone of lab technician as he added dry asbestos fiber to the mixing container on a scale in the laboratory. Most particles * In diameter, average about 2-3-r 3.2 0.7 1.0 0.9 0.2 0.7 0.5 0.2 1.4 ST006835 Biochemical Research laboratory T2.1-1-65 Page 9 Sample . No. 11 12 13 14 Description Dust Concentration, MPPCF finnedlately outside of the bench hood where the dry batch of material was being mixed. 0.5 Length of Time of Sample Electrostatic precipitator sample in the breathing zone while formulation being mixed in the Banbury. 2 min. Dust Cone. mg./m.3 Too little to weigh Breathing zone while work ing the formulation cn the 2-roll mill. Too little to measure. Sample taken in bench hood over the container where the dry mixture was being stirred. This sample was taken only to determine the relative propor tions of the dust constituents in air. CaCO, - Main Constituent Asbestos - 20-3056 SiO. <5* Cd 4 0.02% 9E89001S The resin used for the tile formulation Involved in the work described in Table I was resin 2716, consisting of the polymer made from 15% vinylidene chloride, 85% vinyl chloride. Analysis of Sample 14 was by x-ray diffraction and emission spectrograph; the organic materials ar m t "seen" by this method. ./ Biochemical Research Laboratory T2.1-1-65 Page 10 ST006837 The dust concentrations shown In Table I may be compared with the appropriate Industrial Hygiene Standards, listed In Table II. Industrial Hygiene Standards are concentrations which may be Inhaled as much as 8 hours per day, 5 days per week Indefinitely without 111 effect. Table II Industrial Hygiene Standards Material Standard Asbestos 5.0 mppcf Silica (quartz) Cadmium 5.0 mppcf 0.10 mg./ra^ Calcium Carbonate 15.0 mg./m^ Resin 2716 probably 15.0 mg./m^ An examination of Tables I and II readily shows that at no time were the standards for asbestos or silica exceeded. Since the dust counting microscope determines the number, not the weight of particles in the air some assumptions must be made before the cadmium exposure can be evaluated: (1) assume that the dust encountered near the Banbury mixer, 2-roll mill and callender had the same particle-size distribution as the dust of the dry mixture (confirmed by dark-field microscopic examination); (2) assume the dust particles were spherical with an average diameter of 2.(3) assume the density of the particles was approximately 2.0 g./cc. ST006838 Biochemical Research laboratory T2.1-1-65 Page 11 Using these assumptions, the weight concentration of dust corresponding to the highest observed particle concentration (3*2 mppcf) would be 1.85 mg./m.^. Then, assuming that the particles were 0.02# cadmium, the air concentration of cadmium was about 0.0004 mg./m. , well below the 0.10 mg./m^ Standard, especially considering that all of the assumptions made were conservative. Thermal decomposition products of the resin and plasticizers used could conceivably be the cause of trouble except that a great amount of experience at Dow and at other companies with these materials has shown that no adverse effects are to be expected even under much worse conditions than have been prevalent in 433 Building. Remaining as a possibility is the dust and/or thermal decomposition products from chlorinated polyethylene, a new material. A survey will be made when this material Is again used In vinyl-asbestos tile formulations in order to determine what materials are Inhaled, and in what concentrations. Alsc, this dust, along with the dust of other materials, is soon to be investigated by the Toxicology Laboratory to determine the degree of irritation caused by subdermal injections. This investigation should help to decide whether or not Mr. Spencer's lung injury could have been caused by the resins used in vinyl-asbestos tile formulations. ./' Biochemical Research Laboratory T2.1-1-65 Page 12 The bench hood used In the laboratory for dry mixing was evaluated by measuring air velocities at the face'of the hood with an Anemotherm Air Meter. The attached "Hood Survey Data Sheet" is self explanatory regarding findings and recommendations. ST006839