APPENDIX B
SUMMARY OF DOSES AND CONCENTRATIONS OF ZINC CADMIUM SULFIDE PARTICLES FROM THE ARMY'S DISPERSION TESTS

PREPARED BY

EDMUND CROUCH

CAMBRIDGE ENVIRONMENTAL, INC.

CAMBRIDGE, MASSACHUSETTS



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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests APPENDIX B SUMMARY OF DOSES AND CONCENTRATIONS OF ZINC CADMIUM SULFIDE PARTICLES FROM THE ARMY'S DISPERSION TESTS PREPARED BY EDMUND CROUCH CAMBRIDGE ENVIRONMENTAL, INC. CAMBRIDGE, MASSACHUSETTS

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests SUMMARY OF DOSES AND CONCENTRATIONS OF ZINC CADMIUM SULFIDE PARTICLES FROM THE ARMY'S DISPERSION TESTS I. INTRODUCTION This document has been prepared for the Subcommittee on Zinc Cadmium Sulfide to summarize some estimates of concentrations and potential exposures (time-integrated concentrations) of zinc cadmium sulfide (ZnCdS) that were achieved during the use of this compound in certain air-dispersion tracer tests. The basic source materials were a subset of the references included in an appendix entitled "Zinc Cadmium Sulfide Testing Documents," which listed all known Army-sponsored ZnCdS tests. All reference numbers herein refer to the list for this appendix. The description of the aim of this report is best described by the scope of work: A. SCOPE OF WORK (CAMBRIDGE ENVIRONMENTAL INC.) Dr. Bakshi has provided Cambridge Environmental Inc. with approximately 50 documents (see the reference list for this appendix), most of which contain details of various U.S. Army-sponsored tests using ZnCdS tracer (some provide details of multiple tests in one or more series).

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests Cambridge Environmental, Inc., reviewed these documents and abstracted summaries of them, providing the following details for each test or series of tests whenever such details were available in the documentation: Name of test; Reference; Principal object of test; Number of and naming conventions for releases; A summary of the test conditions (method of release, location of release, mode of release, release vehicle, sampling station information, and so forth); Test material; Place of release; Communities that were affected by measurable concentrations of tracer; Date of releases; Time of day of releases; Period of time during which releases occurred; Distance of releases to affected communities; A summary of weather conditions during the releases; Total quantities of ZnCdS released; Total quantities of any other materials co-released; Maximum time-integrated concentration (microgram-minutes per cubic meter) due to each release; Maximum time-integrated concentration due to each release in any populated area; Maximum concentrations during the releases; Maximum concentrations during the releases in any populated area; Other comments. Not all such details were available in all cases, although certain details always appear to have been provided. In all cases examined, measurements and estimates were made of time-integrated concentrations at various locations.

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests The two measurements of exposure-time—integrated concentration and concentration—are those required for estimating risks using the standard paradigms. In all cases, the release times were relatively short (<24 h), so the maximum concentration was compared with a short-term safety standard. Estimates of lifetime cancer risk are generally made using where R is the lifetime risk estimate, U is the unit risk (m3/µg), T is a standard lifetime (70 years), C is the time-varying concentration, and t is time. This estimate involves the time-integrated concentration directly. B. MISCELLANEOUS NOMENCLATURE Throughout this document, various abbreviations and standard nomenclatures are used. The most important of these are the terms used to describe the two measurements of exposure or potential exposure evaluated. These two terms are Concentration The mass of ZnCdS tracer material per unit volume of air, averaged over a relatively short period (generally 10 s to 2 h, depending on the experiment). All concentrations are reported here in units of microgram per cubic meter. Exposure The time integral of the instantaneous concentration of ZnCdS at a single point of measurement, reported in microgram-minutes per cubic meter. All the documents examined use the nomenclature "dose" to represent the time-integral of the concentration measured in particles of ZnCdS per unit volume (usually measured as particle-minutes per liter). An attempt has been made to distinguish between concentrations and exposures measured in (humanly) populated areas and in unpopulated areas, although this attempt necessarily is limited by the available information.

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests Individuals, particularly those involved in the experiments, might have been subjected to the concentrations or exposures listed as being in unpopulated areas; in some cases, no one might have been subjected to the concentrations and exposures listed as being in populated areas. The material of interest is fluorescent ZnCdS. This nomenclature is used for convenience only. The material used should probably be considered an alloy of zinc and cadmium sulfides, with the fluorescence color determined by minor additions of other elements. The stoichiometry is approximately Zn0.8Cd0.2S, but all masses used in this document refer to the total mass of the ZnCdS—no correction to obtain a mass of cadmium (the principal component of concern to the subcommittee) has been applied. Some of the abbreviations used in the following summaries are ppg particles per gram BG Bacillus globigii MMD mass mean diameter SM Serratia marcescens QR quarterly report C2 Aspergillus fumigatus BMR bimonthly report Conc. concentration JQR joint quarterly report Max. maximum SAL Stanford Aerosol Laboratory Exp. exposure 2. SUMMARY OF RESULTS The entries in Table B-1 are the following: Ref. Reference number in the listing of reports Place Location of the releases Name Any known name given to the operation in which releases occurred Start date Date of first release End date Date of last release

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests TABLE B-1 Exposure Data on ZnCdS Dispersion Tests               Populated Areas Unpopulated Areas             Total Quantity of ZnCdS, kg Max. Exp., µg-min/m3 Max. Conc., µg/m3 Max. Exp., g-min/m3 Max. Conc., µg/m3           No. of Releases Ref. Place Name Start Date End Date Approximate area affected, square miles Releases not at Dugway Proving Ground 2 Camp Cooke, Calif.   1955   39 2.3 <173 <7 60,136 55,650             <10 <10 <1 <1 8 North Carolina, S. Carolina, Georgia DEW I 03/26/52 04/21/52 5 630 98 0.34                 <100,000 <10,000     13 Corpus Christie, Tex. WINDSOC 08/13/59 02/22/60 13 ~1,600 ? ?                 <100,000 <10,000     16 Oklahoma   06/04/62 06/16/62 9 204 39 0.75                   <1,000 <1,000     16 Texas   06/24/62 06/29/69 9 204 36 0.82                   <1,000 <1,000     16 Washington   10/02/62 10/21/62 9 204 6.7 0.3                   <1,000 <1,000     16 Nevada   10/31/62 11/05/62 8 181 23 1.6                   <1,000 <1,000     17& 43 St. Louis   05/27/63 03/17/65 42 984 7,400 40                   <10 <10     19 Chippewa National Forest, Minn.   01/25/64 08/07/64 24 330 1,620 3 2,779 9.1             <1,000 <1,000 <100 <100 20 San Francisco   03/25/64 04/23/67 18 27.75 <1,900 <170 1,900 170             <10 <1 <10 <1 22 Fort Wayne, Ind.   02/02/64 02/04/66 75 ~1,650 410 <20                 <1,000 <1,000     24 Oceanside, Calif. Onshore Offshore releases 06/23/67 07/17/67 45 237 694 1,741               <1 <1               149 1.3               <1,000 <1,000     27 Pack Forest, Wash.   10/15/68 09/05/69 33 1.7     ? ?                 <0.1 <0.1 28 Green Brier Swamp, Md. MATE 08/01/69 10/29/69 111 2.7 <42 ~0.03                 <1 <1     30 Camp Detrick, Md. SELTZER 02/18/53 02/24/53 4 0.022 71 9 785 93             <10 <1 <1 <1

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests               Populated Areas Unpopulated Areas             Total Quantity of ZnCdS, kg Max. Exp., µg-min/m3 Max. Conc., µg/m3 Max. Exp., μg-min/m3 Max. Conc., µg/m3           No. of Releases Ref. Place Name Start Date End Date Approximate area affected, square miles 30 Biltmore Beach WHITEHORSE 03/24/53 05/02/53 12 9.7 150,000 4,800                 <0.1 <0.1     33 Dallas   04/01/61 08/31/61 37   ? ?                   <1,000 <1,000     35 St. Louis   01/19/53 10/18/53 35   2,000 340                   <10 <0.1     35 Minneapolis   05/20/53 06/23/53 102 7.9 2,600 300 17,200 1,100               <10 <0.1     35 Winnipeg   07/09/53 08/01/53 36 5.8 5,600 1,000 920 130             <10 <0.1 <1 <1   36 Stanford University, Calif.   10/15/47 10/15/47 1 0.00083 5 2     37 Palo Alto, Calif.   03/10/50 03/14/50 2 0.976 2.4 0.5                 <100 <100     37 San Francisco   10/20/50 10/27/50 6 22.44 436 15                 <100 <100     41 Palo Alto. Calif.   01/26/62 11/16/62 28 1.4 1,676 ?                 <0.1 <0.1     Releases at Dugway Proving Ground 3 Dugway   05/04/53 06/03/53 2 5.534     <77   4 Dugway   01/21/54 03/14/54 4 0.0348     <2,000   6 Dugway   05/18/55 05/18/55 2 0.0424     <6,00   18 Dugway   05/17/63 08/15/63 9 29.6     1,044   29 Dugway GOOF 08/23/55 11/01/55 5 0.8 <409   14,300   31 Dugway   04/03/58 04/22/58 4 0.0534         32 Dugway   02/70 to 03/7/06   0.21     <137,000   37 Dugway   07/01/50 08/04/50 9 8.244 0.03   <80 0.5

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests Total quantity Quantity released in all known releases, including corrections for missing data Number of releases Total number of known releases of ZnCdS Populated areas Concentrations or exposures in populated communities, or, for Dugway, at the limits of the measurement array Unpopulated areas Concentrations or exposures in unpopulated areas Max. Exp. The maximum exposure (time integral of concentration) of ZnCdS measured Max. Conc. The maximum concentration of ZnCdS measured or es-timated Approx. area affected An order of magnitude estimate of the area affected within exposure. See the summary reports that follow for important caveats on all the reported values. In particular, all exposures are likely to be accurate to a factor of 2 at best, all concentrations will be substantially less accurate than that, and the magnitude of the values given often depends strongly on the placement of the sampling devices. All exposures and concentrations represent the total mass of ZnCdS present. (There is no correction to the mass of only cadmium.) Exposure and concentration values are not directly comparable between experiments because of the different areas affected and the different placement of sampling points. To give an idea of the variation, the table includes (for the non-Dugway releases) some order of magnitude estimates for the areas affected within approximately an order of magnitude of the maximum concentrations or exposures reported. The areas given are approximate upper bounds on the areas affected, rounded up to the nearest power of 10.

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests A missing entry generally indicates a lack of, or irrelevance of, a measurement or estimate for that entry (e.g., exposures to unpopulated areas are irrelevant for releases made over populated areas). In Chapter 5, Table 5-1 is derived from Table B-1. To obtain the cadmium dose, the maximal exposure of ZnCdS (expressed as µg-min/m3 as shown in Table 5-1) is multiplied by 0.0166 m3/min (the volume of air inhaled by an active person in one minute). The product is then multiplied by 0.156 (the mass fraction of cadmium in ZnCdS). The corresponding cadmium doses are 6.8 µg in Minnesota, 14.5 µg in Winnipeg, 24.4 µg in St. Louis, and 390 µg in Biltmore Beach. APPROACH AND METHODS A. BASIC APPROACH An initial scan of the approximately 50 documents available showed that there were too many and too varied a set of experiments to be able to perform complex or even simple analyses beyond those performed by the original experimenters and reported in the references. As far as possible, this report therefore contains simple abstracts of the most relevant data from the references, with as little interpolation as possible, and with only the simplest extrapolations. The original researchers usually provided substantial documentation. A much more thorough job of reconstruction of exposures would in most cases be possible with substantially more resources, but, in view of the orders of magnitude of the exposures, such a reconstruction would probably not add much value for the committee. B. PURPOSE OF ORIGINAL EXPERIMENTS In the references examined, there were two principal purposes for the experiments performed:

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests Experimental confirmation of the practicality of dispersion of biologic warfare agents, empirical observations of the ranges and exposures that might be achieved, and obtaining correlations between the dispersal of biologic agents and inert aerosols. The fluorescent tracer was used as safe indicator of the potential extent of spread of biologic organisms under similar meteorologic conditions. Tracer tests in the atmosphere, to determine how the atmosphere behaves and derive correlations relating the dispersion of gases and aerosols to observable meteorologic conditions. Of course, if correlations could be obtained between dispersal of biologic organisms and inert aerosols, the second purpose would also serve the first, although the second also has much wider application. C. THE TYPICAL EXPERIMENT The fluorescent-particle (FP) tracer technique is extensively described in Ref. 48. The idea is to release into the atmosphere a very large number of small particles as an aerosol that then disperse. The concentration of these particles after dispersion downwind is then measured by counting the individual particles collected by a collection device that samples a known volume of air. ZnCdS, originally developed as a fluorescent paint pigment, was found to be suitable for this application. The useful particle size range is about 0.5 to 5 µm, with the lower end limited by the detectability of the particles, and the upper end limited by the rate of fall-out from the air. The typical experiment used particles with a mass mean diameter of 1 to 2 µm, and an effective dispersal rate of around 1 x 1010 particles per gram (ppg). It was found that the best available fluorescent ZnCdS particles could be reliably detected by eye under an optical microscope (with ultraviolet illumination to excite the fluorescence) at sizes down to around 0.3 µm diameter, allowing measurement of concentrations by counting individual particles collected on filters or other collection devices. Background counts in most areas were very low. No automatic particle-counting

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests methods were described in the references examined. All particle counts were apparently obtained by human microscopic observations, although mechanical methods to improve the efficiency of sample preparation and presentation to the human observer are mentioned. In a typical experiment, grams to kilograms of ZnCdS powder would be released over periods ranging from seconds to hours using an air-driven dispenser designed to efficiently produce an aerosol cloud. The dispenser would be mounted at a particular location (point source), or on the back of a moving vehicle (line source)—trucks, aircraft, and boats were used. The method of dispersion affected the dispersion efficiency, a measure of how much clumping of the particles occurred during release. Typical particles-per-gram values for particular manufacturers' lots of ZnCdS were apparently1 obtained by a standardized test involving the dispersal of a small quantity of the material in an enclosed chamber. The particle count would then be obtained by sampling the aerosol with a filter-type sampler. The dispersion efficiency in an experiment is then the ratio of the particles per gram achieved in the experiment to the standardized value. A blending agent was typically used to improve the flow characteristics of the ZnCdS powder and reduce clumping, but environmental conditions could obviously affect the dispersion efficiency attained. Downwind of the release point or line, sampling stations were set up at locations of interest. These sampling stations sampled the air by drawing a known volume flow rate (typically 6 liters (L)/min) through a filter (an approach that collects practically 100% of the particles on the filter) or by using a Rotorod collector. The latter consists of an H shaped wire (0.016 x 1/16 in.) with vertical members approximately 2.5 in. long, and crossbar 4.75 in. long, rotated upright about the center of the cross-bar. Particle collection is by impact on the 0.016-in.-wide leading edge of the vertical members of the H, which were coated with silicone (vacuum) grease to improve collection efficiency. The effective volume swept by the 1   This description is inferential because no detailed description of the test method was located in the available material.

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests FE 23: The same as that in FE 22, but moved to take account of a wind shift. The first 3.5 miles of the release was in the vicinity of Granite Peak. FE 24: Release line not identifiable from available documents but should have been in a location similar to FEs 22-23. During all the daytime tests, the aerosol cloud and the dust cloud raised by the vehicle emitting the aerosol cloud was observed to rise immediately in the unstable air. The closest samplers did not measure the highest exposures. The following two tests were performed at night. FE 19: Release on a 0.8-mile arc of an 800-yd circle around target X, starting at the east pill box. Wind direction was southeast to south-southeast. FE 25: The same as that in FE 19, with a 1-mile release line. Wind direction was south-southeast to south. Samplers were located at distances from several hundred yards to 14 miles downwind, with some samplers moved into position during or after the release on the basis of wind measurements. San Francisco Releases were from a 100-ft Mine Layer using three or four generators mounted 15 ft above the water, and traveling north to south along a 2- to 6-mile line approximately parallel to the shore and 2 to 10 miles from the shore. For FE 29, two release lines were used, starting from 9.5 miles west of San Francisco. In every case, the release lines were traversed in approximately 30 min. There were 43 sampling stations, 10 of which were equipped with drum samplers giving 1-min resolution. Most remaining stations were equipped with filter samplers, although up to five stations per experiment had no FP measurement equipment (stations were also equipped with samplers for the biologic material released).

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests Test material: New Jersey Zinc Company No. 2266 (ZnCdS). The emission rate stated in QR 1 (Palo Alto) corresponds to 1.82 x 1010 ppg. In QR 2 (Dugway), the particle count is given as 3 x 1010 ppg, although this count appears to be based on an estimated mass mean diameter of about 2.5 µm. In QR 3 (San Francisco), the particle count is said to be 6 x 1010 ppg, a count based on a mass mean diameter of 2 µm. Place of release: Palo Alto FE 15 and FE 16. Along lines northwest of Palo Alto. Dugway See ''Test conditions'' above. San Francisco See "Test conditions" above. The average distance offshore of the releases were 2.5 miles for all experiments except the two releases of FE 29, which were 10 miles out. Dates, times, and quantities of release: FE Date Start Time Period, min Length, miles Amount, g Palo Alto 15 03/10/50 15:30 16 3.58 500.1 16 03/14/50 15:25 14 3.43 475.5 Total         975.6 Dugway 17 07/01/50 14:40 17 3.5 880.5 18 07/11/50 10:00 17 3.6 778 19 07/19/50 03:59 8 0.8 372.7 20 07/29/50 14:18 19 3.5 917 21 07/30/50 15:23 25 pt 625 22 08/03/50 12:00 20 5.5 1012.4 23 08/03/50 15:08 55 10.4 1961.8

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests 24 08/04/50 14:26 24 5.8 1086.2 25 08/04/50 23:48 11 1 610.6 Total         8244.2 San Francisco PDST       26 10/20/50 14:30 28 5.85 3426 27 10/22/50 14:00 30.1 7.09 4328     PST       28 10/25/50 17:00 28 2.7 5263 29 10/26/50 16:15 29 2 2677   10/26/50 17:11 27.2 2.42 2546 30 10/27/50 17:00 30 2.88 4200 Total         22,440 Communities affected: FE 15-16: Palo Alto. FE 17-25: At Dugway test ground. Unclear what was affected. Possibly one or more of the local small communities. FE 26-30: San Francisco and the Bay area. Distances from releases to affected communities: FE 15-16: Not clear from available documents. The experiment was designed so that the main cloud passed through the city of Palo Alto. FE 17-25: It is noted for FE 17 that "a significant dosage was found at the village 14 miles from the source", and "This is the first time at Dugway that any airborne material has been sampled more than a mile or two from its point of release, and is even more noteworthy in view of the fact that the test was run during the day when conditions were least favorable for long distance travel." FE 26-30: Aerosols were generated 2 to 10 miles west of San Francisco, on a course approximately parallel to the shore. Weather conditions:

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests Palo Alto FE 15 and FE 16: Inversions at 3600 ft and 2800 ft. Dugway FE 17, 18, 20, 21: Performed during the day under strong lapse conditions, with the wind from the northwest. FE 22-24: Performed during the day under strong lapse conditions, with the wind from the south to southwest. During FE 23, sand and thunder storms were encountered along the release line. FE 19, 25: Nighttime releases. During FE 19, the lower atmosphere was almost certainly neutral because of the high wind. During FE 25, there was almost certainly an inversion. San Francisco FE 26, 29, and 30 were in clear weather with the typical Bay-area onshore winds with inversion conditions at various heights over the ocean but sufficient heating over the city to provide lapse conditions at least to altitudes of several hundred to 1,000 ft or so. FE 27 had clear sky conditions, but a low, dense offshore fog, again with some inversion conditions over the ocean but lapse conditions over land. FE 28 had fog covering San Francisco to Oakland, keeping the inversion in place. Other materials released: FE 19 (at Dugway): BG was released simultaneously using clusters of E48R2 bombs dropped from the air. FE 25 (at Dugway): SM was released from a cluster of E48 bombs fired statically. FE 26-30: A biologic material was released simultaneously with the FP. Maximum time-integrated concentrations and concentrations: The following table gives estimates of maximum time-integrated concentrations (exposures) for each experiment, together with estimates of the

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests maximum short-term concentrations, where such estimates could be made. In addition, a cumulative estimate is made for the whole series of reported experiments. A maximum exposure for experiment FE 14 is given because it is mentioned in QR 1, and no further documentation of the early FE series is available. The maximum concentrations, where available, are from 1-min resolution drum samplers. For each experiment over San Francisco, the highest measured 1-min concentration has been increased in proportion to the total exposure (i.e., the highest measured 1-min concentration at any drum sampler has been multiplied by the ratio of highest total exposure measured anywhere to the total exposure measured by that drum sampler) because drum samplers were not placed at every sampling location. For San Francisco, the cumulative total exposure is the largest measured at any single location. (It is dominated by the single large value measured in FE 28 during a fog.) For Palo Alto and Dugway, samplers were at different locations for each experiment, so the sum of the maximum total exposures is an overestimate for the cumulative maximum exposure.   Populated Area Unpopulated Area FE Max. Exp., µg-min/m3 Max. Conc., µg/m3 Max. Exp., µg-min/m3 Max. Conc., µg/m3 Palo Alto         14 2.7       15 2.1 0.5     16 0.3 0.1     Cumulative 2.4 0.5     Dugway         17 0.03 (?)   0.5   18     3.1   19     10.0   20     0.1   21     1.5 0.5

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests   Populated Area Unpopulated Area FE Max. Exp., µg-min/m3 Max. Conc., µg/m3 Max. Exp., µg-min/m3 Max. Conc., µg/m3 22     0.2   23     0.1   24     0.0   25     63.2   Cumulative     <78.6 0.5 (?) San Francisco         26 17.3 1.0     27 4.2 1.1     28 410.3 15     29 13.9 0.8     30 18.9 0.7     Cumulative 436 15     Other comments: The first of these QRs reported two tests, numbers 15 and 16, of a series. Evidently, numbers 1 through 14 are reported in other material that is not available. The maps provided in QR 1 are readable but not decipherable. They might be decipherable if the reports for the previous contract were available. There is a reference to tests subsequent to those reported in QR 2 by the Detrick test team. No details are given. In QR 2, figures 9, 11, 12, 14-17, 20, 21, 25-27, 35, 36, and 39-41 are missing. Figure 9 is the site map. In QR 2, Charts A through I from Appendix A, are missing. These show sampling locations, release locations, exposures, meteorologic measurement area, balloon trajectories, and other information.

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests In QR 3, Charts A through E giving details of locations, are missing. There is a notice stating that these charts are available for viewing at the Technical Information Center, Dugway Proving Ground, Utah (801)8313564. Page 23 is missing. DESCRIPTION OF TEST Name of test: Collection Efficiency of the Rotorod FP Sampler Reference-list number: 41 Reference: F.X. Webster. Collection Efficiency of the Rotorod FP Sampler. Technical Report TR 98. Aerosol Laboratory, Metronics Associates, 3201 Porter Drive, Palo Alto, Calif. Contract DA 42-007-CML-543 for the U.S. Army Chemical Corps Research and Development Program. 31 Jan. 1963. Principal object: To investigate and define the collection efficiency of the FP collector rod for the Rotorod sampler with the coating technique as employed at Dugway Proving Ground. Site selection: Apparently for convenience—the field-test sites were not exactly located but were usually not more than a few hundred feet from the Metronics building. Number and nomenclature of releases: Seven field experiments, with four releases each, for a total of 28 releases (most of the releases required two distinct passes; some required as many as four passes). The field experiments were labeled FE 134 through FE 140, and the trials within each field experiment were labeled A, B, C, and D.

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests Test conditions: A line source of FP particles was made from a high-speed blower-type aerosol generator (5-8 g/min) mounted on the tail gate of a station wagon driven slowly along a route approximately 150 to 750 ft upwind of the nearest sampler. Two sampler stations were used, with an array of Rotorod samplers surrounded by reference membrane filter samplers. Two to four passes of the generator were used in each trial, two generally sufficing but as many as four being required in a few cases under highly variable wind conditions. (Test samplers were monitored for enough particle collection to give accurate statistics.) Test material: Various types of FP were used. Abbreviations are MMD mass mean diameter Manf NJZ = New Jersey Zinc Company; USRC = U.S. Radium Corp. Date Date of manufacture DPG Dugway Proving Ground. Color Type MMD ppg Lot Manuf. Date Trial Yellow 2266 1.8 7.0 x 1010 MA 104 NJZ 1954 FE137 Yellow 2266 2.4 3.3 x 1010 SAL 8B NJZ 1952 FE134 & 135 Green 3206 2.4 3.3 x 1010 H324-2 USRC 1961 FE138 Yellow 2267 3.1 1.6 x 1010 1339-2 USRC 1962 FE140 Yellow 2267 3.4 1.2 x 1010 DPG 12-21 USRC 1960 FE139 Yellow 2267 3.8 0.9 x 1010 H310A-E USRC 1960 FE136 Place of release: A few hundred feet from the Metronics building at 3201 Porter Drive, Palo Alto, Calif. Dates, times, and quantities of release: The quantities released were not specified, nor were any data supplied that allow reasonably exact computation. The release rate (in grams per minute and grams per foot) was given for each field experiment, but the time or distance of the release continued for each trial was not given, nor was even the number of passes required for each trial. The following ta-

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests ble gives a rough estimate obtained by assuming the disseminator was on for one-half the total period listed for the experiments. The value so obtained appears to be a reasonable estimate when considering also the length of the line source likely to have been used (about 2 or 3 times the distance to the nearest sampler) and the speed of the disseminator. FE Date Start Time, PST End Time, PST Estimated Amount, g 134 01/26/62 15:15 16:32 193 135 03/27/62 15:18 15:56 154     PDT PDT   136 05/09/62 14:47 15:37 200 137 05/14/62 15:21 17:15 291 138 07/17/62 16:59 17:45 145 139 08/21/62 15:15 16:06 219 140 11/16/62 15:44 16:43 206 Cumulative     1408 Communities affected: Palo Alto, around the Metronics building. Distances from releases to affected communities: Releases were within the community. Weather conditions: Wind speeds generally in the range 8 to 14 mph, although a few trials were conducted with wind speeds as low as 3 mph, and a few others in winds as high as 18 mph. Other materials released: No other materials were mentioned. Maximum time-integrated concentrations in any populated area: These concentrations were measured at 150 to 750 ft from the line source. It is likely that the experiment was set up so that there were no buildings between source and samplers.

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests FE Trial Max. Exp., µg-min/m3 FE Trial Max. Exp., µg-min/m3 134 A 20 138 A 111   B 94   B 56   C 17   C 48   D 37   D 80 135 A 237 139 A 86   C 51     64   D 75     75 136 A 41 140 A 90   B 38   B 66   C 28   C 93   D 34   D 55 137 A 19         B 24   Cumulative 1676   C 14         D 16       The cumulative estimate has been obtained by summing the individual values for each experiment, because most of the experiments were apparently carried out at the same location. Maximum concentrations in any populated area: No time-resolved data were available for estimating concentrations. Other comments: This contract was to improve the efficiency estimate for the Rotorod as used at Dugway. None of the Dugway studies included among the references used Rotorod samplers. Reference is made to CML-543 Final Report (presumably from Metronics) giving tabulations of ppg and MMD for various FP, particularly the "12-series lots" used by Dugway. That might be Ref. 48. FP Lot H324-2 is stated to have been used in Dugway Trial 502 B-7, but that is not in the references.

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Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests Reference is made to Stanford Aerosol Laboratory QR 111-10, July-Aug.-Sept. 1956, Contract DA-42-007-403-CML-111, although only in the context of theoretic analyses. All the tracers listed above "have been used as tracers in atmospheric diffusion studies." H324-2 and DPG 12-21 have been "used extensively at Dugway."