Silicosis in the metal mining industry : a revaluation, 1958-1961.

  • United States Public Health Service
Date:
[1964]
Catalogue details

Licence: Public Domain Mark

Credit: Silicosis in the metal mining industry : a revaluation, 1958-1961. Source: Wellcome Collection.

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    its; whereas, on the basis of the 1962 threshold limits, 104, or 13.2 percent, of the weighted averages were above the threshold limits. Table IV.9 shows results of the full-shift weighted average expo- sure determinations in relation to the threshold limit values in effect during the study, 1958-61, and to those adopted by the American Conference of Governmental Industrial Hygienists in 1962. In the table the 67 mines studied are grouped according to frequency of occurrence of weighted averages above the respective threshold limits. In respect to either set of threshold limit values, the data in table IV.9 show that a few mines contributed a major portion of the full-shift weighted averages that exceeded the limits. The table also shows distribution of the underground mining population at the time of the study and distribution of the 789 weighted average de- terminations among the groups of mines. It is emphasized also that although some mines had no weighted average exposures in excess of suggested limits, some individual impinger samples in all the mines studied contained excessive dust, showing that improved dust control was needed at these particular spots. TABLE IV.9.—Distribution of weighted average exposures that exceeded threshold lamit values* Undergrcund mining Weighted average exposures over Weighted average Mines studied population threshold limit values exposures determined Number | Percent Number Percent Per mine Total Percent | Number] Percent of tctal of men of total of total of total On basis of 1958-61 threshold limits 46 68. 6 8, 629 61.5 0 0 0 499 63. 2 13 19. 4 3, 041 Ja are it 13 29. 6 175 Date, 04 3 4.5 856 6. 1 Z 6 13. 6 Oe Ab 76 Zz 3. 0 316 2.8 3 6 13. 6 74g eh 1 ees 316 2.3 4 4 9.1 16 2. 0 2, 3. 0 852 6. 1 5 and over 15 34. 1 41 a. 2 OF hOG: OF 4 O10: | 200 Ooh. oka otk 44 |100. 0 789 | 100. 0 On basis of 1962 threshold limits 30| 44.8] 4,821| 34.5 0 a ieee 293 | 37. 1 14 20. 9 2, 989 21.3 1 14 en 179 22. 10 14. 9 1, 136 8. 1 2 20 19. 2 100 17 5 es 804 Det 3 15 14. 4 52 6. 6 D4 3. 0 AVF 3. 0 4 8 ok 28 3.0 6 8.9 3, 843 27.4 5 and over 47 45. 2 137 17. 4 67. 1000) 14, 010 1 10000 | ose. oe 104 | 100. 0 789 | 100. 0 *Of 789 full-shift weighted average exposures determined in 67 mines, 44, or 5.6 percent, exceeded the 1958-61 threshold limit values; and 104, or 13.2 percent exceeded the 1962 threshold limits. Jl
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