INSPIRATION CONSOLIDATED COPPER COMPANY, a corporation, Petitioner,
INDUSTRIAL COMMISSION OF ARIZONA and Benjamin Rocha, Respondents.
[85 Ariz. 206] Gust, Rosenfeld, Divelbess & Robinette, and G. H. Ladendorff, Phoenix for petitioner.
James D. Lester, Phoenix, for respondent Industrial Commission of Arizona. John R. Franks, Donald J. Morgan, Robert K. Park, and Frances M. Long, Phoenix, of counsel.
H. S. McCluskey, Phoenix, for respondent Benjamin Rocha.
This matter comes before this court on a writ of certiorari issued upon application of the employer, Inspiration Consolidated Copper Company, a corporation, to review an award by the Industrial Commission of Arizona of compensation and other benefits to Benjamin Rocha for total disability due to silicosis complicated by tuberculosis.
The evidence taken in the light most favorable to claimant shows that Rocha worked for various employers in the mining industry, primarily underground, in the State of Arizona from 1916 to 1924. From that time until 1935 he worked and held various jobs in the course of which he would not ordinarily have been exposed to the inhalation of harmful amounts of silicon dioxide dust. Sometime in 1935 he went to work for petitioner, the Inspiration Consolidated Copper Company, at Inspiration, Arizona, and continued in its employment until January 2, 1957, at which time he became totally disabled with silico-tuberculosis. All of Rocha's work for the Company was on a surface job in what is called the tank house of the electrolytic refinery.
[85 Ariz. 207] In the process of refining copper the ore is taken from open-pit mines, the nearest of which is approximately one-half mile from the tank house. It is then crushed to a proper size and conveyed by belts to large open tanks known as leaching tanks. Thereafter, by chemical action, the copper content is leached from the ore and a solution containing the copper is transported by pipes to the tank house where by electrolysis the copper is removed from the solution and deposited on copper plates. No ore or rock of any kind comes into the tank house. The work there consists for the most part in putting starting sheets into the tanks and removing the sheets after the copper has been deposited upon them, loading the sheets into box
cars for shipment to market, and general cleanup work.
Silicosis is generally defined as a disease cause by the inhalation of free silica, SiO sub2 , usually in the form of quartz. Doctor Reginald H. Smart, a witness in behalf of the Company, qualified as an expert on the subject of silicosis, having spent most of his adult life in the study and treatment of this condition, testified without contradiction that silicon dioxide and free silica are the same thing, and that those terms are used interchangeably. He also stated that silicon dioxide, SiO sub2 , is an allotropic substance; that is, while the chemical formula is the same, the substance exists in several different physical forms of which quartz is one; and that they are classified as free silica in contradistinction to silicates. Silicates are compounds of other elements with silicon.
In 1941, a routine X-ray of the claimant showed that he had silicosis which was described as first stage, possibly between the first and second stage. However, claimant was seemingly otherwise in good health and he continued to work. A series of x-ray examinations of claimant's chest in 1950 revealed early third-stage silicosis with probable superimposed tuberculosis infection. These examinations were made at the Miami Inspiration Hospital, a hospital maintained by several mining companies including the Inspiration Consolidated Copper Company. The 1950 X-ray record contains a notation that sputum and other diagnostic procedures were advised, but no record appears that this advice was ever carried out. No further examinations were made of claimant until January of 1957 when he developed severe dyspnea, at which time further X-ray examinations were made and acid-fast bacilli of Koch were determined to be present in claimant's sputum. This led to the ultimate diagnosis of silico-tuberculosis. By statute, A.R.S. § 23-1101, silicosis when complicated by active pulmonary tuberculosis is presumed to be totally disabling.
Claimant filed for compensation under the Arizona Occupational Disease Disability Act, A.R.S. § 23-1101 et seq., and after various examinations and the hearings, the Commission entered an award finding a non-compensable claim and denying compensation. [85 Ariz. 208] Claimant duly applied for a rehearing which was granted, and upon this rehearing the Commission entered an award for compensation, finding that 'during the last ten years of employment in the State of Arizona, said applicant was exposed to harmful quantities of silicon dioxide dust for a period of 1200 work shifts.' The Company's petition for a rehearing was denied, and this review followed.
The pertinent portion of the applicable Arizona statute provides:
'No compensation shall be paid in case of silicosis or asbestosis unless during the ten years immediately preceding the disablement the injured employee has been exposed to harmful quantities of silicon dioxide dust or asbestos dust for a total period of not less than one thousand two hundred work shifts in employment in this state * * *.' Subd. A, par. 3, A.R.S. § 23-1107.
The Company urges that the Commission's award is not reasonably supported by evidence that petitioner was exposed to harmful quantities of silicon dioxide dust during the course of his employment in the ten years immediately preceding his disablement. This contention requires a more detailed reference to the evidence.
It is uncontradicted that there are certain threshold values which have been established and verified through the years and which are generally accepted as reliable. Doctor Smart testified that threshold values represent limits under which workers may be repeatedly exposed day after day without harmful effect to their health; in quartz dust containing 50% or above free silica the threshold limit is 5 million particles per cubic foot; for dust of less than 50% and down to 5%, 20 million particles per cubic foot; and below 5%, 50 million particles per cubic foot. While it is ...