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Proposal For A Mortality .Study Of l ioland Location Employees Exposed to Vinyl Chloride MGOtt R&S 029898 Obiecti .#es The objectives of this study will be twofold. The first objective will be tc establish, for current and later followup study, a cohort of employees who ex perienced exposure to vinyl chloride prior to 1955. The second objective will be to examine in some detail the to-date mortality experience of this group of em ployees, utilizing internal company records. The Population With the assistance of Harold Hoyle, a number of job classifications within several departments were identified as acceptable for study. These jobs were chosen because they involved more than minimal exposure to vinyl chloride Ce*g* j ,>50 ppm). In a number of instances, measurement data were not available so that the decisions were made subjectively. Concurrent exposure to vinyl and vinylidene chloride did not rule out a job classification. However, if the exposure primarily involved vinylidene chloride, the job was not included. The tentative list of in cluded jobs, by department, is shown in Table 1. One hundred eighty-seven men have been identified who worked in one or more of the job classifications listed in Table 1. These men were identified from annual personnel lists and will define the exposed-to-risk population for this study. The Statistical Strategy The cohort of employees will be subdivided into two sub-cohorts. The first sub-cohort consists of those employees who initially worked in the exposure area before 1950. The second sub-cohort consists of employees who began employment '.n i.ha exposure area between January 1950 and January 1955. One reason for two groups is that better documentation of exposure levels was made after 1950. In order tc examine the relationship of mortality to both duration of expo sure and interval since initial exposure, the data will be summarized according R&S 029899 2- to the format shown in Table 2. The expected number of deaths will be calculated from the mortality rates observed among the cohort of 6500 Dow hourly employees. Although the exposure levels are known to vary from one job to another, and from year-to-year within jobs, in this analysis duration will be the only criterion used to quantify exposure. & 4 `-'able 1. Departments and Job Classifications To Be Included In Study, Saran Poly Semi Plant Foreman Polymer Operator (or equivalent) Asst. Polymer Operator (or equivalent) Wheel Filter Ope~ator (or equivalent) 1947 - 1955 1946 - 1955 1946 - 1955 1946 - 1955 i: Saran Polymer Department (Or Equivalent) Foreman, Shift Foreman, Subforeman* Polymer Operator (or equivalent) Drier Operator (or equivalent) Assistant Operator Tank Car Unloader (or equivalent) Asst. Polymer Operator Asst. Drier Operator Plant Mechanic 1941 - 1950 1941 - 1955 1941 - 1955 1944 - 1955 1951 - 1955 1952 - 1955 1952 - 1955 1941 - 1955 R&S 029900 Chloride Department Foreman Vinyl Chloride Operator 1946 - 1954 1946 - 1954 V1V2 Plant** Shift Foreman 1952 - 1955 Polymer Operator 1952 - 1955 Coagulator Tank Wheel Operator (or Equiv.) 1952 - 1955 Drier Operator 1952 - 1955 *After 1950, per sonnel lists for Saran Polymer and Saran Color and Blending were combined. Thus, it was not possible to distinguish which operations the foremen were connected with. The assumption was made that foremen who were known to supervise the polymerization operations prior to 1950 continued in that section after 1950. **To the extent that employees in Saran V1V2 had previously worked in Soluble Saran, this exposure experience will be considered additive. .However, men who worked only in Soluble Saran would not be included in the study. Table 2. Proposed Format For Summarizing Mortality Experience (A Table will be prepared for total deaths, deaths due to malignant neoplasms and deaths due to respir atory cancer.) Duration of Exposure In Years <1 Interval Since First Exposure <15 15 - 19 20 - 24 25 - 32 Total 1- 5 < 15 15 - 19 20 - 24 25 - 32 Total < 15 15 - 19 >5 20 - 24 25 - 32 Total Number of Deaths Cohort 1 Cohort 2 Observed Expected Observed Expected Lj . - ,, rVw l .:3 .J : 0-H3" J3 0) o N> CD CD O _L