Document B6rDveg9JprqZJ1VZO31gL3E

I INTERNAL CORRESPONDENCE I -J UNION CARBIDE CORPORATION OLD RIDGEBURY ROAD.' DANBURY, CT OSS 1 7 To tNamel DiviEiQP Location Araa A. R. Schnatter D. H. Glenn T. A. Lincoln see October 7, 1982 Originating Deot. HS & EA Area Epidemiology Subject Texas Brain Tumor Rates Dear Rob: Thank you for your data comparison of U.S. and Texas malignant brain cancer rates. Inspection of these data clearly support our hypothesis that an increase in brain tumor mortality rates with age as seen in the Texas City occupational cohort study may not necessarily indicate a latency effect, but rather could be reflecting some other age-related effect. The explanation that comes to mind most readily is that there may be an increase in the detection or reporting of brain cancer in the population aged 55 and over. This could be explained by 1) the development and increased use of computerized axial temography (CAT) scanners since 1965; 2) an Increase in the number of physicians in the region with specialities in the neurological sciences; or 3) the presence of a more general brain cancer carcinogen in the tri-county area. One of the first two explanations would appear to be more likely than the third, since the presence of a general brain cancer carcinogen in the environment should have had the effect of elevating brain cancer mortality rates in the younger population as well. Although we had suspected a county-wide increase in brain cancer in the local Texas City area versus the general U.S. population, the information on the age-specific differential is relatively new information. Because of the tremendous significance this could have, particularly with respect to the law suits, I would appreciate your attempt to carefully document the manner in which we obtained this data and calculated these rates. In addition, could you please revise the table to express these rates per 100,000 population rather than per 1,000 population. Also please specify whether the averages noted at the bottom of the table are crude averages or age standardized average rates. Additionally, we should indicate the approximate size of the population of Texas as well as the three county areas during the respective time periods. Sincerely, SGA/rjk Susan G. Austin, Sc.D. ucc 053169