OCR Text |
Show 80 70 60 ¦ 50 ¦ 40 ¦ 30 -20 -10 -0 U m M D m llfl. - m -, M m ¦ 11 - 10 20 30 40 50 60 70 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 Direction of Wind in Degrees 70 280 290 300 310 320 330 340 350 360 Figure 13. Wind Frequency Graph, Davis County. %¦¦•¦¦ %;:„,,. I .....C \> • ;¦•'¦ ..... ;'""'v.%...........,,4,. jx:.:: : . ^:\ :;>$: Figure 14. Map of Davis County, Containing Referenced Census Tracts and Zip Codes. by residents of Davis County, which divides the county into approximately equal halves. At the same time, the Utah State Health Department - Division of Epidemiology geo-mapped the cases within a five-mile radius of WES as well as for the northern part of the county to see if there was a clustering of cases. The frequency of wind direction and velocity was gathered for the time frame of September 2000-May 2001 from Hill Air Force Base (HAFB) and tabulated to determine the prevailing winds (National Weather Service, Western Region Headquarters, 2001). The prevailing winds map and the case map were overlaid to see if there was a dose-response relationship to wind direction and clustering of brain cancer cases. Results Results of the age adjusted comparison of RRs for the eight most common reportable cancers in Utah along with those for all reportable cancers combined, brain cancer, non-Hodgkin's lymphoma, and soft tissue sarcoma are shown in Table 1. Davis County (see table 1) The highest RRs obtained were for brain cancer in the years 1997, 1998, and 1999, which were 1.52 (95% CI 0.93, 2.46), 1.75 (95% CI 1.11, 2.75), and 1.75 (95% CI 1.06, 2.88) respectively. The rate ratios for brain cancer dropped in the year 2000 (per figure 9). In 2000, the brain cancer RR for Davis County was 0.71 (95% CI 0.36, 1.40) showing that the slight increase in the years 1997-1999 was likely a result of random variation. There are four years (1991, 1997-1999) where the RRs are above one, four years (1990, 1993, 1995, 2000) where the RRs are below one, and three years (1992, 1994, 1996) where the RRs are relatively at one, a situation common with rare diseases. When looking at the RRs in a large population, it is possible to mask an elevation in a rare cancer, so the rates for North Davis County, South Davis County, and Layton (as defined by 1990 census tracts) were calculated. Utah's Health: An Annual Review Volume VIII 43 |