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Table 3 Comparison of percentile categories of PCE exposure by assessment method, no latency

From: Risk of breast cancer following exposure to tetrachloroethylene-contaminated drinking water in Cape Cod, Massachusetts: reanalysis of a case-control study using a modified exposure assessment

   Automated Method, Current Analysis
  N Unexposed < 50thpercentile > 50-75thpercentile >75-90thpercentile > 90thpercentile TOTAL
  Row %       
  Col %       
Manual Method, Prior Analysis Unexposed 1095 410 185 92 28 1810
   60.50% 22.70% 10.20% 5.10% 1.50% 100%
   98.10% 74.80% 70.10% 55.80% 23.30% -
  < 50 th percentile 12 123 42 14 6 197
   6.10% 62.40% 21.30% 7.10% 3.00% 100%
   1.10% 22.40% 15.90% 8.50% 5.00% -
  > 50-75 th percentile 3 13 28 31 18 93
   3.20% 14.00% 30.10% 33.30% 19.40% 100%
   0.30% 2.40% 10.60% 18.80% 15.00% -
  >75-90 th percentile 3 0 7 24 40 74
   4.10% 0.00% 9.50% 32.40% 54.10% 100%
   0.30% 0.00% 2.70% 14.50% 33.30% -
  > 90 th percentile 3 2 2 4 28 39
   7.70% 5.10% 5.10% 10.30% 71.80% 100%
   0.30% 0.40% 0.80% 2.40% 23.30% -
  TOTAL 1116 548 264 165 120 2213
   100% 100% 100% 100% 100%  
  1. Note: Mutually exclusive categories shown here, but categories are overlapping (nested) in breast cancer risk analysis. Prior analysis had an RDD value of 3.6, 15.5, and 41.8 for the 50th, 75th and 90th percentiles. Current analysis had an RDD value of 2.0, 7.1, and 19.5 for the 50th, 75th and 90th percentiles. There are 19 subjects that are excluded because current exposure value could not be calculated due to missing data.