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

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

		Automated Method, Current Analysis
	N	Unexposed	< 50^thpercentile	> 50-75^thpercentile	>75-90^thpercentile	> 90^thpercentile	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%

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 50^th, 75^th and 90^th percentiles. Current analysis had an RDD value of 2.0, 7.1, and 19.5 for the 50^th, 75^th and 90^th percentiles. There are 19 subjects that are excluded because current exposure value could not be calculated due to missing data.

ISSN: 1476-069X