Table 3.

Estimated number of samples needed to detect a difference of 10, 25, 50, and 100% in the 1-hydroxypyrene geometric mean concentration with a statistical power of 80% (p<0.05), for single and repeated sampling for spot, first-morning, and 24-hour void sampling.

Target % difference on GM	Number of repeated samples
	Spot samples				First morning voids				24-Hour voids
	1	2	3	4	1	2	3	4	1	2	3	4
Wet weight concentration (ng/L urine)
10%	1069	624	475	401	618	420	353	320	296	230	208	197
25%	195	114	87	73	113	77	64	58	54	42	38	36
50%	59	34	26	22	34	23	20	18	16	13	11	11
100%	20	12	9	8	12	8	7	6	6	4	4	4
Creatinine-adjusted concentration (ng/g creatinine)
10%	606	470	424	401	415	332	305	291	399	351	335	327
25%	111	86	77	73	76	61	56	53	73	64	61	60
50%	33	26	23	22	23	18	17	16	22	19	19	18
100%	11	9	8	8	8	6	6	5	8	7	6	6