Table 2.

Normalized, log-transformed relative abundances of ions, stratified by Mn exposure status, in samples collected from Puget Sound workers in October 2014 and January 2015, and from Wisconsin workers

			October 2014 PS workers				January 2015 PS workers				Wisconsin workers
			Mn exposed (n=20)	Mn unexposed (n=19)			Mn exposed (n=17)	Mn unexposed (n=15)			Current Mn exposed (n=15)	Current Mn unexposed (n=39)
m/z	RT	mode	mean ± SD	mean ± SD	p*		mean ± SD	mean ± SD	p*		mean ± SD	mean ± SD	p*
201.0240	3.54	ESI−	3.47 ± 0.41	1.91 ± 0.61	<0.001		2.60 ± 0.72	2.35 ± 0.58	0.28		2.63 ± 0.48	2.79 ± 0.47	0.18
246.0098	4.68	ESI−	1.91 ± 0.32	−0.10 ± 1.3	<0.001		1.42 ± 0.41	0.27 ± 1.47	0.01		−0.43 ± 1.62	−0.02 ± 1.32	0.36
297.1007	4.02	ESI−	3.16 ± 0.43	1.80 ± 0.32	<0.001		2.39 ± 0.60	2.19 ± 0.56	0.34		2.10 ± 0.35	2.08 ± 0.50	0.82
415.2201	8.95	ESI−	2.02 ± 0.37	1.58 ± 0.15	<0.001		1.91 ± 0.38	1.84 ± 0.37	0.59		1.70 ± 0.33	1.86 ± 0.35	0.18
553.2446	4.03	ESI−	1.89 ± 0.57	0.67 ± 0.30	<0.001		1.27 ± 0.43	0.79 ± 0.56	0.01		0.68 ± 0.92	0.61 ± 1.18	0.94
311.1164	5.18	ESI−	2.29 ± 0.40	1.42 ± 0.29	<0.001		1.66 ± 0.45	1.53 ± 0.36	0.35		1.47 ± 0.40	1.61 ± 0.38	0.27
321.0961	4.02	ESI+	2.22 ± 0.36	1.52 ± 0.19	<0.001		1.71 ± 0.23	1.48 ± 0.21	0.005		1.44 ± 0.22	1.53 ± 0.24	0.23
177.1115	4.75	ESI+	2.20 ± 0.25	1.51 ± 0.33	<0.001		1.87 ± 0.29	1.62 ± 0.27	0.02		2.12 ± 0.31	2.01 ± 0.44	0.30
459.2202	7.80	ESI+	2.24 ± 0.25	2.61 ± 0.28	<0.001		2.18 ± 0.36	2.07 ± 0.53	0.51		2.11 ± 0.28	2.25 ± 0.30	0.08

PS=Puget Sound; Mn=manganese: RT=retention time (minutes); SD=standard deviation; ESI=electrospray ionization; m/z =mass to charge ratio

^*p-value calculated from two-sided t-test allowing for unequal variances