Table 3.

Adjusted coefficients (β) and (95% CI) in fNIRS oxygenated (HbO) and deoxygenated hemoglobin (HbR) per two-fold increase in toenail (n = 40) and hair (n = 33) Mn concentrations (μg/g) in farmworkers, Zarcero County, Costa Rica, 2016.

	Toenail Mn		Hair Mn
ROI	HbO	HbR	HbO	HbR
L1	−1.0 (−2.9, 0.9)	0.2 (−1.5, 1.9)	0.4 (−1.9, 2.6)	0.2 (−1.5, 2.0)
L2	−0.6 (−2.2, 1.0)	0 (−1.8, 1.8)	0.3 (−1.6, 2.2)	−0.2 (−2.3, 1.9)
L3	−1.0 (−2.8, 0.8)	0.7 (−0.9, 2.2)	0.9 (−1.2, 2.9)	−0.2 (−1.9, 1.5)
L4	−0.7 (−2.5, 1.1)	0.6 (−0.8, 1.9)	0.7 (−1.4, 2.8)	0.1 (−1.5, 1.7)
R1	−1.5 (−3.4, 0.5)	0.6 (−0.8, 1.9)	−0.5 (−2.9, 1.8)	−0.1 (−1.5, 1.3)
R2	−0.3 (−2.0, 1.4)	−0.2 (−1.5, 1.1)	−0.3 (−2.2, 1.7)	−0.8 (−2.2, 0.6)
R3	−1.0 (−2.8, 0.8)	0.9 (−0.9, 2.6)	−0.1 (−2.2, 2.0)	−0.8 (−2.6, 0.9)
R4	−0.7 (−2.7, 1.4)	0.3 (−0.9, 1.5)	−0.1 (−2.4, 2.2)	0.2 (−1.2, 1.5)

Abbreviations: CI, confidence interval; fNIRS, functional near-infrared spectroscopy; ROI, region of interest; L, left hemisphere; Mn, manganese; R, right hemisphere; HbO, oxygenated hemoglobin; HbR, deoxygenated hemoglobin.

Models adjusted for age and education level.

^*Unadjusted p < 0.05.

^†FDR-corrected p < 0.05.