Figure 1

Experimental design overview. Group size equals 4 monkeys per exposure group, with the exception of the 0 and 0.06 mg Mn/m³ exposure groups (n = 6 monkeys/exposure concentration). Lung manganese concentrations and respiratory histologic changes were evaluated after 15, 33, or 65 exposure days or 45 or 90 days after the 65^th exposure day. ^#Denotes animals assigned to cohort 2.