Lead is a non-essential metal and may be a co-exposure in welding fumes. Preclinical data indicate lead may affect iron regulation. The current study investigated blood lead concentrations and their association with brain iron accumulation in workers with chronic welding fume exposure, with a focus on iron-rich subcortical regions of the cerebellum and basal ganglia. Occupational exposure, whole blood metal, and brain MRI data were obtained from 29 controls and 42 welders. R2* (1/T2*) and R1 (T1 relaxation rate) values were used to estimate brain iron and manganese content, respectively. Blood metals and brain R2* [in the red nucleus (RN), dentate nucleus, caudate, putamen, globus pallidus, and substantia nigra] were compared between groups. Associations between brain R2* values and exposure metrics were tested within each group, and analyses were adjusted for potential confounders. Welders had significantly higher levels of whole blood lead, manganese, iron, and copper. Welders also had higher R2* RN (p = 0.002), but not R1. A second-order polynomial modeled the association between R2* RN and a long-term welding exposure metric. In welders, but not controls, R2* RN was associated positively with whole blood lead (r = 0.54, p = 0.003), and negatively with whole blood manganese (r=-0.43, p = 0.02). Higher blood Pb and lower blood Mn independently accounted for variance in high RN R2*. Together, these data suggest that higher RN R2* values may mark lead exposure in welders. Because lead is a known neurotoxicant, additional studies are warranted to confirm this finding, and ascertain its scientific and public/occupational health implications.
BackgroundMobility‐related problems in older people may be relieved by the use of walking canes. However, the influence of the cane length on the postural stability of cane users has not been explored.ObjectiveThe objective of this study is to examine the influence of a single‐point cane with different lengths on the postural sway of regular cane users, older women during two stance positions, with feet parallel and semi‐tandem stance.MethodsEighteen older women, who used a single‐point walking cane for at least 6 months, stood on a force plate with feet parallel or in semitandem position for 40 s. They always used a cane that was adjusted to one of three different lengths resulting from the distance between the wrist crease and the floor, named WF, or this distance plus 7.5 or 10 cm. Amplitude and speed of the centre of pressure (COP) and its components (rambling and trembling) in the anterior‐posterior and medial‐lateral directions and mean vertical force applied to the cane were compared across cane lengths.ResultsThe amplitude and velocity of COP, rambling and trembling increased with the cane length. This effect was observed for the anterior‐posterior with the feet parallel and in the medial‐lateral direction with the semi‐tandem position. More force was applied on the shorter cane (WF) in semitandem position.ConclusionLonger canes increased the postural sway in the older women and restricted the body weight loaded on the cane. Improper cane length influences the postural sway particularly in a semitandem stance of regular cane users. This may cause a negative impact on postural stability required in daily life activities. The current findings may contribute to the prescription of this assistive device for older adults.
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