Home cage locomotor changes in non-human primates after prolonged welding-fume exposure

Abstract

To define the relationship between the brain concentration of manganese and neurological signs, such as locomotion, after prolonged welding-fume exposure, cynomolgus monkeys were acclimated for 1 month and then divided into three concentration groups: unexposed, low concentration (31 mg/m(3) total suspended particulate (TSP), 0.9 mg/m(3) of Mn), and high concentration (62 mg/m(3) TSP, 1.95 mg/m(3) of Mn) of TSP. The monkeys were exposed to manual metal-arc stainless steel (MMA-SS) welding fumes for 2 h per day over 8 months in an inhalation chamber system equipped with an automatic fume generator. The home cage locomotor activity and patterns were determined using a camera system over 2-4 consecutive days. After 25 and 32 weeks of exposure, the home cage locomotor activity of the high-concentration primates was found to be 5-6 times higher than that of the unexposed primates, and this increased locomotor activity was maintained for 7 weeks after ceasing the welding-fume exposure, eventually subsiding to three times higher after 13 weeks of recovery. Therefore, the present results, along with our previous observations of a high magnetic resonance imaging (MRI) T1 signal in the globus pallidus and increased blood Mn concentration, indicate that prolonged welding-fume exposure can cause neurobehavioral changes in cynomolgus monkeys.

The Role of Oxidative Stress in Manganese Neurotoxicity: A Literature Review Focused on Contributions Made by Professor Michael Aschner

“…Nonhuman primates best replicate the neurotoxic effects observed in humans. Manganese-exposed monkeys develop gait and other motor abnormalities that mimic those observed in affected humans [ 39 , 40 , 41 ]. Monkeys also develop reduced levels of striatal and pallidal dopamine and 3,4-dihydroxyphenylacetic acid, in conjunction with loss of dopaminergic neurons.…”

Assessment of negative influence of manganese in welding fumes on welder's health and ways to reduce it

“…Chemical composition of the solid part in the welding fumes primarily depends on the type of filling materials. When the welding arc contacts the metal, evaporations emitted into the air above the working area are gradually oxidized producing fine dust [1][2][3].…”