Tremor, olfactory and motor changes in Italian adolescents exposed to historical ferro-manganese emission

Background and objective: Increased prevalence of Parkinsonism was observed in Valcamonica, Italy, a region impacted by ferroalloy plants emissions containing manganese and other metals for a century until 2001. The aim of this study was to assess neurobehavioral functions in adolescents from the impacted region and the reference area of Garda Lake. Methods: Adolescents age 11–14 years were recruited through the school system for neuro-behavioral testing. Metals including manganese, lead, iron, zinc, copper were measured in airborne particulate matter collected with 24-h personal samplers, and in soil, tap water, blood, urine and hair. Independent variables included parental education and socio-economic status, children’s body mass index, number of siblings, parity order, smoking and drinking habits. Results: A total of 311 subjects (49.2% females), residing in either the exposed (n = 154) or the reference (n = 157) area participated. Average airborne and soil manganese were respectively 49.5 ng/m3 (median 31.4, range 1.24–517) and 958 ppm (median 897, range 465–1729) in the impacted area, and 27.4 ng/m3 (median 24.7, range 5.3–85.9) ng/m3 and 427 ppm (median 409 range 160–734) in the reference area. Regression models showed significant impairment of motor coordination (Luria-Nebraska test, p = 0.0005), hand dexterity (Aiming Pursuit test, p = 0.0115) and odor identification (Sniffin’ task, p = 0.003) associated with soil manganese. Tremor intensity was positively associated with blood (p = 0.005) and hair (p = 0.01) manganese. Conclusion: Historical environmental exposure to manganese from ferroalloy emission reflected by the concentration in soil and the biomarkers was associated with sub-clinical deficits in olfactory and motor function among adolescents.