Blood manganese and alcohol consumption interact on mood states among manganese alloy production workers.

Long-term exposure to manganese (Mn) can induce neurotoxic effects including neuromotor, neurocognitive and neuropsychiatric effects, but there is a great interpersonal variability in the occurrence of these effects. It has recently been suggested that blood Mn (MnB) may interact with alcohol use disorders, accentuating neuropsychiatric symptoms. The objective of the present study was to explore a possible interaction between alcohol consumption and MnB on mood states, using an existing data set on Mn exposed workers. Respirable Mn exposure in the plant averaged 0.23mg/m(3) and was correlated with MnB. All participants for whom all data on MnB concentration and mood (assessed with the Profile of Mood States (POMS)) were available and who reported currently drinking alcohol were included in the analyses (n=74). Workers were grouped according to their MnB concentration (<10 and > or =10 microg/l) and alcohol consumption (<400 and > or =400g per week). Two-way ANOVAs were performed on each POMS scale and Mann-Whitney tests were used to assess group differences. Workers in the higher alcohol consumption group had higher scores on three POMS scales: tension, anger and fatigue. There was no difference for POMS scale scores between MnB subgroups. Dividing the group with respect to alcohol consumption and MnB showed that the group with high alcohol consumption and high MnB displayed the highest scores. In the lower MnB category, those in the higher alcohol consumption group did not have higher scores than the others. The interaction term for alcohol consumption and MnB concentration was statistically significant (P<0.05) for the depression, anger, fatigue and confusion POMS scales. There was a tendency for tension (P<0.06), and it was not significant for vigor. This study shows the first evidence of an interaction between MnB and alcohol consumption on mood states among Mn exposed workers and supports the results from a previous population-based study.