Neuropsychological dysfunction related to earlier occupational exposure to mercury vapor

Abstract

We assessed the neuropsychological test performances of 26 patients (mean age = 41.5 ± 6.1 years; mean years of education = 9.8 ± 1.8; 20 males) diagnosed with chronic occupational mercurialism who were former workers at a fluorescent lamp factory. They had been exposed to elemental mercury for an average of 10.2 ± 3.8 years and had been away from this work for 6 ± 4.7 years. Mean urinary mercury concentrations 1 year after cessation of work were 1.8 ± 0.9 µg/g creatinine. Twenty control subjects matched for age, gender, and education (18 males) were used for comparison. Neuropsychological assessment included attention, inhibitory control, verbal and visual memory, verbal fluency, manual dexterity, visual-spatial function, executive function, and semantic knowledge tests. The Beck Depression Inventory and the State and Trait Inventory were used to assess depression and anxiety symptoms, respectively. The raw score for the group exposed to mercury indicated slower information processing speed, inferior performance in psychomotor speed, verbal spontaneous recall memory, and manual dexterity of the dominant hand and non-dominant hand (P < 0.05). In addition, the patients showed increased depression and anxiety symptoms (P < 0.001). A statistically significant correlation (Pearson) was demonstrable between mean urinary mercury and anxiety trait (r = 0.75, P = 0.03). The neuropsychological performances of the former workers suggest that occupational exposure to elemental mercury has long-term effects on information processing and psychomotor function, with increased depression and anxiety also possibly reflecting the psychosocial context.

Preliminary Findings on the Effects of Occupational Exposure to Mercury Vapor Below Safety Levels on Visual and Neuropsychological Functions

“…4 This study is in agreement with previous results that have not found significant differences in neuropsychological test scores between chloralkali workers exposed to low Hg concentrations and controls. Nevertheless, in that study, concentration of Hg in blood correlated significantly with poorer performances in …”

“…N eurological and neuropsychological impairment because of exposure to mercury (Hg) vapor has been demonstrated in different occupationally exposed populations, [1][2][3][4] and its toxic effect on the human visual system has been reported in several studies. [5][6][7][8][9][10] Nevertheless, there is no clear knowledge of the level of exposure at which Hg vapor causes adverse effects.…”

“…The positive correlation between duration of exposure and scores on BDI reveals more depressive symptoms, which are common in Hg-exposed workers. 4 Because depression is a risk factor for decline of neuropsychological performance, further studies, with larger sample size, should include correlation analysis between depression scores and neuropsychological measures to clarify whether possible impairments are related to Hg exposure or mood disorders.…”

Symptoms of Intoxication in Dentists Associated with Exposure to Low Levels of Mercury

“…Many studies have shown high occurrence of neurological symptoms such as memory problem, sleep disturbances, concentration difficulties and fatigue among dental clinics personnel 8,9) . Studies have also revealed that chronic exposure to mercury may lead to adverse effects such as salivation, gingivitis, insomnia, excitability, depression and sensory losses [10][11][12][13] .…”

The Visual (dis)Function in Neurological Diseases

“…Eye movements are related to functions such as attention, learning and search; pupil changes are present in judgment, reasoning and decisionmaking; flashing the amount is dependent on the attentional status and conducting high level cognitive tasks such as solution problems and making decisions. In this direction, we have been found alterations in neuropsychological tests for visual memory, visuospatial attention related with performances and scores in visual function tests in mercury vapor occupationally intoxicated patients [205,206].…”