Neurobehavioural test results and exposure to inorganic mercury: in search of dose-response relations

Meyer-Baron, Monika; Schaeper, Michael; Thriel, Christoph van; Seeber, Andreas

doi:10.1007/s00204-003-0531-2

Cited by 21 publications

(15 citation statements)

References 23 publications

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“…Two recent reviews with meta-analyses have concluded that long-term exposure to metallic mercury vapour with urine levels beyond 500 nmol/litre can lead to chronic effects on cognition, while there is more doubt as to whether lower exposures can lead to similar effects (Meyer-Baron, Schaeper, van Thriel & Seeber, 2004; Rohling & Demakis, 2006). From recent investigations it also seems evident that questions regarding individual susceptibilities play a significant role in the possible effects of metallic mercury exposure (Echeverria, Woods, Heyer et al ., 2005).…”

Section: Introductionmentioning

confidence: 99%

Neuropsychological function and past exposure to metallic mercury in female dental workers

Sletvold

Svendsen

Aas

et al. 2011

Scandinavian J Psychology

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The aim of this study was to see if dental personnel with previous exposure to metallic mercury have later developed disturbances in cognitive function. Ninety-one female participants who had been selected from a previous health survey of dental personnel were investigated neuropsychologically within the following domains: motor function, short-term memory, working memory, executive function, mental flexibility, and visual and verbal long-term memory. The scores were mainly within normal ranges. Relationships between an exposure score, the duration of employment before 1990, and previously measured mercury in urine as independent variables and the neuropsychological findings as dependent variables, were analyzed by multiple linear regression controlling for age, general ability, length of education, alcohol consumption, and previous head injuries. The only relationship that was statistically significant in the hypothesized direction was between the previously measured urine mercury values and visual long-term memory, where the urine values explained 30% of the variability. As the study had a low statistical power and also some other methodological limitations, the results have to be interpreted with caution. Even so, we think it is right to conclude that neuropsychological findings indicative of subsequent cognitive injuries are difficult to find in groups of otherwise healthy dental personnel with previous occupational exposure to mercury.

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Section: Introductionmentioning

confidence: 99%

Neuropsychological function and past exposure to metallic mercury in female dental workers

Sletvold

Svendsen

Aas

et al. 2011

Scandinavian J Psychology

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“…Information from non-peer-reviewed publications was considered if it pertained to an eligible study. We did not consider neurological effects related to memory and cognitive function, as these findings were the subject of a meta-analysis (Meyer-Baron et al 2002) and systematic review (Meyer-Baron et al 2004). …”

Section: Methodsmentioning

confidence: 99%

Persistence of mercury-induced motor and sensory neurotoxicity: systematic review of workers previously exposed to mercury vapor

Fields¹,

Borak

Louis

2017

Critical Reviews in Toxicology

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Background Elemental mercury (Hg0) is a well-recognized neurotoxicant, but it is uncertain whether and for how long its neurotoxicity persists. Among studies that evaluated previously-exposed workers, only one examined workers during and also years after exposure had ceased. Objective To create a series of ‘synthetic’ longitudinal studies to address the question of persistence of Hg0 neurotoxicity in occupationally exposed workers. Methods We systematically reviewed studies describing objective motor and sensory effects in previously-exposed mercury workers. Data from physical examination (PE), neurobehavioral (NB) tests and electrophysiological studies were extracted into structured tables and examined for their consistency and dose-relatedness and then compared with the corresponding results from studies of currently-exposed workers. Results We identified six cohorts that described neurological findings in 1299 workers, examined an average of 4.8 to 30 years after the cessation of exposure. Historical group mean UHg levels ranged from 23 to >500 μg/L, with UHg levels >6000 μg/L in some individuals. Overall, few findings were significant; most were inconsistent across the remote-exposure studies, and in comparisons between studies of remotely- and currently-exposed workers. Conclusion The results of this systematic review indicate that Hg0-related neurotoxic effects detectable on PE, NB testing, and EPS are substantially reversed over time. To the extent that such effects do persist, they are reported principally in workers who have had very high dose exposures. In addition, based on limited available data, those effects reported to persist have been described as having little or no functional significance.

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“…Unless otherwise stated, we assumed these terms were used in accordance with the following definition: ‘ Subclinical toxicity refers to exposure-induced adverse effects that are too small to produce signs and symptoms evident in a standard clinical examination’ (National Research Council 1992). We did not consider neurological effects related to memory and cognitive function, as these findings were the subject of a meta-analysis (Meyer-Baron et al 2002) and systematic review (Meyer-Baron et al 2004). …”

Section: Methodsmentioning

confidence: 99%

Mercury-induced motor and sensory neurotoxicity: systematic review of workers currently exposed to mercury vapor

Fields¹,

Borak

Louis

2017

Critical Reviews in Toxicology

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Background The neurotoxicity of elemental mercury (Hg0) is well-recognized, but it is uncertain whether and for how long neurotoxicity persists; among studies that evaluated previously exposed workers, only one examined workers during and also years after exposure ceased. Objective To document the type, frequency, and dose-relatedness of objective neurological effects in currently exposed mercury workers and thereby provide first approximations of the effects one would have expected in previously exposed workers evaluated during exposure. Methods We systematically reviewed studies of neurotoxicity in currently exposed mercury workers identified by searching MEDLINE (1950 –2015), government reports, textbook chapters, and references cited therein; dental cohorts were not included. Outcomes on physical examination (PE), neurobehavioral (NB) tests and electrophysiological studies were extracted and evaluated for consistency and dose-relatedness. Results Forty-five eligible studies were identified, comprising over 3000 workers chronically exposed to a range of Hg0 concentrations (0.002 to 1.7 mg/m3). Effects that demonstrated consistency across studies and increased frequency across urine mercury levels (<50; 50–100; 100–200; ≥ 200 µg/L) included tremor, impaired coordination, and abnormal reflexes on PE, and reduced performance on NB tests of tremor, manual dexterity and motor speed. The data suggest response thresholds of UHg ≈275 µg/L for PE findings and ≈20 µg/L for NB outcomes. Conclusion These results indicate that PE is of particular value for assessing workers with UHg > 200 µg/L, while NB testing is more appropriate for those with lower UHg levels. They also provide benchmarks to which findings in workers with historical exposure can be compared.

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Neurobehavioural test results and exposure to inorganic mercury: in search of dose-response relations

Cited by 21 publications

References 23 publications

Neuropsychological function and past exposure to metallic mercury in female dental workers

Neuropsychological function and past exposure to metallic mercury in female dental workers

Persistence of mercury-induced motor and sensory neurotoxicity: systematic review of workers previously exposed to mercury vapor

Mercury-induced motor and sensory neurotoxicity: systematic review of workers currently exposed to mercury vapor

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