RESUMO
With declining exposures to manganese (Mn) in occupational settings, there is a need for more sensitive exposure assessments and clinical diagnostic criteria for manganism and Mn neurotoxicity. To address this issue, a workshop was held on November 12-13, 2020, with international experts on Mn toxicity. The workshop discussions focused on the history of the diagnostic criteria for manganism, including those developed by the Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail (IRSST) in Quebec in 2005 and criteria developed by the Chinese government in 2002 and updated in 2006; the utility of biomarkers of exposure; recent developments in magnetic resonance imaging (MRI) for assessing Mn accumulation in the brain and diagnosing manganism; and potential future applications of metabolomics. The suggestions of the participants for updating manganism diagnostic criteria included the consideration of: i) A history of previous occupational and environmental exposure to Mn; ii) relevant clinical symptoms such as dystonia; iii) MRI imaging to document Mn accumulation in the neural tissues, including the basal ganglia; and iv) criteria for the differential diagnosis of manganism and other neurological conditions. Important research gaps include the characterization of Mn exposure and other co-exposures, exploration of the roles of different brain regions with MRI, understanding the complexity of metal ion transporters involved in Mn homeostasis, and a need for information on other neurotransmitter systems and brain regions underlying the pathophysiology of manganism.
RESUMO
We examined prospective cohort studies evaluating the relation between prenatal and neonatal exposure to polychlorinated biphenyls (PCBs) and neurodevelopment in children to assess the feasibility of conducting a meta-analysis to support decision making. We described studies in terms of exposure and end point categorization, statistical analysis, and reporting of results. We used this evaluation to assess the feasibility of grouping studies into reasonably uniform categories. The most consistently used tests included Brazelton's Neonatal Behavioral Assessment Scale, the neurologic optimality score in the neonatal period, the Bayley Scales of Infant Development at 5-8months of age, and the McCarthy Scales of Children's Abilities in 5-year-olds. Despite administering the same tests at similar ages, the studies were too dissimilar to allow a meaningful quantitative examination of outcomes across cohorts. These analyses indicate that our ability to conduct weight-of-evidence assessments of the epidemiologic literature on neurotoxicants may be limited, even in the presence of multiple studies, if the available study methods, data analysis, and reporting lack comparability.
Foram examinados estudos de grupo que avaliaram a relação entre a exposição pré-natal e neonatal aos bifenilos policlorados (PCB) e o desenvolvimento neuropsicomotor em crianças a fim de avaliar a viabilidade da realização de uma meta-análise para suporte à tomada de decisão. Nós descrevemos os estudos em termos de exposição, categorizações, análise estatística e elaboração de relatórios de resultados. Nós utilizamos esta avaliação para verificar a viabilidade de agrupar os estudos em categorias razoavelmente uniformes. Os testes mais utilizados foram Brazelton Neonatal Behavioral Assessment Scale, a pontuação de otimalidade neurológica no período neonatal, as Escalas Bayley de Desenvolvimento Infantil de 5 a 8 meses de idade, e as Escalas McCarthy de habilidades das crianças em 5 anos de idade. Apesar de administrar os mesmos testes com idades semelhantes, os estudos foram muito diferentes para permitir uma análise quantitativa significativa dos resultados entre grupos. Estas análises indicam que a nossa capacidade de realizar avaliações da literatura epidemiológica sobre neurotóxicos pode ser limitada - mesmo na presença de vários estudos - se não existe nenhuma forma de comparação com os métodos de estudo disponíveis e análise dos dados.