Exposure to heavy metals and being female are associated with a higher incidence of multiple sclerosis (MS), according to a study conducted by Maria Cristina Monti and colleagues from two Italian universities.
The study, “Is Geo-Environmental Exposure a Risk Factor for Multiple Sclerosis? A Population-Based Cross-Sectional Study in South-Western Sardinia,” was published in the journal PLoS One.
Several studies had already reported that MS is triggered by a combination of genetic susceptibility and exposure to environmental factors.
For the recent study, researchers analyzed the possible association between the incidence of MS and environmental factors like exposure to heavy metals, urbanization, and UV exposure on the people of Sardinia, Italy. They took into account the high incidence of MS in the region and that the area economy had been formerly based on the exploitation of different metals — many mining landfills had been created.
The team collected geochemical samples containing six heavy metals (cobalt, chromium, copper, nickel, lead and zinc), and proxy data regarding of UV exposure (percentage of the municipal areas exposed to the south) and urbanization (percentage of urban area included in the municipal area), revealed by geographic information system (GIS) processing. Gender, age, municipality of residence, relative concentrations (in parts per million), UV exposure, and percentage of urbanization were collected on each person in the study.
Results indicated an association between copper levels and gender with MS distribution, whereas UV exposure and urbanization showed no significant association with MS distribution. When copper concentration was increased (by 50 ppm), the incidence of MS was nearly three times higher.
According to the authors, proper levels of copper are fundamental in maintaining the essential function of enzymes and in avoiding the generation of toxic molecules in the brain. On the other hand, an excess of copper is associated with neurodegeneration.
Regarding gender, a marked increase in MS incidence was observed in women who were living in urban areas or who had moved at a young age from rural to urban areas. However, the way in which being female and being exposed to high copper levels influences MS risk remains unknown.
“It has recently been suggested that the causes of MS are pervasive across all population groups, and investigating etiological factors operating at the population level could be more informative than searching for local-level causes of the disease,” the authors wrote in the report, supporting that the results obtained in their study provide relevant information for other MS patients.
Researchers concluded that the high frequency of MS in industrial countries where pollution by heavy metals and copper poisoning is widespread does suggest a relationship, but more research is needed.
“This is a preliminary study aimed at generating hypotheses that will need to be confirmed further,” researchers wrote.