Mercury in the brain (tumor tissues) and in markers (hair and blood) of exposure in Western Amazonia patients.

BACKGROUND

Central nervous system tumors (CNSTs) represent the second most frequent form of malignant tumors in childhood and the second leading cause of death associated with neurological diseases, affecting individuals of all age groups. In adults, CNSTs are the sixth most common cause of death in patients with malignant tumors. Additionally, the brain is the most sensitive and studied organ for mercury (Hg) toxicity.

METHOD: We studied total Hg (THg) in tissue samples (of benign and malignant CNSTs) and explored its associations with THg in exposure markers (hair and blood) from 65 patients (40 females and 25 males) who underwent surgical treatment.

RESULTS

No statistically significant differences were found in THg concentrations in brain tumors or in blood and hair from these patients (classified as malignant/benign or glioma/non-glioma); also, there were no statistically significant differences between males and females. However, statistically significant correlations were found between THg in CNSTs and in hair (rs = 0.4967; p = 0.0001) and in blood (rs = 0.4702; p = 0.0058); but no significant correlations were found between THg in hair and blood (rs = 0.1229; p = 0.5332). In the Western Amazon, with endemic exposure to fish-methylmercury, these urban patients were low to moderate fish consumers; THg concentrations in blood (median: 0.645 µg.L-1; range: 8.01-21.02 µg.L-1; n = 56) and hair (median: 0.686 µg.g-1; range: 0.01-10.02 µg.g-1; n = 65) were relatively low, whereas THg levels in brain tumors (median: 8.194 ng.g-1; range: <0.10-69.16 ng.g-1; n = 65) were within range of published studies in brain autopsies. Additionally, no statistically significant correlations (p = 0.4828) were observed between frequency of fish consumption and THg in the brain.

CONCLUSION

Although no significant THg concentrations in the type of brain tumors (benign versus malignant) were found, the significantly positive correlation between markers of THg exposure (hair and blood) and THg in the brain tissues indicates its usefulness as a marker/proxy for brain-THg load. These findings confirm the value of using hair and blood as constructs of THg in the brain of exposed populations.