Increased thyroid cancer incidence in a basaltic volcanic area is associated with non-anthropogenic pollution and biocontamination

Abstract

The increased thyroid cancer incidence in volcanic areas suggests an environmental effect of volcanic-originated carcinogens. To address this problem, we evaluated environmental pollution and biocontamination in a volcanic area of Sicily with increased thyroid cancer incidence. Thyroid cancer epidemiology was obtained from the Sicilian Regional Registry for Thyroid Cancer. Twenty-seven trace elements were measured by quadrupole mass spectrometry in the drinking water and lichens (to characterize environmental pollution) and in the urine of residents (to identify biocontamination) in the Mt. Etna volcanic area and in adjacent control areas. Thyroid cancer incidence was 18.5 and 9.6/10(5) inhabitants in the volcanic and the control areas, respectively. The increase was exclusively due to the papillary histotype. Compared with control areas, in the volcanic area many trace elements were increased in both drinking water and lichens, indicating both water and atmospheric pollution. Differences were greater for water. Additionally, in the urine of the residents of the volcanic area, the average levels of many trace elements were significantly increased, with values higher two-fold or more than in residents of the control area: cadmium (×2.1), mercury (×2.6), manganese (×3.0), palladium (×9.0), thallium (×2.0), uranium (×2.0), vanadium (×8.0), and tungsten (×2.4). Urine concentrations were significantly correlated with values in water but not in lichens. Our findings reveal a complex non-anthropogenic biocontamination with many trace elements in residents of an active volcanic area where thyroid cancer incidence is increased. The possible carcinogenic effect of these chemicals on the thyroid and other tissues cannot be excluded and should be investigated.

Thyroid Cancer in the Pediatric Age in Sicily: Influence of the Volcanic Environment

“…In particular, the concentration of many metals and trace elements is increased in the urine of adults (25) and in the scalp hair of schoolchildren living in the Mt. Etna volcanic area (26).…”

“…In the volcanic area of Mt. Etna, significantly non-anthropogenic environmental pollution is present, with increased heavy metal levels in the water and the atmosphere, leading to biocontamination of the resident population (25,26).…”

How do etiological factors can explain the different clinical features of patients with differentiated thyroid cancer and their histopathological findings?

“…In both the groups, we found a similar distribution of associated thyroiditis with an increasing trend over time in term of both tumourassociated inflammation and TPOAb positivity. This could be explained by 2 hypothesis: 1) the increase in the iodine intake [51] as a result of programmes of iodine prophylaxis [52]; 2) external factors (still unknown) probably triggering both thyroid disorders, inflammation and tumour [53]. However, if the increased frequency of thyroiditis would be an additional factor contributing to the continuous increase in incidence of thyroid cancer, it is still debated [54,55].…”

Intake of Boron, Cadmium, and Molybdenum enhances rat thyroid cell transformation

“…Human bio-contamination is demonstrated by the increase of these elements in the urine specimens of the residents, although with values in the normal range in most of the cases [15]. Within this multi-elemental pollution, it is hard to identify which element(s) may have a detrimental effect on thyroid function and transformation.…”

“…These elements are increased both in the environment (water and lichens) and in the urine samples of residents of the Mt. Etna volcanic area [15]. …”