Limits...
Association between heavy metal and metalloid levels in topsoil and cancer mortality in Spain

View Article: PubMed Central - PubMed

ABSTRACT

Spatio-temporal cancer mortality studies in Spain have revealed patterns for some tumours which display a distribution that is similar across the sexes and persists over time. Such characteristics would be common to tumours that shared risk factors, including the geochemical composition of the soil. The aim of this study was to assess the possible association between heavy metal and metalloid levels in topsoil (upper soil horizon) and cancer mortality in mainland Spain. Ecological cancer mortality study at a municipal level, covering 861,440 cancer deaths (27 different tumour locations) in 7917 Spanish mainland towns, from 1999 to 2008. The elements included in this analysis were Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Topsoil levels (partial extraction) were determined by ICP-MS at 13,317 sampling points. For the analysis, the data on the topsoil composition have been transformed by the centred logratio (clr-transformation). Principal factor analysis was performed to obtain independent latent factors for the transformed variables. To estimate the effect of heavy metal levels in topsoil composition on mortality, we fitted Besag, York and Mollié models, which included each town’s factor scores as the explanatory variable. Integrated Nested Laplace Approximation (INLA) was used as a tool for Bayesian inference. All results were adjusted for sociodemographic variables. The results showed an association between trace contents of heavy metals and metalloids in topsoil and mortality due to tumours of the digestive system in mainland Spain. This association was observed in both sexes, something that would support the hypothesis that the incorporation of heavy metals into the trophic chain might be playing a role in the aetiology of some types of cancer. Topsoil composition and the presence of potentially toxic elements in trace concentrations might be an additional component in the aetiology of some types of cancer, and go some way to determine the ensuing geographic differences in mortality in Spain. The results support the interest of inclusion of heavy metal levels in topsoil as a hypothesis in analytical epidemiological studies using biological markers of exposure to heavy metals and metalloids.

Electronic supplementary material: The online version of this article (doi:10.1007/s11356-017-8418-6) contains supplementary material, which is available to authorized users.

No MeSH data available.


Factor loading plots for the centred logratio-transformed (clr-transformed) four-factor models (PFA and varimax rotation)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection


getmorefigures.php?uid=PMC5383678&req=5

Fig1: Factor loading plots for the centred logratio-transformed (clr-transformed) four-factor models (PFA and varimax rotation)

Mentions: Figure 1 shows the factor loading plots for the clr-transformed four-factor models (PFA and varimax rotation). The position of the element names in the plot reflects the loading of that element on the different factors. In addition, the percentages at the top of the plots display the cumulative explained percentage of total variability. The scale on the horizontal axis is in accordance with the relative amount of variability explained by each individual factor (Filzmoser et al. 2009). This figure gives an idea of the significance/composition of each factor. The comments refer to items with factor scores ≥/0.4/. Factor F1 was defined by a combination of negative loadings of Zn, Al, Mn and positive loadings of Ni and Cu. Factor F2 was dominated by negative loadings of Cd and positive loadings of Fe and Cr. Factor F3 increased with the Pb/Ni ratio. Factor F4 decreased when the concentration of As increased, whereas the rest of the composition remained almost constant.Fig. 1


Association between heavy metal and metalloid levels in topsoil and cancer mortality in Spain
Factor loading plots for the centred logratio-transformed (clr-transformed) four-factor models (PFA and varimax rotation)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC5383678&req=5

Fig1: Factor loading plots for the centred logratio-transformed (clr-transformed) four-factor models (PFA and varimax rotation)
Mentions: Figure 1 shows the factor loading plots for the clr-transformed four-factor models (PFA and varimax rotation). The position of the element names in the plot reflects the loading of that element on the different factors. In addition, the percentages at the top of the plots display the cumulative explained percentage of total variability. The scale on the horizontal axis is in accordance with the relative amount of variability explained by each individual factor (Filzmoser et al. 2009). This figure gives an idea of the significance/composition of each factor. The comments refer to items with factor scores ≥/0.4/. Factor F1 was defined by a combination of negative loadings of Zn, Al, Mn and positive loadings of Ni and Cu. Factor F2 was dominated by negative loadings of Cd and positive loadings of Fe and Cr. Factor F3 increased with the Pb/Ni ratio. Factor F4 decreased when the concentration of As increased, whereas the rest of the composition remained almost constant.Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

Spatio-temporal cancer mortality studies in Spain have revealed patterns for some tumours which display a distribution that is similar across the sexes and persists over time. Such characteristics would be common to tumours that shared risk factors, including the geochemical composition of the soil. The aim of this study was to assess the possible association between heavy metal and metalloid levels in topsoil (upper soil horizon) and cancer mortality in mainland Spain. Ecological cancer mortality study at a municipal level, covering 861,440 cancer deaths (27 different tumour locations) in 7917 Spanish mainland towns, from 1999 to 2008. The elements included in this analysis were Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Topsoil levels (partial extraction) were determined by ICP-MS at 13,317 sampling points. For the analysis, the data on the topsoil composition have been transformed by the centred logratio (clr-transformation). Principal factor analysis was performed to obtain independent latent factors for the transformed variables. To estimate the effect of heavy metal levels in topsoil composition on mortality, we fitted Besag, York and Mollié models, which included each town’s factor scores as the explanatory variable. Integrated Nested Laplace Approximation (INLA) was used as a tool for Bayesian inference. All results were adjusted for sociodemographic variables. The results showed an association between trace contents of heavy metals and metalloids in topsoil and mortality due to tumours of the digestive system in mainland Spain. This association was observed in both sexes, something that would support the hypothesis that the incorporation of heavy metals into the trophic chain might be playing a role in the aetiology of some types of cancer. Topsoil composition and the presence of potentially toxic elements in trace concentrations might be an additional component in the aetiology of some types of cancer, and go some way to determine the ensuing geographic differences in mortality in Spain. The results support the interest of inclusion of heavy metal levels in topsoil as a hypothesis in analytical epidemiological studies using biological markers of exposure to heavy metals and metalloids.

Electronic supplementary material: The online version of this article (doi:10.1007/s11356-017-8418-6) contains supplementary material, which is available to authorized users.

No MeSH data available.