Preliminary Study on the Spatial Distribution of Iodide in Shallow Groundwater and the Incidence of Thyroid Cancer in Shandong

Objectives  To know well the spatial distribution of Iodide content in shallow groundwater in Shandong province, and to explore the relationship between iodide content in shallow groundwater and thyroid cancer, and to supply research bases for the prevention of endemic diseases and long-term supply of iodized salt.

Methods Combining geostatistics and geographic information technology, fitting spatial variability with actual sample points reference,then using the ordinary Kriging interpolation to get the distribution of iodide contents in shallow groundwater in space. The method of spatial overlay in GIS is used to intuitively show the relationship between iodide in shallow groundwater and spatial aggregation of patients with thyroid cancer. Based on the spatial partition of the spatial interpolation result, the most suitable model to study the relationship between them was discovered, after rasterization by using statistical principle, seeking average, carrying out mathematical statistics, setting up regression analysis etc. Use SPSS to carry on the correlation analysis, establish scatter plot and function model with iodide content as the independent variable, the number of patients with thyroid cancer as dependent variable, and compare parameters.

Results Iodide content of shallow groundwater in Shandong varies from the high iodide area in the west to the suitable iodide region in the east. The distribution of iodide content is consistent with the distribution of thyroid cancer patients:patient distribution is intensive in the high content area, the correlation factor between iodide content and the number of patients is 0.816.

Conclusions When the iodide content in shallow groundwater is above 50 μg/L, the higher the content become the more intensive the patient distribution is, which is strongly correlated with thyroid cancer.