Heavy metal levels in malignant salivary gland tumours: a case-control study

Presence of toxic heavy metals such as lead (Pb) and chromium (Cr) and also low or high levels of essential heavy metals such as zinc (Zn) and copper (Cu) have detrimental health effects. However, malignant salivary gland tumours (MSGTs) have not been considered in this context. The etiopathogenesis of MSGTs and toxicity of heavy metals involve common mechanisms such as oxidative damage and chronic inflammation. The aim of this study was to investigate the possible relationship between MSGTs and heavy metals.

A total of 60 participants (30 patients with MSGTs and 30 matched healthy controls) were investigated. Data including both serum and saliva heavy metal levels of patients and healthy controls were statistically compared. Standard solutions of the elements to be analysed (Fe, Zn, Cu, Mn, Cr, Pb) were prepared using increasing concentrations of 2% nitric acid solution. An inductively coupled plasma mass spectrometer was used for analysis.

In both serum and saliva, Fe levels were not different between patients and controls (p > 0.05), but significantly lower Zn (p < 0.001) and Cu (p ≤ 0.011) and higher Pb (p < 0.001) levels were found in patients compared to controls. Also, in saliva, significantly higher Mn (p < 0.001) and Cr (p < 0.001) levels were found in the patients compared to the controls.

This study revealed that patients with MSGTs are associated with lower levels of Zn and Cu, but higher levels of Pb in both serum and saliva. Furthermore, these cancers are associated with higher levels of Mn and Cr in saliva.