Assessing the Impact of Heavy Metals and Metalloids from Soil on Blood Levelsof Rheumatoid Factor in Patients with Rheumatoid Arthritis

Introduction: Heavy metals can cause disturbances in the functioning of various systems of the human body and play an important role in the development of autoimmune diseases. Objective: To assess the relationship between heavy metals and metalloids in soil and the level of rheumatoid factor (RF) in adult patients with rheumatoid arthritis living in the Republic of Tatarstan. Materials and methods: The study included 380 permanent residents of the Republic of Tatarstan diagnosed with rheumatoid arthritis. Soil samples were collected in residential areas of the cases and tested for heavy metal concentrations. Odds ratios were used to establish the relationship between soil concentrations of heavy metals and the levels of rheumatoid factor in the blood of subjects. Results: Changes in soil levels of heavy metals were found to correlate with those in the levels of rheumatoid factor in the blood of adults with rheumatoid arthritis. Patients with an advanced stage of the disease living in the areas with soil levels of cadmium above 0.7 mg/kg and nickel above 50 mg/kg and having an elevated level of RF were 1.8 (OR = 1.7 CI [1.00: 2.88]) and 2 times more frequent (OR = 2.17 CI [1.06: 4.45]), respectively. Conclusions: Increased levels of heavy metals in soil provoke changes in immunological parameters in patients with various stages of rheumatoid arthritis. In areas with the elevated geochemical background concentrations of cadmium and nickel, higher levels of rheumatoid factor are observed in patients with advanced rheumatoid arthritis.