Cadmium exposure and hypertension: a systematic review and a dose-response meta-analysis

Background and Objective: Cadmium (Cd) is a silvery white, malleable metal present in trace amounts in the Earths crust, air and water. Its name derives from that of the city of Cadmo, near Thebes, where it was extracted in antiquity. This heavy metal reacts easily with zinc and to a lesser extent with lead forming various compounds. The main routes of exposure for humans are diet and inhalation. Breathing low levels of Cd for many years (e.g. smokers) or consuming food and water contaminated at levels normally present in the environment (chronic exposure) can cause its accumulation in the body and lead to various pathological conditions, including hypertension. Our aim is to quantify the increase in blood pressure following chronic Cd exposure. Methods: The protocol of the review has been submitted in PROSPERO. The literature search has been carried out on 3 different databases: PubMed, Web of Science and Embase. We used as mesh-terms: “hypertension”, “cadmium” and “blood pressure”. We defined the following inclusion criteria according to PICOS statement: P = healthy adult population, I = exposure to cadmium, C = subjects not exposed to cadmium, O = variation of arterial blood pressure in relation to the cadmium dose to which one is exposed, S = observational studies (cohort, cross-sectional or case-control). We also plan to perform a dose-response meta-analysis whenever possible. Results: We found 678 articles, of which 95 duplicates. After removing these duplicates, we are scanning the abstract and full-text of the remaining 583 papers. Conclusions: The study is currently ongoing and its results will be presented at the Congress.