Individual Blood Concentrations of Persistent Organic Pollutants and Inorganic Elements, And COVID-19: A Prospective Cohort Study in Barcelona

Background: There is wide heterogeneity in immunological and clinical responses to SARS-CoV-2 infection. Numerous environmental chemicals, including POPs and inorganic elements, are immunomodulatory. There are no prospective studies on the effects of such compounds on the development of SARS-CoV-2 infection and COVID-19.Objective: To investigate the influence of blood concentrations of POPs and inorganic elements measured several years before the pandemic on the development of SARS-CoV-2 infection and COVID-19 in individuals from the general population.Methods: We conducted a prospective cohort study in 154 individuals from the population of Barcelona. POPs and inorganic elements were measured in blood samples collected in 2016-2017. SARS-CoV-2 infection was analyzed by antibody serology using 18 isotype-antigen combinations in blood samples from 2020-2021. We analyzed the associations between the contaminants and SARS-CoV-2 infection and development of COVID-19.Results: Several historically prevalent POPs, as well as arsenic, cadmium, mercury, and zinc, were not associated with COVID-19, nor with SARS-CoV-2 infection. However, DDE (adjusted OR = 5.0 [95% CI: 1.2 – 21]), lead (3.9 [1.0 – 15]), thallium (3.4 [1.0 – 11]), and ruthenium (5.0 [1.8 – 14]) were associated with COVID-19, as were tantalum, benzo(b)fluoranthene, DDD, and manganese. Thallium (3.8 [1.6 – 8.9]), and ruthenium (2.9 [1.3 – 6.7]) were associated with SARS-CoV-2 infection, and so were lead, gold, and (protectively) iron and selenium. We identified mixtures of up to five compounds from several chemical groups, with all compounds independently associated to the outcomes.Conclusions: Our results provide the first prospective evidence of an association between individual concentrations of some contaminants and COVID-19 and SARS-CoV-2 infection. POPs and inorganic elements may contribute to explain the heterogeneity in the development of SARS-CoV-2 infection and COVID-19 in the general population. If the associations are confirmed as causal, means are available to mitigate the corresponding risks.