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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.