High levels of certain chemical pollutants in the blood are associated with an increased risk of SARS-CoV-2 infection and COVID-19 disease, according to a study conducted by the Hospital del Mar Medical Research Institute (IMIM-Hospital de Mar), the Barcelona Institute for Global Health (ISGlobal), a centre supported by the "la Caixa" Foundation, the University of Las Palmas, and the CIBERs of Epidemiology and Public Health (CIBERESP), Obesity and Nutrition (CIBEROBN) and Infectious Diseases (CIBERINFEC). The study has been published in the journal Enviromental Research and is the first prospective analysis of pre-pandemic data on pollutants in healthy people.
The findings provide a possible new explanation for the large differences in susceptibility to SARS-CoV-2 infection and COVID-19 disease. Why do some people with similar exposure to the virus get infected and others do not? And why do some people develop the disease and others do not? This question remains largely unexplained. "What our study shows is that some environmental pollutants increase the risk of infection and the risk of developing the disease", says Miquel Porta, researcher at IMIM-Hospital de Mar and one of the main authors of the study.
Other factors that influence the risk of developing COVID-19 are co-morbidities (i.e. whether the person already suffers from other diseases), smoking, age, education level, density of people in the home, or exposure to the virus on public transport or at work.
Contaminants May Partly Explain the Heterogeneity of SARS-CoV-2 Infection.
The researchers used frozen blood samples from 154 healthy people from a general population cohort in Barcelona, collected in 2016. They associated the level of organic pollutants and chemical elements in the samples with SARS-CoV-2 infection and COVID-19 in those same people during 2020-2021. The findings reveal that people with higher blood levels of certain pollutants had a higher risk of becoming infected and of developing the disease. The risk of developing COVID-19 was associated with DDT derivatives (DDD and DDE), as well as lead, thallium, ruthenium, tantalum, benzo(b)fluoranthene and manganese. High levels of thallium, ruthenium, lead and gold, were associated with a higher risk of infection, while high levels of iron and selenium were associated with a lower risk.
"A very important finding of the study is that it identifies mixtures of up to five substances from different chemical groups that increase the risk of infection and disease", adds Gemma Moncunill, researcher at ISGlobal and last author of the study.
First Evidence of a Possible Link Between Contaminants and COVID-19
The authors consider these results to be of "considerable scientific and social relevance", as they provide the first prospective evidence, based on a healthy general population, of a possible link between individual blood levels of certain pollutants and SARS-CoV-2 infection and COVID-19.
These pollutants enter our bodies through multiple routes, from electronic devices to the food used in intensive animal farming. Therefore, say the authors, "if the associations found are confirmed to be causal, we can control the risks with appropriate policies".
Miquel Porta, José Pumarega, Magda Gasull, Ruth Aguilar, Luis Henríquez-Hernández, Xavier Basagaña, Manuel, Judith Villar, Cristina Rius, Sneha Mehta, Marta Vidal, Alfons Jimenez, Laura Campi, Joan Lop, Octavio Pérez Luzardo, Carlota Dobaño y Gemma Moncunill. Individual blood concentrations of persistent organic pollutants and chemical elements, and COVID-19: a prospective cohort study in Barcelona. Environmental Research. 2023.