Exposure characterization and health risk assessment of indoor metal(loids) from residential buildings Caracterização da exposição e avaliação do risco à saúde de metais internos (lóides) de edifícios residenciais

Abstract

Since people spend around 90% of their time indoors, they are exposed to various air contaminants, including particulate matter (PM). PM with an aerodynamic diameter smaller than 2.5 micrometers (PM2.5), which may originate from internal or external pollution sources, can host various metallic compounds that can enter the human body through inhalation, ingestion, or dermal contact. Due to their non-degradable and highly toxic nature, they may have adverse health effects, particularly among susceptible individuals. Although previous reports tackled human health risks associated with metal exposure, the metallic composition of PM2.5 might substantially vary due to topographic, meteorological, social, and behavioral/lifestyle factors. In Portugal, studies on exposure characterization and associated health risks caused by metals in indoor PM2.5 are scarce and impede the necessary progress toward reducing attributable health risks. This study aims to: (1) determine the levels of a large set of metal(oid)s bounded with PM2.5 in residential buildings located in Porto Metropolitan Area, Portugal; and (2) predict the attributable chronic daily intake (CDI) and the associated human health risk [carcinogenic (CR) and non-carcinogenic (HI)] posed by concurrent exposure to metals associated with PM2.5 via multiple exposure routes. PM2.5 samples were collected from 24 residential buildings over two consecutive days during winter (November 2018-February 2019). Quartz fiber filters used for collecting PM2.5 were preconditioned before and after sampling (48 h in desiccators under a temperature of 25 ± 2 ºC and a relative humidity of 50 ± 5 %). After complete digestion, the sample filters were analyzed using Inductively Coupled Plasma Mass Spectrometer (ICP-MS) for Al, Sb, Cd, Co, Cr, Cu, Ni, Pb, Zn, Ba, Sn, Sr, Fe, Mn, Hg, Mo, Tl, Ti, and V. The analysis also measured a blank and a spiked sample for quality control. Health risk assessment from concurrent exposure to metals in PM2.5 via multiple exposure routes (inhalation, ingestion and dermal contact), was performed to identify CR and HI based on U.S Environmental Protection Agency procedure. A CR between 10-6 and 10-4 indicates an acceptable or tolerable risk, while a low risk was associated with a CR <10-6, and an HI > 1 suggests a possible cancer risk. The study included the residents (mothers and 3-month newborns) of the buildings where PM2.5 samples were collected. Anthropometric data (e.g. body weight) and exposure parameters (e.g. exposure duration) of study participants were obtained via questionnaire and clinical records. Statistical analyses with a deterministic approach are performed using Statistical Package for Social Sciences (SPSS Inc, Chicago, Illinois) Version 26 and Microsoft Excel 2013. The corresponding information would fill existing knowledge gaps by identifying the most relevant metals to human health so that informed health-promoting actions can be delineated and applied.