Children and adults are exposed to dual risks from ingestion of water and inhalation of ultrasonic humidifier particles from Pb-containing water

• Published in: The Science of the total environment 2021-10, Vol.791, p.148248-148248, Article 148248
• Main Authors: Yao, Wenchuo, Gallagher, Daniel L., Gohlke, Julia M., Dietrich, Andrea M.
• Format: Article
• Language: English
• Subjects: Air-water interface; Blood-lead-levels; Indoor air; Particles; Respiratory tract; Water quality
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.148248

Room-sized ultrasonic humidifiers are exposure pathways to aerosolized metals, with dose positively associated with increased concentrations of metals in fill water. This study innovatively quantifies water ingestion along with inhalation doses from humidifiers for 10–1000 μg/L dissolved lead (Pb) in tap water. The subsequent indoor air Pb concentrations, average daily doses, and inhalation deposited respiratory fractions were predicted under four room scenarios for 3-mo, 12-mo, 28-mo, and 6-yr children and adults. Elevated blood Pb levels (BLLs) in children were modeled using USEPA's Integrated Exposure Uptake Biokinetic (IEUBK) model. Indoor air Pb exceeds the USEPA ambient air standard of 0.15 μg/m3 when humidifier fill water contains 33 μg/L Pb in the small room of 33.5 m3 and 0.2 h−1 air exchange rate (AER). For this room, ~40–46% inhaled Pb-containing humidifier particles deposit in children's respiratory tracts; inhaling humidifier particles from ≥500 μg/L Pb water results in >1 μg/dL BLL in 2–7 yr children. For adults, ~23% of particles deposit in the respiratory tract; 8-h inhalation exposure with ≥17 μg/L Pb water exceeds the California EPA reproductive toxicity guideline of 0.5 μg/day. Larger rooms and higher AER decrease Pb inhalation exposure under the same water Pb concentration. [Display omitted] •Predict air μg/m3 Pb from μg/L Pb in water used to fill an ultrasonic humidifier.•Resulting indoor air Pb can exceed USEPA ambient air standard of 0.15 μg/m3 Pb.•Emitted respirable particles have greater deposition fraction in child than adult.•>17 μg/L Pb can cause reproductive toxicity in adults by inhalation or ingestion.•>340 μg/L Pb can cause elevated blood Pb levels in children by inhalation.