The Accumulation of Heavy Metals in Shower System Biofilms: Implications for Emissions and Indoor Human Exposure

Biofilms play a crucial role in absorbing various metals from water, including copper, lead, iron, chromium, nickel, zinc, cadmium, and barium. While their presence was revealed in shower system biofilms, the factors affecting metal accumulation in shower system biofilms were poorly explored. This study aimed to investigate the capacity of shower hose biofilms to accumulate heavy metals, in particular in biofilms growing in energy-efficient showerhead systems, and evaluate the potential emission in water and aerosols of metal pollutants during showering. The adsorption efficiency of various metals in biofilms was assessed by ICP/MS and revealed that biofilms accumulate metals as they age and as biofilm biomass increases, indicating a potential influence of heavy metals on biofilm ecology. Furthermore, the study examined the emission of heavy metals during showering and found that it was sporadic and limited primarily to copper and zinc. These findings raise concerns regarding the role of biofilms in both retaining and releasing metal contaminants in water distribution systems, as well as the associated risk of inhalation during showering. By shedding light on the accumulation dynamics of heavy metals in shower hose biofilms and their potential emission patterns, this research highlights the need for further investigation into the impact of biofilms on water quality and human exposure to metal pollutants. The findings underscore the importance of considering biofilm-related processes when addressing the overall management of heavy metal contamination in shower systems and its potential implications for public health.