Nature, depositional dynamics, sources, and health risk assessment of indoor microplastics in three cities of Punjab, Pakistan

Microplastics (MPs) are ubiquitous environmental particulates, found in all environmental compartments especially the indoor environment, which have been linked to various toxicological effects i.e., respiratory inflammation, endocrine disruption, oxidative stress, and increasing other health risks and diseases in humans. The current study aimed to investigate the depositional dynamics, abundance, and sources of MPs in differing indoor microenvironments. For this purpose, the floor dust from residential areas of three cities (Lahore, Faisalabad, and Vehari) were collected using a handheld vacuum cleaner and were analyzed through standard microplastic determination methods. The results show that Faisalabad (15,425.2 ± 5969.4 MPs/m²) has the highest abundance of MPs followed by Lahore (14,471.2 ± 7690.3 MPs/m²⁾, and Vehari (7140.3 ± 3880.4 MPs/m²). Among the identified MPs, > 98% were fibres, while their size was 100–1570 µm. Compositional analysis revealed that particles with a natural composition such as cellulose were dominant. Among polymers, i.e., polyethylene terephthalates were the most abundant polymer type followed by polyisobutylene, polybutylene-terephthalate, polyacrylamide, polyurethane, polypropylene, and polyamide. The polymeric materials employed in indoor environments greatly influenced the microplastic abundance and composition, and these can easily be taken in by children and other household persons. The estimated daily intake via ingestion revealed that compared to other age groups, infants are more exposed to indoor microplastics than adults. Human activities in an indoor environment lead to the resuspension of particles which may drive further oral exposure and health risks.