Assessing Age-Specific Variability in Microplastic Intake Through Seafood Consumption: A Case Study in Central Java, Indonesia

Microplastics (MPs) are frequently detected in seafood. However, the extent to which seafood consumption contributes to MP intake remains uncertain. Previous studies on MP intake in humans did not consider interindividual variability in exposure. The present study aimed to identify which types of seafood contribute most to the long-term average MP intake of residents of Semarang city in Indonesia, and to determine which groups have the highest exposure level. We utilized published data on MP concentrations in locally caught seafood, where MPs were quantified by microscopy and polymer types were confirmed by μ-FTIR under strict analytical quality assurance measures. These data were then combined with seafood consumption data from questionnaires and 24 h dietary recalls in 982 respondents of various age groups. Estimates of microplastic intake were derived using a Monte Carlo simulation (10,000 iterations), with species-specific mean microplastic concentrations as fixed inputs and seafood consumption sampled from a lognormal distribution. Parameter importance was explored through a sensitivity analysis. Bivalves significantly contribute to MP intake, especially for adolescents (31%) and adults (26.4%). Crabs are the main contributor for toddlers (49.4%) and the elderly (32.7%). Shrimps also contribute substantially to children's MP intake (30.6%). Adolescents are the most exposed age group, with daily intakes at the 99.5th percentile reaching up to 427 particles per person. In contrast, children and toddlers, although consuming smaller per-person amounts, showed the highest intake of MPs per kilogram bodyweight (MP·kg -1·bw·y -1), that is, 1.9 and 1.6 times higher than adults, respectively. Hence, children and toddlers are the most vulnerable groups in terms of exposure.