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Introduction: Long-term contamination of tap water and groundwater by perfluoroalkyl and polyfluoroalkyl substances (PFASs) has been documented in the Veneto region of northern Italy. This study aimed to assess the exposure of individuals residing in the contaminated area and to test several toxicokinetic (TK) models of varying complexities to identify an efficient method for predicting perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) concentrations in human serum using observed data.The ultimate goal is to provide public health officials with guidance on selecting the appropriate TK model for specific contexts, a reliable and rapid tool to support human bio-monitoring (HBM) studies. Methods: Two simpler empirical TK models and a more complex multi-compartment physiologically based toxicokinetic (PBTK) model were compared with individual and aggregate data from an HBM study. In addition, the PBPK model was modified by adjusting input parameters and introducing new terms into the equations within the original model code. These modifications aimed to optimize the results compared to the original model, with some versions incorporating adjustments to account for the influence of menstruation in women. All models were evaluated to understand their strengths and weaknesses, providing guidance on the appropriate model to use according to specific scenarios. Results: The results obtained from the tested models were quite similar, with significant improvements observed only in the modified models. Simpler models also provided satisfactory results in scenarios involving low PFOS serum concentrations and recent exposure cessation. In many cases, predictions demonstrated high accuracy, particularly at the aggregate level and for women. Conclusions: These findings suggest that environmental protection agencies and health authorities may benefit from employing the tested models at the aggregate level as an initial step in HBM studies, rather than conducting more invasive and expensive screening campaigns.
RESUMO
PURPOSE: The authors sought to assess the role of arbitration by a third reader of discordant double readings to reduce the rate of recalls to diagnostic assessment. MATERIALS AND METHODS: A consecutive series of 7,660 double readings of screening examinations were considered. Discordant recalls were arbitrated by an expert reader (negative/positive). Diagnostic assessment was performed irrespective of arbitration results, and its outcome was used as reference standard for the study purpose. Assuming that negative arbitration would deny recall, its impact was assessed in terms of reduced recall rate and reduced cancer detection rate. Cost analysis of introducing arbitration was performed according to these results. RESULTS: Recalls at double reading were 528 (6.8%), of which 230 (43.5%) were concordant and 298 (56.5%) were discordant. The latter underwent arbitration, which was negative in 216 (72.4%) and positive in 82 (27.6%) cases, respectively. Overall, 49 cancers were detected (6.39 screened, 9.2% recalled): 43 cancers were detected among concordant (5.6 screened, 18.6% concordant) and six among discordant recalls (0.7 screened, 2.0% discordant). Six cancers were observed among arbitrated cases: five (6%) in positive and one (4.6 ) in negative arbitrations. Negative arbitration would have spared 216 assessment procedures (2.8% absolute, 40.9% relative reduction of recall rate) while missing one cancer case (0.13 absolute, 2.0% relative reduction of cancer detection rate). Arbitration cost was 74 euro, whereas 216 spared assessment procedures would have cost 14,558.4-23,346 euro. CONCLUSIONS: Arbitration is a cost-effective procedure that could be employed as a first measure to counterbalance excess recall rate observed in a double-reading scenario.
