Multiple Hypothesis Testing with Non-detections using PFAS Environmental Samples and Questionnaires
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Per-and polyfluoroalkyl substances (PFAS) are a group of harmful manufactured chemicals commonly found in aqueous film-forming foams and consumer goods. ATSDR and EPA performed environmental sampling for PFAS in non-drinking water media and administered questionnaires at two sites — Westfield, Massachusetts and New Castle, Delaware. This analysis used questionnaire data to investigate household activities linked to exposure to PFHxS, PFOS, PFOA, PFNA, PFDA, PFUnA, and MeFOSAA.
We joined and evaluated biological and environmental sampling to questionnaire data using multiple two-sided hypothesis testing. The questionnaire data needed sufficient participant responses and appropriate detections for each question response to be considered for analysis. The Benjamini-Hochberg method for false discovery rate was applied to account for multiple hypothesis testing. We created boxplots to investigate the directionality of the correlation between the significant relationships and PFAS species.
We found that certain household characteristics or activities were correlated with the level of specific PFAS species in sampled media. Correlations were found in the presence of living room carpeting with settled dust for PFHxS and MeFOSAA and home vacuum dust levels for MeFOSAA.