Some types of per- and poly-fluoroalkyl substances (PFAS) have been banned over the last two decades, but millions of Americans continue to have exposure to the compounds through drinking water and consumer products. Therefore, understanding the changes in serum PFAS concentrations after their limited use is necessary to protect public health. In this study, we evaluated trends of serum PFAS compounds (PFOS, PFOA, PFHxS, PFDA, and PFNA) to determine their distribution among the United States general population. We analyzed serum concentrations of PFAS measured from random subsamples of the National Health and Nutrition Examination Survey (NHANES) participants. The study results demonstrated that demographic factors such as race/ethnicity, age, and sex may influence the levels of serum PFAS over time. Adults, males, Asians, Non-Hispanic Blacks, and Non-Hispanic Whites had high risks of exposure to the selected PFAS. Overall, serum PFAS levels declined continuously in the studied population from 1999 to 2018. Among the studied population, PFOS and PFDA were the most and least prevalent PFAS in blood serum, respectively. Serum levels of PFDA, PFOA, and PFHxS showed upward trends in at least one racial/ethnic group after 2016, which underscores the need for continuous biomonitoring of PFAS levels in humans and the environment.

Human health is threatened by antibiotic-resistant bacteria and their related infections, which cause thousands of human deaths every year worldwide. Surface waters are vulnerable to human activities and natural processes that facilitate the emergence and spread of antibiotic-resistant bacteria in the environment. This study evaluated the pathways and drivers of antimicrobial resistance (AR) in surface waters. We analyzed antibiotic resistance healthcare-associated infection (HAI) data reported to the CDC’s National Healthcare Safety Network to determine the number of antimicrobial-resistant pathogens and their isolates detected in healthcare facilities. Ten pathogens and their isolates associated with HAIs tested resistant to the selected antibiotics, indicating the role of healthcare facilities in antimicrobial resistance in the environment. The analyzed data and literature research revealed that healthcare facilities, wastewater, agricultural settings, food, and wildlife populations serve as the major vehicles for AR in surface waters. Antibiotic residues, heavy metals, natural processes, and climate change were identified as the drivers of antimicrobial resistance in the aquatic environment. Food and animal handlers have a higher risk of exposure to resistant pathogens through ingestion and direct contact compared with the general population. The AR threat to public health may grow as pathogens in aquatic systems adjust to antibiotic residues, contaminants, and climate change effects. The unnecessary use of antibiotics increases the risk of AR, and the public should be encouraged to practice antibiotic stewardship to decrease the risk.

The designated uses of lakes connect individuals to the natural environment, but some can expose recreational users to pathogens associated with fecal contamination that cause waterborne illnesses. Routine monitoring of fecal indicators in surface waters helps identify and track sources of fecal contamination to protect public health. We examined fecal indicators (Escherichia coli and enterococci) and factors influencing recreational freshwater quality. We collected and analyzed water samples from an urban lake for 12 months to assess water quality. Fecal indicators were detected and enumerated using IDEXX method. E. coli and enterococci were detected in nearly 100 % of all water samples, but their concentrations varied significantly among seasons and land uses. We observed high levels of E. coli and enterococci during the warmer months. The geometric means of E. coli (28.5 MPN/100 mL) and enterococci (39.3 MPN/100 mL) were below and above the recreational water quality standards, respectively. The concentrations of E. coli (7 %) and enterococci (22 %) exceeded the recommended single-sample maximum levels. Sites near urban and forested areas recorded the highest and lowest fecal indicators, respectively. Water temperature, precipitation, salinity, resistivity, DO, and hardness were significant predictors of fecal indicators. The concentrations of fecal indicators were elevated at certain times of the year, indicating the potential presence of pathogens. Overall, the measured water quality parameters of the lake were within normal ranges. This study suggests that effective lake management should focus on the warmer months and runoff from urban and open space/agricultural areas to control nonpoint source pollution.